GLOBAL warming has caused the world's tropical regions to expand much more rapidly than predicted, raising the prospect of an even drier farm belt in southern Australia, and the spread south of diseases such as dengue fever.
As talks on climate change begin at a United Nations meeting in Bali today, research reveals the tropical zone has widened by more than two degrees of latitude over the past 25 years. This is greater than the expansion expected by the end of this century, a study led by Dian Seidel, of the US National Oceanic and Atmospheric Administration, has revealed.
Dr Seidel said the surprisingly rapid expansion of the tropics could lead to "profound changes in the global climate system". Of greatest concern were shifts in rain and wind patterns that would affect natural ecosystems, agriculture and water resources in the world's subtropical dry belts, including southern Australia.
The director of the Research Institute for Climate Change and Sustainability at the University of Adelaide, Barry Brook, said it would push the westerly systems that bring rain to Australia's southern coast closer to the South Pole. "As they shift southwards, progressively more rain is dumped over the Southern Ocean, instead of over continental Australia, where we need it," he said. The expanding tropics would also extend the range of tropical diseases, Professor Brook said.
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http://www.smh.com.au/news/environment/greenhouse-robs-rainfall-in-farm-belt/2007/12/02/1196530481803.html