Tibetan Avalanches Caused by Climate Change

(CN) – Several months after the first of two towering avalanches struck western Tibet, researchers say the once-stable region is danger of more large-scale avalanches due to the effects of climate change.

On July 17, more than 70 million tons of ice broke off from the Aru glacier in the mountains of Tibet, ultimately taking the lives of nine nomadic yak herders as the avalanche buried 3.7 square miles of a valley in the span of five minutes.

While scientists thought surging – a process in which ice flows from the top to the bottom of a glacier and causes it to advance more quickly – was to blame for the avalanche, a team of researchers now believe meltwater produced by global warming over the past 50 years acted as a lubricant that sped up the flow of ice down the mountain.

“Given the rate at which the event occurred and the area covered, I think it could only happen in the presence of meltwater,” said Lonnie Thompson, a professor at Ohio State University and co-author of a study on the avalanche that was published Friday in the Journal of Glaciology.

The authors tracked how much ice fell during the July 17 avalanche through satellite data and GPS, which they used to create computer models that replicated the avalanche virtually. The only simulations that led to an avalanche featured the presence of meltwater.

Thompson believes global warming has led to a meltwater build-up that will likely lead to more avalanches in the region, pointing to a second avalanche in September as an example of future regional disasters.

“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 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,” he said.

The avalanches were unprecedented in western Tibet, a region that has avoided the effects of climate change over the past few decades – glaciers in the region while others melted in southern and eastern Tibet.