Friday, August 24, 2012

Mayans and Rainfall

More evidence for man-made climate change bringing down empires:
The city states of the ancient Mayan empire flourished in southern Mexico and northern Central America for about six centuries. Then, around A.D. 900 Mayan civilization disintegrated.

Two new studies examine the reasons for the collapse of the Mayan culture, finding the Mayans themselves contributed to the downfall of the empire.

Scientists have found that drought played a key role, but the Mayans appear to have exacerbated the problem by cutting down the jungle canopy to make way for cities and crops, according to researchers who used climate-model simulations to see how much deforestation aggravated the drought.

"We're not saying deforestation explains the entire drought, but it does explain a substantial portion of the overall drying that is thought to have occurred," said the study's lead author Benjamin Cook, a climate modeler at Columbia University's Lamont-Doherty Earth Observatory and the NASA Goddard Institute for Space Studies, in a statement.

Using climate-model simulations, he and his colleagues examined how much the switch from forest to crops, such as corn, would alter climate. Their results, detailed online in the journal Geophysical Research Letters, suggested that when deforestation was at its maximum, it could account for up to 60 percent of the drying. (The switch from trees to corn reduces the amount of water transferred from the soil to the atmosphere, which reduces rainfall.)

Other recent research takes a more holistic view.

"The ninth-century collapse and abandonment of the Central Maya Lowlands in the Yucat├ín peninsular region were the result of complex human–environment interactions," writes this team in a study published Monday (Aug 20) in the journal Proceedings of the National Academy of Sciences.
What Was Behind Mysterious Collapse of the Mayan Empire? (Live Science)


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