Scientists Blame Climate Change for Glacier Collapse in Western Tibet
As temperatures warm across the globe, ice sheets and glaciers are being affected--including glaciers that have been stable for decades. A recent study explored the reasons for a glacial collapse in western Tibet, an area of previously stable cold-based glaciers.
Researchers believe that climate change is likely the cause of a deadly avalanche that occurred in western Tibet when a 3km-long, cold-based glacier collapsed.
The avalanche, which occurred on July 17, 2016 and lasted approximately five minutes, reached Aruco Lake, killed nine nomadic yak herders, and buried 3.7 square miles of the valley floor in ice. GPS and satellite photos show before and after pictures of the glacier, the path of the avalanche, and the large deposit of the snow and ice on the valley floor.
Cold-based glaciers are frozen to bedrock, and not temperature-based, which makes the glaciers historically more stable than others. In recent decades, the glacier studied had been reduced by about 4.3 percent. Researchers believe that a temperature increase of about 1.5 degrees Fahrenheit over the last 50 years contributed to the avalanche that caused more than 70 million tons of ice to break away from the previously stable Aru glacier in the Tibetan Plateau.
The short duration of the avalanche that covered such a long distance is not a common occurrence. Researchers believe that to have such a rapid decent rate, meltwater at the base of the glacier must have accelerated the ice flow. Meltwater occurs when temperatures increase enough to melt the snow and ice, and the melted water then seeps below to the base of the glacier.
"This is the first known occurrence of an unexpected, instantaneous collapse of a cold-based glacier in a nonvolcanic region." -- Tian,
In September 2016, just two months after the Aru glacier gave way, another avalanche occurred on the same mountain range, on a neighboring glacier. Although the cause of that avalanche is still being investigated, researchers believe that it was also the result of globally rising temperatures that melted snow and ice, which increased the amount of meltwater at the base of the glacier.
Unprecedented in western Tibet
Glacier collapse is unprecedented in western Tibet. Glaciers there have been stable for decades, even when glaciers in southern and eastern Tibet have continued melting at an accelerated rate.
Glaciers in western Tibet have also expanded due to increased snowfall. In fact, researchers believe that the increased snowfall might have contributed to the amount of meltwater, increasing the risk that the glacier would collapse. With the continued global temperature rise, researchers fear future glacial collapses in this same area, but currently have no way of predicting where or when this might occur.