BALTIMORE, Maryland, February 6, 2009 (ENS) – Increasing greenhouse gases could stall the recovery of stratospheric ozone in some regions of the Earth, according to new research by a team from Johns Hopkins University. The scientists warn that increased rates of skin cancer in those regions might result.

Darryn Waugh, a professor in the Department of Earth and Planetary Sciences at Johns Hopkins University, and his colleagues reported Thursday that climate change could provoke variations in the circulation of air in the lower stratosphere in tropical and southern mid-latitudes, including Australia and South America.

The circulation changes would cause ozone levels in these areas never to return to levels that were present before decline began, even after ozone-depleting substances have been wiped out from the atmosphere.

In tropical and southern mid-latitudes, Waugh says, “Global warming causes changes in the speed that the air is transported into and through the lower stratosphere. You’re moving the air through it quicker, so less ozone gets formed.”

Researchers at NASA Goddard Space Flight Center in Greenbelt, Maryland collaborated with Waugh in the study. The team forecast effects on ozone recovery by means of simulations using a computer model known as the Goddard Earth Observing System Chemistry – Climate Model.

On September 12, 2008, the Antarctic ozone hole reached its maximum size for the year. Though larger than it was in 2007, the 2008 ozone hole was still smaller than the record set in 2006. (Image courtesy NASA)

Waugh says this research will help scientists attribute ozone variations to the right agent.

“Ozone is going to change in response to both ozone-depleting substances and greenhouse gases,” he says, “If you don’t consider climate change when studying the ozone recovery data, you may get pretty confused.”

The research is published in the current issue of “Geophysical Research Letters,” a publication of the American Geophysical Union.

Dan Lubin, an atmospheric scientist who has studied the relationship between ozone depletion and variations in the ultraviolet radiation that reaches the Earth, says Waugh’s findings could cause health problems for people living in the tropics and southern mid-latitudes if ozone levels never return to pre-1960 levels in those regions.

“The risk of skin cancer for fair-skinned populations living in countries like Australia and New Zealand, and probably in Chile and Argentina too, will be greater in the 21st century than it was during the 20th century,” says Lubin, who is at Scripps Institution of Oceanography in La Jolla, California and did not participate in the research.

Ozone is a gas which is naturally present in the atmosphere and absorbs harmful ultraviolet radiation from the Sun. In the stratosphere, ozone blocks ultraviolet light that can cause skin cancers, cataracts, and other damage to animals and plants if it reached the surface.

This protective ozone layer has been in decline in the stratosphere since the 1970s due to an increase in atmospheric concentrations of human-made substances such as chlorofluorocarbon and bromofluorocarbon compounds such as refrigerants, solvents, and foam blowing agents.

Since the late 1980s, most countries have adhered to the Montreal Protocol, an international treaty to phase out production of such ozone-depleting substances.

The ozone layer has not grown thinner since 1998 over most of the world, and it appears to be recovering because of reduced emissions of ozone-depleting substances. Antarctic ozone is projected to return to pre-1980 levels by 2060 to 2075.

Not all regions face worse prospects for ozone recovery as a result of climate change, the Johns Hopkins scientists found.

In polar regions and northern mid-latitudes, restoration of ozone in the lower stratosphere will suffer little impact from increasing greenhouse gases, their projections indicate.

In the upper stratosphere, climate change causes a drop in temperatures that slows down some of the chemical reactions that destroy ozone. So, the Johns Hopkins team concludes, recovery might be reached in those parts of the atmosphere earlier than forecast, even decades before the removal of ozone-depleting substances.

While scientists have long suspected that climate change might be altering the dynamics of stratospheric ozone recovery, Waugh’s team is the first to estimate the effects of increasing greenhouse gases on the recovery of ozone by region.

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CHICAGO, Illinois, January 20, 2009 (ENS) – While the bitter cold of President Barack Obama’s Inauguration Day in Washington may seem to contradict the idea that global warming continues, a new survey reveals consensus among scientists about the reality of climate change and its likely cause.

The survey of 3,146 earth scientists from around the world found overwhelming agreement that in the past 200 years, mean global temperatures have been rising, and that human activity is a “significant contributing factor” in changing mean global temperatures.

Peter Doran, an associate professor of earth and environmental sciences at the University of Illinois at Chicago, along with former graduate student Maggie Kendall Zimmerman, conducted the survey late last year.

The findings appeared Monday in the journal “Eos, Transactions,” a publication of the American Geophysical Union.

“The debate on the authenticity of global warming and the role played by human activity is largely nonexistent among those who understand the nuances and scientific basis of long-term climate processes,” the researchers conclude.

There are many human activities and natural processes that contribute to climate change. Burning coal, oil and gas to generate electricity or to power cars, trucks, trains, planes and ships releases greenhouse gases that blanket the planet, keeping the Sun’s heat from radiating back into space.

Cutting forests prevents the trees from absorbing the main greenhouse gas, carbon dioxide. Methane, an even more potent greenhouse gas, is given off by landfills, coal mines, oil and natural gas operations, agriculture, and melting permafrost.

Natural causes also exist. For instance, volcanoes can affect the climate because they can emit aerosols and carbon dioxide into the atmosphere.

Greenhouse gases rise from a petrochemical refinery in Edmonton, Alberta, Canada. (Photo by Wolfgang Schlegl)

To overcome criticism of earlier attempts to gauge the view of earth scientists on global warming and the human impact factor, Doran and his team sought the opinion of the most complete list of earth scientists they could find, contacting more than 10,200 experts listed in the 2007 edition of the American Geological Institute’s “Directory of Geoscience Departments.”

Experts in academia and government research centers were e-mailed invitations to participate in the on-line poll conducted by the website www.questionpro.com.

Only those invited could participate and computer IP addresses of participants were recorded and used to prevent repeat voting. Questions used were reviewed by a polling expert who checked for bias in phrasing, such as suggesting an answer by the way a question was worded. The nine-question survey was short, taking just a few minutes to complete.

The 3,146 participating scientists were asked two key questions – “Have mean global temperatures risen compared to pre-1800s levels?” and, “Has human activity been a significant factor in changing mean global temperatures?”

About 90 percent of the respondents agreed with the first question and 82 percent the second.

Doran determined that climatologists who are active in research showed the strongest consensus on the causes of global warming, with 97 percent agreeing humans play a role.

Petroleum geologists and meteorologists were among the biggest doubters, with only 47 and 64 percent, respectively, believing in human involvement.

Doran compared their responses to a recent poll showing only 58 percent of the public thinks human activity contributes to global warming.

“The petroleum geologist response is not too surprising, but the meteorologists’ is very interesting,” he said. “Most members of the public think meteorologists know climate, but most of them actually study very short-term phenomena.”

Doran was not surprised by the near-unanimous agreement by climatologists.

“They’re the ones who study and publish on climate science,” he said. “So I guess the take-home message is, the more you know about the field of climate science, the more you’re likely to believe in global warming and humankind’s contribution to it.”

The challenge now, the researchers say, is how to effectively communicate this to policy makers and to a public that continues to mistakenly perceive debate among scientists.

They can draw support from a statistical study published earlier this month by scientists in Germany and Switzerland who determined that the global increase of warmer years after 1990 is no accident.

The likelihood that the 13 warmest years since 1880 could have occurred after 1990 by accident is no more than one in 10,000, they conclude. Or, in other words, the likelihood is the same as tossing 14 heads in a row in a coin toss.

“Our study is of a purely statistical nature and cannot attribute the increase of warm years to individual factors,” said Dr. Eduardo Zorita at the GKSS Research Center in Geesthacht, Germany.

“But it is in full agreement with the results of the Intergovernmental Panel on Climate Change that the increased emission of greenhouse gases is mainly responsible for the most recent global warming,” he said.

The results of the statistical study will be published in the journal “Geophysical Research Letters.”

However, some scientists are still climate skeptics. More than 650 dissenting scientists are listed in a report released January 14 by the U.S. Senate Environment and Public Works Committee’s office of the Ranking Member Republican James Inhofe of Oklahoma.

A typical comment is that of physicist Dr. Will Happer, a professor at the Department of Physics at Princeton University and former director of energy research at the U.S. Department of Energy, who is quoted in the Inhofe report as saying, “I am convinced that the current alarm over carbon dioxide is mistaken. … Fears about man-made global warming are unwarranted and are not based on good science.”

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SAN DIEGO, California, October 24, 2008 (ENS) – A gas used in manufacture of flat panel televisions, computer displays, microcircuits, and thin-film solar panels is 17,000 times more potent a greenhouse gas than carbon dioxide, and it is far more prevalent in the atmosphere than previously estimated.

The powerful greenhouse gas nitrogen trifluoride, NF3, is at least four times more widespread than scientists had believed, according to new research by a team at Scripps Institution of Oceanography at the University of California, San Diego.

Using new analytical techniques, a team led by Scripps geochemistry professor Ray Weiss made the first atmospheric measurements of nitrogen trifluoride, NF3.

“Accurately measuring small amounts of NF3 in air has proven to be a very difficult experimental problem, and we are very pleased to have succeeded in this effort,” Weiss said Thursday, announcing the results of his team’s research.

The research findings will be published October 31 in “Geophysical Research Letters,” a journal of the American Geophysical Union.

Scripps geoscientists Ray Weiss, left, and Jens
Muehle show cylinders used to collect air
samples that they analyzed for
concentrations of nitrogen trifluoride.
(Photo courtesy Scripps Institution of
Oceanography, UC San Diego)

The amount of the gas in the atmosphere, which could not be detected using previous techniques, had been estimated at less than 1,200 metric tons in 2006. The new research shows the actual amount was 4,200 metric tons.

In 2008, about 5,400 metric tons of the gas was in the atmosphere, a quantity that is increasing at about 11 percent per year.

This rate of increase means that about 16 percent of the amount of the gas produced globally is being emitted into the atmosphere, the researchers estimate.

Emissions of NF3 were thought to be so low that the gas was not considered to be a significant potential contributor to global warming.

Nitrogen trifluoride was not covered by the Kyoto Protocol, the 1997 agreement to reduce greenhouse gas emissions signed by 182 countries, although three other fluoride compounds are covered.

The protocol governs the emissions of carbon dioxide, methane, and nitrous oxide as well as other fluoride compounds – sulfur hexafluoride, hydrofluorocarbons, and perfluorocarbons.

In response to the growing use of the gas and concerns that its emissions are not well known, the scientists have recommended adding it to the list of greenhouse gases regulated by the protocol or its successor agreement now under negotiation.

“From a climate perspective, there is a need to add NF3 to the suite of greenhouse gases whose production is inventoried and whose emissions are regulated under the Kyoto Protocol, thus providing meaningful incentives for its wise use,” said Weiss.

Nitrogen trifluoride is one of several gases used during the manufacture of liquid crystal flat-panel displays, thin-film photovoltaic cells and microcircuits.

Many industries have used the gas in recent years as an alternative to perfluorocarbons, which are also potent greenhouse gases, because it was believed that no more than two percent of the NF3 used in these processes escaped into the atmosphere.

To obtain their information, the Scripps team analyzed air samples gathered in California and Tasmania over the past 30 years by the NASA-funded Advanced Global Atmospheric Gases Experiment network of ground-based stations.

The network was created in the 1970s in response to international concerns about chemicals depleting the ozone layer. It is supported by NASA as part of its congressional mandate to monitor ozone-depleting trace gases, many of which are also greenhouse gases.

The researchers found concentrations of NF3 rose from about 0.02 parts per trillion in 1978 to 0.454 parts per trillion in 2008.

Higher concentrations of NF3 were found in the Northern Hemisphere than in the Southern Hemisphere, which the researchers said is consistent with its greater use in Northern Hemisphere countries.

“This result reinforces the critical importance of basic research in determining the overall impact of the information technology industry on global climate change, which has already been estimated to be equal to that of the aviation industry,” said Larry Smarr, director of the California Institute for Telecommunications at University of California, San Diego, who was not involved in the Scripps study.

Michael Prather is a University of California, Irvine atmospheric chemist who predicted earlier this year that based on the rapidly increasing use of NF3, larger amounts of the gas would be found in the atmosphere. Prather said the new Scripps study provides the confirmation needed to establish reporting requirements for production and use of the gas.

“I’d say case closed. It is now shown to be an important greenhouse gas,” said Prather, who was not involved with the Scripps study. “Now we need to get hard numbers on how much is flowing through the system, from production to disposal.”

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FORT LAUDERDALE, Florida, May 27, 2008 (ENS) – Using data from instruments in a constellation of NASA and French satellites, scientists are learning more about the link between clouds, pollution and rainfall.

Four NASA satellites – Aqua, Aura, CloudSat and CALIPSO and the French Space Agency’s PARASOL – make up the string of satellites in the Afternoon Constellation, more commonly called the A-Train.

They orbit only eight minutes apart and can be thought of as an extended satellite observatory, providing unprecedented information about clouds, aerosols and atmospheric composition.

“The A-Train is providing a new way to examine cloud types,” said Mark Schoeberl, A-Train project scientist at NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

Details of the scientists’ findings were presented today at the American Geophysical Union’s 2008 Joint Assembly in Fort Lauderdale, Florida.

Jonathan Jiang of NASA’s Jet Propulsion Laboratory, Pasadena, California, and colleagues used these A-Train sensors to find that South American clouds infused with airborne pollution tend to produce less rain than their clean counterparts during the region’s dry season.

“Typically, it is very hard to get a sense of how important the effect of pollution on clouds is,” said Anne Douglass, deputy project scientist at Goddard for NASA’s Aura satellite. “With the A-Train, we can see the clouds every day and we’re getting confirmation on a global scale that we have an issue here.”

Jiang’s team used the Microwave Limb Sounder on the A-Train’s Aura satellite to measure the level of carbon monoxide in clouds. The presence of carbon monoxide implies the presence of smoke and other aerosols, which usually come from the same emission source, such a power plant or agricultural fire.

An artist’s rendition of six satellites moving
together (Image courtesy NASA)

With the ability to distinguish between polluted and clean clouds, the team next used Aqua’s Moderate Resolution Imaging Spectroradiometer to study how ice particle sizes change when aerosol pollution is present in the clouds.

The team also used NASA’s Tropical Rainfall Measuring Mission satellite to measure the amount of precipitation falling from the polluted and clean clouds.

All three measurements together show the relationship between pollution, clouds and precipitation.

The team found that polluted clouds suppressed rainfall during the June-to-October dry season in South America, which is also a period of increased agricultural burning. During that period it was more difficult for the smaller ice particles in aerosol polluted clouds to grow large enough to fall as rain.

This trend turned up seasonal and regional differences. Aerosol pollution was found, on average, to be less of a factor during the wet monsoon seasons in South America and in South Asia.

Other physical effects, such as large-scale dynamics and rainy conditions that clear the air of aerosol particles, might also be at play, the researchers suggest.

“The complexity of interactions between aerosols and clouds pose difficult problems that no one satellite instrument can solve,” said Jiang. “But when you put parameters from multiple satellites all together, you will find much more information than from a single instrument alone.”

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GREENBELT, Maryland, February 2, 2008 (ENS) – Summertime storms in the southeastern United States drop more rainfall midweek than on weekends, and NASA scientists say air pollution from human activities, such as emissions from traffic, businesses and factories, is likely driving that trend.

The link between rainfall and the day of the week is evident in data from NASA’s Tropical Rainfall Measuring Mission satellite, known as TRMM.

“It appears that we’re making storms more violent,” said Thomas Bell, an atmospheric scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, lead author of the study published online this week in the American Geophysical Union’s “Journal of Geophysical Research.”

The data show that midweek storms tend to be stronger, drop more rain and span a larger area across the Southeast compared to calmer and drier weekends.

“It’s eerie to think that we’re affecting the weather,” said Bell.

Summer rainstorm in Atlanta,
Georgia (Photo credit unknown)

Rainfall measurements collected from ground-based gauges can vary from one gauge site to the next because of fickle weather patterns. So, to identify any kind of significant weekly rainfall trend, Bell and colleagues looked at the big picture from Earth’s orbit.

The team collected data from instruments on the TRMM satellite, which they used to estimate daily summertime rainfall averages from 1998 to 2005 across the entire Southeast. They found that, on average, it rained more between Tuesday and Thursday than from Saturday through Monday.

Newly analyzed satellite data show that summer 2007 echoed the midweek trend with peak rainfall occurring late on Thursdays. However, midweek increases in rainfall were more significant in the afternoon, when the conditions for summertime storms are in place. Based on satellite data, afternoon rainfall peaked on Tuesdays, with 1.8 times more rainfall than on Saturdays, which experienced the least amount of afternoon rain.

The team used ground-based data from gauges, along with vertical wind speed and cloud height measurements, to help confirm the weekly trend in rainfall observed from space.

To find out if pollution from humans indeed could be responsible for the midweek boost in rainfall, the team analyzed particulate matter, the concentrations of airborne particles associated with pollution, across the U.S. from 1998 to 2005.

The data, obtained from the U.S. Environmental Protection Agency, showed that pollution tended to peak midweek, mirroring the trend observed in the rainfall data.

“If two things happen at the same time, it doesn’t mean one caused the other,” Bell said. “But it’s well known that particulate matter has the potential to affect how clouds behave, and this kind of evidence makes the argument stronger for a link between pollution and heavier rainfall.”

Researchers know clouds are seeded by particulate matter. Water and ice in clouds grab hold around the particles, forming additional water droplets. Some researchers think increased pollution thwarts rainfall by dispersing the same amount of water over more seeds, preventing them from growing large enough to fall as rain. Still, other studies suggest some factors can override this dispersion effect.

In the Southeast, summertime conditions for large, frequent storms are already in place, a factor that appears to override the rain-thwarting dispersion effect.

When conditions are poised to form big storms, updrafts carry the smaller, pollution-seeded raindrops high into the atmosphere where they condense and freeze.

“It’s the freezing process that gives the storm an extra kick, causing it to grow larger and climb higher into the atmosphere,” Bell said.

Bell and his colleagues found that the radar on the TRMM satellite showed that storms climb to high altitudes more often during the middle of the week than on weekends. These invigorated midweek storms, fueled by workweek pollution, could drop measurably more rainfall.

The trend does not mean it will always rain on weekday afternoons during summertime in the Southeast, Bell said. Rather, “it’s a tendency,”

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