Forecasting temperature extremes with ozone

Jennifer Chu at MIT News: For the past two summers, Australians have sweated through record heat waves, with thermometers climbing as high as 118 degrees Fahrenheit in parts of the country. In January, officials were forced to halt tennis matches during the Australian Open due to extreme heat — a decision made following several days of sizzling temperatures.

Now MIT researchers have found that the intensity of summer temperatures in Australia and elsewhere in the Southern Hemisphere may be better predicted as early as the previous spring by an unlikely indicator: ozone.

From their study, published in the Journal of Climate, the scientists found that as the springtime ozone hole’s severity varies from year to year, the temperatures in Australia and southern regio
ns of Africa and South America reveal correlations: Years with higher springtime ozone experience hotter summers, and vice versa.

The results suggest that ozone levels may help meteorologists predict the severity of summertime temperatures months in advance.

“No one has actually looked at the variation of ozone as a way to forecast or predict the climate or the next summer’s temperature,” says lead author Justin Bandoro, a graduate student in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “This could be especially important for farmers, and for areas like southeastern Australia, where most of that nation’s population resides.”...

Ozone hole might slightly warm planet

A press release from the America Geophysical Union: A lot of people mix up the ozone hole and global warming, believing the hole is a major cause of the world’s increasing average temperature. Scientists, on the other hand, have long attributed a small cooling effect to the ozone shortage in the hole.

Now a new computer-modeling study suggests that the ozone hole might actually have a slight warming influence, but because of its effect on winds, not temperatures. The new research suggests that shifting wind patterns caused by the ozone hole push clouds farther toward the South Pole, reducing the amount of radiation the clouds reflect and possibly causing a bit of warming rather than cooling.

 “We were surprised this effect happened just by shifting the jet stream and the clouds,” said lead author Kevin Grise, a climate scientist at Lamont-Doherty Earth Observatory of Columbia University in New York City. Grise notes this small warming effect may be important for climatologists trying to predict the future of Southern Hemisphere climate.

The work is detailed in Geophysical Research Letters, a journal of the American Geophysical Union. Grise collaborated on the study with Lorenzo Polvani of Columbia University, George Tselioudis of NASA Goddard Institute for Space Studies, Yutian Wu of New York University, and Mark Zelinka of Lawrence Livermore National Laboratory.

...Dennis Hartmann, an atmospheric scientist at the University of Washington in Seattle unrelated with the project, points out that since predicting cloud behavior is so challenging, the model used in Grise’s study could be underestimating clouds north of the jet stream being pulled toward the equator and in turn reflecting more light, potentially reducing or even negating the warming effect. Hartmann added that he also has some concerns about the modeling of the low-level cloud response. Still, “this is certainly a very interesting topic and potentially important from a practical perspective of predicting Southern Hemisphere climate and even global warming rates,” he commented...

The ozone hole via NASA, on September 22, 2012

Ozone affects forest watersheds

Terra Daily via SPX: U.S. Forest Service and Oak Ridge National Laboratory (ORNL) scientists have found that rising levels of ozone, a greenhouse gas, may amplify the impacts of higher temperatures and reduce streamflow from forests to rivers, streams, and other water bodies. Such effects could potentially reduce water supplies available to support forest ecosystems and people in the southeastern United States.

Impacts of ozone, a global scale pollutant, on forests are not well understood at a large scale. This modeling study indicates that current and projected increases in ozone in the 21st century will likely enhance the negative effects of warming on watersheds, aggravating drought and altering stream flow. Using data on atmospheric water supply and demand and statistical models, researchers with the Forest Service and ORNL were able to show what effects ozone can have on stream flow in dry seasons.

Published in the November issue of the journal Global Change Biology, the study suggests that ozone has amplified the effects of warmer temperatures in reducing streamflow in forested watersheds in the southeastern United States.

"From previous studies, we know a lot about ozone's influences on crops and leaves of young trees. However, no studies have investigated the impacts of ozone on water flow in large forested watersheds," says Ge Sun, research hydrologist with the Forest Service Eastern Forest Environmental Threat Assessment Center "Our studies show that ozone has a possible connection in the reduction of streamflow in late summer when flow is generally lowest, particularly in areas with high ozone levels such as the Appalachian Mountains in the Southeast."

Researchers developed models based on 18 to 26 years of data and observed streamflow in response to climate and atmospheric chemistry during the growing season. The research team evaluated individual and interactive effects of ozone on late season streamflow for six southeastern forested watersheds ranging in size from 38 acres to more than 3,700 square miles. Estimates of ozone's influence on streamflow ranged from 7 percent in the area of lowest ozone in West Virginia to 23 percent in the areas of highest exposure in Tennessee....

Rim of the Gap trail in Georgia, shot by John Foxe, public domain

Link found between climate change, ozone loss and possible increase in skin cancer incidence

EurekAlert: For decades, scientists have known that the effects of global climate change could have a potentially devastating impact across the globe, but Harvard researchers say there is now evidence that it may also have a dramatic impact on public health.

As reported in a paper published in the July 27 issue of Science, a team of researchers led by James G. Anderson, the Philip S. Weld Professor of Atmospheric Chemistry, are warning that a newly-discovered connection between climate change and depletion of the ozone layer over the U.S. could allow more damaging ultraviolet (UV) radiation to reach the Earth's surface, leading to increased incidence of skin cancer.

In the system described by Anderson and his team, water vapor injected into the stratosphere by powerful thunderstorms converts stable forms of chlorine and bromine into free radicals capable of transforming ozone molecules into oxygen. Recent studies have suggested that the number and intensity of such storms are linked to climate changes, Anderson said, which could in turn lead to increased ozone loss and greater levels of harmful UV radiation reaching the Earth's surface, and potentially higher rates of skin cancer.

"If you were to ask me where this fits into the spectrum of things I worry about, right now it's at the top of the list," Anderson said. "What this research does is connect, for the first time, climate change with ozone depletion, and ozone loss is directly tied to increases in skin cancer incidence, because more ultraviolet radiation is penetrating the atmosphere."...

Contrasting the concerns over climate and ozone loss

Janet Raloff in Science News points out the problems with an analogy that I've used myself. Well worth a read for showing what makes addressing climate change so overwhelming: On November 7, ozone and climate scientists met in Washington, D.C., to discuss whether the history of stratospheric ozone protection offered a useful case study about how to catalyze global action on carbon dioxide and other greenhouse gases. Their simple answer: No.

...Even with CFCs, it had been anything but a certainty in the mid 1980s that the public would take action, recalls Mario Molina, one of a trio of physical chemists who would win a Nobel Prize (a decade later) for identifying CFCs’ risk to ozone. But then the Antarctic ozone hole emerged.

It offered the most graphic confirmation imaginable that scientists’ had not overblown concerns about CFCs’ threat to the health of Earth’s ozone layer. Just two years after the 1985 discovery that an ozone hole was seasonally recurring in the stratosphere some 14 to 20 kilometers above Antarctica, nations around the world signed the Montreal Protocol ozone-protection treaty.

...Perhaps the biggest impediment to galvanizing public support for action on climate is the breadth of the contributors, Solomon and others argued at the meeting. With CFCs, only a few manufacturers and sectors of the economy were responsible for the offending pollutants. This meant a relatively small number of players could effect change by tweaking or substituting technologies. By contrast, global warming and its attendant changes stem from pollutant emissions contributed every day through myriad activities by virtually every human alive....

NASA image of the largest ozone hole ever, in 2000

NASA leads study of unprecedented Arctic ozone loss

NASA: A NASA-led study has documented an unprecedented depletion of Earth's protective ozone layer above the Arctic last winter and spring caused by an unusually prolonged period of extremely low temperatures in the stratosphere.

The study, published online Sunday, Oct. 2, in the journal Nature, finds the amount of ozone destroyed in the Arctic in 2011 was comparable to that seen in some years in the Antarctic, where an ozone "hole" has formed each spring since the mid-1980s. The stratospheric ozone layer, extending from about 10 to 20 miles (15 to 35 kilometers) above the surface, protects life on Earth from the sun's harmful ultraviolet rays.

The Antarctic ozone hole forms when extremely cold conditions, common in the winter Antarctic stratosphere, trigger reactions that convert atmospheric chlorine from human-produced chemicals into forms that destroy ozone. The same ozone-loss processes occur each winter in the Arctic. However, the generally warmer stratospheric conditions there limit the area affected and the time frame during which the chemical reactions occur, resulting in far less ozone loss in most years in the Arctic than in the Antarctic.

..."Day-to-day temperatures in the 2010-11 Arctic winter did not reach lower values than in previous cold Arctic winters," said lead author Gloria Manney of NASA's Jet Propulsion Laboratory in Pasadena, Calif., and the New Mexico Institute of Mining and Technology in Socorro. "The difference from previous winters is that temperatures were low enough to produce ozone-destroying forms of chlorine for a much longer time. This implies that if winter Arctic stratospheric temperatures drop just slightly in the future, for example as a result of climate change, then severe Arctic ozone loss may occur more frequently."...

Left: Ozone in Earth's stratosphere at an altitude of approximately 12 miles (20 kilometers) in mid-March 2011, near the peak of the 2011 Arctic ozone loss. Right: chlorine monoxide – the primary agent of chemical ozone destruction in the cold polar lower stratosphere – for the same day and altitude. Image credit: NASA/JPL-Caltech

Climate change set to increase ozone-related deaths over next 60 years

Science Daily: Scientists are warning that death rates linked to climate change will increase in several European countries over the next 60 yrs. A new study, which is being presented at the European Respiratory Society's Annual Congress in Amsterdam, predicts that Belgium, France, Spain and Portugal will see the biggest climate-induced increase in ozone-related deaths over the next 60 years.

The research is part of the Climate-TRAP project and its health impact assessment lead by Prof Bertil Forsberg from the Umea University in Sweden. The aim is to prepare the health sector for changing public health needs due to climate change.

According to the World Health Organization (WHO), climate change that has occurred since the 1970s caused over 140,000 excess deaths annually by the year 2004. In addition to its impact on clean air, drinking water and crop production, many deadly diseases such as malaria and those which cause diarrhea are particularly sensitive to climate change.

In this new research, the scientists used emission scenarios and models to assess the health impacts of a changing climate. They took projections from two greenhouse gas emission scenarios, A2 and A1B, and two global climate models, ECHAM4 and HADLEY, to simulate how the various future ozone levels are affected by climate change.

...The findings revealed that since 1961, Belgium, Ireland, The Netherlands and the UK have seen the biggest impact on ozone-related deaths due to climate change. The results predicted that the biggest increase over the next 50 yrs is likely to be seen in Belgium, France, Spain and Portugal, who could expect an increase of between 10 and 14%. However, Nordic and Baltic countries are predicted to see a decrease over the same period.

Ozone hole on the mend

This blog sometimes seems to provide an unending scroll of downers, so I’m pleased to post an optimistic turn of events, from Alexandra Witze in Science News: Scientists may have spotted Antarctica’s ozone hole on the road to recovery, at least a decade sooner than they thought healing would be noticeable. In 1989, an international agreement called the Montreal Protocol began phasing out chemicals that have gnawed away at Earth’s protective ozone layer. Most researchers thought it would take until at least 2023 to detect the hole’s slow recovery, but researchers in Australia now claim to have seen ozone ticking upward since the late 1990s.

“The key is to account for large year-to-year fluctuations that have obscured a gradual increase in the long-term evolution of ozone,” says atmospheric scientist Murry Salby of Macquarie University in Sydney. His team published its findings online May 6 in Geophysical Research Letters.

First spotted in 1985, the Antarctic ozone hole was quickly linked to chemicals called chlorofluorocarbons, emitted mainly in the Northern Hemisphere but concentrated over the South Pole by atmospheric circulation patterns. Chlorine atoms from these CFCs react with ozone molecules, seasonally destroying the layer that shields Earth from cancer-causing and crop-damaging ultraviolet radiation.

Scientists had predicted that ozone loss would bottom out and start recovering by now. They just didn’t think they would be able detect that change yet, since ozone levels vary dramatically from year to year because of complex atmospheric processes, sometimes by almost as much as the magnitude of the ozone hole itself…

A rendering of the ozone hole from NASA

Record ozone thinning looms in Arctic

Janet Raloff in Science News: The annual thinning of ozone over the Arctic is shaping up to be especially severe this spring, measurements by European scientists indicate. During the past six weeks, a large portion of the region’s stratosphere has lost at least half of the layer that normally filters out much of the sun’s harmful ultraviolet rays.

The new data “are kind of a warning that we might be getting into an ozone hole situation,” says Francis Schmidlin of NASA’s Wallops Flight Facility in Virginia, whose team is not affiliated with the European polar-ozone monitoring group.

Data radioed back from sensors aboard high-altitude weather balloons show the ozone-depleted region spans about 15 million square kilometers — an area about 22 times the size of Texas. Although the affected parcel of air 20 kilometers above Earth’s surface tends to remain roughly centered over the North Pole, it can wander as far south as Italy or Greece for a few days at a time. So people throughout Europe, Canada and much of the northern United States could briefly face exaggerated exposures to ultraviolet radiation this spring.

…Though stratospheric ozone thins annually in the Arctic, the loss has been so rapid and severe this year that it appears headed to chalk up a record, Rex says. The current state of Arctic ozone loss constitutes a severe thinning, Rex emphasizes — not a hole like the one that opens in the Antarctic stratosphere every year. But if the vortex doesn’t break up in late March as it usually does and instead persists into May (as it occasionally has), “we could get conditions very close to an ozone hole in the Arctic,” Rex said….

Stratospheric clouds in the Arctic, from NASA

Monitoring the Arctic ozone hole from aircraft

Max Planck Institute for Chemistry: An international team of researchers is investigating ozone depletion in the polar stratosphere using data gathered during flights over the Arctic region at elevations of up to 20 kilometers. The team of atmosphere researchers - among them Stephan Borrmann, Professor at the Institute of Atmospheric Physics of Johannes Gutenberg University Mainz and one of the directors of the Max Planck Institute of Chemistry in Mainz - hopes to discover how long the processes that result in the formation of the hibernal holes in the ozone layer at the polar caps actually take.

It is also expected that the data collected during the flights undertaken with the high-altitude aircraft "M55 Geophysica" will provide insight into what effect climate change is having on the physical and chemical processes that influence the ozone layer. This would make it possible to extrapolate the future development of the ozone layer under the conditions obtained during on-going changes.

The chlorofluorocarbons (CFCs) released by humans on the surface of the earth are gradually transported into the stratosphere. Here the CFCs are exposed to powerful ultraviolet radiation which decomposes the chlorofluorocarbons to finally release chlorine. This chlorine usually reacts with other chemicals and is bound in substances such as hydrogen chloride vapor and chlorine nitrate, which are not detrimental to ozone. However, in the stratospheric clouds located over the poles, the clorine from CFCs can form aggressive ozone-destroying chlorine monoxide radicals (CIO).

Analysis of these clouds is thus essential to the research being conducted by the Mainz team under Stephan Borrmann. And it is these extraordinary but natural clouds that are formed only in the stratosphere over the Arctic and Antarctic regions during the cold of the polar winters that are implicated in the formation of the holes in the ozone layer.

"As the warming of the atmosphere attributable to climate change also has a direct effect on the physical and chemical processes associated with the ozone layer, we urgently need to conduct new research into this aspect," explains Professor Borrmann….

The M55 Geophysica taking off, photo by Stephan Borrmann, from the Max-Planck University website

First comprehensive review of the state of Antarctica's climate

British Antarctic Survey: The first comprehensive review of the state of Antarctica’s climate and its relationship to the global climate system is published this week (Tuesday 1 December) by the Scientific Committee on Antarctic Research (SCAR). The review — Antarctic Climate Change and the Environment — presents the latest research from the icy continent, identifies areas for future scientific research, and addresses the urgent questions that policy makers have about Antarctic melting, sea-level rise and biodiversity.

Based on the latest evidence from 100 world-leading scientists from 13 countries, the review focuses on the impact and consequences of rapid warming of the Antarctic Peninsula and the Southern Ocean; rapid ice loss in parts of Antarctica and the increase in sea ice around the continent; the impact of climate change on Antarctica’s plants and animals; the unprecedented increase in carbon dioxide levels; the connections between human-induced global change and natural variability; and the extraordinary finding that the ozone hole has shielded most of Antarctica from global warming.

Dr. Colin Summerhayes, Executive Director of the Scientific Committee on Antarctic Research said, “Antarctica is an unrivalled source of information about our planet. This review describes what we know now and illustrates how human activity is driving rapid climate change. By integrating this multidisciplinary evidence into a single source we will help scientists and policy makers understand the distinction between environmental changes linked to the Earth’s natural cycles, and those that are human induced. The work is particularly important because it puts Antarctic climate change into context and reveals the impact on the rest of the planet.”

Professor John Turner of British Antarctic Survey is the lead editor of the review. He said, “For me the most astonishing evidence is the way that one man-made environmental impact — the ozone hole — has shielded most of Antarctica from another — global warming. Understanding the complexities surrounding these issues is a challenge for scientists — and communicating these in a meaningful way to society and to policymakers is essential. There is no doubt that our world is changing and human activity is accelerating global change. This review is a major step forward in making sure that the latest and best evidence is available in one place. It sets the scene for future Antarctic Research and provides the knowledge that we all need to help us live with environmental change.”…

A summary of the report’s findings are detailed in the following 10 key points:
1. Hole in ozone layer has shielded most of Antarctica from global warming
2. Warming of the Southern Ocean will cause changes in Antarctic ecosystem
3. Rapid increase in plant communities across Antarctic Peninsula
4. Rapid ice loss in parts of the Antarctic
5. 10% increase in sea ice around the Antarctic
6. Carbon dioxide levels increasing at fastest pace in 800,000 years
7. Sea ice loss directly affecting krill levels and penguin colonisation
8. Antarctica predicted to warm by around 3°C over this century
9. West Antarctic ice loss could contribute to 1.4 m sea level rise
10. Improved modelling of polar processes required for accurate predictions

Beardmore Glacier, Antarctica, shot by Commander Jim Waldron USNR (Retired), National Science Foundation

Climate change boosts ultraviolet risk for high latitudes

Marlowe Hood and Richard Ingham in Agence France-Presse: Climate change will disrupt Earth's precious ozone layer, boosting ultraviolet (UV) radiation in the deep southern hemisphere and reducing UV in far northern latitudes, a study warned on Sunday. By century's end, UV levels in Antarctica could rise by up to 20 percent at seasonal peaks while average exposure in northern Scandinavia, Siberia and northern Canada could fall by almost a tenth.

The shift could have worrying impacts on human health, as high exposure to UV is linked to cancer, cataracts and crop damage just as low exposure causes vitamin D insufficiency. "Our study is showing that there is a new threat to the ozone layer, and this is climate change, which will either increase or decrease UV depending on the region," said atmospheric physicist Michaela Hegglin of Canada's University of Toronto.

"And while too much UV exposure is known to be a bad thing, too little UV exposure can also have detrimental effects, though these are much less explored."

…Hegglin and co-author Theodore Shepherd put together a computer model simulating the consequences of warmer surface temperatures on an atmospheric pump called the Brewer-Dobson circulation, which drives ozone around the world. Under it, air is moved upwards from the tropics -- where most ozone is produced -- and then shifts polewards before descending to the lower part of the stratosphere. There it lingers for a long time before eventually entering the troposphere, the lower part of the atmosphere that includes ground level….

An Antarctic view by Viajeropolar2008, Wikimedia Commons, under the terms of the GNU Free Documentation License, Version 1.2

Increasing Antarctic sea ice extent linked to the ozone hole

British Antarctic Survey: Increased growth in Antarctic sea ice during the past 30 years is a result of changing weather patterns caused by the ozone hole according to new research published this week (Thurs 23 April 2009).

Reporting in the journal Geophysical Research Letters scientists from British Antarctic Survey (BAS) and NASA say that while there has been a dramatic loss of Arctic sea ice, Antarctic sea ice has increased by a small amount as a result of the ozone hole delaying the impact of greenhouse gas increases on the climate of the continent.

Sea ice plays a key role in the global environment – reflecting heat from the sun and providing a habitat for marine life. At both poles sea ice cover is at its minimum during summer. However, during the winter freeze in Antarctica this ice cover expands to an area roughly twice the size of Europe. Ranging in thickness from less than a metre to several metres, the ice insulates the warm ocean from the frigid atmosphere above. Satellite images show that since the 1970s the extent of Antarctic sea ice has increased at a rate of 100,000 square kilometres a decade.

The new research helps explain why observed changes in the amount of sea-ice cover are so different in both polar regions. Lead author Professor John Turner of BAS says, “Our results show the complexity of climate change across the Earth. While there is increasing evidence that the loss of sea ice in the Arctic has occurred due to human activity, in the Antarctic human influence through the ozone hole has had the reverse effect and resulted in more ice. Although the ozone hole is in many ways holding back the effects of greenhouse gas increases on the Antarctic, this will not last, as we expect ozone levels to recover by the end of the 21st Century. By then there is likely to be around one third less Antarctic sea ice.”….

Icebreaker Kapitan Dranitsyn breaking ice in Antarctica, shot by Turk17, under the terms of the GNU Free Documentation License, Version 1.2

US wildfires pushed ozone past legal limits

New Scientist: Legislate against pollution all you like, but don't expect nature to tow the line. Recent research on the wildfires that raged in California in 2007 shows that ground ozone levels were probably pushed significantly past legal "safe" limits.

[Ground level ozone] is responsible for a number of respiratory illnesses, ranging from coughs to bronchitis and emphysema. It also damages crops. Fires increase ozone levels by releasing nitrogen oxides, which form ozone when exposed to sunlight.

Gabriele Pfister of the US National Center for Atmospheric Research and colleagues focused on fires in California in September and October 2007. They used software to model the chemicals released by the fires and the ozone produced as a result. They also used climate models to show how these chemicals dispersed with the winds. They found that wildfires made it three times more likely that legislated levels be violated. And the effects were would have been far-ranging, reaching into Nevada, many miles away.

"Ozone can hit unhealthy levels even in places where people don't see smoke," says Pfister. "Wildfires are expected to worsen in the future, especially as our climate grows warmer. But we are only now beginning to understand their potential impacts on people and ecosystems – not only nearby but also potentially far downwind." The findings are likely to call into question suggested policies of letting natural wildfires burn themselves out instead of attempting to fight them. Those who advocate "let them burn" policies say wildfires are a natural ecosystem process.

Universal Studios fire, 2008, shot by pinguino k, Wikimedia Commons via Flickr, under Creative Commons Attribution 2.0 License