In May 2025, a massive glacier collapse destroyed the village of Blatten in the Swiss Alps, but careful monitoring allowed the evacuation of nearly all residents. One man who refused to leave was killed in the disaster. The event highlights growing risks to mountain communities amid climate change.
The disaster in Blatten began with early warnings that saved most lives. On 14 May 2025, an official observer for Switzerland’s snow avalanche warning service spotted a small rockfall above the village. These observers, who hold full-time jobs in the area, are trained to monitor slopes.
Images from a camera, installed on the glacier after avalanches in the 1990s, revealed changes on the mountain ridge. “In those photos, they could see changes on the ridge on the mountain,” said Mylène Jacquemart at ETH Zurich in Switzerland. This prompted further investigations confirming a major landslide risk.
Evacuations followed on 18 and 19 May, with 300 people leaving the village. Only a 64-year-old man stayed behind. On 28 May, a large section of the mountain collapsed, described by Jacquemart as “a really, really large rock avalanche on its own.” The glacier, already burdened by rubble from prior rockfalls, gave way entirely. Around 3 million cubic metres of ice and 6 million cubic metres of rock surged into the valley, demolishing most of Blatten and killing the remaining resident.
Switzerland’s response relied not on advanced technology but on clear communication channels. “There was not some fancy alarm system, you know, in someone’s office, a little red light [that] started blinking, saying, hey, there’s an issue there,” Jacquemart explained. Observers knew whom to contact for evacuation decisions.
Global warming contributes to such events by thawing permafrost and allowing water to infiltrate cracks, expanding as it freezes and destabilizing rocks. Switzerland is now nearly 3°C warmer than pre-industrial levels on average. “We see a pretty close connection with climate change and rock failures, or rockfall,” Jacquemart noted, though she cautioned that the slope’s instability might stem from adjustments since the last ice age ended 10,000 years ago.
Rebuilding Blatten on the unstable debris is impossible, and plans to relocate nearby face challenges from landslide risks and high costs for protective measures. “Mountain communities around the world, from the Alps to the Andes and the Himalayas, are threatened by increasing intensity and frequency of mountain-related hazards,” said Kamal Kishore, head of the UN Office for Disaster Risk Reduction. “Their lives, ways of life, culture, and heritage are all threatened.”
