Thursday, July 26, 2007

Recent scientific papers on altered rainfall patterns

Climate Feedback (Olive Heffernan):… While these single events cannot be attributed to climate change, many are questioning if the flash flooding is a sign of what is in store for the future. And scientists have some of the answers.

In a paper coming out in Nature this Thursday, Francis Zwiers of the Canadian Centre for Climate Modelling and Analysis in Toronto and colleagues present the first evidence that human-generated greenhouse gas emissions have altered rainfall patterns in the 20th Century. In the region between 40 and 70 degrees North, covering northern Europe, Russia and parts of North America, rainfall increased by 62 millimetres per century between 1925 and 1999. Zwiers and colleagues say that 50-85% of this increase can be attributed to human activity…

And a recent paper published in Science in June suggests that global warming may result in even more rainfall worldwide than is currently evident in climate model simulations. Frank J. Wentz of Remote Sensing Systems in Santa Rosa, California and co-workers compared global satellite data from 1987 to 2006 and found that rainfall increased at the same rate as atmospheric water vapour per degree Celsius of surface warming. Climate models had projected a dampened response of rainfall to global warming owing to a decrease in surface winds, but Wentz and colleagues found that surface winds have in fact become stronger, leading to heavier rainfall.

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