Thursday, April 30, 2015

Study by Swiss Federal Institute of Technology links weather extremes to global warming

"The moderate global warming that has already occurred as a result of human emissions has quadrupled the frequency of certain heat extremes since the Industrial Revolution," says a study by scientists at the Swiss Federal Institute of Technology published Monday in Nature Climate Change, Justin Gillis reports for The New York Times. The study is the first to "forecast, on a global scale, how those extremes might change with continued global warming." (Reuters photo by Darren Hauck: Corn in Belleville, Wis., has been infected with a fungus due to heat and drought.)

Researchers "warned that a failure to bring greenhouse gases under control could eventually lead to a 62-fold increase in such heat blasts," Gillis writes. "The planetary warming has had a more moderate effect on intense rainstorms, the scientists said, driving up their frequency by 22 percent since the 19th century. Yet such heavy rains could more than double later this century if emissions continue at a high level, they said."

For the study researchers used computer analyses of what the climate would be like if the Industrial Revolution had never happened and "focused on the sort of weather extremes that would be likely to occur in any given location on the earth about once in 1,000 days, or a little less than three years," Gillis writes. "What constitutes a one-in-1,000-day extreme varies from place to place; after all, a hot day in North Dakota might seem pretty routine in Texas. But such extremes can be damaging wherever they occur—especially hot days, which can cut farm yields and drive up food prices."

Researchers said the climate change is leading to heavier rainstorms across large parts of the U.S., specifically in the Northeast, Gillis writes. "At the same time, higher temperatures are drying out the soil and worsening the effects of droughts when they do occur, as in California over the last few years." Researcher Dr. Reto Knutti told Gillis, “The bottom line is that things are not that complicated. You make the world a degree or two warmer, and there will be more hot days. There will be more moisture in the atmosphere, so that must come down somewhere.” (Read more)

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