“When the snow started coming over and it got dark / harder to breathe, I was bricking it and thought I might die,” Shimmin wrote in an Instagram post. Shimmin and his group survived, although one member was sent to the hospital.
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.
On July 3, a glacier chunk as large as an apartment building detached in Italy’s Dolomites region and killed at least 11 hikers. The block separated from a melting glacier on Marmolada mountain and triggered an avalanche of ice, rock and debris below, where many tourists hike during the summer.
The avalanche in Italy occurred in a record-breaking heat wave during the country’s worst drought in 70 years, which was caused partly by a lack of winter snow in the mountains.
Researchers say these events underline the dangers of a rapidly warming world and are expected to increase unless greenhouse gas emissions are curbed.
Rising global temperatures are slowly weakening glacier systems in mountainous areas, where millions of people rely on these reservoirs as a source of fresh water. Climate change is also inducing more extreme heat waves, which can push the weakening glacier systems over the edge.
“There’s no other direction glaciers are going other than retreating” as global warming increases, said Peter Neff, a glaciologist at the University of Minnesota. “The feeling from the event in Italy and [Kyrgyzstan] is this is coming more often.”
The glacial events in Italy and Kyrgyzstan have similar backbones, glaciologist Jeff Kargel said. In the days before the collapse on the Tian Shan mountains, temperatures hit as high as 59 degrees Fahrenheit (15 Celsius) at nearly 12,000 feet (3,600 meters) high. Similarly, temperatures soared about 50 degrees in the days leading to Italy’s fatal glacier accident. Both are examples of heat waves that have plagued the Northern Hemisphere in recent months, some of which have been found to be more intense and frequent due to climate change.
Both were also glacier ice avalanches, rather than primarily snow, in which a glacier broke off and collapsed under the force of gravity. The high density of ice added speed and weight to the avalanche.
In the Tian Shan event, Neff 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 Kargel, a senior scientist at the Planetary Science Institute.
Kargel said ice and snow detachments occur every spring and summer as the glaciers approach the peak of their melt season, build up mass throughout the winter and gently flow down a valley. Often chunks of the glacier become unstable, break off and produce ice avalanches.
Ice avalanches “happen all the time, and they would be happening without climate change as well,” Kargel said. “However, it does seem, qualitatively, that there have been many, many more of these in recent years, over the past decade or so than in previous decades.”
He said more fatalities and damage from such events have probably increased, too, as more trekkers, villages and infrastructure appear closer to these mountainous areas.
One of the most notable glacier collapses of the past decade that Kargel recalls occurred in 2016 in western Tibet, where the entire lower parts of two adjacent glaciers broke within months of each other. One of the avalanches covered more than 3 square miles of land and reached speeds of 90 mph, killing nine people and hundreds of animals. Kargel said these two collapses “almost certainly are connected to climate,” as the glaciers experienced unusually high amounts of heavy rains and meltwater, which helped grease lubricate the underside of the glaciers.
While the glacier collapses in Kyrgyzstan and Italy were much smaller (about 1,000 times smaller in volume than other deadly glacial collapses), Kargel said they probably also have a connection to climate change.
“A pretty solid hypothesis is that as temperatures warm [and] the climate warms, the amount of melting increases,” he 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 movement,” said Farinotti in an email. “This increase in pressure and motion certainly have 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.
Mountain glaciers may have less ice than estimated, straining freshwater supply
“We’re putting [these glaciers] into a state of change,” Neff said. “Ice is going to melt faster and deplete drinking water.”
And more collapses could be on the way as the melt season progresses.
“When the melt season gets going in earnest, I would expect we’ll see more of them,” Kargel said. “But, hopefully, there won’t be more deadly ones.”