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Science/Tech See other Science/Tech Articles Title: Ozone Hole Causes Antarctic Sea Ice to Expand, Slows Warming April 23 (Bloomberg) -- The ozone hole over the South Pole is canceling out the effects of global warming and causing sea ice production to build up around Antarctica, researchers said. The human-induced depletion of the protective ozone layer has altered wind patterns and caused temperatures in most of the southern continent to fall so that more cold air flows over the Southern Ocean, freezing the water, the scientists said today in the journal Geophysical Research Letters. The cooling has led to an increase in ocean ice cover in the southern hemisphere of about 1 percent per decade for the past 30 years, a marked contrast to the other pole, where Arctic sea ice shrank to its lowest recorded level in 2007. “Both these factors are caused by man -- greenhouses gases in the north and the ozone hole in the south,” lead author John Turner, a professor of meteorology with the British Antarctic Survey, said in a telephone interview. “This shows the complexity of man’s impact on the planet.” Greenhouse gases such as carbon dioxide released by human activities, including burning fossil fuels such as coal and oil, are blamed by the United Nations for raising global average temperatures, causing glaciers and Arctic sea ice to melt and changing patterns of drought and rainfall. The ozone layer, which protects humans from carcinogenic ultraviolet radiation, was depleted by manmade compounds such as chlorofluorocarbons (CFCs), whose use in household items such as refrigerators and aerosol cans was banned by the Montreal Protocol, an international treaty in effect since 1989. Until now, the ozone hole has helped spare most of Antarctica from warming, said Turner, who worked with the National Aeronautics and Space Administration on the study. ‘Overwhelmed by Ozone Hole’ “Greenhouse gases have still increased in the Antarctic but the changes have been overwhelmed by the ozone hole,” he said. Even so, changes in wind patterns and storms have caused uneven effects along the southern continent, he said yesterday. While East Antarctica has cooled by less than a degree Celsius (1.8 degrees Fahrenheit) in 30 years, the Antarctic Peninsula, which points toward South America, has warmed “by more than anywhere else in the southern hemisphere” -- at least 2.5 degrees in the past half-century, the researcher said. That’s led to the collapse of ice shelves in the region. Sea ice may begin to wane in the south as the ozone layer recovers because of the ban on CFCs, Turner said. CFCs “are very long-lived in the atmosphere so it’ll take 50 to 100 years for the ozone hole to heal,” he said. “Over that time, greenhouse gases we expect will ramp up, and if that happens, over the next decade we’ll see sea ice extent plateau and then rapidly decrease, and then by the end of the century we expect there to be a third less ice around the Antarctic.” The researchers’ findings will take a key argument away from skeptics of global warming who say Antarctica is evidence that humans aren’t causing temperatures to rise, Turner said. “They were saying this shows that global warming is not real, this is an anomaly, but now we know it’s another anthropogenic factor, which is the ozone hole,” he said. “We’ve really managed to solve another piece of the puzzle of what’s happening in the Antarctic.”
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