On Friday,July 8 around 2:45 p.m., British tourist Harry Shimmin reached the highest point in his trek along the Jukku pass in the Tian Shan mountains in Kyrgyzstan. He separated from the group to take pictures from the edge of a cliff when he heard deep ice cracking behind him. He turned around to an avalanche of glacial ice and snow rushing toward him and within moments found himself in a blizzard.
The avalanche was the second glacier collapse of the week, demonstrating the perils of human-caused climate change amid a blistering hot summer in parts of Europe and Asia. These are glacier ice avalanches, rather than primarily snow, in which a glacier broke off and collapsed under the force gravity. The high density of ice added speed and weight to the avalanche. In the Tian Shan event, glaciologist Peter Neff, of the University of Minnesota, pointed out that there was no apparent snow around the mountain so the avalanche was largely a solid chunk of glacial ice. In high mountain regions with permafrost, warm temperatures not only destabilize the glacier ice but also the density of the ice around it. “It’s very dense, more like a landslide than an avalanche,” he said.
“The British trekker is indeed, as he is aware, very lucky to be alive in the case of the Kyrgyzstan event,” added glaciologist Jeff Kargel, a senior scientist at the Planetary Science Institute. “A pretty solid hypothesis is that as temperatures warm [and] climate warms, the amount of melting increases,” Kargel said. “The effects of meltwater on destabilizing ice masses increases, and so the number, the frequency and magnitude of glacier ice avalanches should be increasing … and that does seem qualitatively to be the case.”
Daniel Farinotti, a glaciologist at ETH Zurich, agreed. “It is long known that meltwater caused by high temperatures increase the pressure in the glaciers’ subglacial drainage system, which in turn can accelerate glacier motion,” said Farinotti in an email. “This increase in pressure and motion have certainly a role to play in such collapses.”
Among the greatest downstream effects from such mountain glacier loss and collapses are on fresh water systems, Neff said. For instance, glaciers in High Mountain Asia play a critical role in funneling freshwater into river basins used for drinking, irrigation and hydropower by nearly 1.5 billion people.