News•October 26, 2016

Tibet Just Had Another Massive Ice Avalanche

An ice avalanche stretching 3.7 miles and burying the land in up to 98 feet of ice is weird. A second one in almost the exact same location just a few months later is essentially unheard of.

And yet that’s exactly what happened in a remote corner of Tibet in late September, when a second massive jumble of ice and rock ripped across the landscape. The second avalanche is just a few miles away from the first one, which occurred on July 17.

“Even one of these gigantic glacier avalanches is very unusual,” Andreas Kääb, a glaciologist at the University of Oslo, told NASA Earth Observatory, which published a new set of images. “Two of them within close geographical and temporal vicinity is, to our best knowledge, unprecedented.”

Before and after imagery shows the July 17 ice avalanche and the recent late September one.
Credit: NASA Earth Observatory

The first avalanche was likely caused by a glacial surge, which causes glaciers to start flowing up to 100 times faster than they normally do. Weather conditions immediately preceding that avalanche don’t appear to have played much of a role as it was cooler than normal and relatively dry.

Scientists have suggested that meltwater underneath the glacier that started flowing heavily in September 2015 could have ultimately led to the ice slide. Whether something similar happened with the second ice avalanche remains to be seen and the window to do fieldwork is rapidly closing as winter draws nearer. But the Earth Observatory notes that blue pools of water near where the slide began indicates it could be a cause.

This wouldn’t be the first case of meltwater speeding up a glacier’s movements, though it certainly is one of — if not the — first instances of it leading to collapse. Scientists have found meltwater playing similar tricks on the Greenland ice sheet. That’s helping send ice to the sea faster and with it, increasing sea levels.

It’s hard to pin what happened in Tibet specifically on climate change, but there’s little doubt that as the world warms, ice will suffer, melt and ultimately disappear from the landscape from Tibet to the Northern Rockies.

“The risk of natural hazards is amplified in the mountains and by the mountains,” Joseph Shea, a scientist at the International Centre for Integrated Mountain Development, told Climate Central after the first avalanche. “And climate change generally acts to enhance these risks even further.”