This is the conclusion of an international team of researchers who have published an analysis of the July 2016 disaster in the Dec. 9 issue of the Journal of Glaciology.
On July 17, more than 70 million tons of ice broke off from the Aru glacier in the mountains of western Tibet. It lasted only four or five minutes (according to witnesses), yet it managed to bury 3.7 square miles of the valley floor in that time.
To perform a kind of forensic analysis of the avalanche, researchers from the Chinese Academy of Sciences joined with two glaciologists from The Ohio State University: Lonnie Thompson, Distinguished University Professor in the School of Earth Sciences and research scientist at the Byrd Polar and Climate Research Center (BPCRC), and Ellen Mosley-Thompson, Distinguished University Professor in Geography and director of BPCRC.
"Likely meltwater at the base of the glacier must have lubricated the ice to speed its flow down the mountain," Thompson said.
The researchers used satellite data and GPS to get precise measurements of how much ice fell in the first avalanche and the area it covered. They've since pieced together more answers by working with computer modelers who were able to replicate the avalanche virtually. In those simulations, the only condition that led to an avalanche was the presence of meltwater.
"We still don't know exactly where the meltwater came from, but given that the average temperature at the nearest weather station has risen by about 1.5 degrees Celsius (2.7 degrees Fahrenheit) over the last 50 years, it makes sense that snow and ice are melting and the resulting water is seeping down beneath the glacier," Thompson said.
Glacial collapse is unprecedented in western Tibet, which for decades has resisted the effects of climate change while glaciers in southern and eastern Tibet have melted at an accelerating rate.
"Increased snowfall has even led to the expansion of some glaciers in western Tibet and the extra snowfall likely played some role in the avalanche by creating additional meltwater", said Lide Tian, a glaciologist at the Institute of Tibetan Plateau Research.
https://www.sciencedaily.com/releases/2016/12/161209080826.htm
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