Footage of the May 28 collapse showed a huge cloud of ice and rubble hurtling down the mountainside, into the hamlet of Blatten.
Ali Neumann, disaster risk reduction advisor to the Swiss Development Cooperation, noted that while the role of climate change in the specific case of Blatten "still needs to be investigated", the wider impacts were clear on the cryosphere -- the part of the world covered by frozen water.
"Climate change and its impact on the cryosphere will have growing repercussions on human societies that live near glaciers, near the cryosphere, and depend on glaciers somehow and live with them," he said.
The barrage largely destroyed Blatten, but the evacuation of its 300 residents last week averted mass casualties, although one person remains missing.
"It also showed that with the right skills and observation and management of an emergency, you can significantly reduce the magnitude of this type of disaster," Neumann said at an international UN-backed glacier conference in Tajikistan.
Stefan Uhlenbrook, Director for Hydrology, Water and Cryosphere at the World Meteorological Organisation (WMO), said it showed the need for vulnerable regions like the Himalayas and other parts of Asia to prepare.
"From monitoring, to data sharing, to numerical simulation models, to hazard assessment and to communicating that, the whole chain needs to be strengthened," Uhlenbrook said.
"But in many Asian countries, this is weak, the data is not sufficiently connected."
- 'Not enough' -
Swiss geologists use various methods, including sensors and satellite images, to monitor their glaciers.
Asia was the world's most disaster-hit region from climate and weather hazards in 2023, the United Nations said last year, with floods and storms the chief cause of casualties and economic losses.
But many Asian nations, particularly in the Himalayas, lack the resources to monitor their vast glaciers to the same degree as the Swiss.
According to a 2024 UN Office for Disaster Risk Reduction report, two-thirds of countries in the Asia and Pacific region have early warning systems.
But the least developed countries, many of whom are in the frontlines of climate change, have the worst coverage.
"Monitoring is not absent, but it is not enough," said geologist Sudan Bikash Maharjan of the Nepal-based International Centre for Integrated Mountain Development (ICIMOD).
"Our terrains and climatic conditions are challenging, but also we lack that level of resources for intensive data generation."
That gap is reflected in the number of disaster-related fatalities for each event.
While the average number of fatalities per disaster was 189 globally, in Asia and the Pacific it was much higher at 338, according to the Belgium-based Centre for Research on the Epidemiology of Disasters' Emergency Events Database.
Geoscientist Jakob Steiner, who works in climate adaptation in Nepal and Bhutan, said it is not as simple as just exporting the Swiss technological solutions.
"These are complex disasters, working together with the communities is actually just as, if not much more, important," he said.
- 'Sad disparity' -
Himalayan glaciers, providing critical water to nearly two billion people, are melting faster than ever before due to climate change, exposing communities to unpredictable and costly disasters, scientists warn.
Hundreds of lakes formed from glacial meltwater have appeared in recent decades. They can be deadly when they burst and rush down the valley.
The softening of permafrost increases the chances of landslides.
Declan Magee, from the Asian Development Bank's Climate Change and Sustainable Development Department, said that monitoring and early warnings alone are not enough.
"We have to think... about where we build, where people build infrastructure and homes, and how we can decrease their vulnerability if it is exposed", he said.
Nepali climate activist and filmmaker Tashi Lhazom described how the village of Til, near to her home, was devastated by a landslide earlier in May.
The 21 families escaped -- but only just.
"In Switzerland they were evacuated days before, here we did not even get seconds," said Lhazom.
"The disparity makes me sad but also angry. This has to change."
How Switzerland's Birch glacier collapsed
Geneva (AFP) May 30, 2025 -
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."
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