February 24, 2012
Mild Drought Linked To Collapse Of Maya Civilization
The Classic Maya Civilization, which flourished from 250 AD to around 950 AD, may have collapsed due to relatively modest reductions in precipitation, according to a new study by Mexican and British researchers.
The study, led by Professors MartÃn Medina-Elizalde of the Yucatan Center for Scientific Research in Mexico and Eelco Rohling of the University of Southampton in the UK, said the relatively mild drought of the Classic Mayan period was much like the conditions that are expected in the coming years due to climate change.Scholars have long theorized that a major drought was the cause of the collapse of the Mayan Civilization, and ancient culture known for its mastery of language, math and astronomy. But the researchers of the new study now think a much less reduction of rainfall was enough to cause the downfall of the empire.
“These reductions amount to only 25 to 40 percent in annual rainfall, but they were large enough for evaporation to become dominant over rainfall, and open water was rapidly reduced,” Rohling told the Press Association.
“Societal disruptions and abandonment of cities are likely consequences of critical water shortages, especially because there seems to have been a rapid repetition of multi-year droughts,” he added.
For their study, published in the journal Science, the team used advanced modeling techniques to estimate rainfall and evaporation rates between 800 and 950 AD, when the Maya Civilization went into sharp decline.
The smaller amounts of rain meant that open water sources in pools and lakes evaporated much faster than precipitation could replenish, according to the study.
“The data suggest that the main cause was a decrease in summer storm activity,” said Rohling.
The water shortages would have spelled doom for an area with no rivers, and one that relied heavily on rain for its water supply.
“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. “Societal disruptions and abandonment of cities are likely consequences of critical water shortages, especially because there seems to have been a rapid repetition of multi-year droughts.”
While modern societies are expected to be better equipped to handle drought, risks remain, said lead author Medina-Elizalde. “What seems like a minor reduction in water availability may lead to important, long-lasting problems. This problem is not unique to the Yucatan Peninsula, but applies to all regions in similar settings where evaporation is high.”
Archaeologists have long been intrigued by the collapse of the Classic Maya Civilization. There have been several theories about the demise of the ancient culture, including social unrest, disease, and deforestation. But drought has long been the most popular theory.
“For more than a century, researchers have related the demise of the Classic Maya Civilization to climate change, and especially to drought. No sound estimates had been made about the severity of this drought, but some have suggested extreme scenarios. New data made it possible to finally get detailed estimates. To do this, we developed a model that coherently explains changes in critical datasets of change in the region's balance between evaporation and rainfall," the researchers said.
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