March 25, 2009
Global Warming 37 Percent Cause Of Droughts
Global warming is 37 percent of the cause of massive droughts in Australia and extensive periods of dryness in the US, according to one Australian scientist.
Peter Baines of Melbourne University in Australia told Reuters that rainfall levels have been dropping over the past 15 years, and global warming is 37 percent to blame for that decrease.
Baines used global rainfall data to construct a model of atmospheric conditions over the past 50 years.
"The 37 percent is probably going to increase if global warming continues," Baines told Reuters.
Baines presented his findings at a climate change conference in Perth this week.
He found that four particular areas in the continental US, southeastern Australia, a large region of equatorial Africa and the Altiplano in South America had experienced notable declines in rainfall levels.
Meanwhile, Baines found that two regions in the tropics had actually been experiencing increased rainfall levels. Those areas were in northwestern Australia and the Amazon Basin.
"This is all part of a global pattern where the rainfall is generally increasing in the equatorial tropics and decreasing in the sub-tropics in mid-latitudes," Baines said.
"This is a little bit like the pattern that the (computer) models predict for global warming but this is coming out of the rainfall observations of the past 30 years," he told Reuters.
He also noted a link between global sea surface temperatures (SST) and the observed rainfall trend.
"If you take the SST data and analyze that over a long period you can break that up into a variety of components, such a global warming component," he said.
He studied the impact of rainfall on the circulation of oceans that influence the world's weather patterns.
Two Pacific circulation patterns, including the Pacific Decadal Oscillation, were also studied for their influence on rainfall, according to Reuters.
Baines added that the Atlantic conveyor belt was 27 percent to blame for dropping rainfall levels, and the circulation patterns in the Pacific ocean were 30 percent to blame.
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