Sunday, February 7, 2010

Western Australia drought is 'proof of climate change'

Sydney Morning Herald: The author behind a new study linking 30-year drought in Western Australia with heavy snowfall in Antarctica says it is strong evidence man-made greenhouse gases have provoked dramatic climate change. The Antarctic Climate and Ecosystems Cooperative Research Centre in Tasmania said it had found a direct link between snowfall in eastern Antarctica and rainfall in Australia's southwest.

The heavier it snows in Antarctica, the less it rains in southern WA, the centre found. Principal research scientist Tas van Ommen said the conclusion had been drawn from a study of 750-year-old ice-core samples.

The samples showed that as recently as about 1970, Southern Ocean winds had changed to deposit unusually heavy snow in Antarctica while circulating dry, cold wind - with little rainfall - to the southwest of Australia. Dr van Ommen said it was the most significant climatic change found in the 750-year-old ice sample, and outside natural variation.

"What we've found is that the last 30 years in our ice core is the largest event in the past 750 years," Dr van Ommen told AAP ahead of the study's release on Monday. "Large scale atmospheric circulation in recent decades seems to have stepped up in a way that brings extra warm, moist air to Antarctica - with extra snowfall - and at the same time the recirculation of cold, dry air up towards Western Australia.

"This has actually reduced the winter rainfall and made a significant contribution to the drought. The drop occurred around 1970 - it's about a 15 per cent drop in (annual) winter rainfall."

Dr van Ommen said that while the ice-core study wasn't conclusive proof of human-induced climate change, there was strong evidence pointing to it. "There's no doubt in everybody's mind that Western Australia has gone into drought," he said….

Murchison River gorge in Kalbarri National Park. Photo taken in April 2006 by Takver (, Wikimedia Commons, under the Creative Commons Attribution ShareAlike 3.0 License

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