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June 27, 2017

https://www.sciencedaily.com/releases/2017/06/170627134524.htm

Ozone recovery may be delayed by unregulated chemicals

Recent increases in an unregulated ozone-depleting substance, could delay recovery of Antarctic ozone levels by 5-30 years, depending on emissions scenarios.

The findings, published in Long-lived chlorine species, such as chlorofluorocarbons (CFCs), led to depletion of the stratospheric ozone layer in the 1980s, most drastically seen in the Antarctic.After introduction of the UN Montreal protocol in 1987, which regulated emissions of ozone-depleting substances, stratospheric ozone began to recover and is projected to return to pre-1980 levels in the second-half of this century.The Antarctic 'ozone hole' is expected to fully recover sometime between 2046 and 2057.However, atmospheric concentrations of dichloromethane -- a short-lived, ozone-depleting substance not regulated by the Montreal Protocol -- have risen in recent years and could be contributing to ozone loss.Study lead author Dr Ryan Hossaini, from the Lancaster Environment Centre at Lancaster University, said: "Dichloromethane is a human-made ozone-depleting chemical that has a range of industrial applications. Unlike CFCs and similar long-lived gases that are responsible for most ozone depletion, dichloromethane has a short atmospheric lifetime so has not been controlled by the Montreal Protocol. Despite this, increased production has led to a rapid increase in its atmospheric concentration over the past decade."While ozone depletion from dichloromethane is currently quite modest, it is uncertain how the amount of this gas in the atmosphere will change in the future. Our results show that continued sustained growth in its concentration could substantially delay recovery of the ozone layer, offsetting some of the future benefits of the Montreal Protocol."Dr Ryan Hossaini of Lancaster University and colleagues use simulations with a global chemical transport model to examine the sensitivity of future stratospheric chlorine and ozone levels to sustained dichloromethane growth. Measurements of dichloromethane in the atmosphere over the past two decades, provided by scientists from the National Oceanic and Atmospheric Administration (NOAA) in the United States, were also analysed.Study co-author Dr Stephen Montzka from the NOAA added: "The increases observed for dichloromethane from our measurements are striking and unexpected; concentrations had been decreasing slowly in the late 1990s, but since the early 2000s have increased by about a factor of two at sites throughout the globe.""It is uncertain what is driving this growth. However, it could be related to increased use of this chemical as a solvent in place of other long-lived chemicals (e.g. CFCs and HCFCs) that have been phased out, or from use as feedstock in the production of other chemicals."Their projections show that continued dichloromethane increases at the average trend observed from 2004-2014 would delay ozone recovery over Antarctica by 30 years. If dichloromethane concentrations stay at current levels, the delay in recovery would be only 5 years. Although the future trajectory of dichloromethane is uncertain, without any regulations on emissions, it is likely concentrations will fall somewhere in between the ranges presented here.Study co-author Professor Martyn Chipperfield, from the University of Leeds' School of Earth and Environment, said: "We need to continue monitoring the atmospheric abundance of this gas and determine its sources. At present, the long-term recovery of the Ozone Layer from the effects of CFCs is still on track, but the presence of increasing dichloromethane will add some uncertainty to our future predictions of ozone and climate."The ozone layer shields Earth's surface from certain wavelengths of harmful solar ultraviolet (UV) radiation that would otherwise be detrimental to human, animal and plant health. Ozone also absorbs terrestrial infrared (IR) radiation and changes in its abundance can influence climate.On the broader implications of the findings and outlook, Dr Hossaini said: "Ozone is an important climate gas and changes to its abundance, including due to the increasing influence of dichloromethane, could be relevant for refining future climate predictions."We should be mindful to the growing threat to stratospheric ozone posed by dichloromethane and similar chemicals not controlled by the Montreal Protocol. There is work to be done to better understand and quantify their main sources to the atmosphere."

Ozone Holes

June 23, 2017

https://www.sciencedaily.com/releases/2017/06/170623155511.htm

Genes, ozone, and autism

A new analysis shows that individuals with high levels of genetic variation and elevated exposure to ozone in the environment are at an even higher risk for developing autism than would be expected by adding the two risk factors together. The study is the first to look at the combined effects of genome-wide genetic change and environmental risk factors for autism, and the first to identify an interaction between genes and environment that leads to an emergent increase in risk that would not be found by studying these factors independently. A paper describing the research appears online in the journal

"Autism, like most human diseases, is complex," said Scott B. Selleck, professor of biochemistry and molecular biology at Penn State and one of the leaders of the research team. "There are probably hundreds, if not thousands, of genes involved and up until now -- with very few exceptions -- these have been studied independently of the environmental contributors to autism, which are real. Our team of researchers represents a merger of people with genetic expertise and environmental epidemiologists, allowing us for the first time to answer questions about how genetic and environmental risk factors for autism interact."The team looked at copy-number variation -- deletions and duplications of repeated elements in the genome that lead to variation among individuals in the number of repeated elements -- as a general measure of genetic variation and five types of air pollution -- traffic-related air pollution, nitrogen oxides, two sizes of particulate matter, and ozone -- in a large set of individuals with autism and a well-matched set of typically developing controls. The study participants -- obtained through the Childhood Autism Risks from Genetics and Environment (CHARGE) Study, a population-based case-control study led by Irva Hertz-Picciotto, professor of epidemiology and chief of the Division of Environmental and Occupational Health at University of California Davis, and one of the leaders of the research team -- includes cases and controls matched for age, sex, and geographic location. Each of 158 cases and 147 controls were genetically scored for genetic deletions, duplications, and total changes in copy number. Environmental exposures for each participant were determined based on residential histories using data from the U.S. Environmental Protection Agency (EPA) Air Quality System."This study used unique resources," said Hertz-Picciotto. "By mapping the homes of the mothers during their pregnancies, we were able to estimate their levels of exposure to several types of air pollutants that are monitored by the U.S. EPA. This allowed us to examine differences between cases of autism and typically developing controls in both their prenatal pollutant exposure and their total load of extra or deleted genetic material."Evaluation of each of the risk factors showed that duplications, total copy-number variation, and particulate matter in the environment had the largest individual impact on risk for autism. However, when the researchers evaluated interactions among the various risk factors they saw a large effect of ozone among children with either duplications or total copy-number variation. Ozone on its own had very little effect on risk for autism, such that in studies that did not take interactions among risk factors into consideration, it may have been ignored. Interactions among the various other factors, even those with large individual effects, appeared to have very little effect on risk."This study showed the effect of a pollutant not previously associated with autism risk. This study may be one example of how taking genomic variation into account can help us identify new risk factors for autism," said Heather Volk, assistant professor in the Department of Mental Health at the Johns Hopkins Bloomberg School of Public Health."If we just look at the raw numbers, before any statistical assessment, we see a ten-fold increase in the risk of autism for individuals in the top 25 percent for level of genetic variation and in the top 25 percent for exposure to ozone as compared to the individuals in the bottom 25 percent for each of these measures," said Selleck. "This increase in risk is striking, but given what we know about the complexity of diseases like autism, perhaps not surprising. It demonstrates how important it is to consider different types of risk factors for disease together, even those with small individual effects."The researchers speculate that the large effect of the interaction between ozone exposure and copy-number variation could be the result of the fact that ozone is an oxidizing agent, and is known to produce reactive oxygen species, like peroxides, that cause cellular stress and can alter cell function in many ways. High levels of copy-number variation may indicate a compromised state that is primed for the type of damage that ozone can cause.

Ozone Holes

June 19, 2017

https://www.sciencedaily.com/releases/2017/06/170619092749.htm

California named state with the worst air quality (again)

​​​​​​​The quality of the air in California may be improving, but it's still dire.

That's according to the American Lung Association's recent "State of the Air 2017" report, which labeled the state and region a leader in air pollution, with the highest ozone levels.The annual study ranks the cleanest and most polluted areas in the country by grading counties in the U.S. based on harmful recorded levels of ozone (smog) and particle pollution. The 2017 report used data collected from 2013 to 2015.The top three regions in the country with the worst smog levels were Los Angeles-Long Beach; Bakersfield; and Fresno-Madera; Salinas, though, was recognized as one of the cleanest cities in the state and the country."The Los Angeles basin is exposed to the highest ozone levels in the country," explains Steve LaDochy, Ph.D., professor of geography and urban analysis at California State University, Los Angeles, an expert in air pollution and climate. "It The air quality in the state was significantly better in northern California, found the report. Nonetheless, more than 90 percent of Californians still live in counties with unhealthy air.The Price of a Growing Population​​Dr. LaDochy says implementing eco-friendly air regulations are key to lowering pollution levels and that the rise in electric vehicle (EV) use and renewable energy sources have helped to improve air quality.That said, he stresses that efforts to reduce pollution shouldn't slow because some progress has been made. "There are a lot of people still living in unhealthy areas and there is still a need for improvement," says LaDochy, who has conducted studies of L.A.'s air quality and climate, many with the help of student researchers at Cal State LA.The federal Clean Air Act, passed in 1970, first addressed the emissions of hazardous air pollution and researchers have long linked poor air quality to asthma, chronic obstructive pulmonary disease (COPD), lung cancer, and premature death.LaDochy suspects that California's continuously growing population is largely to blame for the state's failing grades on "State of the Air" reports and more residents is also behind the Central Valley's recent drop in air quality, according to the report."Population in [the Central Valley] has really bloomed; it's nearly doubled," he says. "The coast is so expensive, so more and more people are moving to central California." The rise and growth of agriculture in the area has also led to a boom in population.According to the U.S. Census Bureau, California's population rose from 15.8 million in 1960 to 39.2 million in 2016.While the state has some of the strictest environmental regulations in the U.S., keeping regulations in full effect is a challenge given the increase in residents, LaDochy adds.What is Ozone?California, and more specifically the Los Angeles region, is especially susceptible to high ozone levels. Says LaDochy, "Our geography and our climate are two very big factors."Ozone, a highly reactive gas, is produced when the sun's rays split oxygen molecules. "It is a byproduct of our sunny weather and so many cars on the road," he explains. "So when the ozone levels go up, it is basically because there are a lot of cars and sunlight present."Ho​​t days are especially bad for smog. "The higher the temperature, the worse the ozone levels," he continues. "So if our city keeps getting hotter, that is going to cause higher levels of ozone."LaDochy believes that recent proposed federal cuts to environmental programs will have a direct impact on the state's air quality. "One thing we can do is cool down these cities, and Los Angeles is trying to do different things to do that," says the air pollution expert, citing the city's efforts in planting trees and implementing cool roofs."We can take a lot out of the ​["State of the Air"] report," he says. "It is telling us that yes, we are improving, but there is still a lot to do. We need to be more sustainable, we need to live less consumptive lives. Everyone needs to do their part, every little bit counts."To help reduce pollution, the American Lung Association suggests driving less (carpool, walk or bike when you can), switching to electric transportation, avoiding burning wood, and using less energy overall.

Ozone Holes

June 7, 2017

https://www.sciencedaily.com/releases/2017/06/170607123835.htm

Climate change misconceptions common among teachers, study finds

Recent studies have shown that misconceptions about climate change and the scientific studies that have addressed climate change are pervasive among the U.S. public. Now, a new study by Benjamin Herman, assistant professor in the Department of Learning, Teaching and Curriculum in the University of Missouri College of Education, shows that many secondary school science teachers also possess several of these same misconceptions.

In the study, Herman surveyed 220 secondary science teachers in Florida and Puerto Rico to determine their knowledge about climate change science. The survey asked questions regarding things that do contribute to climate change, such as greenhouse gas emissions, and things that do not significantly contribute, such as the depletion of the ozone layer and the use of pesticides. The survey also asked whether controlled scientific experiments are required to validate climate change.While the majority of the surveyed teachers accurately responded that fossil fuel use, automobiles and industry emissions were major causes of climate change, they also exhibited notable climate change misconceptions. For instance, nearly all of the Puerto Rico teachers and more than 70 percent of Florida teachers believed incorrectly that ozone layer depletion and pesticide use were at least minor, yet significant, causes of climate change. Additionally, Herman says that nearly 50 percent of Florida teachers and nearly 70 percent of Puerto Rico teachers think that climate change science must be studied through controlled experiments to be valid.Herman says the teachers in his study exhibited climate change science misconceptions at a similar rate to average Americans. He says these results are understandable given that teachers are often overworked and not afforded professional development opportunities that would deepen their climate change science knowledge."Teachers want and need support to keep them abreast of scientific discoveries and developments and how scientists come to their well-established claims regarding climate change," Herman said. "Climate change science involves many different types of science methods stemming from disciplines, including physics, biology, atmospheric science and earth science. Science teachers also need professional development directed at assisting them in their efforts to accurately and effectively engage students on this important issue. Because of existing misconceptions and misinformation regarding climate change, science teachers have a crucial professional and ethical responsibility to accurately convey to their students how climate change is studied and why scientists believe the climate is changing."

Ozone Holes

June 5, 2017

https://www.sciencedaily.com/releases/2017/06/170605155935.htm

Increased risk of ozone loss over the United States in summer, evidence shows

A new study out of Harvard University reveals that the protective stratospheric ozone layer above the central United States is vulnerable to erosion during the summer months from ozone-depleting chemical reactions, exposing people, livestock and crops to the harmful effects of UV radiation.

Powerful storm systems common to the Great Plains inject water vapor that, with observed temperature variations, can trigger the same chemical reactions over the central United States that are the cause of ozone loss over the polar regions, according to a new paper published in the The paper, led by James G. Anderson, the Philip S. Weld Professor of Atmospheric Chemistry at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), found that stratospheric ozone concentrations over the United States in summer are vulnerable to both increases in water vapor and observed variations in temperature from storm systems over the Great Plains. Increased frequency and intensity of these storm systems, as well as longer-term decreases in stratospheric temperatures, are expected to accompany climate change.Using extensive aircraft observations in the Arctic stratosphere from the early 2000's, researchers established the chemical framework defining enhanced ozone loss rates with respect to temperature and water vapor. Then they employed recent NEXRAD weather radar observations to demonstrate that on average 4000 storms each summer penetrate into the stratosphere over the central United States, which is far more frequent than was previously thought.This combination of circumstances puts the stratosphere over states including Texas, Oklahoma, Kansas, Nebraska, Iowa, Missouri, the Dakotas and states that border the Great Plains, at risk for chemical reactions that deplete ozone during summer, potentially leading to higher levels of exposure to damaging UV light from the sun."These developments were not predicted previously and they represent an important change in the assessment of the risk of increasing UV radiation over the central US in summer," said Mario J. Molina of the University of California San Diego, the 1995 Nobel Prize winner in stratospheric chemistry, who was not involved in this research.Stratospheric ozone is one of the most delicate aspects of habitability on the planet. There is only marginally enough ozone in the stratosphere to provide protection from UV radiation for humans, animals and crops. Medical research specific to the United States has determined that a 1 percent decrease in the amount of ozone in the stratosphere corresponds to a 3 percent increase in the incidence of human skin cancer. There are now 3.5 million new cases of skin cancer each year reported in the US alone. Thus, for each 1 percent reduction in ozone, there would be an additional 100,000 new cases of skin cancer annually in the United States."Thunderstorms that hydrate the stratosphere can have significant local and regional impacts on Earth's radiation budget and climate," said Cameron R. Homeyer of the University of Oklahoma, a co-investigator on the paper. "This work demonstrates our increasing knowledge of such storms using ground-based and airborne observations and evaluates their potential for depleting stratospheric ozone now and in the future. The results strongly motivate the need for increased meteorological and chemical observations of such storms.""Every year, sharp losses of stratospheric ozone are recorded in polar regions, traceable to chlorine and bromine added to the atmosphere by industrial chlorofluorocarbons and halons," said Steven C. Wofsy, the Abbott Lawrence Rotch Professor of Atmospheric and Environmental Science at SEAS and co-author of the study. "The new paper shows that the same kind of chemistry could occur over the central United States, triggered by storm systems that introduce water, or the next volcanic eruption, or by increasing levels of atmospheric carbon dioxide. We don't yet know just how close we are to reaching that threshold."The scientific community has observed the chemical reactions that attack ozone over the polar regions in winter, but the important combination of observations that define the cause and the rate of stratospheric ozone loss have never been made over the central US in summer. This represents a major shortcoming in researchers' ability to forecast increases in UV radiation that might result from a volcanic event or climate change now and in the years to come."Rather than large continental-scale ozone loss that occurs over the polar regions in winter characterized, for example, by the term Antarctic ozone hole, circumstances over the central US in summer are very different," said Anderson. "In particular, because of the very frequent storm-induced injection events detailed by studies at Texas A&M and the University of Oklahoma using advanced radar methods, this structure of highly localized but numerous regions of potential ozone loss requires carefully specified observational strategies and systematic surveillance in order to provide the basis for accurate weekly forecasts of ozone loss."The researchers are calling for extensive characterization of the stratosphere over the central United States in order to forecast short-term and long-term ozone loss related to increasing frequency and intensity of storm systems, higher levels of atmospheric carbon dioxide and methane, and other factors.

Ozone Holes

June 1, 2017

https://www.sciencedaily.com/releases/2017/06/170601124132.htm

Pollution 'devastating' China's vital ecosystem, research shows

The startling extent to which human-made pollution is devastating China's vital ecosystem's ability to offset damaging carbon emissions has been revealed.

A pioneering new international study, led by the University of Exeter, has looked at the true impact air pollutants have in impeding the local vegetation's ability to absorb and store carbon from the atmosphere.The study looked at the combined effects that surface ozone and aerosol particles -- two of the primary atmospheric pollutants linked to public health and climate change -- have on China's plant communities' ability to act as a carbon sink.It found that ozone vegetation damage -- which weakens leaf photosynthesis by oxidizing plant cells -- far outweighs any positive impact aerosol particles may have in promoting carbon uptake by scattering sunlight and cooling temperatures.While the damage caused to these vital ecosystems in China is not irreversible, the team of experts has warned that only drastic action will offer protection against long-term global warming.The study is published in the journal Professor Nadine Unger, from the University of Exeter's Mathematics department and co-author of the paper said: "We know that China suffers from the highest levels of air pollution in the world, and the adverse effects this has on human health and climate change are well documented."What is less clearly understood, however, is the impact it has on the regional carbon balance. The land ecosystems in China are thought to provide a natural carbon sink, but we didn't know whether air pollution inhibited or promoted carbon uptake."What is clear from this study is that the negative ozone vegetation damage far outstrips any benefits that an increase in aerosol particles may have. It is a stark warning that action needs to be taken now to tackle the effects human-made pollution is having on this part of the world before it is too late."The team used state-of-the-art Earth System computer models, together with a vast array of existing measurement datasets, to assess the separate and combined effects of human-made ozone and aerosol pollution in Eastern China.The study found that the Net Primary Productivity (NPP) -- or the amount of carbon plants in an ecosystem can take in -- is significantly reduced when the amount of surface ozone increases.Crucially, this reduction is significantly greater than the effect aerosol particles have in encouraging plants to increase carbon intake through reducing canopy temperatures and increasing the scattering of light.Professor Unger added: "Essentially, our results reveal a strong 'dampening effect' of air pollution on the land carbon uptake in China today."This is significant for a number of reasons, not least because the increase in surface ozone produced by human-made pollution in the region will continue to grow over the next 15 years unless something is done."If -- and it is of course a big 'if' -- China reduce their pollution to the maximum levels, we could reduce the amount of damage to the ecosystems by up to 70 per cent -- offering protection of this critical ecosystem service and the mitigation of long-term global warming."

Ozone Holes

May 17, 2017

https://www.sciencedaily.com/releases/2017/05/170517132614.htm

Earth's atmosphere more chemically reactive in cold climates

Unseen in the air around us are tiny molecules that drive the chemical cocktail of our atmosphere. As plants, animals, volcanoes, wildfires and human activities spew particles into the atmosphere, some of these molecules act as cleanup crews that remove that pollution.

The main molecules responsible for breaking down all these emissions are called oxidants. The oxygen-containing molecules, mainly ozone and hydrogen-based detergents, react with pollutants and reactive greenhouse gases, such as methane.A University of Washington study published May 18 in the journal "Oxidants are very reactive, and they react with pollutants and greenhouse gases and clean up the atmosphere," said corresponding author Becky Alexander, a UW associate professor of atmospheric sciences. "We wanted to see how the ability of the atmosphere to clean itself might change with climate."First author Lei Geng, a former UW postdoctoral researcher now at Grenoble Alpes University, analyzed slices from a Greenland ice core in the UW's isotope chemistry lab. The 100,000-year core begins in a relatively warm period, covers a full ice age and ends in the present day, with several shorter temperature swings along the way. The researchers used a new method to get a first-ever read on changes in atmospheric oxidants -- volatile chemicals that are not directly preserved in ice cores.The researchers fed meltwater to bacteria that drank the liquid and then excreted a gas that can be measured by machines that track isotopic composition of gas. Looking at the weight of oxygen atoms from the meltwater let the team see how many had come from the two main oxidants: ozone, which varies in the atmosphere over time, versus the detergent molecules, which are expected to stay fairly constant."We found that the sign of the change was the complete opposite of what we expected," Alexander said. "And that indicates that what we thought were the main drivers for the abundance of oxidants were not actually the main controls, and we had to come up with some other mechanisms."Atmospheric scientists had believed that ozone levels rise as the temperature increases. Ozone is produced with water vapor and emissions from plants, soil bacteria and other living things. All of these go up as the temperature warms. So the authors expected to find more ozone in the warmer climates.Instead, the proportion of ozone actually increased in colder climates. When the temperature changes were small, ozone did increase with temperature, but for big temperature swings that relationship flipped, with more ozone in the cold periods.One hypothesis proposed by the authors is a change in the circulation between the troposphere, the air above our heads, and the stratosphere, the higher-elevation layer close to where most airplanes fly. Air circulates between these two, moving up in the tropics and dropping back down at the poles. The stratosphere contains more ozone that is largely formed at those elevations in the tropics, so if the circulation quickens, then more ozone from the stratosphere would get carried down to the surface."There is evidence -- strong evidence -- showing that the Brewer-Dobson circulation became stronger during the last glacial maximum," said co-author Qiang Fu, a UW professor of atmospheric sciences. "That means there was less stratospheric ozone in the tropics but more in the high latitudes, and then more ozone going down from the stratosphere to the troposphere."That's one explanation for why ozone would go up at the surface during cold climates. This shift in circulation would also cause more ultraviolet radiation to hit the tropics, and UV and water vapor are the main drivers for the formation of the other main group of oxidants, the detergents. The ice-age tropics could then become a rich source of detergents, which break down pollution and greenhouses gases like methane."Traditionally, ice-core methane records have been interpreted solely as a change in the source," Alexander said. "But land-surface models have not been able to simulate the full scale of the change of methane seen in ice cores. That suggests that maybe the lifetime of methane has changed, and the only way to do that is to change the amount of detergent in the atmosphere."A second possible explanation for the puzzling ozone trend, researchers said, is a less-understood group of oxidants: halogens. These molecules are poorly studied, and it's not fully known how they influence climate, but researchers suspect they could react to affect the levels of other oxidants."The largest source of halogens is from sea salt, and we know from ice cores that sea salt is much higher in colder climates," Alexander said. "Sea ice also changes with climate, of course."The authors suspect that both mechanisms -- the high-level circulation and chemical reactions with halogens -- could affect oxidants during big swings in Earth's temperature."The changes we measured in ozone levels seem to be quite large if you only consider one mechanism at a time, suggesting that they might be acting simultaneously, and not necessarily independently from one another," Alexander said.

Ozone Holes

May 17, 2017

https://www.sciencedaily.com/releases/2017/05/170517090555.htm

During heat waves, urban trees can increase ground-level ozone

Planting trees is a popular strategy to help make cities "greener," both literally and figuratively. But scientists have found a counterintuitive effect of urban vegetation: During heat waves, it can increase air pollution levels and the formation of ozone. Their study appears in ACS' journal

Previous research has shown that planting trees in cities can have multiple benefits, including storing carbon, controlling storm water and cooling areas off by providing shade. This has spurred efforts in cities across the U.S. and Europe to encourage the practice. However, it's also known that trees and other plants release volatile organic compounds, or VOCs, that can interact with other substances and contribute to air pollution. And when it's hot, plants release higher levels of VOCs. Galina Churkina and colleagues wanted to investigate what effects heat waves and urban vegetation might have on air pollution.The researchers compared computer models of air pollutant concentrations in the Berlin-Brandenburg metropolitan area in Germany in the summer of 2006, when there was a heat wave, and the summer of 2014, which had more typical seasonal temperatures. The simulation showed that during the summer of 2006, VOCs from urban greenery contributed to about 6 to 20 percent of the ozone formation, and that during the heat wave period, the contribution spiked to up to 60 percent. The researchers suggest that in addition to tree-planting campaigns, efforts to improve cities' environments should include other measures such as reducing vehicular traffic, a major source of nitrogen oxides that can react with VOCs and form ozone.

Ozone Holes

April 17, 2017

https://www.sciencedaily.com/releases/2017/04/170417182928.htm

Banned industrial solvent sheds new light on methane mystery

Since 2007, scientists have been searching to find the cause of a sudden and unexpected global rise in atmospheric methane, a potent greenhouse gas, following almost a decade in which concentrations had stayed relatively constant.  Recent studies have explored a range of possible causes. Suggestions have included a rise in oil and natural gas extraction, increased emissions from tropical wetlands or increases in emissions from growing East Asian economies.

However, a new paper by an international team of scientists in the Lead author, Dr Matt Rigby from the University of Bristol's School of Chemistry and Cabot Institute, said: "A change in the hydroxyl radical concentration would be a neat explanation for the changes in methane that we've seen."It would mean that emissions may not have increased suddenly in 2007, but rather, risen more gradually over the last couple of decades."Since the global concentration of the hydroxyl radical cannot be measured directly, the team's findings were made by studying the rate at which the solvent methyl chloroform, which is also destroyed by hydroxyl, was removed from the atmosphere.Professor Ron Prinn from the Massachusetts Institute of Technology, who co-authored the paper and leads the Advanced Global Atmospheric Gases Experiment (AGAGE), an international project that measures greenhouse gas concentrations, said: "We have been monitoring trends in the methyl chloroform for nearly 40 years because of its role in depleting stratospheric ozone."Because methyl chloroform is now banned under the Montreal Protocol for the Protection of the Stratospheric Ozone Layer, we've see its concentration drop very rapidly."We can examine how this rate of decline changes from one year to the next to infer the hydroxyl radical concentration."Dr Steve Montzka from the National Oceanic and Atmospheric Administration (NOAA), who also co-authored the paper, and operates an independent measurement network for methylchloroform, added: "This paper re-examines some of the assumptions that had previously been made in studies of hydroxyl radical and methyl chloroform and shows how they influence our understanding of methane's atmospheric sink."To me, one of the main findings is that our objective analyses of two sets of observations tells essentially the same story, even as it becomes more and more difficult to measure methyl chloroform given that its concentration is approaching zero."Dr Rigby added that there was still uncertainty remaining. He explained: "Whilst there are strong hints in our study that hydroxyl radical changes could be playing a significant role in the fluctuations in methane growth, our uncertainties are very large."In future, we need to think about new ways to reduce this uncertainty, if we are to truly understand changes in atmospheric methane."The study also lead to a more certain, but unexpected finding: that emissions of methyl chloroform had not dropped to zero.Dr Rigby said: "Because its production is now banned globally, we were expecting to see no emissions of this substance at all. However, we have very strong evidence that emissions are continuing."The team are preparing a follow-up study that would determine where these emissions are originating. Meanwhile, they are continuing to monitor methane in the atmosphere, and are waiting to see whether its current rate of increase will continue.

Ozone Holes

March 1, 2017

https://www.sciencedaily.com/releases/2017/03/170301162137.htm

Concurrent heat waves, air pollution exacerbate negative health effects of each

The combination of prolonged hot spells with poor air quality greatly compounds the negative effects of each and can pose a major risk to human health, according to new research from the University of California, Irvine.

"The weather factors that drive heat waves also contribute to intensified surface ozone and air pollution episodes," said UCI professor of Earth system science Michael J. Prather, co-author of the study, published this week in Heat waves cause widespread discomfort and can be deadly for vulnerable individuals, while surface ozone and air pollution are linked to premature death from heart disease, stroke and lung ailments.Prather's group made the findings after examining 15 years of surface observations (1999-2013) for the eastern United States and Canada. The researchers overlaid a grid of one-degree-square segments onto a map of the region and analyzed the recorded levels of surface ozone, amounts of fine particulate matter (pollution) and maximum temperatures between April and September for each roughly 69-by-69-mile section of the map. This allowed them to construct a climatological picture of the duration, coincidence and overlap of each of these factors.Meteorologically, slow-moving high-pressure systems accumulate pollutants and heat during the summer months. Scorching temperatures, low precipitation, strong sunlight and low wind speeds allow heat and poor-quality air to stagnate in a given location for an extended period of time."These conditions increase the emission of biogenic volatile organic compounds, which boost the production of surface ozone and other aerosols," said lead author Jordan Schnell, a postdoctoral researcher at UCI when the study was conducted who is now at Princeton University. "The droughtlike conditions that exist in heat waves reduce soil moisture, making near-surface temperatures hotter and inhibiting the role played by vegetation in absorbing ozone, resulting in lower air quality."Humans only make the problem worse by consuming more fossil fuel-generated energy to run air conditioners, the researchers noted."It's important to study the combined effects of pollution and prolonged heat events because we expect these conditions to become more prevalent in a warming climate," Prather said. "Our evidence suggests that pollution and heat waves are synergistic stressors that produce disproportionately greater adverse health impacts. Policymakers should be taking these issues into consideration going forward."

Ozone Holes

March 1, 2017

https://www.sciencedaily.com/releases/2017/03/170301084930.htm

Asian pollution, heat waves worsen US smog, study shows

An influx of pollution from Asia in the western United States and more frequent heat waves in the eastern U.S. are responsible for the persistence of smog in these regions over the past quarter century despite laws curtailing the emission of smog-forming chemicals from tailpipes and factories.

The study, led by researchers at Princeton University and the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Laboratory (GFDL), highlights the importance of maintaining domestic emission controls on motor vehicles, power plants and other industries at a time when pollution is increasingly global.Published March 1 in the journal Despite a 50 percent cut in smog-forming chemicals such as nitrogen oxides, commonly known as "NOx," over the past 25 years, ozone levels measured in rural areas of the west have actually climbed. And while ozone in the eastern U.S. has decreased overall, the levels can spike during heat waves.The study traced the increase of ozone in the west to the influx of pollution from Asian countries, including China, North and South Korea, Japan, India, and other South Asian countries. Collectively, the region has tripled its emissions of NOx since 1990. In the eastern U.S., meanwhile, heat waves -- which have become more frequent in the past few decades -- trap polluted air in place, leading to temporary escalations in locally produced ozone.The study explains why springtime ozone levels measured in Yellowstone National Park and other western parks far from urban areas have climbed over the past quarter century. According to the study, springtime ozone levels in the national parks rose during that period by 5 to 10 parts per billion (ppb), which is significant given that the federal ozone standard is 70 ppb.The influx of pollution from Asia could make it difficult for these areas to comply with the federal ozone standards, according to the study's authors. "Increasing background ozone from rising Asian emissions leaves less room for local production of ozone before the federal standard is violated," said lead author Meiyun Lin, a research scholar in the Program in Atmospheric and Oceanic Sciences at Princeton University and a scientist at GFDL.Lin's co-authors were Larry Horowitz, also of GFDL; Richard Payton and Gail Tonnesen of the U.S. Environmental Protection Agency; and Arlene Fiore of the Lamont-Doherty Earth-Observatory and Department of Earth and Environmental Sciences at Columbia University.Using ozone measurements combined with climate models developed at GFDL, the authors identified pollution from Asia as driving the climb in ozone in western U.S. national parks in the spring, when wind and weather patterns push Asian pollution across the Pacific Ocean. In the summer, when these weather patterns subside, ozone levels in national parks are still above what would be expected given U.S. reductions in ozone-precursors.While it has been known for over a decade that Asian pollution contributes to ozone levels in the United States, this study is one of the first to categorize the extent to which rising Asian emissions contribute to U.S. ozone, according to Lin.In the eastern United States, where Asian pollution is a minor contributor to smog, NOx emission controls have been successful at reducing ozone levels. However, periods of extreme heat and drought can trap pollution in the region, making bad ozone days worse. Regional NOx emission reductions alleviated the ozone buildup during the recent heat waves of 2011 and 2012, compared to earlier heat waves such as in 1988 and 1999. As heat waves appear to be on the rise due to global climate change, smog in the eastern U.S. is likely to worsen, according to the study.Climate models such as those developed at GFDL can help researchers predict future levels of smog, enabling cost-benefit analyses for costly pollution control measures. The researchers compared results from a model called GFDL-AM3 to ozone measurements from monitoring stations over the course of the last 35 years, from 1980 to 2014.Prior studies using global models poorly matched the ozone increases measured in western national parks. Lin and co-authors were able to match the measurements by narrowing their analysis to days when the airflow is predominantly from the Pacific Ocean.Modeling the sources of air pollution can help explain where the ozone measured in the national parks is coming from, explained Lin. "The model allows us to divide the observed air pollution into components driven by different sources," she said.The team also looked at other contributors to ground-level ozone, such as global methane from livestock and wildfires. Wildfire emissions contributed less than 10 percent and methane about 15 percent of the western U.S. ozone increase, whereas Asian air pollution contributed as much as 65 percent.These new findings suggest that a global perspective is necessary when designing a strategy to meet U.S. ozone air quality objectives, said Lin.The negative effect of imported pollution on the US's ability to achieve its air quality goals is not wholly unexpected, according to Owen Cooper, a senior research scientist at the University of Colorado and the NOAA Earth System Research Laboratory, who is familiar with the current study but not directly involved. "Twenty years ago, scientists first speculated that rising Asian emissions would one day offset some of the United States' domestic ozone reductions," Cooper said. "This study takes advantage of more than 25 years of observations and detailed model hindcasts to comprehensively demonstrate that these early predictions were right."

Ozone Holes

February 15, 2017

https://www.sciencedaily.com/releases/2017/02/170215101438.htm

'The blob' of abnormal conditions boosted Western US ozone levels

An unusually warm patch of seawater off the West Coast in late 2014 and 2015, nicknamed "the blob," had cascading effects up and down the coast. Its sphere of influence was centered on the marine environment but extended to weather on land.

A University of Washington Bothell study now shows that this strong offshore pattern also influenced air quality. The climate pattern increased ozone levels above Washington, Oregon, western Utah and northern California, according to a study published Feb. 15 in "Washington and Oregon was really the bullseye for the whole thing, because of the location of the winds," said lead author Dan Jaffe, a professor of atmospheric sciences at the University of Washington Bothell. "Salt Lake City and Sacramento were on the edge of this event, but because their ozone is typically higher, those cities felt some of the more acute effects."The other author is Lei Zhang, a postdoctoral researcher at UW Bothell.The study finds that terrestrial effects of "the blob" -- warm temperatures, low cloud cover and calmer air -- were the perfect ingredients to produce ozone. Ozone levels in June 2015 were between 3 and 13 parts per billion higher than average over the northwestern United States. The pattern pushed concentrations in Salt Lake City and Sacramento above federally allowed limits.Ozone is an invisible component of smog that is a secondary pollutant formed by a chain reaction. Cars, factories and other sources emit pollution into the atmosphere. Solar rays then provide the spark for chemical reactions that produce the three linked oxygen atoms of ozone. This molecule is hazardous to human health and is subject to federal regulations.Jaffe's research group has been measuring ozone since 2004 atop Mount Bachelor in central Oregon to tease apart the sources of ozone and other pollutants, such as forest fires, transport of pollution from overseas and domestic pollution from the United States. In June 2015, members noticed a spike in ozone above any previous measurements."At first we were like 'Whoa, maybe we made a mistake.' We looked at our sensors to see if we made an error in the calibration. But we couldn't find any mistakes," Jaffe said. "Then I looked at other ozone data from around the Pacific Northwest, and everybody was high that year."Jaffe's measurements are from the University of Washington's Mount Bachelor Observatory in central Oregon. Members of his group use the ski hill's lifts for transportation and electrical power to support year-round measurements at the 9,000-foot peak. Air is pulled with vacuum pumps into a room to be sampled by a variety of instruments in the summit's lift house.The June 2015 ozone levels at the observatory were 12 parts per billion higher than the average of previous observations for that time. Jaffe learned that air quality managers in Sacramento and Salt Lake City had several times recorded eight-hour averages above the 70 parts per billion limit set by the federal Environmental Protection Agency."This was a very widespread phenomenon going all the way to California," Jaffe said. "Managers saw that air quality was violating the air quality standards on many days, and they didn't know why."The new study analyzes larger-scale climate data to show that the areas that recorded higher-than-normal ozone were the same regions that had high temperatures, weak winds and low cloud cover."Ultimately, it all links back to the blob, which was the most unusual meteorological event we've had in decades," Jaffe said. "Temperatures were high, and it was much less cloudy than normal, both of which trigger ozone production. And because of that high-pressure system off the coast, the winds were much lower than normal. Winds blow pollution away, but when they don't blow, you get stagnation and the pollution is higher."The paper also finds an effect from higher biogenic emissions, the scented emissions from trees and plants that contain natural ozone-producing particles.The study focuses on June 2015 because the wildfire season began in July and dominated conditions in the later summer. Jaffe's group is exploring that effect in a separate project.While it is generally understood that warmer temperatures will favor ozone production, Jaffe said, this study suggests that broader-scale climate patterns also play a role in air quality and human health."Our environmental laws need to be written with an understanding that there's a lot of variability from one year to the next, and with an understanding of the long-term path of where we're heading under climate change," Jaffe said. "This work helps us understand the link between climate variability and air quality, and it can give us an idea of what to expect as our planet continues to warm."

Ozone Holes

February 13, 2017

https://www.sciencedaily.com/releases/2017/02/170213091014.htm

Improvements in short-term forecasting of air pollution levels

The research project carried out by a researcher at UPM has successfully predicted the daily maximum ozone threshold exceedances in the Hong Kong area. The results show that an accurate and prompt prediction of tropospheric ozone concentrations is of great importance to the management of the public pollution warning system.

In recent years the air pollution has caught the public attention since it can cause health problems. The United States Environmental Protection Agency (EPA), the European Union and other countries have established different thresholds for both warning and risk to vegetation or human health taking into account the pollutant and the context.The goal of governments is to guarantee that these thresholds do not exceed the limits, but when this occurs, the prediction of the evolution of values in the following hours becomes an essential element, at least for the corrective measures.The problem arises because computational models have severe limitations in terms of accuracy as they are sensitive to the boundary conditions at certain points thus uncertainty grows rapidly. Besides, the techniques based on regression models often undervalue the pollutant peaks since they tend to minimize the errors made in the dataset. Precisely these peak values are indeed the most interesting to predict since their values will usually mark the measures to be adopted in each case.In order to face this difficulty of predicting the highest values, a researcher from Projects & Quality group from Universidad Politécnica de Madrid has developed a methodology that combines the pre-processing of the datasets to learn the behavior of physical phenomena with regression and artificial intelligence techniques, using a voting technique among different models to improve predictive capacity. Bing Gong, the main author of the study says "the obtained data have good properties of sensitivity and stability and the results improve the traditional techniques between 30% and 80%."This study was carried out in Hong Kong, however other members of the research group are conducting similar projects in other cities such as Marrakech or Mexico.In addition, the team of researchers is currently working on the estimation of human exposure to pollutants, based on the immission values and the geographical location of the person. Joaquín Ordieres, the leader of the research group, says "we aim to add additional elements such as the consideration of the quality of home or office air." It is understood the adding of these elements is the next logical step in order to provide people and health systems with more conclusive evidences of exposure than the registered generic immission values."

Ozone Holes

January 18, 2017

https://www.sciencedaily.com/releases/2017/01/170118163725.htm

Researchers discover greenhouse bypass for nitrogen

Those concerned with water quality are familiar with nitrogen as a major pollutant whose excess runoff into coastal waters can lead to algal blooms and low-oxygen dead zones. Perhaps less familiar is the significant role that a form of nitrogen gas plays in greenhouse warming and the destruction of Earth's ozone layer.

Now, an international group of scientists including Dr. B.K. Song of William & Mary's Virginia Institute of Marine Science have discovered that production of this potent greenhouse gas -- known as N2O or nitrous oxide -- can be bypassed as complex nitrogen compounds in soil, water, and fertilizers break down into the unreactive nitrogen gas (N2) that makes up most of our atmosphere.Their discovery, published in a recent edition of Agriculture contributes more nitrous oxide to the atmosphere than any other human activity -- primarily through nitrogen fertilization. This greenhouse gas is 300 times more effective at trapping heat than carbon dioxide and 10 times more effective than methane. Nitrous oxide also moves into the stratosphere and destroys ozone.Current wisdom holds that nitrous oxide is inevitably produced when soil nitrogen -- including fertilizer components such as ammonia, ammonium, and urea -- breaks down. It's also thought this breakdown process requires the action of microbes, and can only occur in the absence of oxygen.The current research contradicts each of these long-held ideas."Our findings question the assumption that nitrous oxide is an intermediate required for formation of nitrogen gas [N2]," says Phillips. "They also throw doubt on whether microbial production of nitrous oxide must take place in the absence of oxygen.""We now have a pathway that doesn't require microbes," adds Song. "The process of denitrification can happen abiotically, without the need for bacteria or fungi."The team's discovery could lead to practical applications for decreasing the impacts of excess nitrogen in the environment, a topic they focused on while presenting their findings during a recent meeting in Washington D.C. sponsored by the U.S. Department of Agriculture and the National Integrated Water Quality Program."It might give us a way to engineer the system to reduce levels of fixed nitrogen," says Song. "By changing the types and ratios of nitrogen compounds in fertilizer, you might have a better way to reduce excess nitrogen, and to mitigate eutrophication or nutrient enrichment in nearby waters."Phillips adds, "Further research could inform farmers of how to cultivate soil organic matter useful for nitrogen management. Organic forms of soil nitrogen, such as waste products from plants and fungi, could help convert excess inorganic nitrogen -- which would otherwise be leached into water or emitted as nitrous oxide -- into a form that isn't harmful to the environment."However, the scientists say more research is needed to test exactly which forms of organic nitrogen are most effective. The team is now developing proposals for further funding that will allow them to investigate on-farm applications for transforming excess nitrogen from soil and water into unreactive atmospheric N2 gas without producing N2O. This may allow scientists to develop options to manage the fate of agricultural nitrogen while avoiding greenhouse-gas emissions.

Ozone Holes

January 4, 2017

https://www.sciencedaily.com/releases/2017/01/170104125920.htm

People aren't the only beneficiaries of power plant carbon standards

When the Environmental Protection Agency finalized the Clean Power Plan in 2015 it exercised its authority to regulate carbon dioxide emissions to protect public welfare. The Plan, now the focus of escalating debate, also put the nation on course to meet its goals under the Paris Climate Agreement. Given that other pollutants are emitted from power plants -- along with carbon dioxide -- research has shown that carbon emission standards for the power sector benefit human health. New research released today shows that they would also benefit crops and trees.

The study, "Estimating Potential Productivity Co-Benefits For Crops and Trees From Reduced Ozone With U.S. Coal Power Plan Carbon Standards," was recently published in the "In assessing the regulatory impact of the Clean Power Plan the EPA estimated monetary benefits of reduced carbon-dioxide emissions, as well as quantifying and monetizing certain public health benefits, such as reduction in premature mortality and morbidity due to particulate matter or ozone exposure," the researchers write. "The EPA did not quantify the co-benefits to crops and trees but treated these co-benefits qualitatively."According to the study, which included an option similar to the Clean Power Plan, the corresponding reduction in carbon, nitrogen and sulfur emissions from coal power plants would also mean a decrease in ground-level ozone -- a known inhibitor of plant growth. And by modeling these reductions in the year 2020, the researchers found that they would provide a significant boost to the productivity of key indicator crops, such as corn, cotton, soybean and potato; as well as several tree species."Our findings suggest that crops like corn, soybeans and cotton could benefit from substantial productivity gains under moderate carbon standards for power plants," said Shannon Capps, PhD, an assistant professor in Drexel's College of Engineering and an author of the study. "With policies similar to those in the Clean Power Plan, we're projecting more than a 15 percent reduction in corn productivity losses due to ozone exposure, compared to business as usual, and about half of that for cotton and soybeans. Depending on market value fluctuations of these crops over the next few years, that could mean gains of tens of millions of dollars for farmers -- especially in areas like the Ohio River Valley where power plants currently contribute to ground-level ozone."The team used three policy scenarios that encompass a range of emissions targets and reductions measures, and they compared each policy scenario with a "business-as-usual" reference case that represents current clean air policies, as well as energy demand and market projections.Then, using a computer model widely employed to help guide state-level decision making for compliance with the National Ambient Air Quality Standards, the group generated a detailed projection of what the surface-layer ozone would look like across the country under each policy scenario through 2020.The team looked at the consequences of lower ozone for five crops whose primary growing season is June through August, which is the period when ground-level ozone is known to be at its peak. They also evaluated the consequences for 11 tree species, including eastern cottonwood, black cherry, quaking aspen and several species of pine. These crops and trees have been used as standard indicators in environmental research. Based on previous research by crop and tree scientists, the team could relate their models' ozone-exposure findings to the productivity of crop and tree species."The option most similar to the Clean Power Plan has the greatest estimated productivity gains for the crops and trees that we studied," said Capps. "The improvement in crop yield and tree growth was strongly tied to the level of carbon dioxide emissions reductions and adoption of cleaner energy achieved by the policy."Under the business-as-usual scenario, the productivity of soybean, potatoes, and cotton is reduced about 1.5 percent, with only slight impacts on corn. These levels of production only slightly improve under a policy scenario that includes only "inside the fenceline measures" such as improving the efficiency of coal-fired power plants.A second scenario, that most closely resembles the Clean Power Plan and includes demand-side energy efficiency, substituting lower-emitting natural gas plants and zero-emitting solar and wind power into the energy mix -- produces larger results. The potential corn production lost to ozone exposure in the reference scenario is reduced by 15.7 percent, soybean losses are reduced by 8.4 percent and cotton losses are diminished by 6.7 percent.Under the third scenario, which reflects putting a price on carbon, and achieves similar emissions reductions as the second scenario, the researchers project slightly lower reductions in ozone-induced losses for corn (12.1 percent), soybean (6.6 percent) and cotton (3.8 percent).Productivity among tree species, as measured in biomass yield compared to the reference scenario, also suggests that the plants will benefit from ozone-reducing policies. The tree species with the greatest potential for productivity losses, black cherry and eastern cottonwood, show 7.6 and 8.4 percent reductions in the projected ozone-induced biomass reductions, respectively, under the scenario most like the Clean Power Plan."Our work shows the importance of considering the co-benefits of our nation's energy policies going forward," said Charles Driscoll, PhD, professor at Syracuse University and co-author of the study. "These benefits to people and plants are nearly immediate and occur in urban and rural communities across the U.S. We know from this and other studies that the economic value of the added benefits from power plant carbon standards are large and exceed the estimated cost of implementation."Members of the team are also analyzing the co-benefits of power plant carbon standards for reducing regional haze and acid rain and conducting new research on the co-benefits of the final clean power plan as compared to different energy policy futures.

Ozone Holes

December 12, 2016

https://www.sciencedaily.com/releases/2016/12/161212152405.htm

Mitigating the risk of geoengineering

The planet is warming at an unprecedented rate and reducing emissions of greenhouse gasses alone is not enough to remove the risk.

Last year's historic Paris climate agreement set the goal of keeping global temperatures no higher than 1.5 degrees Celsius above the preindustrial levels. Emission reductions will be central to achieving that goal, but supplemental efforts can further reduce risksOne drastic idea is solar geoengineering -- injecting light-reflecting sulfate aerosols into the stratosphere to cool the planet. Researchers know that large amounts of aerosols can significantly cool the planet; the effect has been observed after large volcanic eruptions. But these sulfate aerosols also carry significant risks. The biggest known risk is that they produce sulfuric acid in the stratosphere, which damages ozone. Since the ozone layer absorbs ultraviolet light from the sun, ozone layer depletion can lead to increased rates skin cancer, eye damage and other adverse consequences.Now, researchers from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) have identified an aerosol for solar geoengineering that may be able to cool the planet while simultaneously repairing ozone damage.The research is published in the "In solar geoengineering research, introducing sulfuric acid into the atmosphere has been the only idea that had any serious traction until now," said David Keith, the Gordon McKay Professor of Applied Physics at SEAS and Professor of Public Policy at the Harvard Kennedy School and first author of the paper. "This research is a turning point and an important step in analyzing and reducing certain risks of solar geoengineering."This research fundamentally rethinks what kinds of particles should be used for solar geoengineering, said Frank Keutsch, the Stonington Professor of Engineering and Atmospheric Science at SEAS and Professor of Chemistry and Chemical Biology and coauthor of the paper.Previous research focused on ways to limit the ozone-damaging reactions produced by nonreactive aerosols. But Keutsch and Keith, along with coauthors Debra Weisenstein and John Dykema, took a completely different approach, targeting aerosols that are highly reactive."Anytime you introduce even initially unreactive surfaces into the stratosphere, you get reactions that ultimately result in ozone destruction as they are coated with sulfuric acid," said Keutsch. "Instead of trying to minimize the reactivity of the aerosol, we wanted a material that is highly reactive but in a way that would avoid ozone destruction."In order to keep aerosols from harming the ozone, the particles would need to neutralize sulfuric, nitric, and hydrochloric acid on their surface. To find such a particle, Keutsch turned to his handy Periodic Table. After eliminating the toxic elements, the finicky and rare metals, the team was left with the Alkali and Alkaline Earth Metals, which included sodium and calcium carbonate."Essentially, we ended up with an antacid for the stratosphere," said Keutsch.Through extensive modeling of stratospheric chemistry, the team found that calcite, a constituent of limestone, could counter ozone loss by neutralizing emissions-borne acids in the atmosphere, while also reflecting light and cooling the planet."Calcite is one of the most common compounds found in Earth's crust," said Keith. "The amounts that would be used in a solar geoengineering application are small compared to what's found in surface dust,"The researchers have already begun testing calcite in lab experiments that mimic stratospheric conditions. Keith and Keutsch caution that anything introduced into the atmosphere may have unanticipated consequences."Stratospheric chemistry is complicated and we don't understand everything about it," Keith said. "There are ways that this approach could increase global ozone but at the same time, because of the climate dynamics in the polar regions, increase the ozone hole."The researchers emphasize that even if all the attendant risks could be reduced to acceptable levels, solar geoengineering is not a solution to climate change."Geoengineering is like taking painkillers," said Keutsch. "When things are really bad, painkillers can help but they don't address the cause of a disease and they may cause more harm than good. We really don't know the effects of geoengineering but that is why we're doing this research."

Ozone Holes

December 6, 2016

https://www.sciencedaily.com/releases/2016/12/161206155645.htm

Bacterial mechanism converts nitrogen to greenhouse gas

Cornell Unviersity researchers have discovered a biological mechanism that helps convert nitrogen-based fertilizer into nitrous oxide, an ozone-depleting greenhouse gas. The paper was published online Nov. 17 in the

"The first key to plugging a leak is finding the leak," said Kyle Lancaster, assistant professor of chemistry and chemical biology, and senior author on the research. "We now know the key to the leak and what's leading to it. Nitrous oxide is becoming quite significant in the atmosphere, as there has been a 120 percent increase of nitrous oxide in our atmosphere since pre-industrial times."Lancaster, along with postdoctoral researcher Jonathan D. Caranto and chemistry doctoral candidate Avery C. Vilbert, showed that an enzyme made by the ammonia oxidizing bacterium Nitrosomonas europaea, cytochrome P460, produces nitrous oxide after the organism turns ammonia into an intermediate metabolite called hydroxylamine.N. europaea and similar "ammonia-oxidizing bacteria" use hydroxylamine as their fuel source, but too much hydroxylamine can be harmful -- and the resulting production of nitrous oxide is a chemical coping strategy.Lancaster and his colleagues hypothesize that when ammonia-oxidizing bacteria are exposed to high levels of nitrogen compounds, such as in crop fields or wastewater treatment plants, then nitrous oxide production via cytochrome P460 will ramp up.In the atmosphere, greenhouse gases are a soup of many species, and Lancaster explained that nitrous oxide has 300 times the potency of carbon dioxide. "That's a staggering number," he said. "Nitrous oxide is a really nasty agent to be releasing on a global scale."Lancaster added that nitrous oxide is photochemically reactive and can form free radicals -- ozone-depleting agents -- which aggravates the issue of blanketing Earth's atmosphere with more gas and raising the globe's temperature. "In addition to its role as a greenhouse gas cloak, it's removing our protective shield," Lancaster said.The United States is among the world leaders in importing nitrogen fertilizer, according to the U.S. Department of Agriculture's Economic Research Service. The Food and Agriculture Organization of the United Nations noted that the world's nitrogen fertilizer demand was projected to be 116 million tons for this past agricultural season."For the world, I realize that we are trying to feed more people and that means more fertilizer -- and that means more nitrous oxide," said Lancaster, who noted that about 30 percent of nitrous oxide emissions come from agriculture and its accompanying land use.To reduce the negative impact of nitrogen, farmers already use nitrification inhibitors.Said Lancaster: "While it will be challenging to develop ways to stop this process, now we have pinpointed one biochemical step leading to nitrous oxide production. Future work may lead to inhibitors, molecules that can deactivate or neutralize this bacterial enzyme. Alternatively, we may just use this new information to develop better strategies for nitrogen management."

Ozone Holes

December 6, 2016

https://www.sciencedaily.com/releases/2016/12/161206125207.htm

Inactive lifestyle linked to ozone-related lung disease

An inactive lifestyle may increase the risk of environmentally induced asthma symptoms. In a new study published in the

Young rats were divided into two groups: One group had free access to a running wheel ("active"); the other did not ("sedentary"). For seven weeks, the active rats were allowed to exercise as desired, during which time the sedentary group engaged in everyday activities such as eating and sleeping. After this observation period, both the active and sedentary groups were exposed to either filtered air or three different levels of ozone concentrations for a total of 10 hours over two consecutive days.The research team measured the breathing frequency and volume and glucose tolerance of all animals after ozone or filtered air exposure. The researchers also analyzed cells from the bronchial fluid in the lungs."The two-day exposures to ozone elicited a marked pulmonary inflammatory response as evidenced by an elevation in neutrophils [white blood cells that fight infection], eosinophils [white blood cells that often indicate allergies or infection] and other biomarkers of inflammation in the BALF [fluid in which the lung cells are retrieved and examined,]" the research team wrote. The research team noted that the white blood cell count increased more sharply in the sedentary group. Glucose levels rose in both active and sedentary groups after ozone exposure, but the increase was more significant and took longer to normalize in the sedentary group following a glucose challenge.The study also found that the breathing rate of all animals was negatively affected after ozone exposure. After the first day of the air challenge, the active group exposed to air pollution used their running wheels 71 percent less than the active group exposed to normal air.The findings of this animal study provide clues to environmental exposure in humans, explains the research team. "Such a study could highlight the importance of a model of childhood sedentary versus active lifestyle and effects on susceptibility as an adult."

Ozone Holes

November 16, 2016

https://www.sciencedaily.com/releases/2016/11/161116120201.htm

Salty snow could affect air pollution in the Arctic

In pictures, the Arctic appears pristine and timeless with its barren lands and icy landscape. In reality, the area is rapidly changing. Scientists are working to understand the chemistry behind these changes to better predict what could happen to the region in the future. One team reports in ACS'

The Arctic's wintertime ice hit a record low this year, and its air is warming, according to NASA. Previous research has shown that pollutants, including gaseous nitrogen oxides and ozone, have at times been recorded at levels similar to those one would see in more populated areas. Nitrogen oxides are air pollutants that, in sunlight, lead to the formation of ozone, the main component in smog normally associated with cities. The gases can be processed in the atmosphere and be deposited on Earth as nitrates, which can get trapped in snow. In sunlight, snow can act as a reactor in which nitrates may be transformed back to nitrogen oxide gases. In the Arctic, sea ice and snow contain salt and other impurities that can possibly alter the efficiency of this process. James Donaldson, Karen Morenz and colleagues took a closer look at how salt and nitrate content in snow could affect the levels of nitrogen oxides in the air during sunny conditions.The researchers tested lab-made snow containing nitrate alone or nitrate and salt. They found that under simulated sunlight, about 40 to 90 percent more nitrogen dioxide (NO2) was reformed from the snow with low levels of salt at environmentally relevant concentrations than snow with no salt. Researchers observed the greatest effect when they used realistic sea salt in the experiment. The results suggest that sea ice and salty snow, which previously have not been considered as factors in the balance of ozone-forming chemicals in the atmosphere, should be a part of future models.

Ozone Holes

November 8, 2016

https://www.sciencedaily.com/releases/2016/11/161108085028.htm

Pollution emitted near equator has biggest impact on global ozone

Since the 1980s, air pollution has increased worldwide, but it has increased at a much faster pace in regions close to the equator. Research from the University of North Carolina at Chapel Hill now reveals that this changing global emissions map is creating more total ozone worldwide compared to the amount of pollution being emitted, signaling an effect that could be difficult to reign in without strategic policy planning.

"Emissions are growing in places where there is a much greater effect on the formation of ozone," said Jason West, who led the research at UNC-Chapel Hill with former graduate student and first author Yuqiang Zhang. "A ton of emissions in a region close to the equator, where there is a lot of sunlight and intense heat, produces more ozone than a ton of emissions in a region farther from it."The work, to appear in the Nov. 7 advance online issue of To drive home the point, West explained that China's emissions increased more than India's and Southeast Asia's from 1980 to 2010, but Southeast Asia and India, despite their lower growth in emissions during this period, appear to have contributed more to the total global ozone increase due to their proximity to the equator.The reason is that ozone, a greenhouse gas and toxic air pollutant, is not emitted but forms when ultraviolet light hits nitrogen oxides (basically combustion exhaust from cars and other sources). When these pollutants interact with more intense sunlight and higher temperatures, the interplay speeds up the chemical reactions that form ozone. Higher temperatures near the equator also increase the vertical motion of air, transporting ozone-forming chemicals higher in the troposphere, where they can live longer and form more ozone."The findings were surprising," said West. "We thought that location was going to be important, but we didn't suspect it would be the most important factor contributing to total ozone levels worldwide. Our findings suggest that where the world emits is more important than how much it emits."Zhang, West and colleagues, including Owen Cooper and Audrey Gaudel, from the University of Colorado Boulder and NOAA's Earth System Research Laboratory, used a computer model to simulate the total amount of ozone in the troposphere, the part of the atmosphere where ozone is harmful to humans and agriculture, between 1980 and 2010. Since emissions have shifted south during this period, they wanted to answer, what contributed more to the increased production of ozone worldwide: the changing magnitude of emissions or location?To find out, the team used a unique European data set of ozone observations from commercial aircraft to confirm the strong increases in ozone above Asia. Then they superimposed a map of how much pollution the world was emitting in 1980 onto where the world was emitting it in 2010, and vice versa, in addition to another scenario of the growth of methane gas, to determine what is driving the world's increase in ozone production."Location, by far," said West, associate professor of environmental sciences in the UNC Gillings School of Global Public Health.The findings point to several strategies for reducing ground-level ozone across the world, such as decreasing emissions of ozone precursors in regions close to the equator, particularly those with the fastest growth of emissions. However, concerns exist for policy makers."A more challenging scenario is that even if there is a net reduction in global emissions, ozone levels may not decrease if emissions continue to shift toward the equator," said Cooper. "But continuing aircraft and satellite observations of ozone across the tropics can monitor the situation and model forecasts can guide decision making for controlling global ozone pollution.

Ozone Holes

November 7, 2016

https://www.sciencedaily.com/releases/2016/11/161107112642.htm

Herbivory, climate change factors may significantly increase BVOC emissions from boreal conifers

Boreal conifer forests are sources of biogenic volatile organic compound (BVOC) emissions into the atmosphere. Global warming exposes boreal trees to biotic stress caused by insect outbreaks and they are also affected by abiotic climate change factors.

A recent study from the University of Eastern Finland shows that the combination of insect outbreaks and climate change factors may significantly increase BVOC emissions of conifers in northern Europe. The expected increases in BVOCs may affect atmospheric chemistry and the global climate through the formation of secondary organic aerosols in the atmosphere.Needle damage caused by pine sawflies on Scots pine and bark beetle invasion on Norway spruce trunks substantially increased the BVOC emissions from pine shoots and spruce bark, respectively. Insect herbivores and abiotic climate change factors (warming, elevated ozone and increased soil nitrogen availability), both individually and in combination, had strong impacts on BVOC emissions of Scots pine.The findings presented in the doctoral dissertation of Rajendra Prasad Ghimire, MSc, help in understanding the risks posed by climate change induced insect outbreaks for northern ecosystems. Data on emission responses can be used in, for example, modelling of the impacts of climate change on the secondary aerosol forming capacity of boreal forests.With the aim of assessing BVOC emissions from the shoots and tree bark surface of conifers in response to biotic stress, pine seedlings were experimentally exposed to insect herbivores in growth chambers and in an open-field exposure site. In addition, naturally insect-infested spruce trees were studied in forest site experiments.In order to evaluate the emission responses under multiple biotic and abiotic factors, pine seedlings were exposed to herbivory, warming, elevated ozone and higher nitrogen supply in the open-field exposure site. BVOC samples were collected both from pine shoots and rhizosphere and spruce bark surface using dynamic headspace sampling technique followed by analysis with gas chromatography-mass spectrometry.The findings were originally published in The doctoral dissertation, entitled "Effects of Herbivory and Climate Change Factors on BVOC Emissions from Boreal Conifers" is available for download at

Ozone Holes

October 12, 2016

https://www.sciencedaily.com/releases/2016/10/161012132622.htm

Salty snow could affect air pollution in the Arctic

In pictures, the Arctic appears pristine and timeless with its barren lands and icy landscape. In reality, the area is rapidly changing. Scientists are working to understand the chemistry behind these changes to better predict what could happen to the region in the future. One team reports in ACS'

The Arctic's wintertime ice hit a record low this year, and its air is warming, according to NASA. Previous research has shown that pollutants, including gaseous nitrogen oxides and ozone, have at times been recorded at levels similar to those one would see in more populated areas. Nitrogen oxides are air pollutants that, in sunlight, lead to the formation of ozone, the main component in smog normally associated with cities. The gases can be processed in the atmosphere and be deposited on Earth as nitrates, which can get trapped in snow. In sunlight, snow can act as a reactor in which nitrates may be transformed back to nitrogen oxide gases. In the Arctic, sea ice and snow contain salt and other impurities that can possibly alter the efficiency of this process. James Donaldson, Karen Morenz and colleagues took a closer look at how salt and nitrate content in snow could affect the levels of nitrogen oxides in the air during sunny conditions.The researchers tested lab-made snow containing nitrate alone or nitrate and salt. They found that under simulated sunlight, about 40 to 90 percent more nitrogen dioxide (NO2) was reformed from the snow with low levels of salt at environmentally relevant concentrations than snow with no salt. Researchers observed the greatest effect when they used realistic sea salt in the experiment. The results suggest that sea ice and salty snow, which previously have not been considered as factors in the balance of ozone-forming chemicals in the atmosphere, should be a part of future models.

Ozone Holes

September 16, 2016

https://www.sciencedaily.com/releases/2016/09/160916093045.htm

How and why are measurements of ozone taken from space?

Today is the UN's International Day for the Preservation of the Ozone Layer -- the perfect opportunity to look at how and why measurements of this molecule are taken from space.

The hole in the ozone layer over Antarctica became an international cause for concern in the latter half of the 20th Century, but as EUMETSAT's Atmospheric Composition Product Development Team Leader Dr Christian Retscher points out, issues relating to ozone levels are complex and wide-reaching.Ozone is a molecule consisting of three oxygen atoms and occurs naturally in the atmosphere. However, close to the surface of the Earth, it is considered a pollutant.The ozone layer in the stratosphere, with a bulk concentration at 15-30km above the surface of the Earth, is crucial for protecting humans and other species from the harmful effects of ultraviolet radiation from the sun, Christian said.The ozone layer in the stratosphere absorbs UV radiation. While UV radiation is essential for life on Earth, it is also linked to skin cancer and damage to plant life. That is why the thinning of the ozone layer (often referred to as the ozone hole), causes concern.But measurements of ozone in the troposphere (the lowest level of the Earth's atmosphere, extending up to between 7km above sea level at polar regions and 20km over the tropics) are also needed because this molecule, which can be a by-product of industrial production, is harmful to breathe and damaging to plants.About 90 per cent of ozone is in the stratosphere and 10 per cent in the troposphere, Christian said.EUMETSAT's Metop-A (launched in 2006) and Metop-B (2012) satellites, flying in a sun-synchronised polar orbit approximately 817km above the Earth's surface, carry an instrument called GOME-2 (Global Ozone Monitoring Experiment), which is dedicated to measuring ozone in the atmosphere."GOME-2 maps ozone from above," Christian explains. "It takes total column (through the stratosphere and troposphere) ozone measurements."What is important about GOME-2 is that this is an instrument of an operational satellite mission, in other words, we are flying the same sensor more than once. This provides long time series of measurements, contributes to a better understanding of ozone production and destruction processes and also allows trend analysis."The primary goal is to measure how the ozone layer is changing in general, not only the so-called ozone hole over Antarctica. There, meteorological conditions favour the accelerated depletion of stratospheric ozone, but ozone is thinning over the Arctic as well."When we look at how the ozone is behaving over the long term, what we hope to see is that stratospheric ozone is recovering somewhat."Specifically, measurements from the last couple of years hint at a slight recovery of the stratospheric ozone layer over the South Pole.""When we look at ozone with instruments like GOME-2, we see the whole column, but we want to separate between the troposphere and stratosphere," Christian added."While ozone measurements in the stratosphere are more related to climate aspects, thus long-term effects, ozone in the troposphere has different implications for human health."When we are measuring ozone in the troposphere, short term trends or diurnal variations of ozone concentrations are much more relevant. We are interested in improvements over short time ranges like hours or days and much finer geographical scales, for example, cities."When inhaled, ozone is harmful to the respiratory system, so what is interesting is the understanding of changes of ozone levels on, for example, a daily basis. How much ozone is there and what is the threat level -- is it safe for you to be outside or not? Novel instruments, for example, Sentinel-4, will support this kind of research since ozone profile data will be available on an hourly basis."The GOME-2 instruments are dedicated to monitoring ozone but are not the only satellite-borne instruments taking ozone measurements.Metop satellites also carry the Infrared Atmospheric Sounding Interferometer (IASI) instruments, which measure ozone as well.Other relevant European ozone-monitoring instruments were GOME on ERS-2 , or SCIAMACHY, MIPAS and GOMOS, which were flown on ESA's Envisat satellite. Very important contributions to ozone research are based on the more than 30 years time series of data from satellites flown by, for example, NASA and NOAA, with the successful series of TOMS , SBUV , POAM , and SAGE instruments or the later OMI or the OMPS sensors.Planning is well in hand to continue monitoring ozone into the future.Metop-A is approaching the end of its lifetime in space but Metop-C, also with a GOME-2 instrument, is expected to be launched in 2018, so the all-important long time series of measurements will be maintained.Under the EU's flagship Copernicus programme for monitoring the environment from space, EUMETSAT's Meteosat Third Generation (MTG) geostationary meteorological satellites, and the EPS-Second Generation satellites will carry the Copernicus Sentinel-4 and -5 instruments respectively. Prior to these, ESA will launch the Sentinel-5 Precursor mission. All of these Sentinels have capacity to monitor ozone. In addition, there will be other European sensors in space supporting the monitoring of ozone, although not their primary mission objective, for example, IASI-NG (IASI- Next Generation) on EPS-SG and the IRS (Infrared Sounder) on MTG-S.EUMETSAT will launch its EPS-SG satellites in the 2022-2042 timeframe, while the first in the series of MTG-S (sounding) platforms is expected to be launched in 2022 as well.

Ozone Holes

September 15, 2016

https://www.sciencedaily.com/releases/2016/09/160915173619.htm

Assessing health risks from oil and gas operations

A Colorado State University-led study of air pollutant emissions from northern Front Range oil and gas operations has been presented to state officials.

Jeffrey Collett, professor and head of CSU's Department of Atmospheric Science, was the principal investigator for the three-year North Front Range study, funded by the state of Colorado. Collett presented his team's findings at a Sept. 15 meeting of the Air Quality Control Commission.Data from the North Front Range Oil and Gas Air Pollutant Emission and Dispersion Study -- and a similar Garfield County study completed in June 2016 -- will be used in a state health-risk assessment, to be completed by summer 2018.The Colorado Department of Public Health and Environment will coordinate the health-risk assessment using the data from Collett's studies, and is contracting this work to a third-party consulting company. The department is soliciting formal proposals for the assessment and expects to have a contract in place by December.The CSU study was designed to quantify emissions from three specific oil and gas development activities:CSU researchers conducted 18 experiments to quantify air emission rates and dispersion of air toxics, ozone precursors and greenhouse gases from each of the three processes.Overall, production emissions (which may continue for many years) were found to be lower than the shorter-term fracking and flowback emissions, which last for a few days to a few weeks. Emissions in the North Front Range were slightly lower than in Garfield County, but contained heavier-weight organic compounds, likely due to differences in the geology between the basins.Data from these two studies represent one of the most comprehensive assessments of air toxics, ozone precursors and greenhouse gas emission rates from oil and natural gas well operations to date.Dr. Larry Wolk, CDPHE's executive director and chief medical officer, said: "These studies will provide us with critical information to design a detailed and accurate health risk assessment so we can answer questions related to potential health concerns related to oil and gas operations."

Ozone Holes

September 2, 2016

https://www.sciencedaily.com/releases/2016/09/160902142132.htm

A strange thing happened in the stratosphere

This disruption to the wind pattern -- called the "quasi-biennial oscillation" -- did not have any immediate impact on weather or climate as we experience it on Earth's surface. But it does raise interesting questions for the NASA scientists who observed it: If a pattern holds for six decades and then suddenly changes, what caused that to happen? Will it happen again? What effects might it have?

"The quasi-biennial oscillation is the stratosphere's Old Faithful," said Paul Newman, Chief Scientist for Earth Sciences at NASA's Goddard Space Flight Center, Greenbelt, Maryland, and lead author on a new paper about the event published online in Winds in the tropical stratosphere, an atmospheric layer that extends from about 10 to 30 miles above Earth's surface, circulate the planet in alternating easterly and westerly directions over roughly a two-year period. Westerly winds develop at the top of the stratosphere, and gradually descend to the bottom, about 10 miles above the surface while at the same time being replaced by a layer of easterly winds above them. In turn, the easterlies descend and are replaced by westerlies.This pattern repeats every 28 months. In the 1960s scientists coined it the "quasi-biennial oscillation." The record of these measurements, made by weather balloons released in the tropics at various points around the globe, dates to 1953.The pattern never changed -- until late 2015. As the year came to a close, winds from the west neared the end of their typical descent. The regular pattern held that weaker easterly winds would soon replace them. But then the westerlies appeared to move upwards and block the downward movement of the easterlies. This new pattern held for nearly half a year, and by July 2016 the old regime seemed to resume."It's really interesting when nature throws us a curveball," Newman said.The quasi-biennial oscillation has a wide influence on stratospheric conditions. The amount of ozone at the equator changes by 10 percent between the peaks of the easterly and westerly phases, while the oscillation also has an impact on levels of polar ozone depletion.With this disruption now documented, Newman and colleagues are currently focused on studying both its causes and potential implications. They have two hypotheses for what could have triggered it -- the particularly strong El Niño in 2015-16 or the long-term trend of rising global temperatures. Newman said the scientists are conducting further research now to figure out if the event was a "black swan," a once-in-a-generation event, or a "canary in the coal mine," a shift with unforeseen circumstances, caused by climate change.

Ozone Holes

August 22, 2016

https://www.sciencedaily.com/releases/2016/08/160822155924.htm

Climate change may extend ozone season in the Southeastern US

Extreme weather conditions associated with climate change may extend the ozone season in the Southeastern United States as drought-stressed trees emit more of the precursor compound that helps form the health-threatening pollutant. July and August have traditionally been peak ozone months, but a new study suggests those peaks could extend well into the fall as weather becomes warmer and drier.

In 2010, regional ozone levels reached a peak in October, with higher levels of the pollutant than in July, providing a preview of what may happen as the climate changes. Ironically, the projected extension of ozone season comes at a time when summertime ground-level ozone levels continue to decline as a result of emission reductions mandated by the Clean Air Act."This study shows that our air quality, particularly ozone in the fall, is becoming more sensitive to the effects of climate change," said Yuhang Wang, a professor in the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology. "The direction of climate change is such that we are likely going to see hotter and drier fall seasons, which may create larger ozone extremes in the Southeast. We are likely to have record ozone days in the fall, and we need to prepare for that."The research, which was sponsored by the U.S. Environmental Protection Agency's Science To Achieve Results (STAR) Program, will be reported August 22 in the Early Edition of the journal Ozone is formed in the atmosphere by chemical reactions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) in the presence of sunlight. VOCs are emitted by vehicles, industrial sources and trees, while NOx emissions mainly originate with human-created sources. Because of its large forests, the Southeast is more impacted by natural VOC emissions than other parts of the country.Ozone can harm the lungs of susceptible people, especially the elderly and very young, and stunt the growth of agricultural crops. During the summer, residents of the Southeastern U.S. are often asked to reduce emission of VOCs -- such as refueling vehicles in the morning or evening -- to reduce ozone formation. And sensitive individuals are asked to remain indoors when ozone levels peak.Wang and graduate student Yuzhong Zhang studied ozone and precursor emission data compiled over the past 35 years for the Southeastern states, focusing their detailed modeling on 2008, 2009 and 2010. In two separate years, both since 2000, they identified unexpected ozone peaks during the month of October -- and found that those peaks corresponded to spikes in the level of isoprene, a compound emitted by trees.Though the biochemical cause has not been thoroughly studied, research shows that trees emit more isoprene when they are under stress from heat and drought. In 2010, a summertime drought worsened in October, boosting isoprene emissions to levels substantially higher than in 2008 and 2009.As human-made VOC emissions decrease due to air pollution control measures, the sensitivity of ozone formation to tree emissions increases, Wang said. "If we had lots of VOC emissions from industry and cars in the fall, we probably wouldn't see this much sensitivity to biogenic emissions from trees," he explained.Climate modeling suggests that over the next several decades, the Southeast will experience more periods of weather variability, with hot and dry conditions favorable to isoprene emission from trees becoming more likely.In October in the Southeast, ozone levels have averaged about 40 parts per billion (ppb). But in 2010, monitoring stations reported exceedances over the 70 ppb limit 324 times -- as measured at 112 locations. In 2008 and 2009, ozone exceedances were rare during October.Modeling by the researchers suggests that isoprene emission from trees is more sensitive to the air-plant moisture difference than to temperature. The researchers used a measure called vapor pressure deficit -- tied to a combination of relative humidity and temperature -- to predict emission of isoprene. The vapor pressure deficit describes the level of drought stress on trees, Wang said.If fall ozone peaks become more common, as the study suggests, ozone mitigation activities may have to be extended into the fall to protect humans against the pollutant."We will need more public awareness of the problem, and in particular, we will need the organizations that are involved in public awareness and public warning to know what's coming and be prepared for these extreme conditions," Wang said. "This could have a significant effect on people living in the Southeast United States."

Ozone Holes

August 11, 2016

https://www.sciencedaily.com/releases/2016/08/160811143222.htm

Discovery of sunlight-driven organic chemistry on water surfaces

Fatty acids found on the surface of water droplets react with sunlight to form organic molecules, a new study reports, essentially uncovering a previously unknown form of photolysis.

The results could affect models that account for aerosol particles, including models related to climate.Conventional wisdom holds that carboxylic acids and saturated fatty acids, which are abundant throughout the environment, only react with hydroxyl radicals and are not affected by sunlight.However, these previous conclusions are based on observations of the molecules in a gas phase, or dissolved in solution. Here, Stéphanie Rossignol and colleagues studied nonanoic acid (NA) during a liquid-gas phase, as the molecules interact with surface water.When the researchers studied NA along the surface of a liquid while it was exposed to UV light, they observed the formation of organic compounds. They conducted a series of experiments to adjust for possible contamination, concluding that NA is indeed responsible for the observed photochemistry resulting in these compounds.Based on the type of photochemistry observed, the authors say that similar reactions may be common to all carboxylic acid molecules. Considering how common fatty acids are in the environment, such photochemical processing on aerosols or other aqueous sites could have a significant impact on local ozone and particle formation, the authors say.In a related Perspective, Veronica Vaida notes that these previously unappreciated secondary organic products "will affect secondary organic aerosol mass, composition, and optical properties, in turn defining the particle's overall effect on climate, air quality, and health."

Ozone Holes

August 8, 2016

https://www.sciencedaily.com/releases/2016/08/160808123832.htm

Accounting for ozone: Study first to quantify impact of oil and gas emissions on Denver's ozone problem

The first peer-reviewed study to directly quantify how emissions from oil and gas activities influence summertime ozone pollution in the Colorado Front Range confirms that chemical vapors from oil and gas activities are a significant contributor to the region's chronic ozone problem.

Summertime ozone pollution levels in the northern Front Range periodically spike above 70 parts per billion (ppb), which is considered unhealthy -- on average, 17 ppb of that ozone is produced locally. The new research, published in the "By combining nearly 50,000, high-precision measurements of VOCs in Colorado's Front Range with an equally detailed model, we've been able to parse out the role of oil and gas," said Erin McDuffie, the study's lead author and a scientist at the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder, working in the NOAA Earth System Research Laboratory. "We expect this technique to help us better understand what factors are contributing to air quality challenges elsewhere in the West."Ozone pollution -- which can harm people's lungs and damage crops -- is produced when sunlight sparks reactions between volatile organic compounds (VOCs) and nitrogen oxides (NOx). In cities like Denver, NOx comes primarily from vehicle tailpipes. VOCs can come from both natural sources like trees and anthropogenic ones, like oil and gas activities.Colorado's northern Front Range was an interesting location for this study for a number of reasons, the researchers said. First, it contains the major city of Denver as well as active oil and gas regions to the northeast. "This area is unique, with high concentrations of both nitrogen oxides from urban areas and VOCs from oil and gas. That allows us to look at how oil and gas emissions are influencing ozone production," said McDuffie.Second, the region already has a high natural background of ozone -- and that means there's less room between the background levels and the Environmental Protection Agency standard. The researchers determined that on an average summer day, about 58 ppb of ozone present in air above the surface is from regional background sources or residual ozone produced locally during previous days. Mixing of this ozone to the surface during the day leaves very little room for local production before hitting health-based ozone standards.Third, compared to other parts of the country, the plains of Colorado's Front Range have low levels of VOCs from natural sources during daytime hours when ozone forms -- making the region potentially more sensitive to any oil and gas VOC emissions entering the air.The northern Front Range has seen a big boom in oil and gas activity in recent years: The number of active wells in central Colorado's Wattenberg gas field nearly doubled to over 27,000 between 2008 and 2015, according to state data. Colorado's Air Pollution Control Division experts use a model to identify the sources of ozone formation at various monitoring locations on various days. Considering all sources of emissions, they find that in the Northern Front Range area, the oil and gas sector can be a significant source of VOCs for ozone pollution formation, depending on meteorology and transport.Colorado has been out of compliance with federal ozone standard since 2007. Last year, the EPA tightened the standard from 75 ppb to 70 ppb.This study used measurements of ozone and its precursors -- NOx and VOCs -- made during field campaigns in the summers of 2012 and 2014 at the Boulder Atmospheric Observatory (BAO), a tall tower built specifically for atmospheric research, owned and operated by NOAA. To precisely quantify the contributions of oil and gas air to local ozone production , McDuffie used a custom model that included more than 15,000 chemical reactions.She and her colleagues found that the VOCs from oil and gas contribute an average of 17 percent to local, chemically produced ozone during the summer. "Seventeen percent is small but potentially still significant," said Steven Brown, co-author and scientist at the NOAA Earth System Research Laboratory. "He and his colleagues said they'd like to explore how oil and gas emissions may affect the number of days that ozone is above the standard; this study could not quantify that. And they'd also like to see followup work at a series of coordinated ground sites -- for example, between Denver and Fort Collins to the north -- to capture what's going on in different places across the region. And the team would like to use this new technique in other places in the U.S West, to analyze the various sources that contribute to ozone pollution there.

Ozone Holes

July 20, 2016

https://www.sciencedaily.com/releases/2016/07/160720135641.htm

A recent pause in Antarctic Peninsula warming

The rapid warming of the Antarctic Peninsula, which occurred from the early-1950s to the late 1990s, has paused. Stabilisation of the ozone hole along with natural climate variability were significant in bringing about the change. Together these influences have now caused the peninsula to enter a temporary cooling phase. Temperatures remain higher than measured during the middle of the 20th Century and glacial retreat is still taking place. However, scientists predict that if greenhouse gas concentrations continue to rise at the current rate, temperatures will increase across the Antarctic Peninsula by several degrees Centigrade by the end of this century.

Reporting this week in the journal Lead author, Professor John Turner of British Antarctic Survey says: "The Antarctic Peninsula is one of the most challenging places on Earth on which to identify the causes of decade-to-decade temperature changes. The Antarctic Peninsula climate system shows large natural variations, which can overwhelm the signals of human-induced global warming. In recent years, there has been an international research effort to explain what's happening in the region and to understand the implications for the Antarctic environment and future sea-level rise."Our study highlights the complexity and difficulty of attributing effect to cause. The ozone hole, sea-ice and westerly winds have been significant in influencing regional climate change in recent years. Even in a generally warming world, over the next couple of decades, temperatures in this region may go up or down, but our models predict that in the longer term greenhouse gases will lead to an increase in temperatures by the end of the 21st Century."A wide range of climate data was analysed for this study, including atmospheric circulation fields, sea-ice records, ocean surface temperatures and meteorological observations from six Antarctic Peninsula research stations with near-continuous records extending back to the 1950s.During the Twentieth Century, Antarctic Peninsula temperatures increased by up to 0.5? C per decade, helping to trigger the dramatic collapse of ice shelves and causing many glaciers to retreat. Whilst there was a decrease in sea ice extent around the Antarctic Peninsula towards the end of the last century it has been increasing in recent years, particularly in the north-east of the region. The cold easterly winds observed in the 21st Century have had a greater impact on the region because the sea ice has prevented ocean heat from entering the atmosphere.To set their observations in a longer-term context, the research team looked at a 2,000 year climate reconstruction using the chemical signals in ice cores. As previously reported, analysis suggests that peninsula warming over the whole twentieth century was unusual, but not unprecedented in the context of the past 2,000 years. The reconstruction shows a warming starting in the 1920s, which is consistent with the warming trends recorded by the meteorological stations. The ice core records also reveal periods of warming and cooling over the last several centuries that were comparable to those observed in the post-1950s instrumental record. This highlights the large natural variability of temperatures in this region of Antarctica that has influenced more recent climate changes.Dr Robert Mulvaney, is a leading ice core researcher at British Antarctic Survey. He says: "Meteorological observations from the Antarctic Peninsula research stations only cover the last 60 years or so. If we are to get a better idea of the long-term trend we need to look back in time. The ice core record helps us see how the climate evolves over the longer term. We can also look at the levels of carbon dioxide and other chemicals that were in the atmosphere and compare them with observations from today."In the last month, the levels of the greenhouse gas carbon dioxide (CO

Ozone Holes

July 6, 2016

https://www.sciencedaily.com/releases/2016/07/160706131924.htm

Bees' ability to forage decreases as air pollution increases

Air pollutants interact with and break down plant-emitted scent molecules, which insect pollinators use to locate needed food, according to a team of researchers led by Penn State. The pollution-modified plant odors can confuse bees and, as a result, bees' foraging time increases and pollination efficiency decreases. This happens because the chemical interactions decrease both the scent molecules' life spans and the distances they travel.

While foraging for food, insects detect floral scent molecules in the air. Wind currents can carry these molecules up to thousands of feet from their original source to where bees have their hives."Many insects have nests that are up to 3,000 feet away from their food source, which means that scents need to travel long distances before insects can detect them," said Jose D. Fuentes, professor of meteorology and atmospheric science, Penn State. "Each insect has a detection threshold for certain kinds of scents and they find food by moving from areas of low concentrations of scents to areas of high concentrations."Plant-emitted hydrocarbons break down through chemical interactions with certain air pollutants such as ozone. This breakdown process results in the creation of more air pollutants, including hydroxyl and nitrate radicals, which further increase the breakdown rate of plant odors.The researchers sought to understand how these chemical interactions, which start with the presence of air pollutants, would impact bees' ability to find food. They first estimated the changes in concentrations of flower scents as a result of air turbulence and chemical interactions using a computer simulation, which allowed them to track the concentration and movement of multiple plumes of scents from different flower beds over time. Then, the researchers ran 90,000 simulations representing various bees' foraging and movement patterns amid differing scent levels modified by air pollution and diluted by wind speeds.The team reported in the current issue of The scent molecule alpha-pinene, which survives nearly 40 hours in an ozone-free environment, survived fewer than 10 hours when ozone rose to 60 parts per billion and only 1 hour when ozone was at 120 parts per billion. Another molecule, beta-myrcene, which travels more than 3,000 feet in an ozone-free, windy environment, traveled an average of 1,500 feet when ozone was 60 parts per billion and, when ozone rose to 120 parts per billion, most traveled fewer than 1,000 feet.The changes in air chemistry impacted the number of bees able to detect food sources in a given time frame. In an ozone-free environment, it took 10 minutes for 20 percent of foragers to find the scent molecule beta-caryophyllene. When ozone rose to only 20 parts per billion, it took 180 minutes for the same amount of bees to find the scent. The team found similar results for the six different scent molecules they analyzed."We found that when we confused the bees' environment by modifying the gases present in the atmosphere, they spent more time foraging and would bring back less food, which would affect their colonies," said Fuentes. "It's similar to being asked to get a cup of coffee at the nearest cafeteria while you are blindfolded. It will be hard to locate the coffee shop without using visual cues. The same could happen to insect pollinators while foraging for food in polluted air masses."Because the concentration of scents changes drastically in air polluted environments, this could impact important interactions between plants and insects."There are two types of pollinators, generalists and specialists," said Fuentes. "Generalists can detect a mixture of scents, while specialists can only detect one type of scent. This means that as certain scents decrease their travel distance and life span, specialists and generalists may both have trouble finding food."Declines in the pollination of wild plants may lead to increases in the population of plants that do not rely on pollinators, and pollinator declines would lead to decreases in crop yields, Fuentes noted.These findings highlight that air pollution is one of many factors influencing the decline of the bee population.According to the U.S. Department of Agriculture, managed honeybee populations in the U.S. have declined between 25 and 45 percent per year since 2010, including a 44 percent decline from 2015 to 2016."Honeybees and other pollinators are in trouble almost everywhere, and they pay us a lot of services through their pollination," said Fuentes. "The more we can understand about what factors are affecting their decline in numbers, the more equipped we will be to intervene if needed."

Ozone Holes

June 30, 2016

https://www.sciencedaily.com/releases/2016/06/160630145004.htm

First signs of healing in the Antarctic ozone layer

Scientists at MIT and elsewhere have identified the "first fingerprints of healing" of the Antarctic ozone layer, published today in the journal

The team found that the September ozone hole has shrunk by more than 4 million square kilometers -- about half the area of the contiguous United States -- since 2000, when ozone depletion was at its peak. The team also showed for the first time that this recovery has slowed somewhat at times, due to the effects of volcanic eruptions from year to year. Overall, however, the ozone hole appears to be on a healing path.The authors used "fingerprints" of the ozone changes with season and altitude to attribute the ozone's recovery to the continuing decline of atmospheric chlorine originating from chlorofluorocarbons (CFCs). These chemical compounds were once emitted by dry cleaning processes, old refrigerators, and aerosols such as hairspray. In 1987, virtually every country in the world signed on to the Montreal Protocol in a concerted effort to ban the use of CFCs and repair the ozone hole."We can now be confident that the things we've done have put the planet on a path to heal," says lead author Susan Solomon, the Ellen Swallow Richards Professor of Atmospheric Chemistry and Climate Science at MIT. "Which is pretty good for us, isn't it? Aren't we amazing humans, that we did something that created a situation that we decided collectively, as a world, 'Let's get rid of these molecules'? We got rid of them, and now we're seeing the planet respond."Solomon's co-authors include Diane Ivy, research scientist in the Department of Earth, Atmospheric and Planetary Sciences, along with researchers at the National Center for Atmospheric Research in Boulder, Colorado, and the University of Leeds in the U.K.The ozone hole was first discovered using ground-based data that began in the 1950s. Around the mid-1980s, scientists from the British Antarctic survey noticed that the October total ozone was dropping. From then on, scientists worldwide typically tracked ozone depletion using October measurements of Antarctic ozone.Ozone is sensitive not just to chlorine, but also to temperature and sunlight. Chlorine eats away at ozone, but only if light is present and if the atmosphere is cold enough to create polar stratospheric clouds on which chlorine chemistry can occur -- a relationship that Solomon was first to characterize in 1986. Measurements have shown that ozone depletion starts each year in late August, as Antarctica emerges from its dark winter, and the hole is fully formed by early October.Solomon and her colleagues believed they would get a clearer picture of chlorine's effects by looking earlier in the year, at ozone levels in September, when cold winter temperatures still prevail and the ozone hole is opening up. The team showed that as the chlorine has decreased, the rate at which the hole opens up in September has slowed down."I think people, myself included, had been too focused on October, because that's when the ozone hole is enormous, in its full glory," Solomon says. "But October is also subject to the slings and arrows of other things that vary, like slight changes in meteorology. September is a better time to look because chlorine chemistry is firmly in control of the rate at which the hole forms at that time of year. That point hasn't really been made strongly in the past."The researchers tracked the yearly opening of the Antarctic ozone hole in the month of September, from 2000 to 2015. They analyzed ozone measurements taken from weather balloons and satellites, as well as satellite measurements of sulfur dioxide emitted by volcanoes, which can also enhance ozone depletion. And, they tracked meteorological changes, such as temperature and wind, which can shift the ozone hole back and forth.They then compared their yearly September ozone measurements with model simulations that predict ozone levels based on the amount of chlorine that scientists have estimated to be present in the atmosphere from year to year. The researchers found that the ozone hole has declined compared to its peak size in 2000, shrinking by more than 4 million square kilometers by 2015. They further found that this decline matched the model's predictions, and that more than half the shrinkage was due solely to the reduction in atmospheric chlorine."It's been interesting to think about this in a different month, and looking in September was a novel way," Ivy says. "It showed we can actually see a chemical fingerprint, which is sensitive to the levels of chlorine, finally emerging as a sign of recovery."The team did observe an important outlier in the trend: In 2015, the ozone hole reached a record size, despite the fact that atmospheric chlorine continued to drop. In response, scientists had questioned whether any healing could be determined. Going through the data, however, Solomon and her colleagues realized that the 2015 spike in ozone depletion was due primarily to the eruption of the Chilean volcano Calbuco. Volcanoes don't inject significant chlorine into the stratosphere but they do increase small particles, which increase the amount of polar stratospheric clouds with which the human-made chlorine reacts.As chlorine levels continue to dissipate from the atmosphere, Solomon sees no reason why, barring future volcanic eruptions, the ozone hole shouldn't shrink and eventually close permanently by midcentury."What's exciting for me personally is, this brings so much of my own work over 30 years full circle," says Solomon, whose research into chlorine and ozone spurred the Montreal Protocol. "Science was helpful in showing the path, diplomats and countries and industry were incredibly able in charting a pathway out of these molecules, and now we've actually seen the planet starting to get better. It's a wonderful thing."This research was supported, in part, by the National Science Foundation and the U.S. Department of Energy.

Ozone Holes

June 14, 2016

https://www.sciencedaily.com/releases/2016/06/160614100242.htm

Global ethane concentrations rising again, says study

Global emissions of ethane, an air pollutant and greenhouse gas, are on the uptick again, according to a new study led by the University of Colorado Boulder.

The team found that a steady decline of global ethane emissions following a peak in about 1970 ended between 2005 and 2010 in most of the Northern Hemisphere and has since reversed, said CU-Boulder Associate Research Professor Detlev Helmig, lead study author. Between 2009 and 2014, ethane emissions in the Northern Hemisphere increased by about 400,000 tons annually, the bulk of it from North American oil and gas activity, he said.The decline of ethane and other non-methane hydrocarbons (NMHC) starting around 1970 is believed to be primarily due to better emission controls, said Helmig. The controls resulted in reduced emissions from oil and gas production, storage and distribution, as well as combustion exhaust from cars and trucks."About 60 percent of the drop we saw in ethane levels over the past 40 years has already been made up in the past five years," said Helmig. "If this rate continues, we are on track to return to the maximum ethane levels we saw in the 1970s in only about three more years. We rarely see changes in atmospheric gases that quickly or dramatically."Ethane, propane and a host of other NMHCs are released naturally by the seepage of fossil carbon deposits, volcanic activity and wildfires, said Helmig. But human activities, which also include biomass burning and industrial use, constitute the most dominant source of the NMHCs worldwide."These human sources make up roughly three-quarters of the atmospheric ethane that is being emitted," said Helmig.The air samples for the study were collected from more than 40 sites around the world, from Colorado and Greenland to Germany, Switzerland, New Zealand and Earth's polar regions. More than 30,000 soda bottle-sized air containers were sampled at the National Oceanic and Atmospheric Administration's (NOAA) Earth Systems Research Laboratory (ESRL) in Boulder over the past decade.The study also showed that among the air sampling locations around the world, the largest increases in ethane and shorter-lived propane were seen over the central and eastern United States, areas of heavy oil and gas activity, said Helmig."We concluded that added emissions from U.S. oil and gas drilling have been the primary source for the atmospheric ethane trend reversal," he said.The study, published in The findings from the flask network, which INSTAAR and NOAA have been operating for more than 10 years, were supported by additional measurements showing very similar ethane behavior from a number of continuous global monitoring sites, he said.A component of natural gas, ethane plays an important role in Earth's atmosphere. As it breaks down near Earth's surface it can create ground-based ozone pollution, a health and environmental risk.Chemical models by the team show that the increase in ethane and other associated hydrocarbons will likely cause additional ground-based ozone production, particularly in the summer months, he said."Ethane is the second most significant hydrocarbon emitted from oil and gas after methane," said Helmig. "Other studies show on average there is about 10 times as much methane being emitted by the oil and gas industry as ethane.""There is high interest by scientists in methane since it is a strong greenhouse gas," said Helmig. The new findings on ethane increases indicate there should be more research on associated methane emissions.

Ozone Holes

May 31, 2016

https://www.sciencedaily.com/releases/2016/05/160531182419.htm

High blood pressure linked to short-, long-term exposure to some air pollutants

Both short- and long-term exposure to some air pollutants commonly associated with coal burning, vehicle exhaust, airborne dust and dirt are associated with the development of high blood pressure, according to new research in the American Heart Association's journal

"In our analysis of 17 previously-published studies we discovered a significant risk of developing high blood pressure due to exposure to air pollution," said Tao Liu, Ph.D., lead study author and deputy director and epidemiologist of the environmental health division at Guangdong Provincial Institute of Public Health in China. "People should limit their exposure on days with higher air pollution levels, especially for those with high blood pressure, even very short-term exposure can aggravate their conditions."Researchers performed a meta-analysis of available published studies in the world assessing the health effects of all air pollution on hypertension risk. Meta-analyses combine results from previous studies to estimate the overall effect of a particular variable on a result. In the first study to simultaneously estimate the effects of short-term and long-term exposure to air pollutants on hypertension by meta-analysis, researchers focused on these air pollutants:The meta-analysis found high blood pressure was significantly associated with:For the portion of the study that assessed short-term effects of ozone and carbon monoxide exposure, no significant associations were found. Researchers said ozone and carbon monoxide's links to high blood pressure requires further study.Of the 5,687 air pollution studies initially identified, 17 were the focus of this -- which involves more than 108,000 hypertension patients and 220,000 non-hypertensive controls. High blood pressure was defined as systolic blood pressure more than 140 mm Hg and/or diastolic blood pressure over 90 mm Hg or by antihypertensive drug use. Air pollution exposure was assessed by averaging data from nearest air pollution monitoring stations, or using complex dispersion models or land use regression models.High blood pressure is a major risk factor for cardiovascular disease and stroke.Previous studies have indicated that air pollution might be a risk factor for hypertension but the results were controversial, Liu said. The mechanism by which air pollution could contribute to the development of high blood pressure includes inflammation and oxidative stress, which may lead to changes in the arteries."Next we plan to further delve into the effects of particulate matter and their sources on hypertension risk, which we hope will inform air-pollution control policy-makers," Liu said.

Ozone Holes

May 17, 2016

https://www.sciencedaily.com/releases/2016/05/160517121817.htm

Chemical emitted by trees can impact St. Louis' ozone levels

It is well known that the dog days of summer in St. Louis are hot, humid and hazy. On the warmest of these days, the air arrives from the south, bringing with it high temperatures, moisture and natural forest emissions of chemicals, known as hydrocarbons, from the Ozark Plateau. The hydrocarbons can interact with human-influenced emissions, and in the presence of sunlight, create a cocktail of pollutants -- including ozone -- that are hazardous to human health.

A team of engineers in the School of Engineering & Applied Science at Washington University in St. Louis collaborated with researchers at the University of Minnesota to study the late-summer air quality in the St. Louis area. They found that the way that isoprene, a natural hydrocarbon compound emitted from broadleaf deciduous trees, such as oak, is processed in the atmosphere at night can have a big impact on the ozone in the atmosphere the next day.Brent Williams, the Raymond R. Tucker Distinguished I-CARES Career Development Assistant Professor, and Jay Turner, associate professor of energy, environmental & chemical engineering, both in the School of Engineering & Applied Science; and Dylan Millet, associate professor in the Department of Soil, Water, and Climate at the University of Minnesota, and other members of their research teams discovered the phenomenon after studying data from the St. Louis Air Quality Regional Study (SLAQRS), which took place in 2013 at the St. Louis-Midwest Supersite core monitoring station in East St. Louis, Ill.Results of the study were recently published online in "Here we are looking at ground-level ozone, which is different than the ozone high up in the stratosphere that protects us from UV radiation," Williams said. "What often isn't talked about is that we do need a little ozone here on the ground as well to kick start chemical reactions that clear pollutants out of the atmosphere."However, too much ozone will damage materials and even your lungs. That's why the U.S. Environmental Protection Agency has set limits for ozone concentrations in the atmosphere, which can't exceed 70 parts per billion averaged over an eight-hour period."The EPA considers April 1-Oct. 31 "ozone season" for the St. Louis region, when ozone pollution is more of a problem because of the sunlight and heat. Ozone forms from the combination of nitrogen oxides emitted from combustion sources such as vehicles or power plants, hydrocarbons from natural or human-influenced sources and sunlight. Ozone concentrations generally peak when temperatures are highest during the afternoon hours.Trees in forests emit isoprene, an organic hydrocarbon tied to photosynthesis strongly dependent on light and temperature and emitted during the daylight hours. St. Louis is downwind of the deciduous forests of the Ozark Plateau, a major isoprene source region nicknamed the "isoprene volcano," because it has the largest emission rates of isoprene in the U.S., Williams said.Turner and collaborators previously conducted a field study that examined the isoprene emissions from the isoprene volcano.During the SLAQRS study, southerly winds brought to St. Louis emissions from the Ozark region, however, isoprene had largely underwent chemical reactions and had faded away prior to arriving in St. Louis during the daylight hours. Isoprene that was emitted at the end of the day did not react away and was transported into St. Louis overnight.The team found that if human-influenced emissions of nitrogen oxides were in low abundance in the air at night, isoprene remained in the atmosphere until daybreak, when it reacted with the sunlight and created a burst of ozone production, in stark contrast to the typical peak of ozone levels in mid-late afternoon and extending the daily high-ozone period. That pushed the ozone measurement over 70 parts per billion for a short period, increasing the potential for ozone standard exceedances, Williams said.However, on nights when nitrogen oxides were in large abundance in the atmosphere, they reacted with ozone left over from the daytime and created nitrate radicals. When the sun rose the next morning, those nitrate radicals had reacted with the isoprene overnight to eliminate it -- and ozone -- from the atmosphere. In this case, the presence of nighttime nitrogen oxides prevents excess ozone formation the next morning, whereas daytime nitrogen oxides still produce ozone.The phenomenon likely applies to other cities downwind of forests. Nitrogen oxides still contribute to daytime ozone formation and should be controlled to limit ozone formation, but regulatory agencies should be aware of this nighttime chemistry that influences morning ozone levels, Williams said."We have to control what we can to prevent detrimental health impacts," Williams said. "With the three key ingredients to ozone production, we can control nitrogen oxides and some of the hydrocarbons from combustion sources, but we can't do anything about the hydrocarbons that forest is emitting, nor should we attempt to change the amount of sunlight."An understanding of this chemistry will help to predict elevated morning ozone periods and could even be factored into air quality alerts and awareness efforts," Williams said.

Ozone Holes

May 13, 2016

https://www.sciencedaily.com/releases/2016/05/160513101012.htm

Satellite data could help reduce flights sidelined by volcanic eruptions

A volcano erupting and spewing ash into the sky can cover nearby areas under a thick coating of ash and can also have consequences for aviation safety. Airline traffic changes due to a recent volcanic eruption can rack up unanticipated expenses to flight cancellations, lengthy diversions and additional fuel costs from rerouting.

Airlines are prudently cautious, because volcanic ash is especially dangerous to airplanes, as ash can melt within an operating aircraft engine, resulting in possible engine failure. In the aftermath of a volcanic eruption, airlines typically consult with local weather agencies to determine flight safety, and those decisions today are largely based on manual estimates with information obtained from a worldwide network of Volcanic Ash Advisory Centers. These centers are finding timely and more accurate satellite data beneficial.Researchers at NASA's Goddard Space Flight Center in Greenbelt, Maryland, are using already available satellite measurements of sulfur dioxide (SOA volcanic cloud contains two kinds of aerosols: sulfuric acid droplets converted from SOKnowing both the physical location and the altitude distribution of aerosols in the volcanic cloud allow more accurate forecasts in the days, weeks and months after an eruption. "The capability of mapping the full extent of a three-dimensional structure of a moving volcanic cloud has never been done before," said Nickolay A. Krotkov, physical research scientist with the Atmospheric Chemistry and Dynamics Laboratory at NASA Goddard.Researchers are currently making these measurements using the Limb Profiler instrument, part of Ozone Mapping Profiler Suite (OMPS) instrument, currently flying on the joint NASA/National Oceanic and Atmospheric Administration (NOAA))/Department of Defense Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, launched in October 2011.OMPS is a three-part instrument: a nadir mapper that maps ozone, SO"With the OMPS instrument, the volcanic cloud is mapped as Suomi NPP flies directly overhead and then as it looks back, it observes three vertical slices of the cloud," said Eric Hughes, a research assistant at the University of Maryland, who is working with Krotkov at NASA Goddard.Knowing the timing and duration of an eruption, the altitude and amount of the volcanic emissions are critical for an accurate volcanic forecast model being developed at the Goddard Modeling and Assimilation Office. The height of the plume is particularly critical for forecasting the direction of the plume. Even several kilometers of height can make a significant difference in predicting plume movement. More accurate volcanic cloud forecasts could reduce airline cancellations and rerouting costs.While aviation is a short-term immediate application for volcanic cloud modeling, there are also long-term climate applications. "Sulfate aerosols formed after large volcanic eruptions affect the radiation balance and can linger in the stratosphere for a couple of years," said Krotkov.There have been large volcanic eruptions that have contributed to short-term cooling of Earth from the SO"Nature gives us these volcanic perturbations and then we can see the impact on climate," Krotkov said. "These are the short- and long-term consequences of volcanic eruptions that have both aviation and climate applications."

Ozone Holes

April 26, 2016

https://www.sciencedaily.com/releases/2016/04/160426144918.htm

One oil field a key culprit in global ethane gas increase

A single U.S. shale oil field is responsible for much of the past decade's increase in global atmospheric levels of ethane, a gas that can damage air quality and impact climate, according to new study led by the University of Michigan.

The researchers found that the Bakken Formation, an oil and gas field in North Dakota and Montana, is emitting roughly 2 percent of the globe's ethane. That's about 250,000 tons per year."Two percent might not sound like a lot, but the emissions we observed in this single region are 10 to 100 times larger than reported in inventories. They directly impact air quality across North America. And they're sufficient to explain much of the global shift in ethane concentrations," said Eric Kort, U-M assistant professor of climate and space sciences and engineering, and first author of the study published in The Bakken is part of a 200,000-square-mile basin that underlies parts of Saskatchewan and Manitoba in addition to the two U.S. states. It saw a steep increase in oil and gas activity over the past decade, powered by advances in hydraulic fracturing, or fracking, and horizontal drilling.Between 2005 and 2014, the Bakken's oil production jumped by a factor of 3,500, and its gas production by 180. In the past two years, however, production has plateaued.Ethane is the second most abundant atmospheric hydrocarbon, a family of compounds made of hydrogen and carbon. Ethane reacts with sunlight and other molecules in the atmosphere to form ozone, which at the surface can cause respiratory problems, eye irritation and other ailments and damage crops.Surface-level ozone is one of the main pollutants that the national Air Quality Index measures in its effort to let the public know when breathing outside for long periods of time could be harmful. Low-altitude ozone also plays a role in climate change, as it is a greenhouse gas and the third-largest contributor to human-caused global warming after carbon dioxide and methane.Globally, the atmosphere's ethane levels were on the downswing from 1984 to 2009. The gas gets into the air primarily through leaks in fossil fuel extraction, processing and distribution. Scientists attributed its declining levels to less venting and flaring of gas from oil fields and less leakage from production and distribution systems.But in 2010, a mountaintop sensor in Europe registered an ethane uptick. Researchers looked into it. They hypothesized that the boom in U.S. oil and gas brought about by hydraulic fracturing could be the culprit--even a continent away. Ethane concentrations have been increasing ever since.To gather their data, the researchers flew over the Bakken Formation in a NOAA Twin Otter aircraft, sampling air for 12 days in May 2014. Their airborne measurements from directly over and downwind of oil production areas show that the field's ethane emissions of 0.23 teragrams per year, or roughly 250,000 U.S. tons, effectively cancel out half of the global decline rate."These findings not only solve an atmospheric mystery--where that extra ethane was coming from--they also help us understand how regional activities sometimes have global impacts," said co-author Colm Sweeney, a scientist with the Cooperative Institute for Research in Environmental Sciences at the University of Colorado Boulder, and NOAA. "We did not expect a single oil field to affect global levels of this gas."Ethane emissions from other U.S. fields, especially the Eagle Ford in Texas, likely contributed as well, the research team says. The findings illustrate the key role of shale oil and gas production in rising ethane levels.

Ozone Holes

April 21, 2016

https://www.sciencedaily.com/releases/2016/04/160421112816.htm

Unhealthy ozone days could increase by more than a week in coming decades

If emission rates continue unchecked, regions of the United States could experience between three and nine additional days per year of unhealthy ozone levels by 2050, according to a new study from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) published in

"In the coming decades, global climate change will likely cause more heat waves during the summer, which in turn could cause a 70 to 100 percent increase in ozone episodes, depending on the region," said Lu Shen, first author and graduate student at SEAS.California, the Southwest, and the Northeast would be the most affected, each possibly experiencing up to nine additional days of dangerous ozone levels, with much of the rest of the country experiencing an average increase of 2.3 days.This increase could lead to more respiratory illness with especially dangerous consequences for children, seniors, and people suffering from asthma."Short-term exposure to ozone has been linked to adverse health effects," said Loretta J. Mickley, a co-author of the study. "High levels of ozone can exacerbate chronic lung disease and even increase mortality rates."While temperature has long been known as an important driver of ozone episodes, it's been unclear how increasing global temperatures will impact the severity and frequency of surface level ozone.To address this question, Shen and Mickley -- with coauthor Eric Gilleland of the National Center for Atmospheric Research (NCAR) -- developed a model that used observed relationships between temperature and ozone to predict future ozone episodes.Previous research had not relied so heavily on existing observations, making projections uncertain. Shen and co-authors analyzed ozone-temperature relationships at measurement sites across the US, and found them surprisingly complex."Typically, when the temperature increases, so does surface ozone," said Mickley."Ozone production accelerates at high temperatures, and emissions of the natural components of ozone increase. High temperatures are also accompanied by weak winds, causing the atmosphere to stagnate. So the air just cooks and ozone levels can build up."However, at extremely high temperatures -- beginning in the mid-90s Fahrenheit -- ozone levels at many sites stop rising with temperature. The phenomena, previously observed only in California, is known as ozone suppression.In order to better predict future ozone episodes, the team set out to find evidence of ozone suppression outside of California and test whether or not the phenomena was actually caused by chemistry.They found that 20 percent of measurement sites in the US show ozone suppression at extremely high temperatures. Their results called into question the prevailing view that the phenomenon is caused by complex atmospheric chemistry."Rather than being caused by chemistry, we found that this dropping off of ozone levels is actually caused by meteorology," said Shen. "Typically, ozone is tightly correlated with temperature, which in turn is tightly correlated with other meteorological variables such as solar radiation, circulation and atmospheric stagnation. But at extreme temperatures, these relationships break down.""This research gives us a much better understanding of how ozone and temperature are related and how that will affect future air quality," said Mickley. "These results show that we need ambitious emissions controls to offset the potential of more than a week of additional days with unhealthy ozone levels."

Ozone Holes

March 10, 2016

https://www.sciencedaily.com/releases/2016/03/160310124920.htm

Higher ozone, lower humidity levels associated with dry eye disease

In a study published online by

Air pollution is an important public health concern. According to the World Health Organization, most significant constituents of air pollution include particulate matter (PM), ozone, nitrogen dioxide, and sulfur dioxide. Ambient levels of air pollution are known to be associated with a wide range of adverse health effects that particularly affect the respiratory and cardiovascular systems. Ocular surface abnormalities related to air pollution are thought to be a subtype of dry eye disease (DED); however, to date, there has been no large-scale study evaluating an association between air pollution and DED that includes multiple air pollutants.This study included data on 16,824 participants in the fifth Korea National Health and Nutrition Examination Survey, conducted from January 2010 to December 2012. Dry eye disease was defined as previously diagnosed by an ophthalmologist or the presence of frequent ocular pain and discomfort, such as feeling dry or irritated. Outdoor air pollution measurements (average annual humidity, particulate matter with aerodynamic diameter <10 µm [PM10], ozone, and nitrogen dioxide levels) were collected from 283 national monitoring stations in South Korea.The researchers found that decreased humidity levels and increased ozone levels were associated with DED, after controlling for known risk factors such as sex, dyslipidemia, thyroid disease, subjective health awareness, and previous ocular surgery. "These results, however, are just associations and do not definitively indicate a cause-and-effect relationship between DED and outdoor air pollution."PM10, one of the leading public health issues, was not associated with DED. The authors speculate that possible explanations for this finding is that reflex tearing might help flush PM from the ocular surface, or that environmental PM10 levels currently in Korea are not high enough to induce adverse effects on the ocular surface.

Ozone Holes

March 9, 2016

https://www.sciencedaily.com/releases/2016/03/160309140038.htm

Excess heat significantly affects health of migratory workers

Hot weather is significantly associated with clinical visits among migratory farmworkers compared to other patients, according to a study by researchers at The University of Texas Health Science Center at Houston (UTHealth) published recently in the journal

Lead author Kai Zhang, Ph.D., assistant professor in the Department of Epidemiology, Human Genetics and Environmental Sciences at UTHealth School of Public Health, used data from the Community and Migrant Health Center in Colorado to compare clinical visits among migratory farmworkers, seasonal farmworkers and non-farmworkers.Migratory farmworkers are those who travel for agricultural work while seasonal workers do not change homes or travel away from their established homes for work.Zhang measured heat effects by using weather data obtained from the National Climate Data Center and ozone levels from the U.S. Environmental Protection Agency (EPA).Throughout the summer of 2013, the year in which the data was collected, the average of daily mean temperatures was 71 degrees Fahrenheit and average daily ozone concentrations ranged from 0.036 to 0.074 parts per million. The current national standard for ozone is 0.070 parts per million, according to the EPA.When Zhang compared hot days to average days, he found that migratory workers were 88 percent more likely to visit a clinic when not factoring in ozone levels and 96 percent more likely when factoring in high ozone levels. There was no significant increase for clinic visits among seasonal farmworkers when temperature and ozone levels were high."Migratory workers are more susceptible to heat-related health issues for several possible reasons. They tend to have poorer living environments, including a lack of air conditioning; suffer from poverty, which has been linked to a higher risk of vulnerability to heat; and may lack family support for prolonged periods of time. Also, their immigration status may make them more vulnerable to labor abuses," said Zhang.Zhang found that the impact of heat on migratory farmworkers was more significant among males than females. Men were 118 percent more likely to visit a clinic on hot days compared to normal days while women were 57 percent more likely to visit a clinic on hot days."Heat has a significant impact on migratory farmworkers, even in a moderate summer. This research suggests possible significant impact of heat on migratory farmworkers and provides justification for undertaking further studies, making regulations and developing heat preventive programs," said Zhang.While the research was done in Colorado, Zhang notes that Texas has a much hotter summer than Colorado and is the second largest agricultural state in the United States. With many migratory farmworkers supporting the agricultural industry in Texas, Zhang says his study suggests that migratory farmworkers in Texas might suffer even more heat stress than those in Colorado. He hopes to access the same data in Texas in future research.

Ozone Holes

February 29, 2016

https://www.sciencedaily.com/releases/2016/02/160229182704.htm

Ozone depletion chemicals: Tracking down lingering source of carbon tetrachloride emissions

Carbon tetrachloride (CCl4) was once commonly used as a cleaning agent and remains an important compound in chemical industry. CCl4 is responsible for that sickly sweet smell associated with dry cleaning solvents from decades ago. It's a known air toxin and it eats away at the ozone layer--the gas accounts for about 10-15 percent of the ozone-depleting chemicals in the atmosphere today. As a result, production across the globe has been banned for many years for uses that result in CCl4 escaping to the atmosphere.

Given these stringent limits, the chemical is being released into the air at small rates here in the United States, but a new study reports those rates are still 30 to 100 times higher than amounts reported to emission inventories.That study, led by CIRES scientist Lei Hu and NOAA scientist Stephen Montzka, also suggests that the source of the unexpected emissions in the U.S. appears associated with the production of chlorinated chemicals (such as those ultimately used to create things like Teflon and PVC). The new analysis is published today in the In the 1980s, when scientists discovered that CCl4 was contributing to the destruction of the ozone layer, the synthetic compound was included on a list of substances to be phased out of production. That list, part of the Montreal Protocol on Substances that Deplete the Ozone Layer, required that production for dispersive use (uses that would result in escape to the atmosphere) of CCl4 be discontinued in developed countries by 1996, and in developing countries by 2010.Despite that phase out, the decline of CCl4 in the atmosphere has been unexpectedly slow. That left many scientists puzzled, including Montzka, who works in NOAA's Earth System Research Laboratory (ESRL) and is also a CIRES Fellow. "We've been scratching our heads, trying to understand why," he said. "When we look at the amounts produced and destroyed, which industry throughout the world has reported to the Ozone Secretariat, we would expect the chemical's global concentration to be decreasing at a rate of nearly 4 percent per year. But it's only decreasing at 1 percent per year. So what's happening?"To investigate the U.S. contribution, Montzka, Hu and colleagues from NOAA, CIRES, and other scientific institutions studied observations made from NOAA's North American air sampling network. Since the late 2000s, they tracked the composition of the atmosphere from this network of nine tall towers and many more regular aircraft-sampling sites across North America. "We wanted to identify where these emissions were coming from, as well as their magnitude," Hu said.She and her colleagues considered landfills, where residual amounts of CCl4 might still be leaking from old fire extinguishers or solvent cans, given that CCl4 was used for these purposes in the early to mid-1900s. The team looked at high-density population areas to determine if the use of bleach or chemicals in laundry or swimming pools might be responsible for the emissions they detected. They also checked into industrial sources--and here they had some help. The Environmental Protection Agency requires industries to report CCl4 emissions. Hu and Montzka were able to compare that information against what they derived from their precise atmospheric measurements of CCl4 concentrations across the country. The analysis of all those data suggests that the CCl4 emissions arise from the same geographic areas as those industries reporting to the EPA. Not a huge surprise, but the amount found was 30 to 100 times higher than what was being reported. The most significant hot spot was the Gulf Coast region, with smaller emissions in Colorado and California."We can't tell exactly what the sources of emissions are," said Montzka. "It could be underreporting from known sources, it could be an unknown source, it could be both. It could be some other activity that's geographically tied to the production of chlorinated chemicals and products that hasn't been recognized previously as a significant source."Hu and Montzka said they hope their work inspires more research, both here in the United States and internationally, to better pin down the precise reasons for excess emissions. The researchers reported in the new paper that the United States has been responsible for about 8 percent of the overall global CCl4 emissions in recent years. If the processes that emit CCl4 in the U.S. also happen in other places, it would go a long way towards explaining the slow rate of decline of CCl4 in the global atmosphere."Before this work," said Montzka, "There'd been very little progress on understanding the mystery of continuing global emissions of CCl4. Now we have a better picture, at least in the United States, of where some of those emissions are coming from. That's the first step towards minimizing emissions in the future and speeding up the recovery of the ozone layer."

Ozone Holes

February 25, 2016

https://www.sciencedaily.com/releases/2016/02/160225140040.htm

Ozone does not necessarily promote decline of natural ecosystems

Environmental scientists at the University of Virginia have found that surface ozone, an abundant chemical known to be toxic to many species of vegetation and to humans, does not necessarily inhibit the productivity of natural ecosystems.

"This is a rare piece of good news in the ozone and ecology story," said Manuel Lerdau, an ecologist who, along with graduate student Bin Wang, post-doctoral fellow Jacquelyn Shuman and Professor Hank Shugart, published their findings this week in the Though ozone is essential to the health of the Earth in the upper atmosphere -- where it shields the surface from excess ultraviolet radiation -- the chemical in high concentrations at surface level is hazardous to human and animal health and to many species of plant life. Ozone becomes most abundant at the Earth's surface during the summertime as plants grow and produce chemicals, such as isoprene, that react with the hydroxyl radical and nitric oxide (which comes primarily from automobiles) to produce ozone.While it is known that ozone hinders the growth of many kinds of plants, including crop vegetation, the extent to which ozone damaged natural systems was not well understood.The new finding suggests that unmanaged forests remain productive as systems because they contain multiple tree species, each with a different sensitivity to ozone, and this differential sensitivity to the chemical allows the more resistant species to compensate for the damages suffered by the more sensitive ones.The researchers used a computer model of forest growth and production that is well-tested in a variety of ecosystems to study how species-specific responses to ozone can change the competitive interactions among species. They found that ozone changes the relative abundances of tree species, but that overall ecosystem productivity -- the rate of biomass generation -- and the ability of the ecosystem to store carbon do not change in the face of ozone pollution. Previous research that modeled forests broadly but not species-specifically did not discern these species-specific compensatory changes."While our results do not mean that we can dismiss or ignore ozone's impacts on forests, they do suggest that these impacts will be more in the realm of species composition and less at the scale of forest function," Lerdau said.He added, however, that the study also indicates that low-diversity systems, such as crops and managed forests, will have maximal ozone sensitivity because of the lack of inter-species compensation.The findings also suggest that ozone-resistant species -- which produce the ozone-promoting chemical isoprene -- could, while increasing ozone concentrations, create favorable conditions for their own production. This facilitates a feedback loop of ever-increasingly favorable conditions for ozone-resistant species, likely to the detriment of less-resistant species. This ultimately could result in less diversified forests."The study is an important step toward understanding how individual species and biodiversity affect the health, integrity and functioning of ecosystems," Lerdau said.

Ozone Holes

February 24, 2016

https://www.sciencedaily.com/releases/2016/02/160224223112.htm

Tropical fires fuel elevated ozone levels over western Pacific Ocean

A diverse team of atmospheric chemists, meteorologists and modelers, including scientists from NASA, has traced the origins of mysterious pockets of high ozone concentrations and low water vapor in the air above the western Pacific Ocean near Guam to fires burning in Southeast Asia and in Africa, half a world away.

These pockets of ozone--a powerful greenhouse gas--are three times more concentrated than surrounding air and are found at around 30,000 feet in the lower part of Earth's atmosphere known as the troposphere, within the cruising altitude of most commercial airliners. As a greenhouse gas, ozone in the troposphere is an important contributor to global warming, but because it varies widely in where it occurs and how long it stays aloft, its true impact on climate change is hard to determine.Scientists have observed the anomaly in ozone concentrations in the past, theorizing that the ozone had descended from a higher layer of the atmosphere called the stratosphere, where the air is dry and ozone acts as a protective layer, since it blocks harmful ultraviolet radiation from reaching Earth's surface.But researchers studying the air over Guam during the winter of 2014 during a pair of field campaigns, called the Convective Transport of Active Species in the Tropics and the Co-ordinated Airborne Studies in the Tropics, found something surprising. The scientific instruments aboard the two research aircraft captured a more comprehensive picture of the chemicals traveling with the ozone--chemicals such as hydrogen cyanide and acetonitrile, which originate in fires."When we saw high ozone [concentrations] we also saw very high concentrations of those other [chemical] species, so it was a pretty strong indicator that fires were at least playing some sort of role in the ozone production," said Daniel Anderson, lead author and graduate student at the University of Maryland, College Park, who was part of the international research team studying the atmosphere above the Western Pacific. The effort was funded by the National Science Foundation, the National Oceanic and Atmospheric Administration and NASA. The results were published in the journal To determine if the ozone and the accompanying chemicals came from fires, Anderson and his colleagues used a computer model to trace the air pockets backwards through time based on wind and other factors. The model uses observed weather data combined with the simulated behavior of the atmosphere to find where the wind came from one hour previously, and then based on the new location, where the wind came from the hour before that, and so on, determining the history of the air pocket as it moved through the atmosphere.Anderson and his colleagues traced the ozone-laden air pockets back 10 to 15 days in most cases--right back to fires in either Southeast Asia, about 2,000 miles away, or tropical Africa, over 8,000 miles away."We were surprised at how well it worked out, because it created a very clear picture," Anderson said.Ozone is a byproduct of burning organic material like trees and other vegetation--or of the combustion of fossil fuels in industrial settings. Burning organic matter transforms part of the carbon that was in the vegetation into its gaseous forms, including carbon dioxide, methane and what are known as volatile organic compounds. Volatile organic compounds combine with another byproduct of burning, nitrogen oxides, and together they form ozone in the presence of sunlight.The smoke plumes from the fires and updrafts from large storm systems then lift the ozone--along with ozone precursors, which continue to react in transit, and other tracer compounds produced by fires--high into the atmosphere where winds transport them thousands of miles away.The high-altitude transport also explains why the air pockets are drier than the surrounding air, Anderson said. Dry air is normally associated with the stratosphere--the previous hypothesis--because air found higher in the atmosphere is colder, and thus cannot hold as much moisture. But the upper troposphere is also much colder than the lower troposphere, achieving the same effect of drying out the high ozone air pockets. Then, when they slowly descend over the western Pacific due to normal atmospheric circulation, the air pockets continue to have lower water vapor than their surroundings.Tropical fires have long been known to have an impact on the atmosphere, said Bryan Duncan, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, who was not involved in the research. The next step, he said, will be to evaluate how this new understanding of tropical fires as another the source for ozone in the western Pacific affects the greenhouse potential for both the region and the climate on a broader scale."What they've shown here is that it's more complicated than we thought," he said.

Ozone Holes

February 18, 2016

https://www.sciencedaily.com/releases/2016/02/160218060933.htm

POLSTRACC measurement campaign: Strong ozone depletion above Arctic possible

This winter, the Arctic stratosphere so far has been unusually cold. Hence, all prerequisites are given for strong ozone depletion in the next weeks. This conclusion is based on first results of the POLSTRACC measurement campaign, coordinated by Karlsruhe Institute of Technology (KIT), that has been conducted in the Arctic since December 2015. Of particular importance are vertically extended polar stratospheric clouds that have been observed to cover wide areas of the Arctic. At their surface, chemical reactions take place, which constitute the ground for ozone depletion. This winter, these clouds have been observed down to the lowermost stratosphere, which is very unusual for the Arctic.

"For a period of several weeks, wide areas of the Arctic were covered by polar stratospheric clouds between about 14 and 26 kilometers height. Such conditions are more likely in the Antarctic ozone hole than in the typically much warmer Arctic," Björn-Martin Sinnhuber, KIT, says. He coordinates the POLSTRACC measurement campaign together with his colleague Hermann Oelhaf. At the surface of polar stratospheric clouds, chemical reactions take place, converting passive chlorine compounds into reactive compounds that trigger stratospheric ozone depletion. In addition, particles of these clouds may descend and withdraw reactive nitrogen from the chlorine-activated layer -- active chlorine is one of the substances mainly responsible for ozone destruction. The consequence: Active chlorine buffering is lacking and ozone depletion is enhanced or extended. Actually, the scientists have already observed a redistribution of reactive nitrogen and signs of chlorine activation during measurement flights earlier this winter.Investigating the polar stratosphere under the impact of climate change is the goal of the measurement campaign "The Polar Stratosphere in a Changing Climate" (POLSTRACC), carried out with the German research aircraft HALO. Partners in the campaign are the German Aerospace Center (DLR), Forschungszentrum Jülich (FZJ), the Universities of Frankfurt, Mainz, Heidelberg, and Wuppertal, and the Physikalisch-Technische Bundesanstalt (PTB, national metrology institute of Germany). First research flights were made in December from Germany. Between early January and early February, a total of eight research flights with nearly 70 flight hours were made from Kiruna in northern Sweden to study the Arctic stratosphere up to the North Pole. The campaign is supported by ground-based measurements at various stations, analysis of satellite data, and model calculations."We were very much surprised to find polar stratospheric clouds down to heights of about 14 km," Björn-Martin Sinnhuber says. "These are conditions we know from the Antarctic, but they are highly unusual in the Arctic," Hermann Oelhaf adds. Every spring, an ozone hole forms above the Antarctic due to very cold stratospheric conditions there. In contrast to this, strong ozone depletion above the Arctic was observed in a few cold winters only. Ozone depletion is caused by chlorine and bromine substances emitted in the form of chlorofluorocarbons (CFC) and other substances in the past decades. The production of these substances has been regulated and largely prohibited already for more than 20 years by the Montreal Protocol and further international agreements on the protection of the ozone layer. Nevertheless, previous emissions will remain in the atmosphere for many decades as the ozone depleting substances decompose very slowly. Chlorine and bromine have a particularly high ozone-depleting effect when it is very cold for a sufficiently long period of time. "This is where climate change comes in: While the increase in greenhouse gases leads to the warming of atmospheric layers close to the ground it causes a cooling of the stratosphere. And this may cause massive ozone depletion even in case of reduced loads of chlorine and bromine," Oelhaf points out. To what extent climate change due to the emission of greenhouse gases may favor the formation of an "ozone hole" in the Arctic stratosphere is an important topic of the POLSTRACC campaign.In the last week of February, the researchers will again set out for the Arctic to observe until mid-March the further development in detail. "Then, it will turn out whether the conditions observed now really lead to a strong ozone depletion or whether a currently observed warming of the stratosphere will prevail and may mitigate ozone depletion this winter," Sinnhuber explains. Work then will also focus on studying to what extent chlorine-activated and ozone-depleted air masses will make its way into the densely populated middle latitudes.

Ozone Holes

February 16, 2016

https://www.sciencedaily.com/releases/2016/02/160216104921.htm

In a U.S. first, team measures lightning-produced ozone with lidar

Scientists at The University of Alabama in Huntsville (UAH) have used UAH's Rocket-city Ozone (O3) Quality Evaluation in the Troposphere (RO3QET) Lidar to measure ozone that was chemically produced by summertime lightning over the United States, research that could be important to air quality prediction and assessment once it is developed further.

"This is the first time in the United States that we have used high-resolution Lidar data to determine lightning's impact on tropospheric ozone," says Dr. Lihua "Lucy" Wang, a UAH Earth Systems Science Center (ESSC) research associate who was the lead author of a research paper on the team's findings.The ESSC team used data from a Lidar facility on the top floor of The National Space Science Technology Center (NSSTC) in Cramer Research Hall, one of just five such atmospheric Lidar facilities in the U.S. and about 15 worldwide.Lidar uses a laser beam to collect data, so it is effective only during clear conditions. Vaisala's U.S. National Lightning Detection Network (NLDN) monitors total lightning activity across the continental United States, 24 hours a day, 365 days a year. The UAH team estimated lightning nitric oxide (NO) emissions based on NLDN observations, measured the resulting ozone created by the lightning downwind of the storms, where clear conditions allowed Lidar to function and quantified the ozone enhancements due to lightning.The troposphere is the lowest layer of atmosphere on Earth and produces the planet's weather. Above it is the stratosphere, a layer of thinner atmosphere. The denser troposphere is separated from the stratosphere by a large temperature inversion called the tropopause.Tropospheric ozone -- a greenhouse gas and the kind that affects the air we breathe -- can increase in concentration because of atmospheric conditions, or can result from human activities. In the winter, intermixing of stratospheric ozone with the troposphere in a process called Stratospheric Tropospheric Exchange (STE) is the chief means of ozone transport into our air, but Dr. Wang says in summertime that process subsides and lightning bolts create significant ozone enhancements in the middle to upper troposphere, particularly in the Southeastern US."During the summertime, the lightning produced very important ozone enhancements in the upper troposphere. When lightning introduces ozone into the upper troposphere, there is some downward transport mechanism that will affect lower tropospheric ozone " Dr. Wang says."In the troposphere, ozone is considered a bad gas," says Dr. Wang. "It can worsen bronchitis, emphysema and asthma." If ground-level ozone exceeds 70 parts per billion, the U.S. Environmental Protection Agency issues an air quality advisory."We are investigating the processes that influence the ozone production," Dr. Wang says. The first Lidar measurements of lightning-generated ozone have opened a door to further research. "There are still many uncertainties in this research that we are trying to improve upon."

Ozone Holes

January 25, 2016

https://www.sciencedaily.com/releases/2016/01/160125160348.htm

Ozone levels elevated in presence of wildfire smoke

For those living with the threat to life and property from wildfires, Colorado State University scientists have some more bad news: Wildfire smoke seems to elevate levels of ozone, a nasty air pollutant with proven adverse health effects.

The influence of wildfire smoke on ozone levels during summer months in the United States is not well understood. CSU atmospheric science researchers took a comprehensive, multi-year look at this secondary, insidious effect of raging wildfires. Published in Environmental Science and Technology, the new study quantifies what wildfire smoke does to ozone levels over a nearly 10-year span, integrating data from hundreds of monitoring sites dotting the country.Across the U.S., ozone levels were higher on smoky days than on smoke-free days, according to the study led by Steven Brey, a graduate student working with Emily Fischer, assistant professor of atmospheric science in CSU's College of Engineering. According to Brey's analysis, a number of urban areas had smoke present during 10 percent to 20 percent of days when the standard Environmental Protection Agency ozone levels of 70 parts per billion (ppb) were exceeded. The EPA reset the ozone standard down from 75 ppb late last year, making it more stringent.Ozone is one of six "criteria pollutants" monitored by the EPA, and its adverse effects particularly on the young, elderly and people with asthma are well documented. "Good up high; bad nearby" is the EPA's description of ozone -- the ozone layer of Earth's atmosphere protects us from UV radiation from space, but down where we breathe, it damages lungs and destroys crops and ecosystems.Typically, the effect of smoke on ozone levels is studied on a "plume-by-plume basis," Fischer explained. "A wildfire will be burning and someone will take an aircraft, like the NSF/NCAR C-130 or the NASA DC-8, fly around in it, and take measurements. What Steve did was take ground-level data … to look nationwide, not just at one fire or one plume, but every ground site from 2005 to 2014."Predicting the relationship of ozone and wildfire smoke requires an understanding of nonlinear ozone chemistry, which is tricky. In the past, some individually analyzed smoke plumes have been linked to a dramatic production of ozone, Fischer said, but others have seen ozone production actually suppressed within wildfire smoke.Whether and how much ozone is produced is influenced by many fleeting factors. To make ozone, you need volatile organic compounds, nitrogen oxide and sunlight, interactions that can be determined by the amount of those chemicals in the air, how much sunlight is getting through the smoke, how hot the fire is burning, what is burning, and other variables. And smoke moves, disperses and becomes dilute over time. It's really hard to determine how all these factors work together to make, or not make, ozone.Brey gathered data from 2005-2014 from the NOAA Hazard Mapping System, which uses satellites to visually track smoke plumes from areas of open burning. Armed with that data, Brey compared ozone levels on days when smoke was present with days when smoke wasn't present, and built an expected value of ozone levels for those days. Taken together, on the smoky days, ozone levels were higher.That effect was marked around certain areas in particular: the Northeast corridor, Dallas, Houston, Atlanta, Birmingham, and Kansas City. "Which is not what you'd expect," Fischer said, because wildfires don't necessarily burn near cities. But the data indicate that as the smoke plumes travel, higher levels of ozone can be more often expected in urban than in rural areas.That observation hints that wildfire smoke interacts with pollutants in urban air to create ozone. The data support the hypothesis, but a definitive claim can't be made yet.With climate change predicted to increase overall temperatures and thus the intensity and frequency and wildfires, the study points to more questions about how smoke will affect ozone levels going forward.

Ozone Holes

January 22, 2016

https://www.sciencedaily.com/releases/2016/01/160122103829.htm

Storms, ozone may play pivotal role in rainforest cloud creation

Some storms transport ozone molecules to the canopy of the rainforest, influencing chemical processes that ultimately affect cloud formation, according to an international research team led by Penn State. The team conducted a nine-month study in the central Amazon rainforest of Brazil and their findings could be used to improve climate prediction models to more accurately gauge the Amazon's impact on future global weather patterns.

"The Amazon rainforest plays an important role in the southern hemisphere by transpiring moisture that is transported by clouds to many places that need precipitation," said Jose D. Fuentes, professor of meteorology, Penn State. "However, there's a big gap in our knowledge of the underlying processes that influence the formation of clouds."The team conducted its study in the Brazilian Amazon rainforest because it has a "clean" environment that is relatively free of ozone and pollutants."In the clean tropical Amazon there is typically much less ozone near the Earth's surface compared to more industrialized areas," said Tobias Gerken, postdoctoral scholar in meteorology, Penn State. "This is because ozone is formed from the reactions of pollutants, nitrous oxides, sunlight and oxygen."The team monitored levels of various trace gases, such as ozone, and meteorological variables, such as precipitation and wind speed, under the canopy of the rainforest. They found that deep, convective storms transported ozone-rich air parcels from the Earth's atmosphere to the surface, rapidly increasing surface ozone levels from 5 parts per billion by volume (ppbv) to nearly 40 ppbv."Deep, convective storms have two channels, one with upward moving air and another with downward moving air," said Fuentes. "Downdrafts bring ozone molecules down from the upper troposphere (the lower layer of Earth's atmosphere) to the surface where they can mix and react with other chemicals."This increase of ozone at the Earth's surface can influence several atmospheric chemical processes, some of which may affect cloud formation via the reaction of plant emitted hydrocarbons. These reactions result in the formation of aerosols. Clouds form when water vapor rises into the atmosphere, cools, and condenses onto aerosol particles that act as cloud condensation nuclei or "cloud seeds." When enough water vapor condenses on these nuclei, a visible cloud forms.In the rainforest, the team found that this process can be initiated and accelerated when ozone interacts with hydrocarbons, which are molecules made of hydrogen and carbon that are naturally produced and emitted by vegetation. The hydrocarbons react with ozone -- then, through a chain of chemical reactions, the hydrocarbons transform into other molecules, which condense and can eventually result in the formation of cloud condensation nuclei.In addition, when ozone oxidizes hydrocarbons, it results in the formation of a second kind of molecule that oxidizes and breaks down hydrocarbons -- hydroxyl radicals, which are molecules made of one hydrogen and one oxygen molecule. Hydroxyl radicals are commonly considered the cleaning agent, or detergent, of the lower atmosphere because they initiate the breakdown of many pollutants as well as hydrocarbons. When ozone rose from 5 ppbv to 30 ppbv, this could nearly double the production rate of hydroxyl radicals, the group found.These changes in atmospheric chemistry resulted in a much quicker breakdown rate and shorter lifespan for hydrocarbons, the team found. For example, a group of hydrocarbons known as monoterpenes, which normally live for up to 90 hours when ozone is at 10 ppbv, only lived 20 hours when ozone increased to 40 ppbv.The team also found that ozone levels in the rainforest remained elevated for more than two hours after storms, which highlights the importance of the ozone increases. Storms occurring during both night and day increase the oxidation and breakdown of hydrocarbons in the lower atmosphere for an extended amount of time.This study also investigated the variety and amount of hydrocarbon gases being produced naturally in the Amazon rainforest. The team found the presence of more than 25 different types of hydrocarbons, all of which could play a role in cloud formation."The more we know about the rainforest's atmospheric chemistry and how that can influence cloud formation, the more we'll understand the Amazon's role in global weather patterns -- and how changes in the rainforest could affect those patterns," said Fuentes.The team published its findings in the current issue of Collaborators on the research included Marcelo Chamecki, professor, Dandan Wei and Livia S. Freire, graduate students in meteorology, Penn State; Randy Chase, Brockport State University of New York; Courtney Schumacher, Texas A&M; Luiz Machado and Celso von Randow, Instituto Nacional de Pesquisas Espaciais; Rita V. Andreoli, Rodrigo A. Ferreira de Souza, Rosa M. Nascimento dos Santos and Patrícia dos Santos Costa, Universidade do Estado do Amazonas; Angela Jardine and Antonio Manzi, Instituto Nacional de Pesquisas da Amazonia; Paul Stoy and Amy Trowbridge, Montana State University; and Julio Tiota, Universidade Federal do Oeste do Para.The U.S. Department of Energy funded this work as part of its Observations and Modeling of the Green Ocean Amazon (GOAmazon 2014/5) project.

Ozone Holes

January 20, 2016

https://www.sciencedaily.com/releases/2016/01/160120122759.htm

Long-term exposure to ozone may increase lung and cardiovascular deaths

Adults with long-term exposure to ozone (O

Using data from a large U.S. study begun in 1982, researchers found that every additional 10 parts per billion (ppb) in long-term ozone exposure increased the risk of dying by:Researchers said the increased risk of death was highest for diabetes (16 percent), followed by dysrhythmias, heart failure and cardiac arrest (15 percent) and by COPD (14 percent)."About 130 million people are living in areas that exceed the National Ambient Air Quality standard," said Michael Jerrett, PhD, chair of environmental health sciences at UCLA and study co-author. "While ozone has decreased in the U.S., the reductions are not nearly as big as decreases in other pollutants, and elsewhere in the world, ozone is a growing problem."The authors analyzed data from nearly 670,000 records in the American Cancer Society Cancer Prevention Study (CPS-II). Begun in 1982, the study enrolled participants from all 50 states; the average age at enrollment was 55. The researchers matched cause of death over 22 years with U.S. Environmental Protection Agency and Centers for Disease Control air quality data. During that time, more than 237,000 participants died.Researchers took into account fine particulate (PM2.5) pollution, an established cause of premature mortality, and nitrogen dioxide (NOResearchers found the association between ozone and mortality began at 35 ppb, based on the annual 8-hour average. They said that many communities are above this level, suggesting further reductions in ozone would have immediate health benefits. Dr. Jerrett added that reducing ozone, a potent greenhouse gas, would also provide future health benefits by reducing climate change.Researchers were surprised by one finding: near-source PM2.5, largely attributable to traffic, was more strongly associated with death from cardiovascular disease than regional PM2.5, largely attributable to fossil-fuel burning and secondary formation of the particles in the atmosphere. With each 10-ppb increase in near-source PM2.5, mortality rate rose 41 percent, compared to 7 percent for regional source.Michelle C. Turner, PhD, lead author and a research fellow at the McLaughlin Centre for Population Health Risk Assessment, in Ottawa, and the Centre for Research in Environmental Epidemiology ISGlobal Alliance, in Barcelona, said the findings gave a clearer picture of air pollution's harmful effects. A previous study with fewer participants, shorter follow-up and less detailed exposure models found ozone was associated with a smaller (4 percent) increase in respiratory deaths. In this larger study, researchers were also able to focus on specific causes of mortality."The burden of cardiovascular and respiratory mortality from ozone may be much greater than previously recognized," she said.

Ozone Holes

January 13, 2016

https://www.sciencedaily.com/releases/2016/01/160113100550.htm

Fires burning in Africa, Asia cause high ozone in tropical Pacific

As decision makers from around the world congregated in Paris to prepare a global climate agreement at the 21st Conference of the Parties (COP21), many discussions focused on how to reduce greenhouse gases, including ozone.

While efforts to limit ozone precursor emissions tend to focus on industrial activities and fossil fuel combustion in the United States and China, a new study suggests that future regulations may need to address the burning of forests and vegetation. The study, which was published online January 13, 2016 in the journal Based on observations from two aircraft missions, satellite data and a variety of models, an international research team showed that fires burning in tropical Africa and Southeast Asia caused pockets of high ozone and low water in the lower atmosphere above Guam--a remote island in the Pacific Ocean 1,700 miles east of Taiwan."We were very surprised to find high concentrations of ozone and chemicals that we know are only emitted by fires in the air around Guam," said the study's lead author Daniel Anderson, a graduate student in the University of Maryland Department of Atmospheric and Oceanic Science. "We didn't make specific flights to target high-ozone areas--they were so omnipresent that no matter where we flew, we found them."For the study, two research planes on complementary missions flew over Guam measuring the levels of dozens of chemicals in the atmosphere in January and February 2014. One aircraft flew up to 24,000 feet above the ocean surface during the U.K. Natural Environment Research Council's Coordinated Airborne Studies in the Tropics (CAST) mission. The other flew up to 48,000 feet above the ocean surface during the CONvective Transport of Active Species in the Tropics (CONTRAST) mission."International collaboration is essential for studying global environmental issues these days," said CAST Principal Investigator Neil Harris of the University of Cambridge Department of Chemistry. "This U.S./U.K.-led campaign over the western Pacific was the first of its kind in this region and collected a unique data set. The measurements are now starting to produce insight into how the composition of the remote tropical atmosphere is affected by human activities occurring nearly halfway around the world."Researchers examined 17 CAST and 11 CONTRAST flights and compiled over 3,000 samples from high-ozone, low-water air parcels for the study. In the samples, the team detected high concentrations of chemicals associated with biomass burning--hydrogen cyanide, acetonitrile, benzene and ethyne."Hydrogen cyanide and acetonitrile were the smoking guns because they are emitted almost exclusively by biomass burning. High levels of the other chemicals simply added further weight to the findings," said study co-author Julie Nicely, a graduate student in the UMD Department of Chemistry and Biochemistry.Next, the researchers traced the polluted air parcels backward 10 days, using the National Oceanic and Atmospheric Administration (NOAA) Hybrid Single Particle Lagrangian Integrated Trajectory (HYSPLIT) model and precipitation data, to determine where they came from. Overlaying fire data from NASA's moderate resolution imaging spectroradiometer (MODIS) onboard the Terra satellite, the researchers connected nearly all of the high-ozone, low-water structures to tropical regions with active biomass burning in tropical Africa and Southeast Asia."The investigation utilized a variety of models, including the NCAR CAM-Chem model to forecast and later analyze chemical and dynamical conditions near Guam, as well as satellite data from numerous instruments that augmented the interpretation of the aircraft observations," said study co-author Douglas Kinnison, a project scientist at the University Corporation for Atmospheric Research.In the paper, the researchers also offer a new explanation for the dry nature of the polluted air parcels."Our results challenge the explanation atmospheric scientists commonly offer for pockets of high ozone and low water: that these zones result from the air having descended from the stratosphere where air is colder and dryer than elsewhere," said UMD Professor Ross Salawitch, the study's senior author and principal investigator of CONTRAST. Salawitch holds joint appointments in the university's Department of Atmospheric and Oceanic Science, Department of Chemistry and Biochemistry, and Earth System Science Interdisciplinary Center."We know that the polluted air did not mix with air in the stratosphere to dry out because we found combined elevated levels of carbon monoxide, nitric oxide and ozone in our air samples, but air in the higher stratosphere does not contain much naturally occurring carbon monoxide," said Anderson.The researchers found that the polluted air that reached Guam never entered the stratosphere and instead simply dried out during its descent within the lower atmosphere. While textbooks show air moving upward in the tropics, according to Salawitch, this represents the net motion of air. Because this upward motion happens mostly within small storm systems, it must be balanced by air slowly descending, such as with these polluted parcels released from fires.Based on the results of this study, global climate models may need to be reassessed to include and correctly represent the impacts of biomass burning, deforestation and reforestation, according to Salawitch. Also, future studies such as NASA's upcoming Atmospheric Tomography Mission will add to the data collected by CAST and CONTRAST to help obtain a clearer picture of our changing environment.

Ozone Holes

January 7, 2016

https://www.sciencedaily.com/releases/2016/01/160107094418.htm

Long-term ozone exposure increases acute respiratory disease syndrome risks in critically ill

Critically ill patients who are exposed to higher daily levels of ozone are more likely to develop acute respiratory disease syndrome (ARDS), according to a new study published online ahead of print in the American Thoracic Society's

The researchers analyzed exposure using a heterogenous group of 1558 critically ill patients from the Validating Acute Lung Injury Biomarkers for Diagnosis cohort. They found that as long-term ozone exposure increased, so did rates of ARDS, which developed in 563 patients. The association between ARDS risk and ozone exposure was greatest among trauma patients (n=552). In addition, "Ozone was significantly associated with ARDS only in current smokers and not in non-smokers," wrote the researchers."The generalizability of this most recent study is enhanced given the large and heterogenous cohort we had at our disposal," Dr. Ware said. "However, we acknowledge that future studies need to replicate the findings in more diverse geographic samples so that we may more confidently recommend guidelines for reducing ozone exposure and ARDS risk among this vulnerable group of patients."As the potentially harmful health consequences of ozone exposure continue to draw more concern, the demand for more research will likely increase because this study as well as another study on ozone and mortality appearing in the same issue of the

Ozone Holes

December 10, 2015

https://www.sciencedaily.com/releases/2015/12/151210092853.htm

Ozone and climate: With the HALO research aircraft to the North Pole

Thanks to the Montreal Protocol on the Protection of the Ozone Layer, pollution of Earth's atmosphere by ozone-depleting substances, such as chlorine or bromine from halons and chlorofluorocarbons (CFCs), decreased over the past years. Ozone is, however, not only influenced by these substances, but acts as a greenhouse gas itself: Its impact on climate near the ground is highest in the tropopause region, the transition zone between stratosphere and troposphere at 7 to 17 kilometers altitude. The complex processes taking place there are subject of an extensive measurement campaign with the German research aircraft HALO. The campaign is coordinated by climate researchers of Karlsruhe Institute of Technology (KIT) and carried out in close collaboration with several partners.

"The tropopause region above the Arctic has hardly been studied so far with focused airborne observations. For the present measurement campaign, the HALO research aircraft has been equipped with a combination of specially developed sensors. In particular, we want to better understand the processes influencing ozone and other climate-affecting trace gases in the Arctic tropopause region in winter," Hermann Oelhaf of the KIT Institute of Meteorology and Climate Research, says. He coordinates the campaign together with his colleague Dr. Björn-Martin Sinnhuber."We know that climate change due to the increase in the concentrations of COContrary to the South Pole, where every year in the southern hemisphere spring an ozone hole develops, comparable extreme ozone depletions above the Arctic were observed in a few, very cold winters only. "It is still an open question whether climate change will indeed cause more cold winters in the Arctic stratosphere or whether changes of atmospheric circulation will rather lead to its warming," Sinnhuber says.During the campaign, the researchers will in particular focus on processes controlling ozone, water vapor, and other trace gases in the tropopause region, i.e. in the transition zone between troposphere and stratosphere at 7 to 17 kilometers altitude. At polar latitudes, it is found at 7 to 12 km altitude. "The distribution of climate-influencing trace gases in the tropopause region is controlled by transport pathways, by which air masses from the Arctic enter the mid-latitudes and vice versa, and by exchange processes between the stratosphere and troposphere," Hermann Oelhaf explains. HALO (High Altitude and Long Range Research Aircraft) can reach altitudes of up to 15 km and has a range of more than 8,000 km, which makes it particularly suited for such studies.An important measurement instrument on board of HALO is the GLORIA infrared spectrometer developed and built jointly by scientists and engineers of KIT and Forschungszentrum Jülich. "With GLORIA, we can observe temperature, cloud parameters, and a number of relevant trace gases in the atmosphere," Hermann Oelhaf says. The infrared spectrometer analyzes thermal radiation of the atmosphere and identifies trace gases based on their spectral signature, much like a fingerprint of the molecules. As thermal radiation emitted by the atmosphere itself is measured, the method also works during polar night. GLORIA combines a spectrometer with an infrared camera and, in this way, can observe two-dimensional trace gas distributions -- resembling finely woven curtains along the flight path -- in far more detail than before. "We obtain new insights into vertical and horizontal transport processes as well as into the interaction between high thin cirrus clouds and trace gases, such as water vapor, in the tropopause region. Both are critical parameters in the climate system," Oelhaf explains.About 70 scientists, engineers, technicians, pilots, and logistics specialists will be present at the "Arena Arctica" hangar in Kiruna, Sweden, near the polar circle. Partners in the project "POLSTRACC -- Polar Stratosphere in a Changing Climate" alongside the Karlsruhe Institute of Technology (KIT) are the Forschungszentrum Jülich (FZJ), the German Aerospace Center (DLR), and the Universities of Heidelberg, Frankfurt, Mainz, and Wuppertal, as well as the Physikalisch-Technische Bundesanstalt. Presently, first test flights are carried out from the DLR base at Oberpfaffenhofen near Munich. Between January and March 2016, the "Arena Arctica" will be used as the base for 10 to 15 research flights across the polar sea towards Greenland and the North Pole.The HALO research aircraft is a collective initiative by German environment and climate research bodies. HALO is funded by contributions from the German Federal Ministry of Education and Research (Bundesministerium für Bildung und Forschung; BMBF), the German Research Foundation (Deutsche Forschungsgemeinschaft; DFG), the Helmholtz Association, the Max Planck Society, the Leibniz Association, the Free State of Bavaria, the Karlsruhe Institute of Technology, the German Research Centre for Geosciences (Deutsches GeoForschungsZentrum; GFZ), the Jülich Research Centre (Forschungszentrum Jülich) and the German Aerospace Center (Deutsches Zentrum für Luft- und Raumfahrt; DLR).More about the KIT Climate and Environment Center:

Ozone Holes

December 8, 2015

https://www.sciencedaily.com/releases/2015/12/151208165210.htm

Vision researcher links environmental change to eye health hazards

Another reason to worry about climate change: Expanding areas of arid land, air pollution, and greater exposure to ultraviolet (UV) radiation all present potential health hazards to your eyes, according to Sheila West, Ph.D., vice chair for research at the Wilmer Eye Institute, Johns Hopkins University. In October, West discussed these hazards at a symposium on the health consequences of climate change.

The tissues at the front of the eye -- the cornea, eye lid, the white part called the sclera, and even the lens -- are all exposed to the environment. Adverse environmental changes may therefore have deleterious effects on the eye, West said at the symposium, which was sponsored by the NIH Global Health Interest group. The National Eye Institute also contributed to the event.Regions of arid land are expanding as rising temperatures and shifting atmospheric circulation patterns force dry air into regions that had previously seen more rain. Drier air means that more people may be likely to suffer from dry eye symptoms, in which tears aren't produced properly or evaporate too quickly.While there's no evidence that drier conditions cause dry eye, "it can accelerate symptoms in people who are prone to dry eye. As we see these areas [of drought] spread we are liable to see people who are prone to dry eye, but who may not be symptomatic, go on to develop symptoms," West said.In the U.S., about $3.8 billion is spent annually treating dry eye. Those expenditures are likely to increase as the areas with rising temperatures and increasingly arid conditions expand.Another consequence of climate change is an increased burden of airborne particles that can irritate the eye. Air pollution has long been linked to respiratory disorders; more recently it's been shown to play a role in eye disease, West said. Drought conditions, now increasingly seen as a consequence of climate change, can prolong the fire season from naturally occurring fires, which emit irritants into the air. As an example of how these fire emissions affect the eye, West pointed to the use of intentional fires set for crop clearing. "We're seeing more ocular exposure to irritants in the air in these farmland areas," she said.West's own research has shown that exposure to wood or charcoal cooking fires ubiquitous in many developing countries appears to accelerate the scarring caused by trachoma, the leading infectious cause of blindness worldwide. Trachoma is caused by the bacterium By studying women living in areas of rural Africa where trachoma is endemic, West found that after adjusting for other factors that may contribute to trachoma scarring, the more time the women spent cooking over wood burning stoves, the more likely they were to have moderate to severe scarring of the eyelid.On another front, ozone depletion can lead to higher levels of UV light exposure, which is a known risk factor for cortical cataract. Chronic exposure to the sun's damaging rays can alter the orderly arrangement of proteins in the lens of the eye, or damage lens epithelium, causing the lens to become cloudy.Efforts such as the Montreal Protocol, an international treaty aimed at phasing out the production of ozone-depleting substances, may help reduce UV levels, "but that may not occur until the middle of the century," West said. Even with the Protocol's measures, West and her colleagues estimated that by 2050, rising UV exposure will lead to an additional 150,000 to 200,000 cases of cataract -- over and above the expected number associated with aging. West estimates that $1.1 billion will be spent on care and surgical treatment of these additional cases.The good news is that these estimates are based on assumptions of how much UV actually reaches the lens of the eye, a controllable risk factor. Wearing a hat can reduce UV exposure by 30 percent. Sunglasses, even simple plastic lenses that offer full UV protection, can reduce exposure by nearly 100 percent.

Ozone Holes

November 3, 2015

https://www.sciencedaily.com/releases/2015/11/151103140111.htm

Some chemicals less damaging to ozone can degrade to long-lived greenhouse gas

Some substitutes for ozone-damaging chemicals being phased out worldwide under international agreements are themselves potent greenhouse gases and contribute to warming. Now, a new study published Nov. 2 in

Specifically, when some chemicals widely used as refrigerants break down in the stratosphere -- a layer in the middle atmosphere -- under some conditions, they can form a potent greenhouse gas that lasts for up to 50,000 years, according to scientists from the Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder and the NOAA Earth System Research Laboratory (ESRL) in Boulder."This compound, carbon tetrafluoride or CF4, essentially lasts forever because there aren't any known removal mechanisms in the atmosphere," said James Burkholder, a research chemist at NOAA ESRL and lead author of the study.Burkholder's colleague Aaron Jubb, a CIRES scientist working at NOAA ESRL and now at Oak Ridge National Laboratory, did the laboratory work showing how CF4 can be made from some halocarbons, chemicals that include hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) and are substitutes for the more ozone-damaging chemicals that have largely been phased out. Jubb started with trifluoroacetyl fluoride -- a compound produced in the atmosphere when some halocarbons breaks down -- exposed it to short-wavelength UV radiation, and looked at the reaction products that formed. CF4 was one of those breakdown products.The amount of CF4 produced by this photochemical process was shown to be a small fraction of atmospheric CF4; industrial sources are much larger emitters of CF4. Still, identifying this particular source of such a potent and lasting greenhouse gas is important, particularly since its production could continue to grow depending on which "parent" products are used by industry."We really need to understand the chemistry of the compounds we use," Jubb said. "Even as we move towards shorter-lived halocarbons for industrial use, during atmospheric degradation they can produce a long-lived atmospheric effect."

Ozone Holes

October 29, 2015

https://www.sciencedaily.com/releases/2015/10/151029185555.htm

Annual Antarctic ozone hole larger and formed later in 2015

The 2015 Antarctic ozone hole area was larger and formed later than in recent years, said scientists from NASA and the National Oceanic and Atmospheric Administration (NOAA).

On Oct. 2, 2015, the ozone hole expanded to its peak of 28.2 million square kilometers (10.9 million square miles), an area larger than the continent of North America. Throughout October, the hole remained large and set many area daily records. Unusually cold temperature and weak dynamics in the Antarctic stratosphere this year resulted in this larger ozone hole. In comparison, last year the ozone hole peaked at 24.1 million square kilometers (9.3 million square miles) on Sept. 11, 2014. Compared to the 1991-2014 period, the 2015 ozone hole average area was the fourth largest."While the current ozone hole is larger than in recent years, the area occupied by this year's hole is consistent with our understanding of ozone depletion chemistry and consistent with colder than average weather conditions in Earth's stratosphere, which help drive ozone depletion," said Paul A. Newman, chief scientist for Earth Sciences at NASA's Goddard Space Flight Center in Greenbelt, Maryland.The ozone hole is a severe depletion of the ozone layer above Antarctica that was first detected in the 1980s. The Antarctic ozone hole forms and expands during the Southern Hemisphere spring (August and September) because of the high levels of chemically active forms of chlorine and bromine in the stratosphere. These chlorine- and bromine-containing molecules are largely derived from human-made chemicals that steadily increased in Earth's atmosphere up through the early 1990s."This year, our balloon-borne instruments measured nearly 100 percent ozone depletion in the layer above South Pole Station, Antarctica, that was 14 to 19 kilometers (9 to 12 miles) above Earth's surface," said Bryan Johnson, a researcher at NOAA's Earth System Research Laboratory in Boulder, Colorado. "During September we typically see a rapid ozone decline, ending with about 95 percent depletion in that layer by October 1. This year the depletion held on an extra two weeks resulting in nearly 100 percent depletion by October 15."The ozone layer helps shield Earth from potentially harmful ultraviolet radiation that can cause skin cancer, cataracts, and suppress immune systems, as well as damage plants. The large size of this year's ozone hole will likely result in increases of harmful ultraviolet rays at Earth's surface, particularly in Antarctica and the Southern Hemisphere in the coming months.Ozone depletion is primarily caused by human-made compounds that release chlorine and bromine gases in the stratosphere. Beginning in 1987, the internationally agreed-upon Montreal Protocol on Substances that Deplete the Ozone Layer has regulated these ozone-depleting compounds, such as chlorine-containing chlorofluorocarbons used in refrigerants and bromine-containing halon gases used as fire suppressants. Because of the Protocol, atmospheric levels of these ozone depleting compounds are slowly declining. The ozone hole is expected to recover back to 1980 levels in approximately 2070.This year, scientists recorded the minimum thickness of the ozone layer at 101 Dobson units on October 4, 2015, as compared to 250-350 Dobson units during the 1960s, before the Antarctic ozone hole occurred. Dobson units are a measure of the overhead amount of atmospheric ozone.The satellite ozone data come from the Dutch-Finnish Ozone Monitoring Instrument on NASA's Aura satellite, launched in 2004, and the Ozone Monitoring and Profiler Suite instrument on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite, launched in 2011. NOAA scientists at the South Pole station monitor the ozone layer above that location by using a Dobson spectrophotometer and regular ozone-sonde balloon launches that record the thickness of the ozone layer and its vertical distribution. Chlorine amounts are estimated using NOAA and NASA ground measurements and observations from the Microwave Limb Sounder aboard NASA's Aura satellite. These satellites continue a data record dating back to the early 1970s.

Ozone Holes

October 27, 2015

https://www.sciencedaily.com/releases/2015/10/151027143023.htm

Wave-particle interaction in atmosphere

A Dartmouth-led study sheds light on the impact of plasma waves on high-energy electrons streaking into Earth's magnetic field from space.

The findings are important because relativistic electrons can lead to ozone depletion and threaten orbital satellites, spacecraft and astronauts, and understanding the evolution of Earth's radiation belts could help lessen the effects of these particles.The findings appear in Lead author Richard Denton, a research professor in Dartmouth's Department of Physics and Astronomy, uses computational research to study the magnetosphere, the region shielded by the Earth's magnetic field from solar wind; he also studies various wave phenomena, including plasma waves, which are like sound waves in air except these occur in ionized gas so the electric and magnetic fields are affected. He focuses on Alfven waves, which are similar to the oscillations of a guitar string with the magnetic field supplying the tension analogous to the string.In their new paper, the researchers studied the resonance of relativistic electrons with electromagnetic ion cyclotron waves in the Earth's radiation belts -- in other words, how these waves affect the electrons' motion. Also known as the Van Allen radiation belts, these giant concentric layers of charged particles are held in place by the Earth's magnetic field. An increase in particle density and charge brought about by solar activity can raise the level of threat to satellites.Relativistic electrons have been thought to more easily resonate with electromagnetic ion cyclotron waves if the total density is large. But the researchers found that the lower minimum resonant energy for these electrons interacting with these waves results mainly not from high bulk density, but from low temperature of the protons that drive the instability. High density may lead to lower minimum resonant energy through causing the helium ion cyclotron mode to be dominant."Electromagnetic ion cyclotron waves have been thought to be a major loss mechanism for relativistic electrons in the Van Allen radiation belts," says Denton. "Previously, high density was thought to lower the minimum energy of radiation belt particles for resonance. We show that high density is not the most important factor, though it can indirectly have an effect on the minimum resonant energy by causing a particular kind of ion cyclotron wave to grow."

Ozone Holes

October 26, 2015

https://www.sciencedaily.com/releases/2015/10/151026093045.htm

Earth’s first bacteria made their own sunscreen

Earth in the days when life was just beginning had no protective ozone layer, so light-dependent, iron-oxidizing bacteria formed iron minerals around themselves to protect them from damaging ultraviolet rays. In this way, living beings were able to survive in the rough environment of 3-4 billion years ago. This is the conclusion reached by Tübingen geomicrobiologists Tina Gauger and Professor Andreas Kappler following a series of laboratory experiments in collaboration with Professor Kurt Konhauser of the University of Alberta in Edmonton, Canada. The results of this research have been published in the latest issue of

The atmosphere we breathe today is composed of about 20 percent oxygen, which is not just essential to many organisms -- it also provides protection from the sun's more dangerous rays. In the presence of sunlight, oxygen molecules in the atmosphere react to form ozone. Up in the stratosphere, the ozone layer absorbs harmful UV radiation coming from space -- protecting humans, animals and plants from the damage UV does. Three to four billion years ago, the atmosphere contained little oxygen and there was no ozone layer. "The earth's surface -- and areas of shallow water -- were subject to high levels of ultra-violet radiation," Andreas Kappler explains. "And yet, microbial life came to be. We wondered how that was possible."Certain bacteria which need light are able to eat dissolved iron (FeIn their experiments, the geomicrobiologists subjected the bacteria to high doses of ultraviolet radiation -- either in the presence or the absence of the iron minerals the bacteria themselves produce. "In the presence of their own rust, considerably more bacteria survived and were active," says Tina Gauger. "We also saw that the bacterial cells' DNA suffered less damage. In our experiments, more bacteria survived with mineral sunscreen than without." The new findings are helping the researchers to understand how very early organisms survived despite the high level of radiation, and how life was even able to develop in shallow seas with sufficient sunlight.

Ozone Holes

September 29, 2015

https://www.sciencedaily.com/releases/2015/09/150929142300.htm

Air quality, ozone pollution models for forested areas may be too simple

A new study assessing the influence of species diversity of canopy trees on the amount of ozone precursors a forest emits suggests that atmospheric chemistry models in use now may underestimate the importance of tree species mix and size to ozone pollution, says lead author Alexander Bryan, a postdoctoral fellow in the Northeast Climate Science Center at the University of Massachusetts Amherst.

Details appear in an early online edition of the journal, Current models usually represent the forest as a single dominant tree species or a blend of a few, so they may not capture the right mix of compounds emitted from trees and their oxidation products, he says. "The lesson from this study is that we may need to include more complexity in modeling," he says.Even with this clue on how models might be improved, Bryan and colleagues note, the magnitude of natural volatile organic compound (VOC) emissions is still "highly uncertain due to the complexity of emissions and chemistry" in forested areas.Forest trees naturally emit the biogenic VOCs monoterpenes and isoprene, two main pre-cursor ingredients that combine in the atmosphere with nitric oxide (NO), which is emitted mainly by soils, to form the pollutant ozone. NO was once found in very low concentrations in the air until industrialization and human activities such as driving trucks, trains and cars changed atmospheric chemistry, Bryan says.For this study, while he was a doctoral student of Allison Steiner, a biosphere-atmosphere interactions expert at the University of Michigan, Bryan used data collected by others on the ratio of tree species within a 197-foot (60-meter) circle at the university's biological station in the northern Lower Peninsula. He also measured the height of 248 broadleaf and needle-leaved trees in the circle.Broadleaf trees such as aspen and oak emit isoprene as a function of light and temperature, while most needle-leaved trees emit monoterpenes as a function of temperature only, he points out. This is important because forest light varies due to shade from leaves and branches, "so the vertical location of broadleaves and needle-leaves likely matters for how much they emit," he explains.Bryan and colleagues used tree height data to add vertical layering to their emissions model then conducted simulations using two different emissions schemes. One simulated a homogeneous mixture of broadleaf and needle-leaved trees, with vertically uniform emission potentials. The other case includes a heterogeneous or mixed canopy with emission potentials that varied with the proportion of foliage from each tree species at each model layer. Emission potentials are then converted to emission rates the same way in both simulations using the same daily cycle of light and temperature, a control that allowed the researchers to isolate the effect of different leaf type distributions.Bryan says, "We found that in modifying these models, it may be important to represent as realistically as possible how leaf type changes throughout the height of the forest. You need to know how many tall trees there are, how tall they are and what percent of the forest they represent, because these are the trees which receive the most light and thus have the greatest potential for emitting ozone precursors."Overall, findings "highlight the importance of adequately representing complexities of forest canopy structure when simulating light-dependent biogenic VOC emissions and chemistry," the authors state.They also simulated a homogeneous and heterogeneous canopy with aspen and birch removed to assess the impact of canopy heterogeneity on projections of biogenic VOC chemistry in late-successional forests. They found that VOC emissions declines from aspen loss were 10 percent greater when heterogeneity was considered.Bryan says these findings are generalizable across the Northeast because forests there and in the Midwest are similarly a mix of broadleaf and northern needle-leaved trees growing in cooler latitudes. But he cautions that while this model is more complex than its predecessors, it's not clear whether the added complexity improves the simulation of forest chemistry. "However, we now know that forest chemistry simulations are very sensitive to how forest structure is represented in models," he adds.

Ozone Holes

September 24, 2015

https://www.sciencedaily.com/releases/2015/09/150924083623.htm

Curbing short-lived pollutants: A win-win for climate and air quality

Ozone, methane and aerosols (tiny pollutant particles) remain in the atmosphere for a shorter time than CO

In the EU, the reduction in life expectancy due to air pollution was 7.5 months in 2010, and legislation already in place to improve air quality aims to reduce this loss to 5.2 months by 2030. The team says the new measures targeting short-lived pollutants could boost air quality and reduce loss of life expectancy even further: by a month in Europe, about two months in China and one year in India.The new mitigation measures would also bring climate benefits, reducing global temperatures by about 0.22°C by 2050, relative to a scenario without these measures. The reduced warming in the Arctic would be even larger, close to half a degree, while in Southern Europe the measures would not only reduce temperatures but also increase rainfall by about 15 mm/year, or about 4% of the total precipitation. "This could help to alleviate expected future drought and water shortages in the Mediterranean region," says lead-author Andreas Stohl from the Norwegian Institute of Air Research.Working within a European project called ECLIPSE, the international consortium of researchers considered short-lived substances that not only affect warming but are also air pollutants, or are transformed into air pollutants once in the atmosphere. Methane, for example, is the second strongest contributor to climate warming after CO"We have found that the measures to reduce methane and other ozone precursors would significantly improve the ozone air quality, especially over northern continents. This would be good for human health and would improve crop yields, confirming the additional benefits of mitigation," says co-author William Collins from the University of Reading, UK. Overall, the new measures would lower global anthropogenic emissions of methane by 50% and of black carbon aerosols, also known as soot, by 80%.The scientists say the most important measures concern the oil and gas industry. Preventing unintended leaks during the extraction of shale gas would diminish methane emissions, for example. Ending the flaring of gas produced during oil extraction, on the other hand, would lower emissions of black carbon."There are also other important measures to reduce methane emissions from coal mining, municipal waste treatment and gas distribution, for example, as well as black carbon emission reductions through elimination of high-emitting vehicles, use of cleaner biomass cooking and heating stoves, replacement of kerosene wick lamps with LED lamps and other measures," adds Zbigniew Klimont of the International Institute for Applied Systems Analysis, Austria, who also took part in the study."There is no doubt that the most important factor causing climate warming are COAs detailed in the Atmospheric Chemistry and Physics study, the team looked into emission scenarios for various short-lived pollutants and into climate models to find out what the impact of specific emission reductions on climate would be. While methane and black carbon contribute to warming, other aerosols, like those formed from sulphur dioxide (released in volcanic emissions and from coal-fired power plants, for example), have a cooling effect. The team focused on emission reductions that resulted in win-win situations between climate policy and air quality policy.While the researchers hope to see policymakers implement the ECLIPSE measures, they caution that short-lived pollutants are only a small part of the climate problem. "The project results clearly show that reductions in the emissions of short-lived species cannot replace CO

Ozone Holes

September 16, 2015

https://www.sciencedaily.com/releases/2015/09/150916112555.htm

What happens on the molecular level when smog gets into the lungs?

Coughing. A sore throat. Maybe a pain in your chest as you take a deep breath.

These are all common symptoms for many city-living people when smog levels are high. And while it is well understood that smog can cause such problems, new research has for the first time given us a glimpse as to what might be happening at the molecular level.The University of Melbourne's Professor Richard O'Hair, from the School of Chemistry's Bio21 Institute, in collaboration with Professor Stephen Blanksby (from the Queensland University of Technology and formerly the University of Wollongong) co-authored a study examining how ozone reacts with models of lung proteins.Smog is made up of ozone -- an invisible gas and a well-known air pollutant made up of three oxygen atoms. Ozone is also the pollutant that leaves a distinctive smell in the air after using a photocopier.Using a mass spectrometer, the research team was able to introduce the amino acid cysteine -- a component of lung proteins -- with ozone molecules in a highly-controlled, near-vacuum environment.The effect was instant, or in scientific terms, close to the "collision rate.""We observed that the cysteine became 'radicalised' in the presence of ozone," said Professor O'Hair."No one had really noticed that you can form free radicals in the reaction of proteins with ozone, and since these are highly reactive species, you don't want them around."Free radicals can unleash fury and cause many chemical transformations."If they get out of control, they can just chew through a system and destroy it. For example, free radical damage is thought to play a key role in heart disease and some cancers."So when free radicals are formed in the body, such as the lining of the lung, damage occurs, that may ultimately result in inflammation and breathing difficulties."The research pushes forward the understanding of the molecular effect of ozone on proteins. But because the tests were conducted in an artificial environment, more work needs to be done to confirm the creation of protein free radicals in lungs and link their effects on human lung physiology.Professor O'Hair hopes the research inspires fellow scientists to build on the findings.Associated research will be of the most benefit to those with asthma, other respiratory illnesses or the young and the elderly who are most susceptible to smog."If there is free radical damage to lung proteins, it's unlikely to be reversible, so you won't be able to design a magic-bullet drug to undo the damage," Professor O'Hair said."Ozone is the result of pollution. So the message has to go out that we need to be proactive on reducing smog levels and pollution."

Ozone Holes

August 29, 2015

https://www.sciencedaily.com/releases/2015/08/150829123705.htm

Pollution and weather influence outcomes after heart attack

Pollution and weather influence outcomes after a heart attack, according to research presented at ESC Congress today by Ms Aneta Cislak, research fellow in the Silesian Centre for Heart Diseases, Medical University of Silesia in Zabrze, Poland.

"Weather changes like rain or heat affect our daily activity and even our productivity at work," said Ms Cislak. "Since this influence is so noticeable we were interested to see if weather has any connection with cardiovascular diseases including acute coronary syndromes. Moreover, air pollution affects our health, especially in highly industrialised areas. We performed our research in Silesia, the most urbanised and industrialised region in Poland."The study examined the relationship between environmental factors and severity of clinical status and short-term prognosis in patients with non ST-segment elevation acute coronary syndromes (NSTE ACS). These include NSTE myocardial infarction (NSTEMI) (heart attack) and unstable angina.The study enrolled 2 388 patients admitted for NSTE ACS between 2006 and 2012. Data on meteorological conditions and air pollutants was obtained from the Silesian Air Monitoring Website. Weather factors included atmospheric pressure, air temperature, wind speed, humidity and total solar radiation intensity measured on the day of admission. Air concentrations of the most common pollutants (sulphur dioxide, nitric oxides, carbon monoxide, ozone and particulate matters) were recorded.Weather and pollution parameters were correlated with clinical status expressed by left ventricular ejection fraction, a measurement of how well the heart pumps with each beat; MI rates; GRACE risk score, which assesses future risk of death or MI; and CRUSADE Bleeding Score, which assesses bleeding risk.The researchers found that patients with high risks of MI and bleeding and low left ventricular ejection fraction were admitted for NSTE ACS on warmer, sunnier, drier and windy days with higher carbon monoxide and ozone air concentrations (Figure 1). Ms Cislak said: "These were the sickest patients. The findings may be explained by the fact that their organs may be more sensitive to weather changes, leading to decompensation."Treatment with percutaneous coronary intervention (PCI) to widen blocked coronary arteries was more frequently successful when the weather was sunnier and less windy but colder and with lower concentrations of ozone, carbon monoxide and nitric oxides (Figure 2). "One of the possible explanations for this finding is that air pollutants like carbon monoxide bind irreversibly to haemoglobin and impair blood oxygen transport. This can cause hypoxia and lead to worse clinical status and less successful treatment," said Ms Cislak.Higher in-hospital and one month mortality was observed on colder, more sunny and less windy days. "For now, we are not able to explain this phenomenon, but we hope that further studies will help us to verify and understand it better," said Ms Cislak.She added: "This was a small observational study and our analysis was univariate so we cannot rule out the possibility that the associations were caused by the co-existence of other factors. Multivariate analysis is needed to confirm our observations. Possible mechanisms for our observations are various. They may include seasonal growth of death rates reported in the general population in Poland. Also the negative influence of air pollutants on the cardiovascular system could be explained by their connection with inflammation, affecting the respiratory system and as an effect impaired oxygenation. There is no doubt that the analysed factors may potentiate or diminish each other's effects e.g wind purifies the air by blowing pollutants or lower temperature causes more intensive home heating and combustion products emission."Ms Cislak concluded: "It should be remembered that not only do humans influence the environment, but the environment also influences humans. Our study suggests that environmental factors may affect the severity of clinical status and short-term prognosis in patients with NSTE ACS. We are now investigating the impact of meteorology and air pollution on 600 000 patients in the Silesian Cardiovascular Database who were hospitalised with cardiovascular diseases in the last ten years in Silesia."

Ozone Holes

August 17, 2015

https://www.sciencedaily.com/releases/2015/08/150817132558.htm

Degrading more than 95% of metabolism-altering water pollutants

At the Center for Research and Assistance in Technology and Design of the State of Jalisco (CIATEJ) at the east of Mexico, an oxidation process was developed that uses ozone to degrade contaminants in water that alter the synthesis, transport, action or elimination of natural hormones, responsible for maintain self-regulation of metabolic and reproductive processes in living beings.

These compounds represent a potential risk to human health associated with problems in the male and female reproductive systems, and some of them are precursors of breast and prostate cancer.The research team led by PhD Alberto Lopez at CIATEJ carries out the procedure by gas-liquid reactors, where the water with the presence of such substances called disrupting compounds of the Endocrine System (EDCs) is passed through a gas stream with ozone, which is a major oxidant.And under certain conditions of temperature, pH, pressure and ozone dosage the EDCs are degraded to less than 95 percent of its initial concentration, exceeding conventional water treatment processes that just reach a 50 percent removal.EDCs are found in surface water, soil and air. There is great diversity of them, basically solvents, organochlorine pesticides, flame retardants, plasticizers and synthetic and natural hormones.The project led by Dr. Lopez was aimed at developing analytical methodologies to identify and quantify these compounds in different types of water, as well as the development of a process of advanced oxidation based on Ozone (POA-03) to degrade EDCs present in the water in order to establish the technical, scientific and optimal treatment conditions for a future scaling process.This research led to a technology that can be integrated in the final part of a water purification system. Furthermore, the results provide a precedent to regulate the presence of these compounds through quality standards and reduce public health risks.The process is aimed as a complement of a traditional system of water purification where despite the application of methods such as coagulation, flocculation, filtration and chlorination EDCs persist.Liquid waste, from industrial or domestic sources contain low concentrations of these compounds. Even when treated by conventional methods, EDCs remain in the effluent, which usually lead to a river or lake that serves as a drinking source.Conventional treatments for water as activated sludge or coagulation-flocculation process are not sufficient to remove these compounds that are recalcitrant to natural or controlled biological degradation, therefore removal efficiency is very low.The process was developed and validated at a laboratory and pilot scale and instances are currently seeking to transfer the technology. This project has resulted in a patent called: Process to degrade recalcitrant compounds present in the water, which was granted in 2014.The scientific working group consisted of researchers at CIATEJ and had the collaboration of specialists from the National Institute of Applied Sciences in Toulouse, France and the Polytechnic University of Valencia.

Ozone Holes

July 29, 2015

https://www.sciencedaily.com/releases/2015/07/150729093014.htm

Intensive biofuel planting poses risk to human health

The race to meet carbon-neutral biofuel targets could put human health and food crop production at risk unless it is carefully planned, according to new research.

A new study, led by Professor Nick Hewitt of Lancaster University, examined changes in ground level ozone in response to projected land use change associated with future biofuel cultivation.Publishing in the journal Biofuels -- usually derived from specialist crops such as poplar, willow or eucalyptus -- offer alternative energy sources to carbon-intensive fossil fuels.However, many plant species grown for biofuel emit more isoprene, an ozone precursor, than the traditional crops and vegetation they replace.Too much ozone poses a well-documented risk to human health -- 22,000 premature deaths are linked to ground-level ozone exposure in Europe every year. It can also damage food crops including two of the most commercially important food crops in Europe, maize and wheat.Species of poplar with high biomass yields emit more isoprene than lower-yielding poplar. Planting large areas of higher yield poplar close to densely populated areas could result in increases in ground level ozone, which in turn could increase the number of ozone-related premature deaths.Because background levels of ground-level ozone across Europe are already high, the study found that even small increases in ozone resulting from the large scale planting of poplar, willow or eucalyptus would add to the likelihood of damaging concentrations occurring.Professor Nick Hewitt said: "In coming years we can anticipate a rapid expansion in poplar plantations in Europe driven by EU carbon-reduction initiatives. The current focus in policy-making circles and the biomass industry is on maximising yields but this should not be the only consideration. High yielding crops also produce the most isoprene and have the greatest impact on air quality and human health."Co-author Dr Oliver Wild said: "Our model results show that the large-scale planting of poplar as a biofuel feedstock in Europe may increase ground-level ozone concentrations across the region. This deterioration in air quality will lead to small but quantifiable impacts on human health and mortality and crop yields, the magnitudes of which will vary with the type of poplar cultivars used and the chosen locations of large plantations."We demonstrate that mitigation of these impacts could be achieved through European-wide strategic planning of plantation siting. For example a decision could be made to cultivate poplar on a large scale in areas of Europe with low population density and less intensive agriculture."

Ozone Holes

July 9, 2015

https://www.sciencedaily.com/releases/2015/07/150709093001.htm

Volcanic eruptions slow down climate change -- temporarily

Although global concentration of greenhouse gases in the atmosphere has continuously increased over the past decade, the mean global surface temperature has not followed the same path. A team of international reseachers, KIT scientists among them, have now found an explanation for this slowing down in global warming: the incoming solar radiation in the years 2008-2011 was twice as much reflected by volcanic aerosol particles in the lowest part of the stratosphere than previously thought. The team presents their study in

For the lowest part of the stratosphere -- i. e. the layer between 10 and 16 kilometres -- little information was available so far, but now the international IAGOS-CARIBIC climate project combined with satellite observations from the CALIPSO lidar provided new essential information. According to the study, the cooling effect due to volcanic eruptions was clearly underestimated by climate models used for the last Intergovernmental Panel on Climate Change (IPCC) report. Led by the University of Lund, Sweden, and supported by the NASA Langley Research Center, USA, and the Royal Netherlands Meteorological Institute, three major German atmospheric research institutes were also involved: the Max Planck Institute for Chemistry in Mainz (MPI-C), the Leibniz Institute for Tropospheric Research in Leipzig (TROPOS) and the Karlsruhe Institute of Technology (KIT). Since more frequent volcanic eruptions and the subsequent cooling effect are only temporary the rise of Earths' temperature will speed up again. The reason is the still continuously increasing greenhouse gas concentration, the scientists say.In the first decade of the 21st century the average surface temperature over the northern mid-latitude continents did increase only slightly. This effect can be now explained by the new study on volcanic aerosol particles in the atmosphere reported here. The study uses data from the tropopause region up to 35 km altitude, where the former is found between 8 km (poles) and 17 km (equator) altitude. The tropopause region is a transition layer between the underlying wet weather layer with its clouds (troposphere) and the dry and cloud-free layer above (stratosphere). "Overall our results emphasize that even smaller volcanic eruptions are more important for the Earth´s climate than expected," summarize CARIBIC coordinators Dr. Carl Brenninkmeijer, MPI-C, and Dr. Andreas Zahn, KIT. The IAGOS-CARIBIC observatory was coordinated and operated by the MPI-C until the end of 2014, since then by the KIT.To collect their data the team combined two different experimental approaches: sampling and in situ measurements made by IAGOS-CARIBIC together with observations from the CALIPSO satellite. In the IAGOS-CARIBIC observatory trace gases and aerosol particles in the tropopause region are measured since 1997. A modified air-freight container is loaded once per month for four intercontinental flights into a modified Airbus A340-600 of Lufthansa. Altogether about 100 trace gas and aerosol parameters are measured in situ at 9-12 km altitude as well as in dedicated European research laboratories after flight. TROPOS in Leipzig is responsible for the in situ aerosol particle measurements in this unique project. KIT runs 5 of the 15 installed instruments, also the one for ozone. Collected particles are analyzed at the University of Lund, Sweden, using an ion beam accelerator for measuring the amount of particulate sulfur. When comparing this particulate sulfur concentration to the in situ measured ozone concentration this ratio is usually quite constant at cruise altitude. However, volcanic eruptions increase the amount of particulate sulfur and thus the ratio becomes an indicator of volcanic eruption influencing the tropopause region. "The ratio of particulate sulfur to ozone from the CARIBIC measurements clearly demonstrates the strong influence from volcanism on the tropopause region," report Dr. Sandra M. Andersson and Professor Bengt G. Martinsson of the University of Lund, who are the lead authors.The second method is based on satellite observations. The Cloud-Aerosol Lidar and Pathfinder Satellite Observation (CALIPSO) mission, a collaboration between the National Aeronautics and Space Administration (NASA) in the US and the Centre National d'Etude Spatiale (CNES) in France, has provided unprecedented view on aerosol and cloud layers in the atmosphere. Until recently, the data had only been scrutinized above 15 km, namely where volcanic aerosol are known to affect our climate for a long time. Now also aeorosol particles of the lowermost stratosphere have been taken into account for calculating the radiative balance of the atmosphere, to evaluate the impact of smaller volcanic eruptions on the climate.The influence from volcanic eruptions on the stratosphere was small in the northern hemisphere between 1999 and 2002. However, strong signals of volcanic aerosol particles were observed between 2005 and 2012. In particular three eruptions stand out: the Kasatochi in August 2008 (USA), the Sarychev in June 2009 (Russia), and the Nabro in June 2011 (Eritrea). Each of the three eruptions injected more than one megaton sulfur dioxide (SO2) into the atmosphere. "Virtually all volcanic eruptions reaching the stratosphere lead to more particles there, as they bring in sulfur dioxide, which is converted to sulfate particles," explains Dr. Markus Hermann of TROPOS, who conducts the in situ particle measurements in CARIBICWhether a volcanic eruption has a global climate impact or not depends on several factors. There is the amount of volcanic sulfur dioxide as well as the injection height. But also the latitude of the eruption is important: As the air flow in northern hemispheric stratosphere is largely disconnected from the southern hemisphere, only volcanic eruptions near the equator can effectively distribute the emitted material over both hemispheres. As in the Tambora eruption on the Indonesian Island Sumbawa 200 years ago. This eruption led to such a strong global cooling that the year 1816 was called "year without summer," including worldwide crop failures and famines. Also the Krakatau eruption 1883 on Indonesia or the Pinatubo 1991 on the Philippines led to noticeable cooling. The present study now indicates that "the cooling effect of volcanic eruptions was underestimated in the past, because the lowest part of the stratosphere was mostly not considered. Interestingly our results show that the effect also depends on the season. The eruptions investigated by us had their strongest impact in late summer when the incoming solar radiation is still strong," explains Dr. Sandra M. Andersson.

Ozone Holes

July 8, 2015

https://www.sciencedaily.com/releases/2015/07/150708151231.htm

Stratospheric accomplice for Santa Ana winds and California wildfires

Southern Californians and writers love to blame the hot, dry Santa Ana winds for tense, ugly moods, and the winds have long been associated with destructive wildfires.

Now, a new study finds that on occasion, the winds have an accomplice with respect to fires, at least: Natural atmospheric events known as stratospheric intrusions, which bring extremely dry air from the upper atmosphere down to the surface, adding to the fire danger effects of the Santa Anas, and exacerbating some air pollution episodes.The findings suggest that forecast models with the capacity to predict stratospheric intrusions may provide valuable lead time for agencies to issue air quality alerts and fire weather warnings, or to reallocate firefighting resources before these extreme events occur."The atmosphere could give us an early warning for some wildfires," said Andrew Langford, a research chemist at the National Oceanic and Atmospheric Administration's (NOAA) Earth System Research Laboratory in Boulder, Colorado, and lead author of the study.Researchers at NOAA's National Environmental Satellite, Data, and Information Service (NESDIS) and the Cooperative Institute for Research in Environmental Sciences (CIRES) at CU-Boulder coauthored the work, which has been accepted for publication in The authors took a detailed look at the May 2013 "Springs Fire" that burned 100 square kilometers (25,000 acres) about 75 kilometers (50 miles) northwest of Los Angeles. The researchers used a NOAA forecast model that incorporates satellite observations of ozone, wind data, and other atmospheric information to detect the occurrence of the intrusions.The analysis showed that in the early hours before the Springs Fire, a tongue of air characteristic of the stratosphere--extremely dry and very high in ozone from the stratosphere's ozone layer--reached to the surface in southern California and extended as far south as Baja California.The researchers found that ground-based monitoring stations near the fire's origin also confirmed the telltale signs of the intrusion right before the fire broke out: A large drop in relative humidity and a rise in ozone. As the day went on, a combination of factors accelerated the fire: Low humidity, persistent high winds, dry condition of the grasses and other vegetation, clear skies and bright sunlight, and very warm surface temperatures. A few days later, cloudy skies, a drop in temperature, a shift in winds, and widespread rainfall helped extinguish the fire.The stratospheric intrusion also had another downside during the Springs Fire: It added ozone from the upper atmosphere to the urban and fire-related pollution produced in the lower atmosphere. On the second and third days of the fire, this helped to push levels of ozone--which can harm people's lungs and damage crops--over the federal ozone limit at 24 monitoring sites across southern California. Monitors as far away as Las Vegas also saw a spike in ozone on the third day of the fire. The observed exceedances of the ozone standard were unusual for the region for that time period, suggesting that the stratospheric intrusions were a contributing factor."Stratospheric intrusions are double trouble for Southern California," said Langford. "We knew that the intrusions can add to surface ozone pollution. Now we know that they also can contribute to the fire danger, particularly during La Niña years when deep intrusions are more frequent, as recently shown by our NOAA colleagues at the Geophysical Fluid Dynamics Laboratory. The good news is that with models and observations, we can get an early warning from the atmosphere in some cases."The authors note that stratospheric intrusions have previously been implicated in the explosive development of wildland fires in New Jersey and Michigan, but have not previously been connected to fires in southern California or to the Santa Ana winds. The frequent occurrence of stratospheric intrusions above the west coast during the fall, winter, and spring suggests that similar circumstances may have played a role in other major southern California fires, including the series of destructive fires that burned more than 3,000 square kilometers (more than 800,000 acres) in October of 2003, and burned about 4,000 square kilometers (nearly a million acres) in October of 2007, say the authors.

Ozone Holes

June 29, 2015

https://www.sciencedaily.com/releases/2015/06/150629162226.htm

Atmospheric mysteries unraveling

It's been difficult to explain patterns of toxic mercury in some parts of the world, such as why there's so much of the toxin deposited into ecosystems from the air in the southeastern United States, even upwind of usual sources.

A new analysis led by researchers at the University of Colorado Boulder shows that one key to understanding mercury's strange behavior may be the unexpected reactivity of naturally occurring halogen compounds from the ocean."Atmospheric chemistry involving bromine and iodine is turning out to be much more vigorous than we expected," said CU-Boulder atmospheric chemist Rainer Volkamer, the corresponding author of the new paper published in the The new chemistry that Volkamer and his colleagues have uncovered, with the help of an innovative instrument developed at CU-Boulder, may also help scientists better understand a longstanding limitation of global climate models. Those models have difficulty explaining why levels of ozone, a greenhouse gas, were so low before the Industrial Revolution."The models have been largely untested for halogen chemistry because we didn't have measurements in the tropical free troposphere before," Volkamer said. "The naturally occurring halogen chemistry can help explain that low ozone because more abundant halogens destroy ozone faster than had previously been realized."Volkamer is a Fellow of CIRES, the Cooperative Institute for Research in Environmental Sciences, at CU-Boulder and is an associate professor in the Department of Chemistry and Biochemistry. For the new paper, he worked with scientists from the U.S., China, Denmark and England.The international team relied on a differential optical absorption spectroscopy instruments (DOAS) that Volkamer's research group built to measure tiny amounts of atmospheric chemicals including highly reactive bromine oxide and iodine oxide radicals. Those radicals are very short-lived in the air, and collecting air samples doesn't work well. DOAS uses solar light, measuring the scattering and absorption of sunlight by gases and particles to identify the chemicals' distinct spectroscopic fingerprints and to quantify extremely small amounts directly in the atmosphere.Reactions involving those bromine and iodine radicals can turn airborne mercury--emitted by power plants and other sources--into a water-soluble form that can stay high in the atmosphere for a long time. High in the air, the mercury can sweep around the world. Towering thunderstorms can then pull some of that mercury back out of the atmosphere to the ground, lakes or oceans. There, the toxin can accumulate in fish, creating a public health concern.Volkamer's team's measurements show that the first step in that process, the oxidation of mercury in the atmosphere by bromine, happens up to 3.5 times faster than previously estimated because of halogen sources in oceans. Their work may help explain a mystery: For many pollutants, thunderstorms can rain out the chemicals quickly, so by the end of the storm there's little left in the air. Not so for mercury. Volkamer said its concentration in rainwater remains constant throughout a storm."To some extent, because of these halogens, we have a larger pool of oxidized mercury up there," Volkamer said.Naturally occurring bromine in air aloft illustrates the global interconnectedness between energy choices affecting mercury emissions in developing nations, and mercury deposition in the U.S.Finally, the measurements will be helpful for climate modelers seeking to improve their understanding of halogen impacts on ozone and other greenhouse gases.

Ozone Holes

June 4, 2015

https://www.sciencedaily.com/releases/2015/06/150604162453.htm

Stricter limits for ozone pollution would boost need for science, measurements

A tougher federal standard for ozone pollution, under consideration to improve public health, would ramp up the importance of scientific measurements and models, according to a new commentary published in the June 5 edition of

The commentary, led by Owen Cooper of the Cooperative Institute for Research in Environmental Sciences and NOAA's Earth System Research Laboratory, looks at how a new, stricter ozone standard would pose challenges for air quality managers at state and local levels. In November, the Environmental Protection Agency proposed lowering the primary ozone standard from 75 parts per billion (ppb) to 70 or 65 ppb, based on ozone's known effects on children, the elderly and people who have lung diseases, such as asthma. A decision by the EPA Administrator is expected in October 2015.The problem for state and local officials is that ozone pollution has several sources, some of which are beyond their borders. At any given place, a certain amount of the ozone pollution comes from local emissions by vehicles and other sources. Additional amounts can blow in from pollution sources across the ocean or in other parts of the United States. And some ozone is produced from natural sources or descends from the upper atmosphere's ozone layer.Sorting all this out is where science comes in, says Cooper."It's not easy, but we do know how to figure out where the ozone comes from," he said. "This source information is exactly what air quality managers will need to know when the margin for allowable locally produced ozone shrinks."Ozone is a pollutant that has respiratory health effects in humans and also impairs plant growth and damages crops. It is produced when emissions of nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight. Controls on NOx and VOC emissions from vehicles, power plants and other sources have enabled many U.S. counties to meet the 75 ppb standard, but the number of counties in "nonattainment" status (currently at 227) would jump to 358 or 558 if the standard is revised to 70 or 65 ppb, respectively.The new commentary suggests that to quantify how much ozone flows into the United States from all upwind sources, additional measurements would be needed, from instruments on the ground, on balloons and on aircraft. These observations could help scientists and air quality managers evaluate the performance of the computer models that are used to determine sources of ozone at a particular location. Once the models can successfully replicate the observed ozone levels, scientists and air quality managers will have greater confidence in the model estimates of how much of that observed ozone is beyond the reach of domestic control measures.That information is critical because the U.S. regulatory framework has procedures for exceptions and other allowances if non-local factors are significant for a given locality. And, those outside factors have been growing in recent decades, with sources in South and East Asia pushing up the baseline of ozone that enters the western U.S., for example."The ozone baseline is rising, especially in high-elevation regions of the western U.S. that are more strongly influenced by high ozone coming from upwind sources or from the stratosphere. Lowering the federal ozone standard to protect public health will reduce the wiggle room for air quality managers. We point out that measurements and science will be crucial to successfully navigating the new regulatory landscape," Cooper said.The EPA has stated that it will assist states in ensuring that sources of ozone outside of U.S. borders do not create unnecessary control obligations.

Ozone Holes

May 26, 2015

https://www.sciencedaily.com/releases/2015/05/150526124811.htm

Severe ozone depletion avoided

We are already reaping the rewards of the Montreal Protocol, with the ozone layer in much better shape than it would have been without the UN treaty, according to a new study in

Study lead author Professor Martyn Chipperfield, from the School of Earth & Environment at the University of Leeds, said: "Our research confirms the importance of the Montreal Protocol and shows that we have already had real benefits. We knew that it would save us from large ozone loss 'in the future', but in fact we are already past the point when things would have become noticeably worse."Although the Montreal Protocol came into force in 1987 and restricted the use of ozone-depleting substances, atmospheric concentrations of these harmful substances continued to rise as they can survive in the atmosphere for many years. Concentrations peaked in 1993 and have subsequently declined.In the new study, the researchers used a state-of-the-art 3D computer model of atmospheric chemistry to investigate what would have happened to the ozone layer if the Montreal Protocol had not been implemented.Professor Chipperfield said: "Ozone depletion in the polar regions depends on meteorology, especially the occurrence of cold temperatures at about 20km altitude -- colder temperatures cause more loss. Other studies which have assessed the importance of the Montreal Protocol have used models to predict atmospheric winds and temperatures and have looked a few decades into the future. The predictions of winds and temperatures in these models are uncertain, and probably underestimate the extent of cold winters."We have used actual observed meteorological conditions for the past few decades. This gives a more accurate simulation of the conditions for polar ozone loss."The researchers suggest that the hole in the ozone layer over the Antarctic would have grown in size by an additional 40% by 2013. Their model also suggests that had ozone-depleting substances continued to increase, the ozone layer would have become significantly thinner over other parts of the globe.Professor Chipperfield said he undertook this study because of the exceptionally cold Arctic winter of 2010/11."We could see that previous models used to predict the impact of the Montreal Protocol in the future would not have predicted such extreme events and we wondered how much worse things could have been if the Montreal Protocol had not been in place," he said.Without the Montreal Protocol, the new study reveals that a very large ozone hole over the Arctic would have occurred during that cold winter and smaller Arctic ozone holes would have become a regular occurrence.The Montreal Protocol has been strengthened over time through amendments and adjustments, supported by ongoing research. The researchers behind the new study say that scientists must continue to monitor the situation to ensure all potential threats to the ozone layer are mitigated.

Ozone Holes

May 14, 2015

https://www.sciencedaily.com/releases/2015/05/150514102809.htm

Climate change helped to reduce ozone levels, study shows

Researchers at the University of Houston have determined that climate change -- in the form of a stronger sea breeze, the result of warmer soil temperatures -- contributed to the drop in high-ozone days in the Houston area.

Robert Talbot, professor of atmospheric chemistry, said that also should be true for coastal regions globally.The researchers describe their findings in a paper published this week in the journal The study relied upon ground-level ozone data collected over the past 23 years by the Texas Commission on Environmental Quality. The meteorological data was collected by the National Oceanic and Atmospheric Administration.The researchers said they did not set out to find a connection between climate change and lower ozone levels -- the number of days in which ozone levels exceeded federal standards varied from year to year but overall, dropped dramatically between 1990 and 2013. For example, in Aldine, one of four sites studied, the number of days during which ozone levels exceeded federal standards over an eight-hour period dropped to an average of 11 days per year during 2001-2013, down from 35 days per year during 1990-2000.Talbot said the steep decline made him suspect something was happening beyond a city-led effort to reduce nitrogen oxide emissions, one of the components of ozone.Liu said they first ruled out other meteorological factors, including temperature, humidity and solar radiation. After they discovered the lower ozone readings coincided with days the southerly flow was strongest, they realized that climate change -- in the form of warmer soil temperatures -- had increased the southerly flow, she said."The frequency of southerly (air) flow has increased by a factor of ~2.5 over the period 1990-2013, likely suppressing O3 (ozone) photochemistry and leading to a 'cleaner' Houston environment," they wrote. "The sea breeze was enhanced greatly from 1990 to 2013 due to increasing land surface temperatures, increased pressure gradients, and slightly stronger on-shore winds. These patterns driven by climate change produce a strengthening of the sea breeze, which should be a general result at locations worldwide."Industrial plants and vehicle exhaust mix with heat and sunlight to produce ground-level ozone, which can worsen asthma and other conditions. The city's rapid population growth -- more people means more cars -- and the refineries and petrochemical plants along the Houston Ship Channel are key factors in Houston's ground-level ozone.The U.S. Environmental Protection Agency in 1997 classified Houston as a "severe" nonattainment area due to ozone levels measured over an eight-hour period. By 2008, the city was classified as a "moderate" nonattainment area.For the study, researchers focused on data from four locations: Galveston, Clinton Drive near the Houston Ship Channel, Aldine and a site in Northwest Harris County. They also used data on background ozone levels collected from the roof of Moody Tower, a high-rise residence hall on the UH campus.Background ozone levels have remained constant over the past seven years, they report, dropping just one part per billion. The average background level over that period was 30 parts per billion.But the number of days in which ground-level ozone exceeded federal standards in one-hour and eight-hour measures dropped sharply at all four sites between 1990 and 2013. (Data for the Galveston site is available only back to 1997.)In contrast, "the length of time per year Houston is under the influence of southerly flow has more than doubled from 1990 to 2013," the researchers wrote. " ... We propose that the increased flow of 'cleaner' air is diluting the dirty Houston air, lowering the mixing ratios of NOX, O3 and precursor hydrocarbons. It also would advect the polluted air away from Houston," leading to lower potential to produce ozone.They compared land and sea temperatures over the 23-year period to determine how temperature differences impact southerly flow. Land temperatures increase faster than water temperatures on a daily time scale, Liu said. As the heated air over land rises, cooler air from the sea rushes in, dispersing both ozone and the chemical elements that contribute to ozone."We weren't looking at it from a climate change perspective at first," Talbot said. "Then once we saw it was the sea breeze, we knew it had to be climate."

Ozone Holes

May 14, 2015

https://www.sciencedaily.com/releases/2015/05/150514095741.htm

Climate scientists find warming in higher atmosphere: Elusive tropospheric hot spot located

Researchers have published results in

The inability to detect this hotspot previously has been used by those who doubt human-made global warming to suggest climate change is not occurring as a result of increasing carbon dioxide emissions."Using more recent data and better analysis methods we have been able to re-examine the global weather balloon network, known as radiosondes, and have found clear indications of warming in the upper troposphere," said lead author ARC Centre of Excellence for Climate System Science Chief Investigator Prof Steve Sherwood."We were able to do this by producing a publicly available temperature and wind data set of the upper troposphere extending from 1958-2012, so it is there for anyone to see."The new dataset was the result of extending an existing data record and then removing artefacts caused by station moves and instrument changes. This revealed real changes in temperature as opposed to the artificial changes generated by alterations to the way the data was collected.No climate models were used in the process that revealed the tropospheric hotspot. The researchers instead used observations and combined two well-known techniques -- linear regression and Kriging."We deduced from the data what natural weather and climate variations look like, then found anomalies in the data that looked more like sudden one-off shifts from these natural variations and removed them," said Prof Sherwood."All of this was done using a well established procedure developed by statisticians in 1977."The results show that even though there has been a slowdown in the warming of the global average temperatures on the surface of Earth, the warming has continued strongly throughout the troposphere except for a very thin layer at around 14-15km above the surface of Earth where it has warmed slightly less.As well as confirming the tropospheric hotspot, the researchers also found a 10% increase in winds over the Southern Ocean. The character of this increase suggests it may be the result of ozone depletion."I am very interested in these wind speed increases and whether they may have also played some role in slowing down the warming at the surface of the ocean," said Prof Sherwood."However, one thing this improved data set shows us is that we should no longer accept the claim that there is warming missing higher in the atmosphere. That warming is now clearly seen."

Ozone Holes

May 12, 2015

https://www.sciencedaily.com/releases/2015/05/150512103808.htm

New research will help forecast bad ozone days over the Western US

New research published in

Recognizing this link offers an opportunity to forecast ozone several months in advance, which could improve public education to reduce health effects. It would also help western U.S. air quality managers prepare to track these events, which can have implications for attaining the national ozone standard.Exposure to ozone is harmful to human health, can cause breathing difficulty, coughing, scratchy and sore throats, and asthma attacks, and can damage sensitive plants."Ozone in the stratosphere, located 6 to 30 miles (10 to 48 kilometers) above the ground, typically stays in the stratosphere," said Lin. "But not on some days in late spring following a strong La Niña winter. That's when the polar jet stream meanders southward over the western U.S. and facilitates intrusions of stratospheric ozone to ground level where people live."Over the last two decades, there have been three La Niña events -- 1998-1999, 2007-2008 and 2010-2011. After these events, scientists saw spikes in ground level ozone for periods of two to three days at a time during late spring in high altitude locations of the U.S. West.While high ozone typically occurs on muggy summer days when pollution from cars and power plants fuels the formation of regional ozone pollution, high-altitude regions of the U.S. West sometimes have a different source of high ozone levels in late spring. On these days, strong gusts of cold dry air associated with downward transport of ozone from the stratosphere pose a risk to these communities.Lin and her colleagues found that these deep intrusions of stratospheric ozone could add 20 to 40 parts per billion of ozone to the ground-level ozone concentration, which can provide over half the ozone needed to exceed the standard set by the U.S. Environmental Protection Agency. The EPA has proposed tightening that standard currently set at 75 parts per billion for an eight-hour average to between 65 and 70 parts per billion.Under the Clean Air Act, these deep stratospheric ozone intrusions can be classified as "exceptional events" that are not counted towards EPA attainment determinations. As our national ozone standard becomes more stringent, the relative importance of these stratospheric intrusions grows, leaving less room for human-caused emissions to contribute to ozone pollution prior to exceeding the level set by the U.S. EPA."Regardless of whether these events count towards non-attainment, people are living in these regions and the possibility of predicting a high-ozone season might allow for public education to minimize adverse health effects," said Arlene Fiore, an atmospheric scientist at Columbia University and a co-author of the research.Predicting where and when stratospheric ozone intrusions may occur would also provide time to deploy air sensors to obtain evidence as to how much of ground-level ozone can be attributed to these naturally occurring intrusions and how much is due to human-caused emissions.The study involved collaboration across two NOAA laboratories, NOAA's cooperative institutes at Princeton and the University of Colorado Boulder, and scientists at partner institutions in the U.S., Canada and Austria. It was also supported in part by the NASA Air Quality Applied Sciences Team whose mission is to apply earth science data to help address air quality management needs."This study brings together observations and chemistry-climate modeling to help understand the processes that contribute to springtime high-ozone events in the western U.S.," said Andrew Langford, an atmospheric scientist at NOAA's Earth System Research Laboratory in Boulder, Colorado, whose teams measure ozone concentrations using lidar and balloon-borne sensors."You've heard about good ozone, the kind found high in the stratosphere that protects Earth from harmful ultraviolet radiation," said Langford. "And you've heard about bad ozone at ground level. This study looks at the factors that cause good ozone to go bad."

Ozone Holes

March 31, 2015

https://www.sciencedaily.com/releases/2015/03/150331102451.htm

Travelling pollution: East Asian human activities affect air quality in remote tropical forests

Researchers from the UK and Malaysia have detected a human fingerprint deep in the Borneo rainforest in Southeast Asia. Cold winds blowing from the north carry industrial pollutants from East Asia to the equator, with implications for air quality in the region. Once there, the pollutants can travel higher into the atmosphere and impact the ozone layer. The research is published in

Rainforests are often associated with pure, unpolluted air, but in Borneo air quality is very much dependent on which way the wind blows. "On several occasions during northern-hemisphere winter, pockets of cold air can move quickly southwards across Asia towards south China and onward into the South China Sea," says Matthew Ashfold, Assistant Professor at the University of Nottingham Malaysia Campus.In a new study, Ashfold and his team show that these 'cold surges' can very quickly transport polluted air from countries such as China to remote parts of equatorial Southeast Asia. "The pollution travels about 1000 km per day, crossing the South China Sea in just a couple of days," states Ashfold, who was based at the University of Cambridge, UK, when he conducted parts of the study.The researchers were initially looking for chemical compounds of natural origin: they wanted to test whether the oceans around Borneo were a source of bromine and chlorine. They designed their experiments to measure these gases, but also detected another gas called perchloroethene, or perc, in the air samples they collected from two locations in the Borneo rainforest. "This gas is a common 'marker' for pollution because it does not have natural sources," says Ashfold.The team wanted to find out where the human-made gas came from, and where it might go. "We used a UK Met Office computer model of atmospheric transport to look back in time, at where the air samples we collected had travelled from." Their experiments suggested the high levels of perc in the air samples were influenced by East Asian pollution, as reported in the Perc is produced in a number of industrial and commercial activities, such as dry cleaning and metal degreasing, and exposure to large amounts (above about 100 parts per million) can affect human health. While global emissions of perc have declined in the past 20 years or so, it is not clear whether this has been the case in East Asia, where air pollution has increased over the past couple of decades.The researchers say the levels of perc measured in Borneo are low, at a few parts per trillion. But because the gas does not occur naturally, even small concentrations are a sign that other more common pollutants, such as carbon monoxide and ozone, could be present. Ozone, for example, can damage forests when in high concentrations, as it reduces plant growth.Indeed, the team's measurements showed the amounts of perc varied strongly over the course of about a week, and models they analysed indicated this variation to be related to similar changes in carbon monoxide and ozone. "During the one 'cold surge' event we studied in detail, levels of these pollutants over Borneo appeared to be double typical levels," Ashfold points out.But diminished air quality in the remote rainforest is not the only way East Asia pollution affects the tropics. "The atmosphere over Southeast Asia and the Western Pacific is home to unusually strong and deep thunderstorms during the northern hemisphere winter. Because of this, the region is an important source of air for the stratosphere," says Ashfold.In their study the researchers show that, once in the deep tropics, the polluted air is lifted towards the upper atmosphere. "This can introduce a range of industrial chemicals with atmospheric lifetimes of just a few months to the stratosphere, which could have a potentially negative impact on the ozone layer."

Ozone Holes

March 26, 2015

https://www.sciencedaily.com/releases/2015/03/150326122056.htm

Deadly Japan earthquake and tsunami spurred global warming, ozone loss

Buildings destroyed by the 2011 Tohoku earthquake released thousands of tons of climate-warming and ozone-depleting chemicals into the atmosphere, according to a new study.

New research suggests that the thousands of buildings destroyed and damaged during the 9.0 magnitude earthquake and tsunami that struck Japan four years ago released 6,600 metric tons (7,275 U.S. tons) of gases stored in insulation, appliances and other equipment into the atmosphere.Emissions of these chemicals, called halocarbons, increased by 21 percent to 91 percent over typical levels, according to the new study accepted for publication in The study is the first to look at how the Tohoku earthquake affected the release of halocarbons into the atmosphere and likely one of the first to examine emissions of these gases following a natural disaster, according to the study's authors."What we found is a new mechanism of halocarbon emissions coming from the earthquake," said Takuya Saito, a senior researcher at the National Institute for Environmental Studies in Tsukuba, Japan, and lead author of the new paper.Halocarbons released as a result of the earthquake include chemicals that deplete the ozone layer and contribute to global warming -- including some gases that are no longer used because of those harmful effects on the environment. These include chlorofluorocarbons like CFC-11, a powerful ozone-depleting chemical used in foam insulation until it was phased out in 1996, and hydrochlorofluorocarbons like HCFC-22, an ozone-depleting refrigerant that is also a powerful greenhouse gas and is in the process of being phased out of use. Among other halocarbons released by the earthquake were hydrofluorocarbons, or HFCs, and sulfur hexafluoride, both potent greenhouse gases.The emissions of the six halocarbons released from Japan in 2011 are equivalent to the discharge of 1,300 metric tons (1,433 U.S. tons) of CFC-11 alone -- equal to the amount of CFC-11s found in 2.9 million refrigerators manufactured before the chemical was banned. The total emissions of the six chemicals are also equivalent to the release of 19.2 million metric tons (21.2 million U.S. tons) of carbon dioxide into the atmosphere -- an amount equal to about 10 percent of Japanese vehicle emissions in 2011, according to the study's authors.Saito and his colleagues decided to investigate halocarbon emissions and their relationship to the earthquake after ground-based air monitoring stations in Japan recorded surprising high levels of these chemicals. The stations are on Hateruma Island, east of Taiwan; Cape Ochiishi, on the east side of Hokkaido; and Ryori, north of Tokyo on Honshu.The study's authors combined these measurements with an atmospheric model and other mathematical methods to figure out that increased emissions from the earthquake were involved, how much of the emissions could be attributed to the disaster and how they compared to previous years.They found that emissions of all six halocarbons were higher from March 2011 to February 2012, following the earthquake, than they were during the same time the year before the event and during the same period the year after it.About 50 percent of the halocarbon emissions after the earthquake were of HCFC-22, likely due to damage to refrigerators and air conditioners. Emissions of the gas were 38 percent higher than the years before and after the earthquake. Emissions of CFC-11 were 72 percent higher than emissions before and after the earthquake, likely due to damage to insulation foams used in appliances and buildings, according to the study. Emissions of two types of HFCs -- HFC-134a and HFC-32 -- rose by 49 percent and 63 percent compared to the years before and after the disaster.The new study also calculates the total impact of the increased emissions on ozone depletion and global warming. The earthquake-triggered surge of halocarbons increased ozone loss from Japanese emissions of those six gases by 38 percent from March 2011 to February 2012 compared to the same time period in the years before and after the event. The amount of heat trapped in the atmosphere because of Japan's emissions of those six gases rose 36 percent from March 2011 to February 2012 compared to earlier and later years because of the extra emissions from the earthquake, according to the new study.Saito said the new study shows the importance of including the release of gases from natural disasters in emissions estimates. Although the global effect of one event is small -- emissions associated with the Tohoku earthquake accounted for 4 percent or less of global emissions in 2011 -- the cumulative effect could be larger, he said. Natural disasters accelerate the release of halocarbons and replacement of these gases could lead to the use of more halocarbons, according to the study.National halocarbon emissions estimates by the Japanese government did not factor in the release of the chemicals due to the earthquake and are likely underestimating the amount of these substances in the atmosphere, according to Saito. Governments rely on inventories of chemicals and generic data about how they are used to estimate their amounts in the atmosphere -- called a "bottom-up" approach" -- whereas the new study uses actual measurements of the gases -- called a "top-down" approach. "It is apparent that there are unreported emissions," Saito said.The new study shows that there could be a need to include the amount of halocarbons released by catastrophic events in emissions estimates, said Steve Montzka, a research chemist at the National Oceanic and Atmospheric Administration in Boulder, Colorado, who was not involved in the research. It also highlights the need for more measurements of halocarbons in the atmosphere, he added, rather than relying on bottom-up emissions estimates from inventories."Atmospheric scientists often say that relying solely on bottom-up inventories to tell you how greenhouse gas emissions change is like going on a diet without weighing yourself," Montzka said.

Ozone Holes

March 22, 2015

https://www.sciencedaily.com/releases/2015/03/150322080208.htm

Air pollutants could boost potency of common airborne allergens

A pair of air pollutants linked to climate change could also be a major contributor to the unparalleled rise in the number of people sneezing, sniffling and wheezing during allergy season. The gases, nitrogen dioxide and ground-level ozone, appear to provoke chemical changes in certain airborne allergens that could increase their potency. That, in combination with changes in global climate, could help explain why airborne allergies are becoming more common.

The findings will be presented today at the 249"Scientists have long suspected that air pollution and climate change are involved in the increasing prevalence of allergies worldwide. But understanding the underlying chemical processes behind this phenomenon has proven elusive," says Ulrich Pöschl, Ph.D., of the Max Planck Institute in Germany. "Our research is just a starting point, but it does begin to suggest how chemical modifications in allergenic proteins occur and how they may affect allergenicity."About 50 million people in the United States suffer from nasal allergies, according to the American College of Allergy, Asthma and Immunology. And those numbers are on the rise.In previous work, Pöschl; Christopher Kampf, Ph.D.; Manabu Shiraiwa, Ph.D.; and colleagues at the Max Planck Institute explored how allergy-causing substances are altered in the air. Building on that work, they decided to dig deeper into how that happens and examine how traffic-related air pollutants could increase the strength of these allergens.In laboratory tests and computer simulations, they studied the effects of various levels of ozone and nitrogen dioxide on the major birch pollen allergen called Bet v 1.The researchers determined that ozone -- the main component of smog -- oxidizes an amino acid called tyrosine that helps form Bet v 1 proteins. This transformation sets in motion a chain of chemical reactions that involves reactive oxygen intermediates and can bind proteins together, altering their structures and their potential biological effects. When this occurs, Kampf says the cross-linked proteins can become more potent allergens.Pöschl's team also found that nitrogen dioxide, a component of automobile exhaust, appears to alter the polarity and binding capabilities of Bet v 1 allergenic proteins. This, in conjunction with the effects of ozone, the researchers predict, may enhance the immune response of the body to these particles, particularly in humid, wet and smoggy environments.The scientists plan to identify other modified allergenic proteins in the environment and hope, in collaboration with biomedical researchers, to study their effects on the human immune system, which may also be affected by other physiological factors."Our research is showing that chemical modifications of allergenic proteins may play an important role in the increasing prevalence of allergies worldwide," Kampf says. "With rising levels of these pollutants we will have more of these protein modifications, and in turn, these modifications will affect the allergenic potential of the protein."The researchers acknowledge funding by the Max Planck Society.

Ozone Holes

March 10, 2015

https://www.sciencedaily.com/releases/2015/03/150310105307.htm

Small eddies produce global effects on climate change

The increasing strength of winds over the Southern Ocean has extended its ability to absorb carbon dioxide, effectively delaying the impacts of global warming.

New research published in the The increased movement and overturning of these eddies and jets has accelerated the carbon cycle and driven more heat into the deep ocean."Considering the Southern Ocean absorbs something like 60% of heat and anthropogenic CO2 that enters the ocean, this wind has a noticeable effect on global warming," said lead author Dr Andy Hogg from the Australian National University Hub of the ARC Centre of Excellence for Climate System Science."To put this in some kind of context, if those small scale eddies did not increase with wind stress then the saturation of carbon dioxide in the Southern Ocean sink would occur twice as rapidly and more heat would enter our atmosphere and sooner."Despite having one of the most powerful currents in the world in the form of the Antarctic Circumpolar Current, eddies dominate the circulation of the Southern Ocean. Until this research, a major uncertainty around the future impacts of climate change was whether the eddy field would change with stronger winds or whether it would remain static.Using satellite observations the study has given the first direct evidence that the Southern Ocean eddy field has increased in recent decades and that this increase can be attributed to the increase in winds around the Southern Ocean.The intensification of winds in the Southern Ocean is a result of both the depletion of ozone and global warming's affects on the Southern Annular Mode (SAM). The SAM is a measure of the position of a belt of westerly winds that circle Antarctica.When climate scientists talk about a positive SAM it means that belt of westerlies has moved closer to the Antarctic. A negative SAM means the wind belt has moved closer to the equator. The position of the SAM can vary from year to year but the long-term trend has been for increasingly positive SAM events."Interestingly, we found the movement and strength of the SAM played the largest role in increasing the energy of the eddies in the Southern Ocean over periods of less than a decade but there were clear delays between the timing of the SAM and its effect on the eddies," said Dr Hogg."The increase in kinetic energy of these eddies actually only became apparent a few years after a strong SAM event."Although the impact of SAM events over the short term was an interesting finding, it was the long-term trend over multiple decades of observations that gave a crucial indication of the changes occurring in the Southern Ocean."If the winds continue to increase as a result of global warming, then we will continue to see increased energy in eddies and jets that will have significant implications for the ability of the Southern Ocean to store carbon dioxide and heat," said Dr Hogg."Remarkable as it seems these relatively small eddies and jets are doing the heavy lifting in the ocean driving heat into the Southern Ocean and slowing the impacts of global warming."

Ozone Holes

March 2, 2015

https://www.sciencedaily.com/releases/2015/03/150302121609.htm

Munching bugs thwart eager trees, reducing the carbon sink

In a high carbon dioxide world, the trees would come out ahead. Except for the munching bugs.

A new study published in The finding is significant because climate change models typically fail to consider changes in the activities of insects in the ecosystem, says Richard Lindroth, a professor of ecology at the University of Wisconsin-Madison and the leader of the study. The research suggests it's time to add insects to the models.Carbon dioxide typically makes plants grow faster and makes them more efficient in how they use nutrients. But the amount of damage caused by leaf-munching bugs in the study nearly doubled under high carbon dioxide conditions, leading to an estimated 70g of carbon-sequestering biomass lost per meter squared per year."This is the first time, at this scale, that insects have been shown to compromise the ability of forests to take up carbon dioxide," Lindroth says.In addition, as feeding increased, more nutrients moved from the canopy to the forest floor in the form of insect fecal material and chewed-on leaf scraps, mixing into the soil and likely altering the nutrient profile of the forest."Insects are munching on leaves and they're pooping out remnants, so they are changing the timing of nutrient cycling as well as the quality," Lindroth says.John Couture, a former graduate student in Lindroth's lab and the lead author of the study, spent three years with his team studying the impact of elevated carbon dioxide alone, elevated ozone (which is highly toxic to plants) alone, and elevated levels of both gases combined on stands of aspen and birch growing in what was once one of the largest simulated ecosystems in the world, the Aspen Free-Air Carbon dioxide and ozone Enrichment (Aspen FACE) experiment located near Rhinelander, Wisconsin.Unlike a greenhouse or atmospheric chamber, the FACE site (now decommissioned) was a massive outdoor experimental area that allowed trees to grow under natural conditions, like natural soil, sunlight, and rainfall. The only artificial conditions were those that were experimentally manipulated.The site consisted of a dozen stands of trees growing in 30 meter diameter plots, surrounded by a network of PVC pipes designed to vent gases into the environment around them.They were exposed to carbon dioxide and ozone at levels predicted for the year 2050, although Lindroth says the 560 parts-per-million carbon dioxide level studied is probably too low.The trees were planted as saplings in the mid-1990s and by the time Couture collected data for the study from 2006 though 2008, they had grown to resemble any number of the disturbed forest stands found throughout Wisconsin.Couture and his team walked through each site, clipping leaves from the canopy using scissors at the end of pruner poles or from scaffolding near the top of the canopy. They also set out frass baskets -- laundry baskets lined with sheets -- to collect scraps of leaves dropped by messy, munching caterpillars and other bugs dining in the canopy, and to collect their fecal droppings.Tens of thousands of leaves and countless frass baskets later, Couture measured the amount of leaf area consumed by the insects in each plot and sifted through the frass and food droppings in the baskets to assess just how much eating the bugs were doing, to measure the amount of nutrients leaving the trees via their droppings, and to assess the loss of tree biomass.Why insects would do more munching in a carbon dioxide rich forest is in part a matter of chemistry. Because carbon dioxide is a limiting resource for plant growth, high levels of the gas change the way trees use other resources, like nitrogen, typically leading to less nutritious plants."It's like a slice of Wonder Bread versus a slice of high density, protein-rich bakery bread; there's a lot more protein in the bakery bread than the white bread," says Couture. "Insects have a base level of nutrients they need in order to grow and to reach that, they can choose either to eat higher-nutrient food -- unfortunately, insects don't always have that choice -- or to eat more."Overall, the team found high ozone plots were less hospitable to insects, reducing their munching behavior and leading to less biomass loss.With the findings, the researchers created models allowing them to predict what could happen in forests under changing environmental conditions."The big question is, will northern forests grow faster under elevated carbon dioxide?" says Lindroth. "Carbon dioxide is a substrate for photosynthesis. It gets converted into sugars, which then become plant biomass. Will trees take up more carbon dioxide and thus help reduce its increase in the atmosphere?"As humans continue to contribute more carbon dioxide to Earth's atmosphere, the answer should be yes as trees act as sponges for the greenhouse gas. But it turns out, very hungry caterpillars and their bug brethren -- in their own quest for food in an elevated carbon dioxide environment -- may limit that growth and reduce the capacity of forests to slow climate warming.

Ozone Holes

February 16, 2015

https://www.sciencedaily.com/releases/2015/02/150216130241.htm

New ozone-destroying gases on the rise; not controlled by treaty

Scientists report that chemicals that are not controlled by a United Nations treaty designed to protect the Ozone Layer are contributing to ozone depletion.

In the new study, published today in Study lead author Dr Ryan Hossaini, from the School of Earth and Environment at the University of Leeds, said: “VSLS can have both natural and industrial sources. Industrial production of VSLS is not controlled by the United Nations Montreal Protocol because historically these chemicals have contributed little to ozone depletion.“But we have identified now that one of these chemicals is increasing rapidly and, if this increase is allowed to continue, it could offset some of the benefits to the Ozone Layer provided by the Montreal Protocol.”In the study, the researchers used a 3D computer model of the atmosphere to determine the impact of VSLS on ozone and climate.Measurements of VSLS in the atmosphere over the past two decades, provided by collaborators from the National Oceanic and Atmospheric Administration (NOAA) in the United States, were also analysed. These measurements revealed a rapid increase in atmospheric concentrations of dichloromethane, a man-made VSLS used in a range of industrial processes.Study co-author Professor Martyn Chipperfield, from Leeds’ School of Earth and Environment, said: “We need to continue monitoring the atmospheric abundance of these gases and determine their sources. At present, the long-term recovery of the Ozone Layer from the effects of CFCs is still on track, but the presence of increasing dichloromethane will lead to uncertainty in our future predictions of ozone and climate.”The researchers found that while the amount of ozone depletion arising from VSLS in the atmosphere today is small compared to that caused by longer-lived gases, such as CFCs, VSLS-driven ozone depletion was found to be almost four times more efficient at influencing climate.Dr Hossaini explained: “Due to their short atmospheric lifetimes, VSLS break down and destroy ozone in the lowermost part of the stratosphere. This is important, as a molecule of ozone lost in this region has a far larger impact on climate than a molecule destroyed at higher altitudes by longer-lived gases.”The researchers also separated out natural sources of VSLS – such as seaweed in the ocean – and those released due to human activity – such as industrial processes – in order to determine the relative importance of each.At present, naturally-emitted VSLS account for around 90% of the total ozone loss caused by VSLS in the lower stratosphere. However, the contribution from man-made VSLS compounds is increasing and appears set to increase further in coming years.Study co-author Dr Stephen Montzka from the NOAA added: “The increases observed for dichloromethane are striking and unexpected; concentrations had been decreasing slowly in the late 1990s, but since then have increased by about a factor of two at sites throughout the globe.”Dr Hossaini said: “It is uncertain what is driving this growth. However, it could be partly due to the fact that dichloromethane is used in the manufacturing process of some HFCs, the 'ozone-friendly' gases which were developed to replace CFCs. This would mean, ironically, that production of ozone-friendly chemicals is actually releasing some ozone-destroying gases into the atmosphere.”

Ozone Holes

December 1, 2014

https://www.sciencedaily.com/releases/2014/12/141201113128.htm

Key role of ozone in climate change highlighted

Many of the complex computer models which are used to predict climate change could be missing an important ozone 'feedback' factor in their calculations of future global warming, according to new research led by the University of Cambridge and published today (1 December) in the journal

Computer models play a crucial role in informing climate policy. They are used to assess the effect that carbon emissions have had on the Earth's climate to date, and to predict possible pathways for the future of our climate.Increasing computing power combined with increasing scientific knowledge has led to major advances in our understanding of the climate system during the past decades. However, the Earth's inherent complexity, and the still limited computational power available, means that not every variable can be included in current models. Consequently, scientists have to make informed choices in order to build models which are fit for purpose."These models are the only tools we have in terms of predicting the future impacts of climate change, so it's crucial that they are as accurate and as thorough as we can make them," said the paper's lead author Peer Nowack, a PhD student in the Centre for Atmospheric Science, part of Cambridge's Department of Chemistry.The new research has highlighted a key role that ozone, a major component of the stratosphere, plays in how climate change occurs, and the possible implications for predictions of global warming. Changes in ozone are often either not included, or are included a very simplified manner, in current climate models. This is due to the complexity and the sheer computational power it takes to calculate these changes, an important deficiency in some studies.In addition to its role in protecting the Earth from the Sun's harmful ultraviolet rays, ozone is also a greenhouse gas. The ozone layer is part of a vast chemical network, and changes in environmental conditions, such as changes in temperature or the atmospheric circulation, result in changes in ozone abundance. This process is known as an atmospheric chemical feedback.Using a comprehensive atmosphere-ocean chemistry-climate model, the Cambridge team, working with researchers from the University of East Anglia, the National Centre for Atmospheric Science, the Met Office and the University of Reading, compared ozone at pre-industrial levels with how it evolves in response to a quadrupling of COWhat they discovered is a reduction in global surface warming of approximately 20% -- equating to 1° Celsius -- when compared with most models after 75 years. This difference is due to ozone changes in the lower stratosphere in the tropics, which are mainly caused by changes in the atmospheric circulation under climate change."This research has shown that ozone feedback can play a major role in global warming and that it should be included consistently in climate models," said Nowack. "These models are incredibly complex, just as the Earth is, and there are an almost infinite number of different processes which we could include. Many different processes have to be simplified in order to make them run effectively within the model, but what this research shows is that ozone feedback plays a major role in climate change, and therefore should be included in models in order to make them as accurate as we can make them. However, this particular feedback is especially complex since it depends on many other climate processes that models still simulate differently. Therefore, the best option to represent this feedback consistently might be to calculate ozone changes in every model, in spite of the high computational costs of such a procedure."Climate change research is all about having the best data possible. Every climate model currently in use shows that warming is occurring and will continue to occur, but the difference is in how and when they predict warming will happen. Having the best models possible will help make the best climate policy."

Ozone Holes

November 6, 2014

https://www.sciencedaily.com/releases/2014/11/141106113301.htm

Future air quality could put plants, people at risk

By combining projections of climate change, emissions reductions and changes in land use across the USA, an international research team estimate that by 2050, cumulative exposure to ozone during the summer will be high enough to damage vegetation.

Although the research findings -- published in "Modelling future air quality is very complex, because so many factors need to be taken into account at both a global and local scale," says Dr Val Martin. "The picture isn't uniform across the USA, with some areas seeing much higher surface ozone levels than others. However, our findings show that the emissions reductions we're expecting to achieve won't guarantee air quality on their own, as they will be offset by changes in climate and land use and by an increase in wildfires. This is an issue that will affect all parts of the world, not just the USA."The research looked at air quality under two scenarios set out by the Intergovernmental Panel on Climate Change: one which envisages greenhouse gas emissions peaking in 2040 and then falling, the other in which emissions continue to rise until 2100. The team combined data on climate change, land use and emissions to create a picture of air quality across the USA in 2050.The model showed that, if greenhouse gas emissions peak in 2040, then by 2050 surface ozone will remain below levels set to safeguard human health, despite increases in ozone caused by higher temperatures and changes in agriculture and forestation. If emissions continue to rise until 2100, then some areas of the USA will see surface ozone above the safe levels set for human health.However, when the researchers looked at the cumulative impact of ozone over three months in the summer -- a standard growing season -- they found that under both scenarios, the surface ozone levels would be high enough to cause damage to plants. This was particularly because during the summer, there were higher emissions from transport and industry of nitrogen oxides, which react with sunlight to create ozone."Ozone affects photosynthesis, causing pigmentation on leaves, stunting growth and reducing yield," explains Dr Val Martin. "At a time when the world will need to be feeding a growing population, we need to be sure that our ability to do this isn't compromised by surface ozone. Our model shows that we may need more stringent controls of certain emissions -- such as nitrogen oxides or methane -- that contribute to ozone levels."Co-researcher Professor Colette Heald, from Massachusetts Institute of Technology, adds: "Poor air quality is not just an issue in cities. Air pollution in pristine regions such as National Parks degrades visibility and can damage ecosystem health. Protecting natural ecosystems -- and our enjoyment of them -- will require us to consider and manage the impacts of emissions and climate change on future air quality."

Ozone Holes

November 5, 2014

https://www.sciencedaily.com/releases/2014/11/141105154559.htm

Ah-choo! Expect higher grass pollen, allergen exposure in coming century

Results of a new study by scientists at the University of Massachusetts Amherst strongly suggest that there will be notable increases in grass pollen production and allergen exposure up to 202 percent in the next 100 years, leading to a significant, worldwide impact on human health due to predicted rises in carbon dioxide (CO2) and ozone (O3) due to climate change.

While CO2 stimulates reproduction and growth in plants, ozone has a negative impact on plant growth, the authors point out. In this study in Timothy grass, researchers led by environmental health scientist Christine Rogers of the UMass Amherst School of Public Health and Health Sciences (SPHHS) determined the interactive effects of CO2 and ozone at projected higher levels on pollen production and concentrations of a Timothy grass pollen protein that is a major human allergen. Findings are reported in the current issue of Rogers and plant science colleagues at UMass Amherst, with postdoctoral researcher and first author Jennifer Albertine, write, "The implications of increasing CO2 for human health are clear. Stimulation of grass pollen production by elevated CO2 will increase airborne concentrations and increase exposure and suffering in grass pollen-allergic individuals."Rogers notes that, "This is the first evidence that pollen production is significantly stimulated by elevated carbon dioxide in a grass species and has worldwide implications due to the ubiquitous presence of grasses in all biomes and high prevalence of grass pollen allergy. These results are similar to our other studies performed in other highly allergenic taxa such as ragweed but with more extreme outcomes and wider impacts."For these experiments, the researchers exposed grass plants in specially designed continuously stirred tank reactor chambers that allow researchers to expose plants to different atmospheric gas concentrations. They established four experimental atmospheric treatments:At the appropriate plant development stage, Albertine and colleagues bagged flowers, captured and measured pollen amounts and extracted the allergen protein Phl p 5 from pollen samples for measurement by enzyme-linked immunosorbent assay (ELISA).They found that elevated CO2 of 800 ppm, increased pollen production per flower by 53 percent while the different ozone levels had no effect on the amount of pollen produced. There was also a trend of increased number of plants flowering in response to elevated CO2 further increasing pollen production up to 200 percent. While elevated ozone did decrease the Phl p 5 allergen content in pollen, "the strong CO2-stimulation of pollen production suggests increased exposure to Timothy grass allergen overall," even if O3 projections are realized, the authors note.They add that the health implications of increased ozone are "more complex" because higher levels of this greenhouse gas irritate mucous membranes and worsen the allergic airway response. Projected ozone increases "would likely elicit negative respiratory health effects independent of any health effects as a result of increased pollen by elevated CO2."

Ozone Holes

November 5, 2014

https://www.sciencedaily.com/releases/2014/11/141105131935.htm

Increase in ozone-destroying substances, but Montreal Protocol on track

Research from the University of Leeds and an international team of scientists has shown a recent increase in atmospheric hydrogen chloride (HCI), a substance linked to destruction of the ozone layer.

It was anticipated that there would be a decline in HCI under the Montreal Protocol, the international treaty designed to protect the ozone layer by phasing out the production of ozone-depleting substances.Dr Emmanuel Mahieu from the University of Liège in Belgium, who led the research, explained: "It's important to say that the Montreal Protocol is still on track, and that this is a transient reversal in the decline of HCl, which can be explained through a change in atmospheric circulation, rather than rogue emissions of ozone-depleting substances."The study, published today in the journal Professor Martyn Chipperfield from the University of Leeds, who led the modelling work for the study, said: "The expected deterioration of ozone-destroying chemicals in the atmosphere is certainly more complex than we had imagined. Rather than a steady decline, these findings have presented a rather more complicated picture."Through comparison with detailed computer models, we have identified this decline as temporary due to changes in upper atmospheric wind patterns, so we remain optimistic that the ozone layer will recover during the second half of the century."The recent increase in HCl concentrations was only observed in the Northern Hemisphere, whilst in the Southern Hemisphere, HCI continues to decrease, as expected, in line with the Montreal Protocol.Professor Chipperfield added: "There are natural differences in the atmosphere between the Northern and Southern Hemispheres, due to the influence of the Earth's surface topography and slight variations in the Earth's orbit around the Sun during the year. While atmospheric chlorine levels remain high we may see cases of large ozone depletion, especially over the polar regions."The findings are based on measurements by a network with stations in Spitsbergen, Greenland, Sweden, Switzerland, Japan, Tenerife, Australia and New Zealand. These are backed up by satellite observations and model simulations.Professor Peter Bernath, from the University of York, who was also part of the international team of scientists, added: "Atmospheric variability and perhaps climate change can significantly modify the path towards full recovery and, ultimately, it will be a bumpy ride rather than a smooth evolution."The recovery of ozone-depleting chemicals in the atmosphere is a slow process and will take many decades. During this time the ozone layer remains vulnerable."

Ozone Holes

October 30, 2014

https://www.sciencedaily.com/releases/2014/10/141030213801.htm

2014 Antarctic ozone hole holds steady

The single-day maximum area was similar to that in 2013, which reached 24.0 million square kilometers (9.3 million square miles). The largest single-day ozone hole ever recorded by satellite was 29.9 million square kilometers (11.5 million square miles) on Sept. 9, 2000. Overall, the 2014 ozone hole is smaller than the large holes of the 1998-2006 period, and is comparable to 2010, 2012, and 2013.

With the increased atmospheric chlorine levels present since the 1980s, the Antarctic ozone hole forms and expands during the Southern Hemisphere spring (August and September). The ozone layer helps shield life on Earth from potentially harmful ultraviolet radiation that can cause skin cancer and damage plants.The Montreal Protocol agreement beginning in 1987 regulated ozone depleting substances, such as chlorine-containing chlorofluorocarbons and bromine-containing halons. The 2014 level of these substances over Antarctica has declined about 9 percent below the record maximum in 2000."Year-to-year weather variability significantly impacts Antarctica ozone because warmer stratospheric temperatures can reduce ozone depletion," said Paul A. Newman, chief scientist for atmospheres at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "The ozone hole area is smaller than what we saw in the late-1990s and early 2000s, and we know that chlorine levels are decreasing. However, we are still uncertain about whether a long-term Antarctic stratospheric temperature warming might be reducing this ozone depletion."Scientists are working to determine if the ozone hole trend over the last decade is a result of temperature increases or chorine declines. An increase of stratospheric temperature over Antarctica would decrease the ozone hole's area. Satellite and ground-based measurements show that chlorine levels are declining, but stratospheric temperature analyses in that region are less reliable for determining long-term trends.Scientists also found that the minimum thickness of ozone layer this year was recorded at 114 Dobson units on Sept. 30, compared to 250-350 Dobson units during the 1960s. Over the last 50 years satellite and ground-based records over Antarctica show ozone column amounts ranging from 100 to 400 Dobson units, which translates to about 1 millimeter (1/25 inch) to 5 millimeters (1/6 inch) of ozone in a layer if all of the ozone were brought down to the surface.The ozone data come from the Dutch-Finnish Ozone Monitoring Instrument on NASA's Aura satellite and the Ozone Monitoring and Profiler Suite instrument on the NASA-NOAA Suomi National Polar-orbiting Partnership satellite. NOAA measurements at South Pole station monitor the ozone layer above that location by means of Dobson spectrophotometer and regular ozone-sonde balloon launches that record the thickness of the ozone layer and its vertical distribution. Chlorine amounts are estimated using NOAA and NASA ground measurements and observations from the Microwave Limb Sounder aboard NASA's Aura satellite.NASA and NOAA are mandated under the Clean Air Act to monitor ozone-depleting gases and stratospheric depletion of ozone. Scientists from NASA and NOAA have been monitoring the ozone layer and the concentrations of ozone-depleting substances and their breakdown products from the ground and with a variety of instruments on satellites and balloons since the 1970s. These observations allow us to provide a continuous long-term record to track the long-term and year-to-year evolution of ozone amounts.

Ozone Holes

October 29, 2014

https://www.sciencedaily.com/releases/2014/10/141029141245.htm

Clean smell doesn't always mean clean air

Some of the same chemical reactions that occur in the atmosphere as a result of smog and ozone are actually taking place in your house while you are cleaning. A researcher in Drexel's College of Engineering is taking a closer look at these reactions, which involve an organic compound -called limonene- that provides the pleasant smell of cleaning products and air fresheners. His research will help to determine what byproducts these sweet-smelling compounds are adding to the air while we are using them to remove germs and odors.

Secondary organic aerosols (SOAs) are microscopic particles created when ozone reacts with volatile organic gases such as limonene -the chemical name for the smell of oranges- or its cousin α-pinene, which is part of the smell of pine trees. Outdoors, this reaction happens all the time. It drives the formation of much of the atmospheric organic aerosol present in our environment. And in, population-dense urban areas -where enough suspended particles can be amassed- it contributes to the formation of the visible haze called smog.While a large amount of aerosols that exist in the Earth's atmosphere are naturally occurring -- created by processes such as mechanical suspension by wind or sea spray -- much is produced as a result of industrialization. And while researchers are still striving to fully understand the health and environmental impact of increased levels of secondary organic aerosols in the atmosphere, studies have linked exposure to outdoor aerosols generally to morbidity and mortality outcomes.Few researchers, however, have considered the formation of SOAs in our indoor environments. Michael Waring, PhD, an assistant professor in Drexel University's College of Engineering, is taking the deepest look yet at the formation and behavior of these particles indoors."SOAs can come from ozone reactions with numerous sources, especially with compounds called terpenes that produce the scents we associate with cleaners, pine, lavender, and oranges," Waring said. "Limonene is the terpene that makes an orange's smell. It's a very popular scent for cleaning products, so we're taking a closer look at how it reacts indoors -where people are using it in high concentrations."The first step toward understanding the health implications is finding how many of these microscopic SOA particles are created when household cleaning products and air fresheners react with ozone indoors. In research recently published in For the research, Waring and his team used an air testing chamber that they specifically designed to study the reactive behavior of air in an indoor environment. With it, they were able to simulate limonene being added to the environment in pulses -- the way it would be introduced indoors when spraying a limonene-containing cleaning product. They are also able to control the amount of ozone in the chamber -- an aspect of indoor environments that can vary with outdoor ozone concentrations and the opening of windows and doors or the use of a few certain household appliances.By adjusting elements of the test, such as the air exchange rate, which is the number of times per hour indoor air is replaced by outdoor air, as well as the concentrations of terpene and ozone in the chamber, the group was able to ascertain how those variables each affected the formation of secondary organic aerosols.This process is unique to Waring's research. Other labs have undertaken this sort of examination, but almost always using a constant flow of terpene and ozone into the environment. But by pulsing limonene into the chamber operated at different air exchange rates, the Drexel researchers are more closely recreating actual usage scenarios in hopes of generating more representative results."We found that one of the biggest factors contributing to SOA formation by limonene ozonolysis was the air exchange rate," Waring said. "This is because certain chemical reactions that form SOAs take longer than others. If the air is exchanged before these reactions can take place then the SOA production is weaker indoors."With 18 different scenarios tested, the team calculated a range of peak formation of secondary organic aerosols when typical concentrations of limonene were introduced to ozone-rich environments with a range of air exchange rates. The resulting mass concentration of secondary organic aerosols was roughly between five and 100 μg/m"For reference, the EPA's National Ambient Air Quality Standard for fine aerosol is an annual average of 12 μg/mWhile the next step in this line of research would be to examine the health impacts of indoor SOA, a few ways to reduce indoor aerosols would be to use unscented cleaners and open windows while cleaning. Even though open windows bring in more ozone from outside, the reduction in the indoor limonene concentration and SOA formation strength more than make up for it, as less secondary organic aerosol is formed inside.

Ozone Holes

October 14, 2014

https://www.sciencedaily.com/releases/2014/10/141014083846.htm

Solar activity impacts polar ozone

The increase in greenhouse gases explains, to a large extent, the rise in the average temperature of Earth. According to the research study published in

Humankind is responsible for the global warming of our climate by increasing the amount of greenhouse gases in the atmosphere. However, according results published today, fluctuations in the activity of the Sun impact middle atmosphere ozone, providing a potential link to regional scale climate variability. This climate variability is not a trend, like climate change, but rather year-to-year fluctuations following solar activity. "The detected ozone variation may in part help understand the alternation of local mild and cold winter seasons, as hints have been obtained in previous research that the ozone changes in the middle atmosphere may link as far as the surface of Earth and affect, among other things, polar wind streams," Finnish Meteorological Institute researcher Dr Pekka Verronen reflects.The research team was able to confirm, for the first time, the long-term implications of solar-driven electron impact on the upper middle atmosphere ozone. The results showed strong effects in the polar latitudes. The amount of ozone at 70-80 km altitude was found to vary more than 30 percent during a solar cycle, a period of approximately 11 years. The ozone variation between the extremes of the Sun's activity is so great that it is likely to impact the temperature balance of the atmosphere. These temperature changes can in turn have an effect on atmospheric winds.According to the research study conducted by the Finnish Meteorological Institute, University of Otago and the British Antarctic Survey, the electrons, similar to those behind the aurora, cause significant solar cycle variation in the polar mesosphere ozone. The amount of ozone is smaller when more electrons enter the atmosphere. "These results are only the first step but an important one, allowing us to better understand the long-term impacts of this type of solar activity, and its role in regional climate variability," says Dr Monika Andersson who lead the study at Finnish Meteorological Institute.Earth's radiation belts are regions in near-Earth space that contain vast quantities of solar energetic electrons, trapped there by Earth's magnetic field. During magnetic storms, which are solar wind-driven, the electrons accelerate to high speeds and enter the atmosphere in the polar regions. In the atmosphere, the electrons ionize gas molecules, leading to the production of ozone-depleting catalyst gases. Based on currently available satellite observations, electron precipitation may, during solar storms lasting a few days, reduce ozone in the upper atmosphere (60-80 km) as much as 90 per cent on a momentary basis.

Ozone Holes

October 8, 2014

https://www.sciencedaily.com/releases/2014/10/141008122102.htm

Antarctic sea ice reaches new record maximum

Sea ice surrounding Antarctica reached a new record high extent this year, covering more of the southern oceans than it has since scientists began a long-term satellite record to map sea ice extent in the late 1970s. The upward trend in the Antarctic, however, is only about a third of the magnitude of the rapid loss of sea ice in the Arctic Ocean.

The new Antarctic sea ice record reflects the diversity and complexity of Earth's environments, said NASA researchers. Claire Parkinson, a senior scientist at NASA's Goddard Space Flight Center, has referred to changes in sea ice coverage as a microcosm of global climate change. Just as the temperatures in some regions of the planet are colder than average, even in our warming world, Antarctic sea ice has been increasing and bucking the overall trend of ice loss."The planet as a whole is doing what was expected in terms of warming. Sea ice as a whole is decreasing as expected, but just like with global warming, not every location with sea ice will have a downward trend in ice extent," Parkinson said.Since the late 1970s, the Arctic has lost an average of 20,800 square miles (53,900 square kilometers) of ice a year; the Antarctic has gained an average of 7,300 square miles (18,900 sq km). On Sept. 19 this year, for the first time ever since 1979, Antarctic sea ice extent exceeded 7.72 million square miles (20 million square kilometers), according to the National Snow and Ice Data Center. The ice extent stayed above this benchmark extent for several days. The average maximum extent between 1981 and 2010 was 7.23 million square miles (18.72 million square kilometers).The single-day maximum extent this year was reached on Sept. 20, according to NSIDC data, when the sea ice covered 7.78 million square miles (20.14 million square kilometers). This year's five-day average maximum was reached on Sept. 22, when sea ice covered 7.76 million square miles (20.11 million square kilometers), according to NSIDC.A warming climate changes weather patterns, said Walt Meier, a research scientist at Goddard. Sometimes those weather patterns will bring cooler air to some areas. And in the Antarctic, where sea ice circles the continent and covers such a large area, it doesn't take that much additional ice extent to set a new record."Part of it is just the geography and geometry. With no northern barrier around the whole perimeter of the ice, the ice can easily expand if conditions are favorable," he said.Researchers are investigating a number of other possible explanations as well. One clue, Parkinson said, could be found around the Antarctic Peninsula -- a finger of land stretching up toward South America. There, the temperatures are warming, and in the Bellingshausen Sea just to the west of the peninsula the sea ice is shrinking. Beyond the Bellingshausen Sea and past the Amundsen Sea, lies the Ross Sea -- where much of the sea ice growth is occurring.That suggests that a low-pressure system centered in the Amundsen Sea could be intensifying or becoming more frequent in the area, she said -- changing the wind patterns and circulating warm air over the peninsula, while sweeping cold air from the Antarctic continent over the Ross Sea. This, and other wind and lower atmospheric pattern changes, could be influenced by the ozone hole higher up in the atmosphere -- a possibility that has received scientific attention in the past several years, Parkinson said."The winds really play a big role," Meier said. They whip around the continent, constantly pushing the thin ice. And if they change direction or get stronger in a more northward direction, he said, they push the ice further and grow the extent. When researchers measure ice extent, they look for areas of ocean where at least 15 percent is covered by sea ice.While scientists have observed some stronger-than-normal pressure systems -- which increase winds -- over the last month or so, that element alone is probably not the reason for this year's record extent, Meier said. To better understand this year and the overall increase in Antarctic sea ice, scientists are looking at other possibilities as well.Melting ice on the edges of the Antarctic continent could be leading to more fresh, just-above-freezing water, which makes refreezing into sea ice easier, Parkinson said. Or changes in water circulation patterns, bringing colder waters up to the surface around the landmass, could help grow more ice.Snowfall could be a factor as well, Meier said. Snow landing on thin ice can actually push the thin ice below the water, which then allows cold ocean water to seep up through the ice and flood the snow -- leading to a slushy mixture that freezes in the cold atmosphere and adds to the thickness of the ice. This new, thicker ice would be more resilient to melting."There hasn't been one explanation yet that I'd say has become a consensus, where people say, 'We've nailed it, this is why it's happening,'" Parkinson said. "Our models are improving, but they're far from perfect. One by one, scientists are figuring out that particular variables are more important than we thought years ago, and one by one those variables are getting incorporated into the models."For Antarctica, key variables include the atmospheric and oceanic conditions, as well as the effects of an icy land surface, changing atmospheric chemistry, the ozone hole, months of darkness and more."Its really not surprising to people in the climate field that not every location on the face of Earth is acting as expected -- it would be amazing if everything did," Parkinson said. "The Antarctic sea ice is one of those areas where things have not gone entirely as expected. So it's natural for scientists to ask, 'OK, this isn't what we expected, now how can we explain it?'"

Ozone Holes

October 7, 2014

https://www.sciencedaily.com/releases/2014/10/141007091653.htm

High-pollution days linked to increased risk of cardiac arrest

Rates of out-of-hospital cardiac arrest are elevated after days with high levels of air pollutants, reports a Japanese study in the October

Dr Takashi Yorifuji of Okayama University and colleagues analyzed the relationship between daily air pollution levels and cardiac arrest rates. The study included 559 patients with out-of-hospital cardiac arrest in Okayama City between 2006 and 2010.The data suggested that cardiac arrest rates were higher a few days after increased levels of several air pollutants. For example, 48 to 72 hours after days with high levels of particulate air pollution, the risk of out-of-hospital cardiac arrest increased by 17 percent.There was a 40 percent increase in risk 72 to 96 hours after days with higher ozone levels. The effects of increased particulate pollution were greater in older patients, while increased ozone levels had a greater effect in younger patients. Particulate pollution showed a greater effect in men.Many recent studies have reported associations between outdoor air pollution and cardiovascular disease. The findings linking increased pollutant levels to a subsequent increase in cardiac arrest in Japan are consistent with previous data from other countries."The evidence presented provides further support for the hypothesis that exposure to outdoor air pollution increases the risk of cardiac arrest," Dr Yorifuji and coauthors conclude. The results suggest that particulate matter and ozone may induce cardiac arrest via "two distinct pathways." Exposure to particulate pollution may result in myocardial infarction, while ozone may worsen other cardiac conditions, increasing the risk of cardiac arrest.

Ozone Holes

October 6, 2014

https://www.sciencedaily.com/releases/2014/10/141006085120.htm

Atmospheric chemistry hinges on better physics model

New theoretical physics models could help us better grasp the atmospheric chemistry of ozone depletion. Indeed, understanding photoabsorption of nitrous oxide (N

The work has led to new calculations of the probability of an absorption process taking place, also referred to as absorption cross section. These calculations confirm experimental results.In this study, the author introduces improvements in an established calculation approach, referred to as the ab initio time-dependent method. It helps calculate the absorption cross section, or spectrum, of nitrous oxide. The advantage of this approach is that it immediately yields the energy dependence of a cross section or spectrum from a single calculation. By taking into account key factors such as the correct angular momentum coupling of the molecule and the component of the transition dipole moment vector, the theoretical model of calculated spectrum has produced better results than previously obtained and more closely matches experimental observations.Daud's calculation thus provides an improved theoretical prediction of how nitrous oxide evolves and breaks down over time, thus contributing to the nitrous oxide photoabsorption process. As such processes occur in a small gap between the absorption band of oxygen and that of ozone, the predicted major dissociation pathway allows us to understand the involvement of nitrous oxide in the formation of ozone at the molecular level.

Ozone Holes

October 1, 2014

https://www.sciencedaily.com/releases/2014/10/141001133016.htm

Wintertime ozone pollution in Utah oil and gas fields explained

Chemicals released into the air by oil and gas exploration, extraction and related activities can spark reactions that lead to high levels of ozone in wintertime, high enough to exceed federal health standards, according to new NOAA-led research, published today in

The study comes at a time when new technologies are helping to accelerate oil and gas development in Utah's Uintah Basin, elsewhere in the United States and in many other countries, and its findings may help air quality managers determine how to best minimize the impact of ozone pollution.When ozone levels spike, Environmental Protection Agency (EPA) experts recommend that people, especially those in sensitive groups -- children, the elderly, and anyone with pre-existing respiratory conditions -- limit time outdoors.Winter ozone pollution is surprising because normally, the more intense sunlight of the summer season can spark the chemical reactions that create ozone pollution, said lead author Peter Edwards, a scientist with NOAA's Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder at the time of the study, and now with University of York in England.However, Edwards and his colleagues showed that in winter in northeastern Utah, levels of volatile organic compounds (VOCs) build high enough that they can trigger pollution-forming reactions themselves. In winter, warm air aloft can trap cold air below, creating an inversion that concentrates VOCs. The presence of snow increases light reflection and accelerates ozone production.For instance, in 2013, ozone in Ouray, Utah, exceeded the national air quality standards 49 times during the winter season. By contrast, in the densely populated, urban area of Riverside, California, the standards were exceeded about half that amount that same year, but during the summer."So it's the same starting ingredients, nitrogen oxides and VOCs, that form ozone in Riverside, but it's a different spark in Utah in winter," said coauthor Steven Brown, a scientist with NOAA's Earth System Research Laboratory in Boulder, Colorado. "Under wintertime conditions, the much higher VOCs in Utah break down to make carbonyl compounds, which set off the ozone production."The research is based on data collected in a series of wintertime studies in Uintah Basin led by James Roberts, of NOAA's ESRL. "We encountered a range of conditions during the three winters, from snowy in 2013 and 2014, to virtually no snow in 2012," said Roberts. "Oil and gas emissions of VOCs were high in all three years, but high ozone occurred only in the cold, snowy stagnant periods."Researchers from NOAA, CIRES, and other institutions made detailed measurements of ozone and the chemical ingredients, such as VOCs and nitrogen oxides, that "cook up" into the pollutant, and they used chemical models to better understand the chemistry behind the wintertime ozone formation."These studies in Utah have caused us to think about air pollution chemistry a little differently," said coauthor Joost de Gouw, a researcher with CIRES working at NOAA ESRL. "Our findings could help state and local air quality managers who are faced with ozone episodes to design policies, and industry representatives to meet air quality standards in the regions where they operate."

Ozone Holes

September 26, 2014

https://www.sciencedaily.com/releases/2014/09/140926141008.htm

Key reaction for producing 'atmosphere's detergent' observed

Earth's atmosphere is a complicated dance of molecules. The chemical output of plants, animals and human industry rise into the air and pair off in sequences of chemical reactions. Such processes help maintain the atmosphere's chemical balance; for example, some break down pollutants emitted from the burning of fossil fuels.

Understanding exactly how these reactions proceed is critical for predicting how the atmosphere will respond to environmental changes, but some of the steps of this dance are so quick that all of the molecules involved haven't been measured in the wild.A University of Pennsylvania team has now observed one of these rapid atmospheric reactions in the lab. They identify an important intermediate molecule and track its transformation to hydroxyl radicals, also demonstrating the amount of energy necessary for the reaction to take place.Their findings help explain how the atmosphere maintains its reserves of hydroxyl radicals, highly reactive molecules that are called the "atmosphere's detergent."The study was led by Marsha Lester, professor of chemistry in Penn's School of Arts & Sciences, along with members of her lab: graduate student Fang Liu and postdoctoral researcher Joseph Beames. They collaborated with Andrew Petit, also a postdoctoral researcher in the Department of Chemistry, and Anne McCoy, professor of chemistry at The Ohio State University.Their work was published in Hydroxyl radicals are composed of a hydrogen atom bonded to an oxygen atom. They are highly reactive, readily stealing hydrogen atoms from other molecules to form water. Many common pollutants and greenhouse gases, such as methane and more complex hydrocarbons, are initially broken down by these radicals."Hydroxyl radicals are called the atmosphere's detergent because most pollutants that go into the air are broken down by them," Lester said. "Since they're so reactive, the question is then. 'How is it that there is so much of it in the atmosphere?' They're reacting away all of the time, so they must be constantly replenished."The sun is responsible for most of the hydroxyl radicals in the air in the daytime. Sunlight has sufficient energy to breakdown ozone, releasing oxygen atoms that react with water vapor to produce hydroxyl radicals. However, another important source of these molecules does not require sunlight. This less-well-understood process, investigated by the Lester team, is the dominant source of hydroxyl radicals at night, and plays a large role in the atmosphere during the winter.In 1949, German chemist Rudolf Criegee hypothesized that alkenes, a class of chemicals with carbon double bonds, were broken down in reaction with ozone by way of intermediate molecules that were even more reactive and short-lived, so much so that they eluded detection until very recently. These intermediate molecules are now known as "Criegee intermediates."Lester's team is now the first to track a Criegee intermediate through the reaction that results in a hydroxyl radical, using a technique known as infrared action spectroscopy."We used a laser to generate a 'fingerprint' of this intermediate molecule, based on the wavelengths of light it absorbs," Lester said. "The laser also supplies the energy necessary to drive the reaction, which would be provided by heat under atmospheric conditions.""At the end," said Beames, "we also detected the hydroxyl radicals, so we're the first to actually show that the hydroxyl radicals are produced directly from the Criegee intermediate.""We see that a hydrogen atom from one end of the intermediate molecule transfers over and bonds to an oxygen atom on the other side," said Liu. "The molecule then breaks apart, resulting in a hydroxyl radical."The team believes that the new understanding of the amount of energy necessary to drive this hydrogen transfer reaction will have implications for many of the hydroxyl-radical-producing reactions that involve Criegee intermediates."If you're going over a mountain -- the energy it takes to drive the reaction -- there are certain pathways it makes sense to follow," Petit said. "We're studying the simplest of this class of molecules so we think this pathway will be relevant to the others in the series."A more complete picture of how the hydroxyl radicals are produced on an hour-to-hour and season-to-season basis will be instrumental to developing more accurate models of the atmosphere. Hydroxyl radical production through this route can also vary geographically, as the precursors to the reaction -- alkenes -- are more readily found above urban and forested regions."You can't measure everything," Lester said, "so we need good models to predict how the atmosphere will respond to changes in the environment, whether those changes are temperature, ozone levels or the presence of petrochemicals."

Ozone Holes

September 22, 2014

https://www.sciencedaily.com/releases/2014/09/140922175749.htm

Actions on climate change bring better health, study says

The number of extremely hot days in Eastern and Midwestern U.S. cities is projected to triple by mid-century, according to a new study led by University of Wisconsin-Madison researchers and published today in the

Milwaukee and New York City could experience three times as many 90-degree days by 2046; Dallas could see twice as many days topping 100 degrees. The new analysis offers climate data through the lens of public health, in a study that represents a synthesis of the latest science at the intersection of climate change and human health.In presenting their synthesis, the study authors seek to encourage efforts that benefit both the health of the planet and the health of people, the so-called co-benefits of reducing fossil fuel consumption and adapting to changes that are already underway."Climate change already is affecting global health," says Jonathan Patz, director of the UW-Madison Global Health Institute and lead author of the new study. "The good news is that clear health benefits are immediately available, from low-carbon strategies that today could result in cleaner air or to more active transport options that can improve physical fitness, ultimately saving lives and averting disease."Patz will present the article today at the Civil Society Event on Action in Climate Change and Health in New York. Acting U.S. Surgeon General Boris Lushniak; Maria Neira, World Health Organization (WHO) director for public health and the environment; Gina McCarthy, administrator of the U.S. Environmental Protection Agency; and many others will also participate in the event.The study also includes UW-Madison associate professors Tracey Holloway and Daniel Vimont, both in the Nelson Institute for Environmental Studies and the Department of Atmospheric and Oceanic Sciences; Howard Frumkin from the University of Washington; and Andrew Haines of the London School of Hygiene and Tropical Medicine. It reviews the science behind some of the current and projected climate-related health risks.Those include more extreme heat waves and storms, increased waterborne and infectious disease risks, more chronic health risks related to air pollution, and increased malnutrition and obesity-related risks from unhealthy, carbon-intensive diets."Climate change is an enormous public health challenge because it affects our health through multiple pathways," says Patz, also a professor in the Nelson Institute and the Department of Population Health Sciences at UW-Madison. "But if the risks are so interdependent, so, too, are the opportunities."These opportunities include improvements to air quality, such as through reductions in unhealthy ozone, or smog. The study highlights a close association between the number of extremely hot days and the number of high-ozone days over the last several years in cities like Chicago, Milwaukee and Madison, Wisconsin.This is "consistent with well-known linkages between climate and ozone in urban areas, and serves as a major pathway for the health impacts of climate change," Holloway says.The analysis also lays out a number of science-based strategies to reduce global consumption of fossil fuels while improving health. These include designing sustainable cities, eating less meat, enacting better carbon policies (the costs of which could be more than offset by the potential health benefits they afford) and promoting active transport like walking or biking to work."Evidence shows there is a significant health benefit in active transport, particularly in the area of chronic disease," Patz says. "And with current disease trends in industrializing nations, burning less fossil fuel can yield potentially large dividends for public health."The new study relied on an interdisciplinary team of experts in public health, air quality and climate science and offers opportunities across sectors."These findings dovetail with recent World Health Organization (WHO) studies that identified major health benefits from low carbon housing, transport and agriculture," says WHO health policy expert Carlos Dora. "Many of these benefits come from reductions in air pollution, but low carbon strategies also can increase physical activity, reduce traffic injuries and improve food security."Patz is optimistic about recent policy developments and he says the article presents "a blueprint" for the public health benefits possible "if we really took on climate change."

Ozone Holes

September 21, 2014

https://www.sciencedaily.com/releases/2014/09/140921092938.htm

Fracking's environmental impacts scrutinized

Greenhouse gas emissions from the production and use of shale gas would be comparable to conventional natural gas, but the controversial energy source actually faired better than renewables on some environmental impacts, according to new research.

The UK holds enough shale gas to supply its entire gas demand for 470 years, promising to solve the country's energy crisis and end its reliance on fossil-fuel imports from unstable markets. But for many, including climate scientists and environmental groups, shale gas exploitation is viewed as environmentally dangerous and would result in the UK reneging on its greenhouse gas reduction obligations under the Climate Change Act.University of Manchester scientists have now conducted one of the most thorough examinations of the likely environmental impacts of shale gas exploitation in the UK in a bid to inform the debate. Their research has just been published in the leading academic journal Applied Energy and study lead author, Professor Adisa Azapagic, will outline the findings at the Labour Party Conference in Manchester on 22 September."While exploration is currently ongoing in the UK, commercial extraction of shale gas has not yet begun, yet its potential has stirred controversy over its environmental impacts, its safety and the difficulty of justifying its use to a nation conscious of climate change," said Professor Azapagic."There are many unknowns in the debate surrounding shale gas, so we have attempted to address some of these unknowns by estimating its life cycle environmental impacts from 'cradle to grave'. We looked at 11 different impacts from the extraction of shale gas using hydraulic fracturing -- known as 'fracking'- as well as from its processing and use to generate electricity."The researchers compared shale gas to other fossil-fuel alternatives, such as conventional natural gas and coal, as well as low-carbon options, including nuclear, offshore wind and solar power (solar photovoltaics).The results of the research suggest that the average emissions of greenhouse gases from shale gas over its entire life cycle are about 460 grams of carbon dioxide-equivalent per kilowatt-hour of electricity generated. This, the authors say, is comparable to the emissions from conventional natural gas. For most of the other life-cycle environmental impacts considered by the team, shale gas was also comparable to conventional natural gas.But the study also found that shale gas was better than offshore wind and solar for four out of 11 impacts: depletion of natural resources, toxicity to humans, as well as the impact on freshwater and marine organisms. Additionally, shale gas was better than solar (but not wind) for ozone layer depletion and eutrophication (the effect of nutrients such as phosphates, on natural ecosystems).On the other hand, shale gas was worse than coal for three impacts: ozone layer depletion, summer smog and terrestrial eco-toxicity.Professor Azapagic said: "Some of the impacts of solar power are actually relatively high, so it is not a complete surprise that shale gas is better in a few cases. This is mainly because manufacturing solar panels is very energy and resource-intensive, while their electrical output is quite low in a country like the UK, as we don't have as much sunshine. However, our research shows that the environmental impacts of shale gas can vary widely, depending on the assumptions for various parameters, including the composition and volume of the fracking fluid used, disposal routes for the drilling waste and the amount of shale gas that can be recovered from a well."Assuming the worst case conditions, several of the environmental impacts from shale gas could be worse than from any other options considered in the research, including coal. But, under the best-case conditions, shale gas may be preferable to imported liquefied natural gas."The authors say their results highlight the need for tight regulation of shale gas exploration -- weak regulation, they claim, may result in shale gas having higher impacts than coal power, resulting in a failure to meet climate change and sustainability imperatives and undermining the deployment of low-carbon technologies.Professor Azapagic added: "Whether shale gas is an environmentally sound option depends on the perceived importance of different environmental impacts and the regulatory structure under which shale gas operates."From the government policy perspective -- focusing mainly on economic growth and energy security -- it appears likely that shale gas represents a good option for the UK energy sector, assuming that it can be extracted at reasonable cost."However, a wider view must also consider other aspects of widespread use of shale gas, including the impact on climate change, as well as many other environmental considerations addressed in our study. Ultimately, the environmental impacts from shale gas will depend on which options it is displacing and how tight the regulation is."Study co-author Dr Laurence Stamford, from Manchester's School of Chemical Engineering and Analytical Science, said: "Appropriate regulation should introduce stringent controls on the emissions from shale gas extraction and disposal of drilling waste. It should also discourage extraction from sites where there is little shale gas in order to avoid the high emissions associated with a low-output well.He continued: "If shale gas is extracted under tight regulations and is reasonably cheap, there is no obvious reason, as yet, why it should not make some contribution to our energy mix. However, regulation should also ensure that investment in sustainable technologies is not reduced at the expense of shale gas."

Ozone Holes

September 10, 2014

https://www.sciencedaily.com/releases/2014/09/140910162324.htm

Earth's ozone layer on track to recovery, scientists report

Earth's protective ozone layer is well on track to recovery in the next few decades thanks to concerted international action against ozone depleting substances, according to a new assessment by 300 scientists.

The Assessment for Decision-Makers, a summary document of the The stratospheric ozone layer, a fragile shield of gas, protects Earth from harmful ultraviolet rays of the sun. Without the Montreal Protocol and associated agreements, atmospheric levels of ozone depleting substances could have increased tenfold by 2050. According to global models, the Protocol will have prevented 2 million cases of skin cancer annually by 2030, averted damage to human eyes and immune systems, and protected wildlife and agriculture, according to UNEP.The phase-out of ozone depleting substances has had a positive spin-off for the global climate because many of these substances are also potent greenhouse gases. However, the assessment report cautions that the rapid increase in certain substitutes, which are themselves also potent greenhouse gases, has the potential to undermine these gains. The assessment also notes that there are possible approaches to avoiding the harmful climate effects of these substitutes."There are positive indications that the ozone layer is on track to recovery towards the middle of the century. The Montreal Protocol -- one of the world's most successful environmental treaties -- has protected the stratospheric ozone layer and avoided enhanced UV radiation reaching the earth's surface," said UN Under-Secretary-General and UNEP Executive Director Achim Steiner."However, the challenges that we face are still huge. The success of the Montreal Protocol should encourage further action not only on the protection and recovery of the ozone layer but also on climate. On September 23, the UN Secretary General will host Heads of State in New York in an effort to catalyse global action on climate. The Montreal Protocol community, with its tangible achievements, is in a position to provide strong evidence that global cooperation and concerted action are the key ingredients to secure the protection of our global commons," he added."International action on the ozone layer is a major environmental success story," said WMO Secretary-General Michel Jarraud. "This should encourage us to display the same level of urgency and unity to tackle the even greater challenge of climate change. This latest assessment provides solid science to policy-makers about the intricate relationship between ozone and climate and the need for mutually-supportive measures to protect life on earth for future generations.""Human activities will continue to change the composition of the atmosphere. WMO's Global Atmosphere Watch programme will therefore continue its crucial monitoring, research and assessment activities to provide scientific data needed to understand and ultimately predict environmental changes, as it has done for the past 25 years" said Mr Jarraud.The Scientific Assessment Panel is expected to present the key findings of the new report at the annual Meeting of the Parties to the Montreal Protocol, to be held in Paris in November 2014. The full body of the report will be issued in early 2015.The Scientific Assessment of Ozone Depletion 2014 was prepared and reviewed by 282 scientists from 36 countries (Argentina, Australia, Austria, Belgium, Botswana, Brazil, Canada, People's Republic of China, Comoros, Costa Rica, Cuba, Czech Republic, Denmark, Finland, France, Germany, Greece, India, Israel, Italy, Japan, Korea, Malaysia, New Zealand, Norway, Poland, Russia, South Africa, Spain, Sweden, Switzerland, The Netherlands, Togo, United Kingdom, United States of America, Zimbabwe.)Co-Chairs of the ozone assessment are: Prof. Ayité Lô Nohende Ajavon, Université de Lomé, Togo; Prof. John Pyle, University of Cambridge and National Centre for Atmospheric Science, UK; Dr. Paul Newman, NASA/ Goddard Space Flight Center, USA; Prof. A.R. (Ravi) Ravishankara, Colorado State University, USA.The pre-print version of the ADM can be downloaded from:

Ozone Holes

September 10, 2014

https://www.sciencedaily.com/releases/2014/09/140910083333.htm

High-altitude balloon over Ontario, Canada: Researchers measure ozone-depleting bromine

How much does bromine affect stratospheric ozone? Answering this question is the primary objective of measurements by a multi-instrument gondola carried by a high-altitude balloon. The gondola accommodates a unique combination of remote sensing instruments coordinated by Karlsruhe Institute of Technology (KIT) in cooperation with the German Aerospace Center (DLR) and the University of Heidelberg. The balloon flight was launched from Timmins (Ontario/Canada) on Sunday, September 07 as part of the international StratoScience2014 campaign that is operated by the Canadian and French space agencies.

Thanks to the Montreal Protocol on the reduction of production of ozone-depleting substances, which became effective in 1989, the total abundance of chlorine in the stratosphere has been decreasing since the 1990s. The total bromine concentration, by contrast, reached its maximum only a few years ago and now starts to drop very slowly. Hence, the relative hazard potential of bromine for ozone has even increased compared to that of chlorine. The amount of bromine in the stratosphere and major details of its photochemistry are less understood. So far, no simultaneous measurement of the most important bromine substances, bromine oxide (BrO) and bromine nitrate (BrONOThe balloon launched from Timmins (Ontario/Canada) had a size of about 400,000 m³, it carried a load of about 760 kg, and ascended up to a height of nearly 40 km. The gondola accommodates three complex remote sensing instruments that cover a wide range of the electromagnetic spectrum. These instruments complement each other ideally in measuring stratospheric substances: The MIPAS-B infrared spectrometer of the KIT Institute of Meteorology and Climate Research -- Atmospheric Trace Gases and Remote Sensing Division (IMK-ASF), the far-infrared/sub-mm spectrometer TELIS of the German Aerospace Center (DLR), and the UV/vis spectrometer mini-DOAS of Heidelberg University. This world-wide unique combination of instruments can measure about 40 ozone- and climate-relevant trace gases simultaneously," explains the coordinator of the balloon measurements, Hermann Oelhaf, IMK-ASF. Remote sensing means that the gases are not measured directly. Instead, electromagnetic radiation is detected. From it, atmospheric parameters are extracted, as they interact with the solar and/or terrestrial radiation.The pointing and stabilization system of the gondola was developed by KIT's IMK-ASF and ensures that all three instruments measure the same air masses. The remote sensing method also allows for the two- and three-dimensional daytime-dependent continuous measurement of trace gases. In this way, photochemical reactions of the species involved can be studied, which is an important prerequisite for improving chemistry and climate models. The campaign is embedded in an international balloon campaign under cooperation between the French and Canadian Space Agencies CNES and CSA.The measurements are primarily aimed at precisely balancing in a height-dependent manner reactive bromine in the stratosphere, including the most important compounds of the bromine family, BrO and BrONOAs the combination of MIPAS-B/TELIS/mini-DOAS can measure practically all ozone- and climate-relevant gases, the project also serves to analyze budgets, partitioning, and photochemical coupling for all chemical families and to determine vertical profiles of major climate-relevant gases. Moreover, the measurements are used to validate the active satellite devices MLS/AURA (USA) and ACE-FTS (Canada).In the 21

Ozone Holes

September 8, 2014

https://www.sciencedaily.com/releases/2014/09/140908135431.htm

How conversion of forests to cropland affects climate

The conversion of forests into cropland worldwide has triggered an atmospheric change that, while seldom considered in climate models, has had a net cooling effect on global temperatures, according to a new Yale study.

Writing in the journal Using sophisticated climate modeling, Unger calculated that a 30-percent decline in BVOC emissions between 1850 and 2000, largely through the conversion of forests to cropland, produced a net global cooling of about 0.1 degrees Celsius. During the same period, the global climate warmed by about 0.6 degrees Celsius, mostly due to increases in fossil fuel carbon dioxide emissions.According to her findings, the climate impact of declining BVOC emissions is on the same magnitude as two other consequences of deforestation long known to affect global temperatures, although in opposing ways: carbon storage and the albedo effect. The lost carbon storage capacity caused by forest conversion has exacerbated global warming. Meanwhile, the disappearance of dark-colored forests has also helped offset temperature increases through the so-called albedo effect. (The albedo effect refers to the amount of radiation reflected by the surface of the planet. Light-colored fields, for instance, reflect more light and heat back into space than darker forests.)Unger says the combined effects of reduced BVOC emissions and increased albedo may have entirely offset the warming caused by the loss of forest-based carbon storage capacity."Land cover changes caused by humans since the industrial and agricultural revolutions have removed natural forests and grasslands and replaced them with croplands," said Unger, an assistant professor of atmospheric chemistry at F&ES. "And croplands are not strong emitters of these BVOCs -- often they don't emit any BVOCs.""Without doing an earth-system model simulation that includes these factors, we can't really know the net effect on the global climate. Because changes in these emissions affect both warming and cooling pollutants," she noted.Unger said the findings do not suggest that increased forest loss provides climate change benefits, but rather underscore the complexity of climate change and the importance of better assessing which parts of the world would benefit from greater forest conservation.Since the mid-19Not all of these compounds affect atmospheric chemistry in the same way. Aerosols, for instance, contribute to global "cooling" since they generally reflect solar radiation back into space. Therefore, a 50 percent reduction in forest aerosols has actually spurred greater warming since the pre-industrial era.However, reductions in the potent greenhouse gases methane and ozone -- which contribute to global warming -- have helped deliver a net cooling effect.These emissions are often ignored in climate modeling because they are perceived as a "natural" part of Earth system, explained Unger. "So they don't get as much attention as human-generated emissions, such as fossil fuel VOCs," she said. "But if we change how much forest cover exists, then there is a human influence on these emissions."These impacts have also been ignored in previous climate modeling, she said, because scientists believed that BVOC emissions had barely changed between the pre-industrial era and today. But a study published last year by Unger showed that emissions of these volatile compounds have indeed decreased. Studies by European scientists have produced similar results.The impact of changes to ozone and organic aerosols are particularly strong in temperate zones, she said, while methane impacts are more globally distributed.The sensitivity of the global climate system to BVOC emissions suggests the importance of establishing a global-scale long-term monitoring program for BVOC emissions, Unger noted.

Ozone Holes

September 4, 2014

https://www.sciencedaily.com/releases/2014/09/140904131643.htm

Ozone pollution in India kills enough crops to feed 94 million in poverty

In one year, India's ozone pollution damaged millions of tons of the country's major crops, causing losses of more than a billion dollars and destroying enough food to feed tens of millions of people living below the poverty line.

These are findings of a new study that looked at the agricultural effects in 2005 of high concentrations of ground-level ozone, a plant-damaging pollutant formed by emissions from vehicles, cooking stoves and other sources. Able to acquire accurate crop production data for 2005, the study's authors chose it as a year representative of the effects of ozone damage over the first decade of the 21Rising emissions are causing severe ozone pollution in some of India's most populated regions. Pollution in Delhi, the nation's capital, has reached levels comparable to Beijing, one of the most polluted cities in the world, according to India's Air Monitoring Center.The main component of smog, ozone at ground level can cause leaf damage that stifles plant growth, injuring and killing vegetation. There are currently no air quality standards in India designed to protect agriculture from the effects of ground-level ozone pollution, according to the new study. Ground-level ozone is formed when nitrogen oxides, carbon monoxide and volatile organic compounds react with sunlight after the chemicals' release from vehicles, industry, or burning of wood or other plant or animal matter.According to the new study published Aug.14 in India could feed 94 million people with the lost wheat and rice crops, about a third of the country's poor, according to Sachin Ghude, an atmospheric scientist at the Indian Institute of Tropical Meteorology (IITM) in Pune, India and lead author of the new study. There are about 270 million Indians that live in poverty, according to the study.Wheat -- one of the country's major food sources -- saw the largest loss by weight of the four crops studied in the new paper, with ozone pollution damaging 3.5 million metric tons (3.8 million U.S. tons) of the crop in 2005. Another major food source, rice, saw losses of 2.1 million metric tons (2.3 million U.S. tons), according to the new study.Cotton -- one of India's major commercial crops -- lost more than 5 percent of its 3.3 million metric ton (3.6 million U.S. tons) annual output in 2005, costing the country $70 million, according to the new research.Ghude said the new paper, which is the first to quantify how much damage India's ozone pollution has caused the country's major crops on a national level, could help policymakers craft new ozone pollution standards.It could also help India, a country with a high rate of poverty, as the country implements a new law that subsidizes grain for two-thirds of the country's residents, he said. The new food security bill requires the country to provide 61.2 million metric tons (67.5 million U.S. tons) of cereal grains -- that include wheat and rice -- to India's poor each year at a subsidized rate. The new study found that the 5.6 million metric tons (6.2 million U.S. tons) of wheat and rice lost to ozone pollution was equal to 9.2 percent of the new law's subsidized cereal requirement."The (amount of lost wheat and rice) are what surprised me," said Veerabhadran Ramanathan, a professor of climate and atmospheric sciences at Scripps Institution of Oceanography, at the University of California San Diego and a co-author of the new study.Under the new law, residents who qualify to receive cereal at the subsidized rate can purchase 60 kilograms (132 pounds) of grain per year. Based on these numbers, the 5.6 million metric tons (6.2 million U.S. tons) of wheat and rice lost could therefore feed 94 million people in India, according to the new study.The researchers calculated the amount of total crop damage from ozone pollution by comparing emissions estimates from 2005 with data about how much ozone each of the four crops could withstand. Plants start to exhibit damage when they are exposed to ozone levels that reach 40 parts per billion or above, according to previous research.A computer model used by researchers calculated ozone levels during crop growing seasons that were more than 40 to 50 parts per billion over most of the country. The team ran the model with different emissions estimates to come up with an average amount of each crop that was lost due to ozone pollution.India's economic loss from ozone's harm to crops amounted to $1.29 billion in in 2005, the study found. Declines in rice and wheat crops made up the majority of the loss, accounting for a combined $1.16 billion in losses, according to the new research.Despite air quality standards passed in the 1980s to curb industrial and vehicle emissions, cities in India are some of the most polluted in the world, according to the World Health Organization. The number of vehicles on the road in India has nearly tripled in the past decade, with 130 million vehicles on the road in 2013 compared to 50 million in 2003, according to the International Council on Clean Transportation.Long-term measurements of surface ozone over India -- measured on the ground or by aircraft -- are not available, making it difficult to get a clear picture of how ozone levels in the country have changed, Ghude said. But satellite-based studies show ozone has increased over the country in the last two decades, Ghude said. Warmer temperatures that are expected with climate change could also increase ground-level ozone, according to previous research.Ramanathan said that unlike most studies, which look at the effect emissions will have on agriculture decades in the future, the new study examined how ozone emissions are already affecting crops in India. He said the new study could help spur interest in the issue and help policymakers enact new air quality standards or mandate use of new technology to cut emissions.

Ozone Holes

August 27, 2014

https://www.sciencedaily.com/releases/2014/08/140827111858.htm

Greenhouse gases: New group of soil micro-organisms can contribute to their elimination

INRA research scientists in Dijon have shown that the ability of soils to eliminate N2O can mainly be explained by the diversity and abundance of a new group of micro-organisms that are capable of transforming it into atmospheric nitrogen (N2).

Nitrous oxide (NNitrous oxide (NINRA scientists, working in collaboration with Swedish and Irish colleagues, have analysed 47 soil samples collected throughout Europe and demonstrated very considerable differences between these soils in terms of their capacities to eliminate NTheir work has shown that this variability is linked to a new group of N2O-consuming micro-organisms. These organisms had been identified by the same research teams in 2013, but had never previously been taken into account in studies aiming at understanding NThis study has also helped to clarify the influence of the physicochemical properties of soils on the development of these micro-organisms. Thanks to a metagenomic approach and the analysis of several hundreds of thousands of DNA sequences, the scientists were also able to identify several groups of micro-organisms that could act as bioindicators for the capacity of European soils to transform NAll these findings underline the importance of the biodiversity of soil micro-organisms to the functioning of soils and the services they deliver.

Ozone Holes

August 22, 2014

https://www.sciencedaily.com/releases/2014/08/140822084248.htm

Despite significant reduction in smog-producing toxins, the Greater Toronto Area still violates Canada's standards for ozone air pollution

Despite a significant reduction in smog-producing toxins in past decade, GTA still violates Canada's ozone standards

A new study shows that while the Greater Toronto Area (GTA) has significantly reduced some of the toxins that contribute to smog, the city continues to violate the Canada-wide standards for ozone air pollution.Smog, which can cause or aggravate health problems such as asthma, emphysema and chronic bronchitis, is produced by a set of complex photochemical reactions involving volatile organic compounds (VOCs), nitrogen oxides and sunlight, which form ground-level ozone. Smog-forming pollutants come from many sources including automobile exhaust, power plants, factories and many consumer products, such as paint, hairspray, charcoal starter fluid and chemical solvents. In a typical urban area, at least half of the smog precursors come from cars, buses, trucks and boats. Research led by Jennifer Murphy of the Department of Chemistry at the University of Toronto has found that in the GTA between 2004 and 2012, nitrogen oxides and VOCs were reduced by at least 20 per cent between 2004 and 2012."These reductions are in line with the city's 2007 commitment to reducing smog precursors, and can be attributed to the implementation of pollution control measures like the Drive Clean program, and the closure of coal-fired power plants in the region," said Murphy.Despite this good news, ozone concentrations are not following the same encouraging patterns. Canada-wide standards for ozone continued to be exceeded at all monitoring stations in the GTA. While the team noted lower ozone levels between 2008 and 2011 than in previous years, 2012 marked one of the highest recorded summer ozone concentrations as well as a large number of smog episodes.Major smog occurrences often are linked to heavy motor vehicle traffic, high temperatures, sunshine and calm winds. Weather and geography affect the location and severity of smog. Because temperature and sunlight regulates the length of time it takes for smog to form, smog can occur more quickly and be more severe on a hot, sunny day."We are able to show that high ozone in 2012 was due to the relatively high number of sunny days that allowed ozone to be produced quickly, and low winds, that allowed the pollution to accumulate locally," said Murphy.The team obtained the data from federal and provincial government monitoring sites throughout the GTA between 2000 and 2012. Their study, entitled "The impacts of precursor reduction and meteorology on ground-level ozone in the Greater Toronto Area," was published in

Ozone Holes

August 20, 2014

https://www.sciencedaily.com/releases/2014/08/140820173544.htm

Ozone-depleting compound persists, NASA research shows

NASA research shows Earth's atmosphere contains an unexpectedly large amount of an ozone-depleting compound from an unknown source decades after the compound was banned worldwide.

Carbon tetrachloride (CClHowever, the new research shows worldwide emissions of CCl"We are not supposed to be seeing this at all," said Qing Liang, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland, and lead author of the study. "It is now apparent there are either unidentified industrial leakages, large emissions from contaminated sites, or unknown CClAs of 2008, CClFor almost a decade, scientists have debated why the observed levels of CCl"Is there a physical CClWith zero CClTo investigate the discrepancy, Liang and colleagues used NASA's 3-D GEOS Chemistry Climate Model and data from global networks of ground-based observations. The CClModel simulations of global atmospheric chemistry and the losses of CClIn addition to unexplained sources of CCl"People believe the emissions of ozone-depleting substances have stopped because of the Montreal Protocol," said Paul Newman, chief scientist for atmospheres at NASA's Goddard Space Flight Center, and a co-author of the study. "Unfortunately, there is still a major source of CClNASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.For more information about NASA's Earth science activities in 2014, visit: For information on the Antarctic ozone hole, visit:

Ozone Holes

August 4, 2014

https://www.sciencedaily.com/releases/2014/08/140804151407.htm

Sulfur signals in Antarctic snow reveal clues to climate, past and future

Sulfur signals in the Antarctic snow have revealed the importance of overlooked atmospheric chemistry for understanding climate, past and future.

Eruptions of huge volcanoes, the disruptive weather pattern known as El Niño, and a fire season from hell each left distinctive chemical marks in layers of snow excavated near the South Pole, researchers from the University of California, San Diego and France report in the Sorting out the chemical reactions that must have led to those traces revealed a process, known but overlooked, that should be included in models of climate, both forecasts of climate to come and those built to understand Earth's early history."We observed huge signals from ENSO driven changes like extreme dry weather and ensuing biomass burning, which surprised me," said Robina Shaheen, a project scientist in chemistry at UC San Diego and lead author of the report. "The pattern we saw fits signals that have been observed in pre-Cambrian rocks, which prompted us to take another look at which molecules play a role in this chemistry."The element sulfur is everywhere and occurs in four stable forms, or isotopes, each with a slightly different mass. Ordinary reactions incorporate sulfur isotopes into molecules according to mass.But sometimes sulfur divvies up differently so that the relative ratios of the different isotopes is anomalous. Shaheen and her colleagues measured the direction and degree of that anomaly for individual layers of snow representing a single season's snowfall.The snow record they analyzed spans the years 1984 through 2001. Two large volcanoes erupted in that time including Pinatubo and Cerro Hudson, both in 1991.Volcanoes this large inject sulfate into the stratosphere, Earth's high atmosphere above where clouds and weather normally prevail. This sulfur shows up in the snow, lots of it, and the isotope ratio within it is anomalous.Experiments have shown this pattern can result from the influence of shortwave UV light, which doesn't penetrate very far into the atmosphere. Sulfur anomalies in the present-day atmosphere are a sign of reactions that occurred in the stratosphere, above 25 kilometers or 82,000 feet. That is, above Earth's shield of ozone.Shaheen and colleagues also saw sulfur anomalies in snow that fell during years of the cyclical weather pattern called El Niño-Southern Oscillation, or ENSO. That snow held no extra sulfur, only an anomalous pattern of isotopes in the sulfate molecules. Because the pattern resembles anomalies originating from volcanic eruptions, it likely results from similar processes: photochemistry of sulfur compounds in the presence of short wave UV light, above the ozone.Stratospheric sulfur has climate consequences we don't yet fully understand, but it scatters incoming solar radiation. Weather cooled in the years following the eruptions of Pinatubo and Cerro Hudson. And a recent study has attributed the apparent hiatus in global warming over the past 15 years to the extreme ENSO of 1997-1998.The surprise in the snow was for the year following this super ENSO, which had the largest sulfur anomaly of all. There was also an odd spike of potassium, which proved a valuable clue. No large volcanoes erupted, but in the dry season following record monsoons, large swaths of land burned."Earth was on fire," said Mark Thiemens, professor of chemistry at UC San Diego and co-author of the report. "The Amazon, central Africa, Australia, much of Indonesia, the whole middle of the planet, the tropics, heated."Large fires pump smoke all the way into the stratosphere in huge pyrocumulonimbus clouds. It's a mix of molecules like potassium, which marks forest fires in ice cores going back to the 18th century, nitrogen compounds, and sulfur in two important forms.One is sulfur dioxide, the gas most often associated with volcanoes. The other is carbonyl sulfide, a very stable molecule that dissociates when it encounters UV light to form another source of sulfur dioxide. That extra source is the boost, they think, that produced such a large sulfur anomaly signal in the year after the super ENSO.The role of this reaction in creating sulfur anomalies has been little considered in models of climate. That's important because carbonyl sulfide is created whenever biomass or fossil fuels combust at high temperatures. And we're combusting a lot of fossil fuel.It could also be important for interpreting Earth's history. Undisturbed snow, or snow compacted into ice, holds a record of Earth's atmosphere, but so does stone. The oldest rocks, those older than 2.4 billion years, have sulfur anomalies as well. They are thought to have formed in an environment with little oxygen so that Earth's lower atmosphere without its shroud of protective ozone was bathed in short wave UV light.Carbonyl sulfide has been found in geothermal waters, volcanoes, the atmosphere of Venus, comets and dense molecular clouds in interstellar space, so it's plausible to think it was abundant on early Earth as well. What's interesting is that the present-day reaction, in an atmosphere of abundant oxygen, yields a sulfur isotope signal that so closely matches those found in ancient rocks.

Ozone Holes

July 27, 2014

https://www.sciencedaily.com/releases/2014/07/140727165702.htm

Climate change and air pollution will combine to curb food supplies

Many studies have shown the potential for global climate change to cut food supplies. But these studies have, for the most part, ignored the interactions between increasing temperature and air pollution -- specifically ozone pollution, which is known to damage crops.

A new study involving researchers at MIT shows that these interactions can be quite significant, suggesting that policymakers need to take both warming and air pollution into account in addressing food security.The study looked in detail at global production of four leading food crops -- rice, wheat, corn, and soy -- that account for more than half the calories humans consume worldwide. It predicts that effects will vary considerably from region to region, and that some of the crops are much more strongly affected by one or the other of the factors: For example, wheat is very sensitive to ozone exposure, while corn is much more adversely affected by heat.The research was carried out by Colette Heald, an associate professor of civil and environmental engineering (CEE) at MIT, former CEE postdoc Amos Tai, and Maria van Martin at Colorado State University. Their work is described this week in the journal Heald explains that while it's known that both higher temperatures and ozone pollution can damage plants and reduce crop yields, "nobody has looked at these together." And while rising temperatures are widely discussed, the impact of air quality on crops is less recognized.The effects are likely to vary widely by region, the study predicts. In the United States, tougher air-quality regulations are expected to lead to a sharp decline in ozone pollution, mitigating its impact on crops. But in other regions, the outcome "will depend on domestic air-pollution policies," Heald says. "An air-quality cleanup would improve crop yields."Overall, with all other factors being equal, warming may reduce crop yields globally by about 10 percent by 2050, the study found. But the effects of ozone pollution are more complex -- some crops are more strongly affected by it than others -- which suggests that pollution-control measures could play a major role in determining outcomes.Ozone pollution can also be tricky to identify, Heald says, because its damage can resemble other plant illnesses, producing flecks on leaves and discoloration.Potential reductions in crop yields are worrisome: The world is expected to need about 50 percent more food by 2050, the authors say, due to population growth and changing dietary trends in the developing world. So any yield reductions come against a backdrop of an overall need to increase production significantly through improved crop selections and farming methods, as well as expansion of farmland.While heat and ozone can each damage plants independently, the factors also interact. For example, warmer temperatures significantly increase production of ozone from the reactions, in sunlight, of volatile organic compounds and nitrogen oxides. Because of these interactions, the team found that 46 percent of damage to soybean crops that had previously been attributed to heat is actually caused by increased ozone.Under some scenarios, the researchers found that pollution-control measures could make a major dent in the expected crop reductions following climate change. For example, while global food production was projected to fall by 15 percent under one scenario, larger emissions decreases projected in an alternate scenario reduce that drop to 9 percent.Air pollution is even more decisive in shaping undernourishment in the developing world, the researchers found: Under the more pessimistic air-quality scenario, rates of malnourishment might increase from 18 to 27 percent by 2050 -- about a 50 percent jump; under the more optimistic scenario, the rate would still increase, but that increase would almost be cut in half, they found.Agricultural production is "very sensitive to ozone pollution," Heald says, adding that these findings "show how important it is to think about the agricultural implications of air-quality regulations. Ozone is something that we understand the causes of, and the steps that need to be taken to improve air quality."Denise L. Mauzerall, a professor of environmental engineering and international affairs at Princeton University who was not involved in this research, says, "An important finding … is that controls on air-pollution levels can improve agricultural yields and partially offset adverse impacts of climate change on yields. Thus, the increased use of clean energy sources that do not emit either greenhouse gases or conventional air pollutants, such as wind and solar energy, would be doubly beneficial to global food security, as they do not contribute to either climate change or increased surface-ozone concentrations."The research was supported by the National Science Foundation, the National Park Service, and the Croucher Foundation.

Ozone Holes

July 25, 2014

https://www.sciencedaily.com/releases/2014/07/140725163557.htm

Trees save lives, reduce respiratory problems

In the first broad-scale estimate of air pollution removal by trees nationwide, U.S. Forest Service scientists and collaborators calculated that trees are saving more than 850 human lives a year and preventing 670,000 incidents of acute respiratory symptoms.

While trees' pollution removal equated to an average air quality improvement of less than 1 percent, the impacts of that improvement are substantial. Researchers valued the human health effects of the reduced air pollution at nearly $7 billion every year in a study published recently in the journalThe study by Dave Nowak and Eric Greenfield of the U.S. Forest Service's Northern Research Station and Satoshi Hirabayashi and Allison Bodine of the Davey Institute is unique in that it directly links the removal of air pollution with improved human health effects and associated health values. The scientists found that pollution removal is substantially higher in rural areas than urban areas, however the effects on human health are substantially greater in urban areas than rural areas."With more than 80 percent of Americans living in urban area, this research underscores how truly essential urban forests are to people across the nation," said Michael T. Rains, Director of the Forest Service's Northern Research Station and the Forest Products Laboratory. "Information and tools developed by Forest Service research are contributing to communities valuing and managing the 138 million acres of trees and forests that grace the nation's cities, towns and communities."The study considered four pollutants for which the U.S. EPA has established air quality standards: nitrogen dioxide, ozone, sulfur dioxide, and particulate matter less than 2.5 microns (PM2.5) in aerodynamic diameter. Health effects related to air pollution include impacts on pulmonary, cardiac, vascular, and neurological systems. In the United States, approximately 130,000 PMTrees' benefits vary with tree cover across the nation. Tree cover in the United States is estimated at 34.2 percent but varies from 2.6 percent in North Dakota to 88.9 percent in New Hampshire."In terms of impacts on human health, trees in urban areas are substantially more important than rural trees due to their proximity to people," Nowak said. "We found that in general, the greater the tree cover, the greater the pollution removal, and the greater the removal and population density, the greater the value of human health benefits.""Tree and Forest Effects on Air Quality and Human Health in the United States," is available online at:

Ozone Holes

July 18, 2014

https://www.sciencedaily.com/releases/2014/07/140718102727.htm

A 10-year endeavor: NASA's Aura and climate change

Nitrogen and oxygen make up nearly 99 percent of Earth's atmosphere. The remaining one percent comprises gases that -- although present in small concentrations -- can have a big impact on life on Earth. Trace gases called greenhouse gases warm the surface, making it habitable for humans, plants and animals. But these greenhouse gases, as well as clouds and tiny particles called aerosols in the atmosphere, also play vital roles in Earth's complex climate system.

Celebrating its 10th anniversary this week, NASA's Aura satellite and its four onboard instruments measure some of the climate agents in the atmosphere, including greenhouse gases, clouds and dust particles. These global datasets provide clues that help scientists understand how Earth's climate has varied and how it will continue to change.When the sun shines on Earth, some of the light reaches and warms the surface. The surface then radiates this heat back outward, and greenhouse gases stop some of the heat from escaping to space, keeping the surface warm. Greenhouse gases are necessary to keep Earth at a habitable temperature, but since the Industrial Revolution, greenhouse gases have increased substantially, causing an increase in temperature. Aura provides measurements of greenhouse gases such as ozone and water vapor, helping scientists understand the gases that influence climate.People, plants and animals live in the lowest layer of the atmosphere, called the troposphere. In this layer, the temperature decreases with altitude, as mountain climbers experience. The temperature starts to increase again at the tropopause, about 8 miles (12.9 kilometers) above the surface at temperate latitudes, like those of the United States and Europe. Closer to the equator, the tropopause is about 11 miles (17.7 kilometers) from the surface.In the middle and upper troposphere, ozone acts as a greenhouse gas, trapping heat in Earth's atmosphere. Tropospheric ozone is one of the most important human-influenced greenhouse gases.Aura's Tropospheric Emission Spectrometer (TES) instrument, built and managed by NASA's Jet Propulsion Laboratory, Pasadena, California, delivers global maps showing annual averages of the heat absorbed by ozone, in particular in the mid troposphere. Using these maps and computer models, researchers learned that ozone trapped different amounts of heat in Earth's atmosphere depending on its geographic location. For instance, ozone appeared to be a more effective greenhouse gas over hotter regions like the tropics and cloud-free regions like the Middle East."If you want to understand climate change, you need to monitor the greenhouse gases and how they change over time," said Bryan Duncan, an atmospheric scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland.Along with ozone, Aura measures other important greenhouse gases such as methane, carbon dioxide and water vapor.In addition to greenhouse gases, Aura measures several other constituents relevant to climate -- smoke, dust and clouds including the ice particles within the clouds -- that are important for testing and improving climate models."If you don't have any data, then you don't know if the models are right or not," said Anne Douglass, Aura project scientist at Goddard. "The models can only be as good as your knowledge."The way clouds affect Earth's climate depends on their altitude and latitude. Two of Aura's instruments have provided information about tropical clouds. Like greenhouse gases, high, thin clouds in the tropics absorb some of Earth's outgoing heat and warm the surface. Aura's High Resolution Dynamics Limb Sounder (HIRDLS) instrument provided global maps showing cirrus clouds in the upper altitudes in the tropics. Researchers have used these data along with data records from previous satellites going back to 1985 to show that the tropical cirrus cloud distribution has been steady, giving scientists information about the interplay among water vapor, ice and the life cycle of these clouds.Aura's Microwave Limb Sounder (MLS) instrument, also built and managed by JPL, made the first global measurements of cloud ice content in the upper troposphere, providing new data input for climate models. MLS showed cloud ice is often present over warm oceans. Along with satellite rainfall data, MLS shows that dirty, polluted clouds rain less than clean clouds. The novel relationships obtained from HIRDLS and MLS connect ocean temperatures with clouds and ice and quantify effects of pollution on tropical rainfall -- which are important assessments for climate models.Aerosols influence climate, but their influence is challenging to decipher because they play several different roles. Aerosols reflect radiation from the sun back into space; this tends to cool Earth's surface. Aerosols such as dust and smoke also absorb radiation and heat the atmosphere where they are concentrated. Aura's Ozone Monitoring Instrument (OMI) is especially good at observing these absorbing aerosols above clouds and bright deserts. Both OMI and TES also provide data on gases, such as sulfur dioxide and ammonia, which are primary ingredients for other types of less-absorbing aerosols. Aura data, in conjunction with other satellite data, are helping scientists understand how aerosols interact with incoming sunlight in Earth's atmosphere; this, in turn, helps scientists improve long-term predictions in climate models.Researchers investigated how natural phenomena such as El Niño affect tropospheric ozone concentrations -- a study made possible by Aura's extensive data set.El Niño is an irregularly occurring phenomenon associated with warm ocean currents near the Pacific coast of South America that changes the pattern of tropical rainfall. The occasional appearance of areas of warmer temperatures in the Pacific Ocean shifts the stormiest area from the west to the east; the region of upward motion -- a hallmark of low ozone concentrations over the ocean -- moves along with it.Without a decade-long data record, researchers would not be able to conduct such a study. Using the extensive data set, researchers are able to separate the response of ozone concentrations to the changes in human activity, such as biomass burning, from its response to natural forcing such as El Niño."Studies like these that investigate how the composition of the troposphere responds to a natural variation are important for understanding how the Earth system will respond to other forcing, potentially including changes in climate," said Douglass. "The Earth system is complex, and Aura's breadth and the length of the composition data record help us to understand this important part of the system."For more information on Aura, visit: For more on TES, visit: For more on MLS, visit: NASA monitors Earth's vital signs from land, air and space with a fleet of satellites and ambitious airborne and ground-based observation campaigns. NASA develops new ways to observe and study Earth's interconnected natural systems with long-term data records and computer analysis tools to better see how our planet is changing. The agency shares this unique knowledge with the global community and works with institutions in the United States and around the world that contribute to understanding and protecting our home planet.For more information about NASA's Earth science activities in 2014, visit:

Ozone Holes