Climate modelers see modern echo in '30s...(he change in sea-surface temperature. Th...)

Date:4/30/2008

he change in sea-surface temperature. This showed a 5% drop in rainfall, centered over northern Mexico and the U.S. southwest, where little agriculture then took place. This would have affected the Great Plains too, but probably would have not brought disaster. Then the modelers added in the effects of dust, using data from the 30s that indicated dust sources, and allowing the computer to create dust storms. This yielded a simulated event eerily like the real one, with a full 10% drop in rainto just 18 inches a year--and centered over the prairie farm regions of north Texas, Oklahoma, Missouri, Kansas, Nebraska and Iowa.

Lead author Benjamin Cook, a National Oceanic and Atmospheric Administration postdoctoral researcher affiliated with both Lamont and Goddard, said the effect occurred because dust particles suspended in air reflect solar radiation. Studies by researchers in other parts of the world show that this causes a drop in temperatures at or near the soil surface, lessening evaporation of moisture into the air, and thus decreasing precipitation even further. Dust on the Great Plains helped draw the drought northward like a siphon, said Cook. This is what made the Dust Bowl the Dust Bowl, he said. It was a process that fed on itself.

The U.S. southwest is currently suffering a serious long-term drought that threatens agriculture and population growth there. Cook said it is unlikely that this by itself will cause another Dust Bowl in the United States. Among other things, the U.S. Natural Resources Conservation Service, founded in response to the 30s crisis, has shifted farmers into more sustainable practices. On the other hand, Cook points out that many scientists believe hard-pressed farmers and herders in China and Africas Sahel region may be repeating the experience, ruining marginal lands in order to feed themselves in the short term. This highlights the fact that humans can alter natural events and make them worse, said coautho
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Contact: Kevin Krajick kkrajick@ei.columbia.edu 212-854-9729 The Earth Institute at Columbia University Source:Eurekalert

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