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Antarctic cools in warmer world
By David Derbyshire, Science Correspondent
THE Antarctic has cooled during the past 35 years despite the worldwide temperature rise, according to a study published today.
The finding challenges the belief that global warming is raising temperatures across the whole of the southern continent.
But the authors accept that some Antarctic "hotspots" have got warmer over the past few decades.
The findings, published today in Nature magazine online, come from the American National Science Foundation's long-term ecological research site in Antarctica's Dry Valleys, a snow-free mountainous area on McMurdo Sound.
Dr Peter Doran, of the University of Illinois at Chicago, the lead author of the paper, said long-term data from weather stations across the continent, coupled with a separate set of measurements from the Dry Valleys, supported a cooling trend.
"Our 14-year continuous weather station record from the shore of Lake Hoare reveals that seasonally averaged surface air temperature has decreased by 0.7C per decade," the authors report.
"The temperature decrease is most pronounced in summer and autumn. Continental cooling, especially the seasonality of cooling, poses challenges to models of climate and ecosystem change."
A drop in Antarctic temperatures is a puzzle because most climate models suggest that polar regions should respond first and most rapidly to worldwide temperature changes.
Previous claims that the Antarctic is warming may have been skewed because the measurements were taken largely on the Antarctic Peninsula, which extends toward South America and which is warming five times more quickly than the rest of the world.
"Averaging the temperature readings from the more numerous stations on the Peninsula has led to the misleading conclusion that there is a net warming continent-wide," said Dr Doran.
"Our approach shows that if you remove the Peninsula from the dataset, and look at the spatial trend, the majority of the continent is cooling."
The findings could prove to be headache for climate change modellers, he added.
"Although some do predict areas of cooling, widespread cooling is a bit of a conundrum that the models need to start to account for," he said.
But Dr David Vaughan, of the British Antarctic Survey, said temperature records going back 50 years showed that the continent had been getting warmer over the longer term. "There are regional differences in climate change," he added.
"If we are going to predict climate change for the next 100 years . . . we need to know what is going to happen to the Antarctic Peninsula, to the Falkland Islands, or to Hampshire. That is the scale that impacts people."
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Polar research - National Science Foundation
Understanding Antarctic weather - USA Today
Antarctic warming: early signs of global climate change - Greenpeace