The health risks have already led to the development of devices that measure ultraviolet (UV) radiation and issue warnings by illuminating color-coded warning lights.

On a recent day in Santiago, a building site foreman sounded a whistle that made a dozen workers stop what they were doing amid steel, cement and cranes. Only after rubbing sunscreen on to exposed flesh did they return to work.

Chile is one of the countries in South America most deeply endangered by UV light, especially in its northern regions, where the sign beats down hard throughout the year.

Chilean law requires employers to inform their workers daily about UV levels. They also are required to provide them with protection, such as hats, sunglasses and sunscreen if they work in the sun.

A sign at the entrance of one job site warns about extreme UV levels, compelling Jonathan Fernandez, a risk prevention expert, to urge workers to apply sun cream.

"The important thing is to create awareness among the workers to break the stereotype that sunscreens are only for women and visits to the beach," Fernandez told AFP.

In Chile and other southern hemisphere nations, radiation levels reach their peak in December and January.

Cecilia Orlandi, a consulting dermatologist at the National Cancer Corporation, told AFP that "the main problem is that people are unaware their skin receives ultraviolet radiation throughout the year, especially in summer, and that the doses are cumulative."

"We have studies that have shown a young man at 18 years old receives the amount he should have accumulated at 60 years," the dermatologist said.

At current rates, when the sun is at its highest point, only five to 10 minutes of unprotected exposure during the peak hours of radiation (between 11:00 am and 4:00 pm) can produce a skin burn.

This season, solar radiation is averaging 10 percent higher than the same period in 2008.

"We could see in late September that UV radiation was higher than previous years," Ernesto Gramsch, a University of Santiago physicist who heads the National Network for Ultraviolet Measurements, told AFP.

"We think that a roughly one percent reduction in the density of ozone is what made the levels rise," Gramsch said.

The ozone layer protects the earth and its atmosphere from the sun's potentially harmful ultraviolet light. Pollution is blamed for causing the ozone layer to dissipate.

The thinning ozone layer is directly related to increases in Chile's skin cancer cases, which have risen by 106 percent in the past decade. In 2009, 213 Chileans died from skin cancer blamed on exposure to the sun.

Chile's vulnerability has led the country to become a pioneer in innovations to prevent the sun's harmful effects.

One innovation are the special warning lights called "solmaforos" -- a term combining the Spanish words for "sun" and "traffic light."

Their ability to measure ultraviolet radiation prompted Chileans to install them at popular resorts and on tour rides. They also are found commonly in mining operations and at construction sites.

Gramsch makes some of the devices in a small workshop in Santiago. A color code built into them illuminates a green light when radiation levels are "low;" yellow when the risk is "medium;" red when the ultraviolet light is "dangerous;" and purple when it is "extreme."

"An electronic circuit amplifies the signal, separates it and illuminates the corresponding light," Gramsch told AFP. He has sold about 200 of the units and exported them to countries such as Spain, Peru, Colombia and Mexico.

]]> Tue, 21 FEB 2012 08:57:46 AEST Karlsruhe, Germany (SPX) Jan 20, 2012 - Extraordinarily cold temperatures in the winter of 2010/2011 caused the most massive destruction of the ozone layer above the Arctic so far: The mechanisms leading to the first ozone hole above the North Pole were studied by scientists of the KIT Institute of Meteorology and Climate Research (IMK).

According to these studies, further cooling of the ozone layer may enhance the influence of ozone-destroying substances, e.g. chlorofluorocarbons (CFC), such that repeated occurrence of an ozone hole above the Arctic has to be expected.

About a year ago, IMK scientists, together with colleagues from Oxford, detected that ozone degradation above the Arctic for the first time reached an extent comparable to that of the ozone hole above the South Pole. Then, the KIT researchers studied the mechanisms behind. Their results have now been published in the journal "Geophysical Research Letters".

According to IMK studies, occurrence of the Arctic ozone hole was mainly due to the extraordinarily cold temperatures in the ozone layer that is located at about 18 km height in the stratosphere, i.e. the second layer of the earth's atmosphere.

There, chlorine compounds originating from chlorofluorocarbons (CFC, e.g. greenhouse gases and refrigerants) and other pollutants are converted chemically at temperatures below -78C.

These chemical conversion products attack the ozone layer and destroy it partly. One of the main statements in the study: If the trend to colder temperatures in the stratosphere observed in the past decades will continue, repeated occurrence of an Arctic ozone hole has to be expected.

The team of IMK researchers analyzed measurements of the chemical composition of the atmosphere by the MIPAS satellite instrument developed by KIT. In addition, model calculations were made to determine concrete effects of further cooling of the ozone layer.

"We found that further decrease in temperature by just 1C would be sufficient to cause a nearly complete destruction of the Arctic ozone layer in certain areas," says Dr. Bjorn-Martin Sinnhuber, main author of the study.

Observations over the past thirty years indicate that the stratosphere in cold Arctic winters cooled down by about 1C per decade on the average. According to Sinnhuber, further development of the ozone layer will consequently be influenced also by climate change.

He points out that the increase in carbon dioxide and other greenhouse gases will warm up the bottom air layers near the ground due to the reflection of part of the thermal radiation by the bottom layer of the atmosphere towards the earth's surface, but also result in a cooling of the air layers of the stratosphere above, where the ozone layer is located.

After the first discovery of the Antarctic ozone hole in the mid-1980s, CFCs were rapidly identified to be the cause and their use was prohibited by the Montreal Protocol of 1987. However, it will take decades until these substances will have been removed completely from the atmosphere.

"Future cooling of the stratosphere would enhance and extend the impacts of these substances on the ozone layer," says Dr. Bjorn-Martin Sinnhuber. It is now necessary to study potential feedbacks on climate change.

The present study is embedded in long-term programs of IMK in this field. In December, the researchers started a new measurement campaign in the Arctic ozone layer in Northern Sweden using a high-altitude aircraft.

Again, they encountered extraordinarily low temperatures. However, it is not yet possible to predict whether temperatures will be low enough over a longer term to cause a comparably large degradation of ozone in this winter.

]]> Tue, 21 FEB 2012 08:57:46 AEST Madrid, Spain (SPX) Dec 09, 2011 - The reconstruction of ozone levels over the Iberian Peninsula between 1979 and 2008 reveals that positive trends began eight years after the ratification of the Montreal Protocol. Furthermore, results show that Spain quickly recovered part of its lost ozone thanks to tropospheric ozone, a secondary pollutant derived from industrial emissions.

Researchers from the Andalusian Centre for Environmental Studies and the University of Granada have rebuilt the ozone column trends recorded between 1978 and 2008 that rise up over the Iberian Peninsula. The study was published weeks ago in the Atmospheric Environment journal.

The results highlight the influence that the prohibition of aerosols and chlorofluorocarbon gases (CFC) has had. According to Manuel Anton from the Department of Applied Physics of the University of Granada, "although these types of emissions were banned by the 1987 Montreal Protocol, our study reveals that stratospheric ozone did not show signs of recovery until 1995."

"We established two measurement periods. For the first, between 1979 and 1994, we saw that stratospheric ozone depletion was significant with higher levels in the north of the peninsula," states Anton.

According to the study, the effects of depletion were felt more in cities such as Barcelona, Santander and La Coruna who all saw a reduction in ozone levels of approximately 4% per decade due to dynamic factors in the stratosphere.

The second period studied, between 1995 and 2008, differed from the first. For example, ozone levels showed positive trends with greater recovery levels (2.5% per decade) in the north-east of the Peninsula where levels were higher than other regions due to industrial emissions. Anton says that "we have seen that the troposphere ozone contributes in recovering total ozone levels."

In contrast to the stratospheric ozone, which acts as a filter against harmful radiation, the tropospheric or ground-level ozone found in the lowest layer of the atmosphere is a secondary pollutant.

It mainly comes from the photochemical processes that transform nitrogen oxides and volatile particles from burning fossil fuels into ozone. Heat and light from the sun stimulate such processes which is why ground-level ozone is such a common pollutant in Spain.

The results show that in highly industrial areas such as the north-east of Spain, the recovery of the ozone layer was quicker thanks to the ozone contribution of the troposphere to the stratosphere. However, the authors of the study warn that "other anthropogenic effects could complicate the recovery process and result in areas with altered ozone levels."

The ozone level measurement data used in the study were taken from two satellites. These were the US satellite TOMS (Total Ozone Mapping Spectrometer, which has provided daily images of the spatial distribution of the ozone between 1978 and 2005) and the European satellite GOME (Global Ozone Monitoring Experiment which more recently took measurements from July 1995 to June 2011).

The University of Evora (Portugal), the Institute of Atmospheric Sciences and Climate in Bologna (Italy) and the German Aerospace Centre also participated in the study.

M. Anton, D. Bortoli, P. S. Kulkarni, M. J. Costa, A. F. Domingues, D. Loyola, A. M. Silva, L. Alados-Arboledas. Long term trends of total ozone column over the Iberian Peninsula. Atmospheric Environment. Doi: 10.1016/j.atmosenv.2011.08.058.

]]> Tue, 21 FEB 2012 08:57:46 AEST Greenbelt MD (SPX) Oct 24, 2011 - The Earth's thinning ozone layer is synonymous with a singing and dancing seagull named Sid - at least it is in New Zealand and Australia.

"This time of year there is a huge push to 'Slip, Slop, Slap,'" says Hamish Talbot, a native New Zealander. These publicly funded commercials implore people to "slip" on a t-shirt, "slop" on some sunscreen and "slap" on a hat.

All this protection is necessary because New Zealand's location in the Southern Hemisphere puts it very close to the "ozone hole" that forms over the South Pole at this time every year. The ozone is so thin in this part of the world that the weather report on the nightly news includes five-minute sunburn alerts.

Ozone is Earth's natural sunscreen. The ozone layer in the upper atmosphere, or stratosphere, absorbs harmful ultraviolet rays from the sun. In the 1980s, scientists discovered that manmade chemicals destroy ozone to the point where an actual ozone hole occurs.

The good news is that this hole isn't getting any larger.

"In fact, we have definitive evidence to show that these manmade chemicals are decreasing," says Paul Newman, NASA Goddard Space Flight Center's chief atmospheric scientist.

These chemicals, chlorofluorocarbons (CFCs), peaked in the year 2000 and began coming down due to actions taken to save the protective ozone layer beginning in the1980s. That's when nearly 200 nations agreed to the Montreal Protocol, which strongly regulates ozone-depleting chemicals.

Scientists believe that about 80 percent of the chlorine molecules in the stratosphere are due to human-produced chemicals. Halogens such as chlorine and bromine, which are mainly responsible for chemical ozone depletion, come from chlorine-containing CFCs, which were commonly used as aerosols and in refrigerators, and bromine-containing halons, which were used in fire suppression, among other uses.

Originally thought to be harmless, scientists discovered that these chemicals travel into Earth's stratosphere. Once there, ultraviolet radiation splits the CFCs or halons apart, and the chlorine and bromine containing molecules can then react with ozone, ultimately tearing away at the ozone layer.

Even though CFCs are now regulated, Newman cautions that they have a long lifetime.

"In 2100, CFCs will still be 20 percent more abundant in the atmosphere than they were in 1950. So while it's not getting any worse, it won't get better fast."

A complication to this chemistry is cold temperatures.

"Surface temperature doesn't affect ozone, but it is extraordinarily cold about 70,000 feet above Antarctica," Newman says.

At that altitude, clouds form in the polar regions that enable a chemistry to occur that doesn't happen anywhere else. "These clouds are made up of water, nitric acid and sulfuric acid," Newman says.

These clouds kick start the process by releasing chlorine from a chemically inactive form into a form that can catalytically destroy ozone. With a little bit of sunlight to energize the reactions, a chlorine atom can destroy thousands of ozone molecules.

"So you need CFCs for the chlorine, really cold temperatures for the clouds, and a little bit of sun. That's the recipe for the ozone hole," Newman says.

While it is very hard to predict year-to-year stratospheric temperatures, scientists have been able to measure the success of ozone protection efforts for more than 40 years using NASA satellites. Data records began with the NASA Backscatter UltraViolet (BUV) Instrument on Nimbus-4 in 1970.

By 1979, scientists were able to measure the size of the ozone hole using NASA's Total Ozone Mapping Spectrometer (TOMS). The record continued with the Ozone Monitoring Instrument (OMI), supplied by the Netherlands and Finland on the NASA Earth Observing System satellite Aura.

"At first scientists made predictions that chlorine was destroying the ozone, and we indeed found that it was happening," Newman says. "Now the challenge is to confirm that our predictions of ozone recovery are playing out as we said they would."

Researchers will continue to collect ozone data with the launch of the NPOESS Preparatory Project (NPP), scheduled for Oct. 28. Aboard NPP is the Ozone Mapping and Profiler Suite (OMPS), a new design consisting of two ozone-measuring instruments.

The 'limb profiler' views the edge of the atmosphere from an angle to help scientists observe ozone at various levels above the Earth's surface, including the protective ozone layer in the stratosphere. The other instrument is "nadir-viewing," meaning it looks down from the satellite, measuring the total amount of ozone between the ground and the atmosphere.

NASA satellite data and models predict that the ozone hole will not return to pre-1980 levels for decades. In the meantime, Newman says OMPS will continue the data record into the future - and additional ozone-monitoring instruments are already planned for after NPP.

"We need to really care about the ozone because it is our natural sunscreen. UV radiation can lead to skin cancer, cause cataracts, suppreses the immune system, impact crops, and contribute to degradation of materials," says Newman.

While OMPS and other instruments will continue to monitor the health of our ozone layer, the fact that it will take a long time for our atmosphere to recover from the damage caused by CFCs, means that Sid the Seagull will keep on singing "Slip, Slop, Slap" - warning people to spend less time outside and more time under a floppy hat.

]]> Tue, 21 FEB 2012 08:57:46 AEST Paris (AFP) Oct 2, 2011 - An ozone hole five times the size of California opened over the Arctic this spring, matching ozone loss over Antarctica for the first time on record, scientists said on Sunday.

Formed by a deep chill over the North Pole, the unprecedented hole at one point shifted over eastern Europe, Russia and Mongolia, exposing populations to higher, but unsustained, levels of ultra-violet light.

Ozone, a molecule of oxygen, forms in the stratosphere, filtering out ultraviolet rays that damage vegetation and can cause skin cancer and cataracts.

The shield comes under seasonal attack in both polar regions in the local winter-spring.

Part of the source comes from man-made chlorine-based compounds, once widely used in refrigerants and consumer aerosols, that are being phased out under the UN's Montreal Protocol.

But the loss itself is driven by deep cold, which causes water vapour and molecules of nitric acid to condense into clouds in the lower stratosphere.

These clouds in turn become a "bed" where atmospheric chlorine molecules convert into reactive compounds that gobble up ozone.

Ozone loss over the Antarctic is traditionally much bigger than over the Arctic because of the far colder temperatures there.

In the Arctic, records have -- until now -- suggested that the loss, while variable, is far more limited.

Satellite measurements conducted in the 2010-2011 Arctic winter-spring found ozone badly depleted at a height of between 15 and 23 kilometres (9.3 and 14.3 miles).

The biggest loss -- of more than 80 percent -- occurred between 18 and 20 kms (11.25 and 12.5 miles).

"For the first time, sufficient loss occurred to be reasonably be described as an Arctic ozone hole," says the study, appearing in the British science journal Nature.

The trigger was the polar vortex, a large-scale cyclone that forms every winter in the Arctic stratosphere but which last winter was born in extremely cold conditions, Gloria Manney, of the Jet Propulsion Laboratory in California, told AFP in email.

"The ozone destruction began in January, then accelerated in late February and March, so that ozone values in the polar vortex region were much lower than usual from early March through late April, after which the polar vortex dissipated.

"Especially low total column ozone values (below 250 Dobson Units) were observed for about 27 days in March and early April.

"The maximum area with values below 250 Dobson Units was about two million square kilometres (772,000 square miles), roughly five times the area of Germany or California."

This was similar in size to ozone loss in Antarctica in the mid-1980s.

In April, the vortex shifted over more densely populated parts of Russia, Mongolia and eastern Europe for about two weeks.

Measurements on the ground showed "unusually high values" of ultra-violet, although human exposure was not constant as the vortex shifted location daily before eventually fading, said Manney.

The study, published by the journal Nature, challenges conventional thinking about the Arctic's susceptibility to ozone holes. This thinking is based on only a few decades of satellite observations.

Stratospheric temperatures in the Arctic have been extraordinarily varied in the past decade, the paper notes. Four out of the last 10 years have been amongst the warmest in the past 32 years, and two are the coldest.

In the stratosphere, ozone is protective. At ground level, where it is produced in a reaction between traffic exhaust and sunlight, it is a dangerous irritant for the airways.

]]> Tue, 21 FEB 2012 08:57:46 AEST Washington DC (SPX) Sep 05, 2011 - The White House has issued a press release stating they would not move to issue a final standard on ozone pollution. The American Thoracic Society strongly condemns this decision.

"This is not change we believe in," said ATS President-Elect Monica Kraft, MD, professor of medicine and director of the Asthma, Allergy and Airway Center at Duke University.

Ozone, also known as smog, is known to endanger patients with asthma, COPD and other respiratory conditions. Scientific studies have consistently shown that ozone at the current EPA-approved levels leads to missed school days, more emergency room visits and hospitalizations-and even premature death.

"What President Obama has called a 'regulatory burden' is what we physicians call a protective health standard," noted Dr. Kraft.

A number of physician groups have called upon President Obama to issue a stricter ozone standard, including the American Medical Association, the American Academy of Pediatrics and the American Thoracic Society.

"President Obama's announcement represents a big set back for the public's health," said Dr. Kraft. "The ATS urges the President to reconsider today's disappointing decision, and we plan to redouble our efforts to educate and advocate for cleaner air for the benefit of all U.S. citizens."

]]> Tue, 21 FEB 2012 08:57:46 AEST Washington (AFP) Sept 2, 2011 - US President Barack Obama on Friday shelved new anti-smog standards, dismaying supporters with his latest concession to the Republican agenda enforced by the jobs crisis and sickly economy.

Obama, who will next week unveil a major plan designed to create jobs, is facing fierce pressure from Republicans on multiple fronts, including demands by his foes for him to slice regulations they say are shackling businesses.

After pressure from Republicans and big business, Obama on Friday decided to ask Environmental Protection Agency (EPA) administrator Lisa Jackson to withdraw draft Ozone National Ambient Air Quality Standards.

"I have continued to underscore the importance of reducing regulatory burdens and regulatory uncertainty, particularly as our economy continues to recover," Obama said in a statement.

Opponents had argued that introducing the new standards would cost more than an EPA estimate of up to $90 billion a year at a time when the stuttering economy has stopped creating new employment.

But environmentalists, who formed a key part of Obama's political base in 2008, reacted with outrage.

"This is a new low for President Obama," said Kieran Suckling, executive director of the Center for Biological Diversity, which works to tackle air pollution and global warming.

"He sold out public health and environmental protection to appease polluters. Mr Obama's shortsighted political decision will have long-term health consequences for millions of Americans."

League of Conservation Voters President Gene Karpinski accused Obama of "caving to big polluters at the expense of protecting the air we breathe."

The Sierra Club condemned the decision to delay "critical, long-overdue protections from smog, an acidic air pollutant that when inhaled is like getting a sunburn on your lungs."

Environmental concerns are particularly important to the legions of young supporters who flocked to Obama's campaign in 2008, and who he needs again to turn out in huge numbers in his 2012 reelection bid.

The ozone announcement came hours after the Labor Department issued dismal data showing that the stagnant US economy failed to create any jobs in August at a time of 9.1 percent unemployment and deepening economic gloom.

Obama, with polls showing record low approval for his economic management, is hemmed in by Republicans who control the House of Representatives and is being forced into political concessions which dismay his base.

A White House official insisted however that Obama's decision on ozone regulations was taken purely on the merits of the case.

"This has nothing to do with politics," the official said on condition of anonymity, arguing that the administration had an unprecedented record of protecting the environment.

Obama also insisted he was not ditching his political principles.

"I will continue to stand with the hardworking men and women at the EPA as they strive every day to hold polluters accountable and protect our families from harmful pollution," Obama said.

But Obama supporters have been dismayed by compromises Obama has made in recent months since Republicans seized the House in mid-term elections seen as a repudiation of his leadership.

Liberals were furious that Obama agreed to an extension of tax cuts for the rich passed by president George W. Bush that were due to expire last year.

They were also angry that his deal with Republicans on raising the US debt ceiling in July included huge spending cuts but no new tax hikes for wealthy Americans.

Obama's authority was further compromised in a row this week with House speaker John Boehner over the timing of his address on jobs to a joint session of Congress, now set for Thursday.

Environmentalists meanwhile have despaired that Obama was unable to push legislation on framing a cap and trade system to curb greenhouse gas emissions through a hostile Congress.

Republicans have made clear that they are determined to deprive Obama of a second term and immediately crowed at the president's concession on Friday, and cranked up pressure for more concessions.

"It is only the tip of the iceberg when it comes to stopping Washington Democrats' agenda of tax hikes, more government 'stimulus' spending, and increased regulations," said Boehner spokesman Michael Steel.

]]> Tue, 21 FEB 2012 08:57:46 AEST Milwaukee (UPI) Jul 11, 2011 - A U.S. company says its ozone-based laundry disinfectant system can cut the cost of doing commercial laundry in half.

Ecowash, a company launched in Wisconsin last year, makes commercial laundry systems that use ozone to disinfect and remove stains, and says since the technology doesn't require hot water it offers a significant energy saving, the Milwaukee Journal Sentinel reported Sunday.

Ozone as a disinfectant has been used in Europe since the 1800s but has only recently been utilized in the United States.

Wisconsin's Focus on Energy program has begun offering incentives for customers to deploy the technology, saying it cuts energy use by 45 percent, as well as cutting detergent, chemical and hot water use.

Though not suitable for light washing loads or home use, Focus on Energy recommends it for places that go through a lot of laundry, such as hotels, nursing homes or buildings that have at least 1,000 pounds of laundry to wash every day.

]]> Tue, 21 FEB 2012 08:57:46 AEST New York NY (SPX) Apr 27, 2011 - In a study to be published in the April 21st issue of Science magazine, researchers at Columbia University's School of Engineering and Applied Science report their findings that the ozone hole, which is located over the South Pole, has affected the entire circulation of the Southern Hemisphere all the way to the equator.

While previous work has shown that the ozone hole is changing the atmospheric flow in the high latitudes, the Columbia Engineering paper, "Impact of Polar Ozone Depletion on Subtropical Precipitation," demonstrates that the ozone hole is able to influence the tropical circulation and increase rainfall at low latitudes in the Southern Hemisphere.

This is the first time that ozone depletion, an upper atmospheric phenomenon confined to the polar regions, has been linked to climate change from the Pole to the equator.

"The ozone hole is not even mentioned in the summary for policymakers issued with the last IPCC report," noted Lorenzo M. Polvani, Professor of Applied Mathematics and of Earth and Environmental Sciences, Senior Research Scientist at the Lamont-Doherty Earth Observatory, and co-author of the paper. "We show in this study that it has large and far-reaching impacts. The ozone hole is a big player in the climate system!"

"It's really amazing that the ozone hole, located so high up in the atmosphere over Antarctica, can have an impact all the way to the tropics and affect rainfall there - it's just like a domino effect," said Sarah Kang, Postdoctoral Research Scientist in Columbia Engineering's Department of Applied Physics and Applied Mathematics and lead author of the paper.

The ozone hole is now widely believed to have been the dominant agent of atmospheric circulation changes in the Southern Hemisphere in the last half century.

This means, according to Polvani and Kang, that international agreements about mitigating climate change cannot be confined to dealing with carbon alone- ozone needs to be considered, too. "This could be a real game-changer," Polvani added.

Located in the Earth's stratosphere, just above the troposphere (which begins on Earth's surface), the ozone layer absorbs most of the Sun's harmful ultraviolet rays. Over the last half-century, widespread use of manmade compounds, especially household and commercial aerosols containing chlorofluorocarbons (CFCs), has significantly and rapidly broken down the ozone layer, to a point where a hole in the Antarctic ozone layer was discovered in the mid 1980s.

Thanks to the 1989 Montreal Protocol, now signed by 196 countries, global CFC production has been phased out. As a result, scientists have observed over the past decade that ozone depletion has largely halted and they now expect it to fully reverse, and the ozone hole to close by midcentury.

But, as Polvani has said, "While the ozone hole has been considered as a solved problem, we're now finding it has caused a great deal of the climate change that's been observed." So, even though CFCs are no longer being added to the atmosphere, and the ozone layer will recover in the coming decades, the closing of the ozone hole will have a considerable impact on climate.

This shows that through international treaties such as the Montreal Protocol, which has been called the single most successful international agreement to date, human beings are able to make changes to the climate system.

Together with colleagues at the Canadian Centre for Climate Modelling and Analysis in Victoria, BC, Kang and Polvani used two different state-of-the-art climate models to show the ozone hole effect. They first calculated the atmospheric changes in the models produced by creating an ozone hole.

They then compared these changes with the ones that have been observed in the last few decades: the close agreement between the models and the observations shows that ozone has likely been responsible for the observed changes in Southern Hemisphere.

This important new finding was made possible by the international collaboration of the Columbia University scientists with Canadian colleagues.

Model results pertaining to rainfall are notoriously difficult to calculate with climate models, and a single model is usually not sufficient to establish credible results. By joining hands and comparing results from two independent models, the scientists obtained solid results.

Kang and Polvani plan next to study extreme precipitation events, which are associated with major floods, mudslides, etc. "We really want to know," said Kang, "if and how the closing of the ozone hole will affect these."

]]> Tue, 21 FEB 2012 08:57:46 AEST Washington (AFP) April 21, 2011 - The hole in the ozone layer over Antarctica is a significant driver of climate change and rain increases in the southern hemisphere over the past 50 years, US scientists said Thursday.

The findings by a team at Columbia University's School of Engineering and Applied Science are the first to link ozone depletion in the polar region to climate change all the way to the equator.

Researchers said the analysis should lead policy-makers to consider the ozone layer along with other environmental factors such as Arctic ice melt and greenhouse gas emissions when considering how to tackle climate change.

"It's really amazing that the ozone hole, located so high up in the atmosphere over Antarctica, can have an impact all the way to the tropics and affect rainfall there," said Sarah Kang, lead author of the study in the journal Science.

"It's just like a domino effect," she said.

Scientists say the Antarctic ozone hole, discovered in the 1980s, was created by the extensive use of manmade aerosols containing chlorofluorocarbons (CFCs).

Since the signing by 196 countries of the 1989 Montreal Protocol, most CFC production around the world has stopped, and experts expect the hole to close by the middle of this century.

"While the ozone hole has been considered as a solved problem, we're now finding it has caused a great deal of the climate change that's been observed," said co-author Lorenzo Polvani, senior research scientist at the Lamont-Doherty Earth Observatory.

The study used two independently drawn climate models -- the Canadian Middle Atmosphere Model and the United States' National Center for Atmospheric Research (NCAR) Community Atmosphere Model.

In four experiments comparing data on sea ice, surface temperatures, precipitation and the ozone hole, the analysis showed the hole was the main driver of heavy summer rains across eastern Australia, the southwestern Indian Ocean and the Southern Pacific Convergence Zone.

"We show in this study that it has large and far-reaching impacts. The ozone hole is a big player in the climate system," said Polvani.

"This could be a real game-changer."

Next, the researchers plan to look at "extreme precipitation events," the sort that cause devastating floods and landslides.

"We really want to know if and how the closing of the ozone hole will affect these," said Kang.

]]> Tue, 21 FEB 2012 08:57:46 AEST Subscribe to our daily selection of space, military, environment and energy newsletters responseText http://visitor.constantcontact.com/manage/optin/ea?v=0016gbbKsaiGSpQFojVO8ZoHw%3D%3D