Swiss glacier collapse renews focus on risks of climate change as glaciers retreat around the world
The landslide that buried most of a Swiss village this week is focusing renewed attention on the role of global warming in glacier collapses around the world and the increasing dangers.
How glaciers collapse — from the Alps and Andes to the Himalayas and Antarctica — can differ, scientists say. But in almost every instance, climate change is playing a role.
In Switzerland, the mountainside gave way Wednesday near the village of Blatten, in the southern Lötschental valley, because the rock face above the Birch Glacier had become unstable when mountain permafrost melted, causing debris to fall and cover the glacier in recent years, said Martin Truffer, a physics professor at the University of Alaska who studies how glaciers move.
While the debris insulated the glacier and slowed melting, its weight caused the ice to begin moving — which accelerated dramatically a few weeks ago. Authorities ordered the evacuation of about 300 people, as well as all livestock, from the village in recent days, 'when it became clear that there's a whole mountainside that's about to collapse,' said Truffer, who grew up in Switzerland.
Glacial lakes pose threat
Lakes that form at the base of glaciers as they melt and retreat also sometimes burst, often with catastrophic results. Water can even lift an entire glacier, allowing it to drain, said Truffer, adding that Alaska's capital of Juneau has flooded in recent years because a lake forms every year on a rapidly retreating glacier and eventually bursts.
In 2022, an apartment building-sized chunk of the Marmolada glacier in Italy's Dolomite mountains detached during a summer heat wave, sending an avalanche of debris down the popular summer hiking destination, killing 11.
A glacier in Tibet's Aru mountain range suddenly collapsed in 2016, killing nine people and their livestock, followed a few months later by the collapse of another glacier.
There also have been collapses in Peru, including one in 2006 that caused a mini tsunami; most recently, a glacial lagoon overflowed in April, triggering a landslide that killed two.
'It's amazing sometimes how rapidly they can collapse,' said Lonnie Thompson, a glacier expert at the Ohio State University. 'The instability of these glaciers is a real and growing problem, and there are thousands and thousands of people that are at risk.'
Scientists say melting glaciers will raise sea levels for decades, but the loss of inland glaciers also acutely affects those living nearby who rely on them for water for drinking water and agriculture.
No way to stop the melting
Scientists say greenhouse gases from the burning of fossil fuels such as coal have already locked in enough global warming to doom many of the world's glaciers — which already have retreated significantly.
For example, glaciers in the Alps have lost 50% of their area since 1950, and the rate at which ice is being lost has been accelerating, with 'projections ... that all the glaciers in the Alps could be gone in this century,' Thompson said.
Switzerland, which has the most glaciers of any country in Europe, saw 4% of its total glacier volume disappear in 2023, the second-biggest decline in a single year after a 6% drop in 2022.
A 2023 study found that Peru has lost more than half of its glacier surface in the last six decades, and 175 glaciers disappeared due to climate change between 2016 and 2020, mostly due to the increase in the average global temperature.
A study published Thursday in Science said that even if global temperatures stabilized at their current level, 40% of the world's glaciers still would be lost. But if warming were limited to 1.5 degrees Celsius (2.7 degrees Fahrenheit ) — the long-term warming limit since the late 1800s called for by the 2015 Paris climate agreement — twice as much glacier ice could be preserved than would be otherwise.
'There's places in Alaska where we've shown that it doesn't take any more global warming,' for them to disappear, Truffer said. 'The reason some ... (still) exist is simply because it takes a certain amount of time for them to melt. But the climate is already such that they're screwed.'
___
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Yahoo
a day ago
- Yahoo
How Switzerland's Birch glacier collapsed
A cascade of events in the Swiss Alps led to the dramatic collapse of the Birch glacier, wiping out Blatten village in the valley below, glaciologists and geoscientists told AFP on Friday. Experts knew days ahead of Wednesday's landslide that the glacier was likely to suffer a catastrophic failure. But the reasons why date back much further. There are strong theories on the causes, and to what degree the disaster is linked to climate change -- but these are yet to be confirmed by scientific analysis. "This can be considered as a cascading event, because we have different processes involved," explained Christophe Lambiel, senior lecturer at the University of Lausanne's Institute of Earth Surface Dynamics. - Mountain above the glacier - The 3,342-metre (10,965-foot) high Kleines Nesthorn mountain above the glacier was already somewhat unstable, and rockfalls accelerated dramatically around 10 days beforehand. Experts feared a total collapse within hours, but instead there were successive rockfalls over several days, which was actually the best-case scenario. - Rockfall onto glacier - Three million cubic metres of rock were deposited on the glacier. "If you put a lot of weight on an unstable foundation, it can just slip away. And this is what actually happened," Matthias Huss, the director of Glacier Monitoring Switzerland (GLAMOS), told AFP. "The glacier accelerated strongly in response to this additional loading, and then the disaster struck." - The Birch glacier - The Birch glacier was a special case: the only Swiss glacier that was advancing rather than shrinking. However, this was not because of extra snowfall. Its advance "was quite likely due to the pre-loading with rockfalls from this mountain, which has finally collapsed. So the landslide didn't start from nothing," said Huss. The glacier was on a steep slope, and even steeper at the front, worsening the dynamics. Smaller-scale falls from the front of the glacier Tuesday were expected to continue, with Wednesday's sudden total collapse considered a less-probable scenario. - How the glacier collapsed - The rockfalls altered the stress equation between the weight of the glacier and the slope, which governs its forward speed, Lambiel told AFP. Like pushing a car, it takes a lot of force to initiate movement, but less once it is on the move, he explained. Huss said the 1,000 metres of elevation between the glacier and the Lotschental valley floor added a "huge amount of potential energy", which through friction melts part of the ice, making the fall "much more dynamic than if it was just rock". - Role of melting permafrost - Permafrost conditions are degrading throughout the Alps. Ice inside the cracks in the rocks has been thawing to ever-deeper levels over the last decade, especially after the summer 2022 heatwave. "Ice is considered as the cement of the mountains. Decreasing the quality of the cement decreases the stability of the mountain," said Lambiel. Huss added: "At the moment, we can't say it's because of permafrost thaw that this mountain collapsed -- but it is at least a very probable explanation, or one factor, that has triggered or accelerated this process of the mountain falling apart." - Role of climate change - Jakob Steiner, a geoscientist at the University of Graz in Austria, told AFP: "There is no clear evidence as of yet, for this specific case, that this was caused by climate change." Huss said making such a direct link was "complicated". "If it was just because of climate change that this mountain collapsed, all mountains in the Alps could collapse -- and they don't," he said. "It's a combination of the long-term changes in the geology of the mountain. "The failing of the glacier as such -- this is not related to climate change. It's more the permafrost processes, which are very complex, long-term changes." Lambiel said of a link between climate change and the glacier moving forward over time: "Honestly, we don't know. "But the increasing rockfalls on the glacier during the last 10 years -- this can be linked with climate change." - Other glaciers - Modern monitoring techniques detect acceleration in the ice with high precision -- and therefore allow for early warning. Lambiel said around 80 glaciers in the same region of Switzerland were considered dangerous, and under monitoring. "The big challenge is to recognise where to direct the detailed monitoring," said Huss. Lambiel said sites with glacier-permafrost interactions above 3,000 metres would now need more research. But they are difficult to reach and monitor. Steiner said: "Probably the rapidly changing permafrost can play some kind of role. "This is concerning because this means that mountains are becoming a lot more unstable." rjm-burs/phz/jhb
USA Today
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- USA Today
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Yahoo
a day ago
- Yahoo
Swiss glacier collapse renews focus on risks of climate change as glaciers retreat around the world
The landslide that buried most of a Swiss village this week is focusing renewed attention on the role of global warming in glacier collapses around the world and the increasing dangers. How glaciers collapse — from the Alps and Andes to the Himalayas and Antarctica — can differ, scientists say. But in almost every instance, climate change is playing a role. In Switzerland, the mountainside gave way Wednesday near the village of Blatten, in the southern Lötschental valley, because the rock face above the Birch Glacier had become unstable when mountain permafrost melted, causing debris to fall and cover the glacier in recent years, said Martin Truffer, a physics professor at the University of Alaska Fairbanks who studies how glaciers move. While the debris insulated the glacier and slowed melting, its weight caused the ice to begin moving — which accelerated dramatically a few weeks ago. Authorities ordered the evacuation of about 300 people, as well as all livestock, from the village in recent days, 'when it became clear that there's a whole mountainside that's about to collapse,' said Truffer, who is from Switzerland. Glacial lakes pose threat Lakes that form at the base of glaciers as they melt and retreat also sometimes burst, often with catastrophic results. Water can even lift an entire glacier, allowing it to drain, said Truffer, adding that Alaska's capital of Juneau has flooded in recent years because a lake forms every year on a rapidly retreating glacier and eventually bursts. In 2022, an apartment building-sized chunk of the Marmolada glacier in Italy's Dolomite mountains detached during a summer heat wave, sending an avalanche of debris down the popular summer hiking destination, killing 11. A glacier in Tibet's Aru mountain range suddenly collapsed in 2016, killing nine people and their livestock, followed a few months later by the collapse of another glacier. There also have been collapses in Peru, including one in 2006 that caused a mini tsunami; most recently, a glacial lagoon overflowed in April, triggering a landslide that killed two. 'It's amazing sometimes how rapidly they can collapse,' said Lonnie Thompson, a glacier expert at the Ohio State University. 'The instability of these glaciers is a real and growing problem, and there are thousands and thousands of people that are at risk.' Scientists say melting glaciers will raise sea levels for decades, but the loss of inland glaciers also acutely affects those living nearby who rely on them for water for drinking water and agriculture. No way to stop the melting Scientists say greenhouse gases from the burning of fossil fuels such as coal have already locked in enough global warming to doom many of the world's glaciers — which already have retreated significantly. For example, glaciers in the Alps have lost 50% of their area since 1950, and the rate at which ice is being lost has been accelerating, with 'projections ... that all the glaciers in the Alps could be gone in this century,' Thompson said. Switzerland, which has the most glaciers of any country in Europe, saw 4% of its total glacier volume disappear in 2023, the second-biggest decline in a single year after a 6% drop in 2022. A 2023 study found that Peru has lost more than half of its glacier surface in the last six decades, and 175 glaciers disappeared due to climate change between 2016 and 2020, mostly due to the increase in the average global temperature. A study published Thursday in Science said that even if global temperatures stabilized at their current level, 40% of the world's glaciers still would be lost. But if warming were limited to 1.5 degrees Celsius (2.7 degrees Fahrenheit ) — the long-term warming limit since the late 1800s called for by the 2015 Paris climate agreement — twice as much glacier ice could be preserved than would be otherwise. Even so, many areas will become ice-free no matter what, Truffer, the University of Alaska expert. 'There's places in Alaska where we've shown that it doesn't take any more global warming,' for them to disappear, Truffer said. 'The reason some ... (still) exist is simply because it takes a certain amount of time for them to melt. But the climate is already such that they're screwed.' ___ The Associated Press' climate and environmental coverage receives financial support from multiple private foundations. AP is solely responsible for all content. Find AP's standards for working with philanthropies, a list of supporters and funded coverage areas at Tammy Webber, The Associated Press
