Recent Extreme Weather Attributed to Human-Caused Climate Warming: Probability of Some Droughts, Heat Waves Now Much Greater
Raloff, Janet, Science News
Texans sweltered through the hottest, driest spring and summer on record last year. Much of the blame can be attributed to a recurring climate pattern known as La Nina, which emerges every few years as surface waters chill in the eastern equatorial Pacific. But Earth's steadily warming climate contributed as well, a new analysis concludes.
Since the 1960s, the likelihood of Texas seeing extremely hot, dry weather in a La Nina year has mushroomed 20-fold due to human-induced global warming, David Rupp of Oregon State University in Corvallis and his colleagues calculate.
The researchers were one team among six international groups probing climate's link to extreme events in late 2010 through 2011. The collected findings appear July 10 in the Bulletin of the American Meteorological Society.
"People may very well remember this as a year of extreme weather and climate," says Jessica Blunden of the National Climatic Data Center and an editor of State of the Climate in 2011, a report published as a supplement to the July 10 Bulletin of the American Meteorological Society.
Severe food shortages gripped the Horn of Africa last year after drought left the land parched from winter 2010 through the following spring. La Nina played a role there, too. And computer analyses of global climate conditions since 1979 find that a recent warming of surface waters in the Indian and Pacific oceans has destabilized La Nina weather patterns. Chris Funk of the U.S. Geological Survey in Santa Barbara, Calif., concludes that this process probably intensified 2011's drought in East Africa.
Other teams pointed to global warming as a likely contributor to excessive heat in central Europe last summer and to unusually balmy temperatures in central England in November 2011. In the British case, that kind of heat could be expected to recur every 20 years now--a 62-fold increase over the 1960s.
Yet global warming can't be blamed for all monster weather. Unprecedented flooding that submerged large tracts of northern Thailand, including its capital, for up to two months last year resulted from rainfall at an intensity the region had encountered before. …