Alpine communities face uncertain future after 2025 glacier collapse

In May, the village of Blatten in the Swiss Alps was destroyed by the collapse of a huge piece of glacier, but thanks to careful monitoring, almost all its inhabitants were saved.

The first signs of impending disaster appeared on May 14, when official observer The Swiss Avalanche Warning Service reported a small rockfall over the village. These spotters have other full-time jobs in the area, but are trained to monitor the slopes.

The service then examined images from a camera installed on a glacier above the village after avalanches in the 1990s. “In these photographs they could see changes on the ridge of the mountain,” says Mylene Jacquemart at ETH Zurich in Switzerland. “It just so happened that the camera was looking at him from a very useful angle.”

This led to further investigation, which showed the potential for a major landslide. On May 18 and 19, 300 people were evacuated from the village, while only one 64-year-old man refused to leave.

On May 28, most of the mountain above the glacier collapsed. “It’s a really, really big rock avalanche in itself,” Jacquemart says.

The glacier was already covered in large amounts of debris from small rockfalls in the previous months and years. When it was hit by a rockfall, the entire lower part collapsed, causing 3 million cubic meters of ice and 6 million cubic meters of rock to fall into the valley and destroy much of the village. The man who refused to leave was killed.

According to Jacquemart, many media reports suggest that there was some kind of high-tech monitoring of the glacier, but this is not the case. “There wasn't some fancy alarm system, you know, there's a little red light in somebody's office [that] started blinking and saying, “Hey, there’s a problem here.”

But what the Swiss system does have are clear lines of communication and responsibility, she says. Starting with the observers, people know who to talk to and who makes the decision to evacuate or not.

So what caused this disaster? Icefall risk decreases as alpine glaciers are shrinking, but there is no doubt that global warming is increasing the frequency of rockfalls. The upper parts of the mountains are usually permanently frozen, and the ice seals any cracks and crevices.

Because these regions are warm – Switzerland is now on average almost 3°C ​​warmer than in pre-industrial times – permafrost sometimes melts and water often falls as rain rather than snow. This means that cracks can fill with liquid water, which expands when it freezes, tearing the rocks apart.

“We see a pretty strong connection with climate change and rock falls or rockfalls,” Jacquemart says. “There are dramatic changes happening in the highlands, and as far as I can tell, they are all bad.”

But she is cautious about blaming recent warming for events on the scale of Blatten's disaster. It's possible that warming is the main cause, since the last ice age ended about 10,000 years ago, she says. “It is possible that this slope is adapting to its ice-free conditions compared to the last ice age, and this adaptation is very slow and ultimately leads to failure.”

What will happen next to the residents of Blatten is also unclear. The village cannot be rebuilt on the unstable rubble – a mixture of rock and ice – but local authorities have already said so. plans to rebuild nearby. However, this area is also at risk of landslides, and the construction of protective structures is extremely expensive.

“Mountain communities around the world, from the Alps to the Andes and the Himalayas, are under threat due to the increasing intensity and frequency of mountain-related hazards,” Kamal KishoreHead of the UN Office for Disaster Risk Reduction, said in a statement after the disaster. “Their lives, way of life, culture and heritage are under threat.”