Angkor Wat doomed by drought, floods, suggests tree ring study

http://content.usatoday.com/
via CAAI News Media

Mar 29, 2010

The ancient Cambodian capital of Angkor Wat suffered decades of drought interspersed with monsoon lashings that doomed the city six centuries ago, suggests a Monday tree-ring study.

A 979-year record of tree rings taken from Vietnam's highlands, released by the Proceedings of the National Academy of Sciences journal and led by Brendan Buckley of Columbia University, finds the, "Angkor droughts were of a duration and severity that would have impacted the sprawling city's water supply and agricultural productivity, while high-magnitude monsoon years damaged its water control infrastructure."

By Elsevier, Department of Angkor Conservation

Alternating effects of El Nino and La Nina conditions in the Pacific Ocean, as the northern hemisphere shifted a period of medieval warmth to the "Little Ice Age" of the 17th Century, may have whipsawed the region where Angkor Wat once stood. The "hydraulic city", center of the Khmer empire from the 9th to the 15th Century, was built of impressive temples standing amid nearly 400 square miles of canals and reservoirs called "baray", according to a 2009 Journal of Environmental Management study.

Many of those canals and baray appear silted up by drought, says the PNAS paper, which left them wide open for flooding from the intense monsoons of the early 15th century. "Much like the Classic Maya cities in Mesoamerica in the period of their ninth century 'collapse' and the implicated climate crisis, Angkor declined from a level of high complexity and regional hegemony after the droughts of the fourteenth and early fifteenth centuries," says the study. " The temple of Angkor Wat itself, however, survived as a Buddhist monastery to the present day."

A 2005 Journal of Archaeological Science study found that a typical Angkor temple may have taken more than a century to build.

While some scholars suggest that trade interests led to the capital moving to Phnom Penh in the mega-monsoon era, the study concludes, "decades of weakened summer monsoon rainfall, punctuated by abrupt and extreme wet episodes that likely brought severe flooding that damaged flood-control infrastructure, must now be considered an additional, important, and significant stressor occurring during a period of decline. Interrelated infrastructural, economic, and geopolitical stresses had made Angkor vulnerable to climate change and limited its capacity to adapt to changing circumstances."

Tree Rings, Climate Change and the Rainy Season from Earth Institute on Vimeo.
By Dan Vergano