Saturday, February 25, 2012

Climate change, here and now ... by gimleteye

Having just returned from India, and clear pictures how hundreds of millions of rural poor are dependent on monsoon rains, I noted with interest today's story, "Mild drought killed off Mayan civilization".
"The collapse of the Mayan civilization was likely due to a relatively mild drought, much like the drier conditions expected in the coming years due to climate change, scientists said Thursday. Scholars have long believed that a major drought caused severe dry conditions that killed off the ancient culture known for its mastery of language, math and astronomy. But researchers from the Yucatan Center for Scientific Research in Mexico and the University of Southampton in Britain said their analysis shows the drought only caused reductions of 25 to 40 percent less annual rain. The smaller amounts of rain meant that open water sources in pools and lakes evaporated faster than could be replaced by more precipitation, said the study in the journal Science. "The data suggest that the main cause was a decrease in summer storm activity," said co-author Eelco Rohling of the University of Southampton. The study is the first of its kind to attempt to assess exactly how much rainfall decreased between 800 and 950 AD when Mayan civilization went into decline, and bases its modeling data on records of past rainfall changes from stalagmites and shallow lakes. The analysis showed that modest dry spells could have sparked major water shortages in an area with no rivers, and no source of water other than rain. "Summer was the main season for cultivation and replenishment of Mayan freshwater storage systems and there are no rivers in the Yucatan lowlands," added Rohling."

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