Just one week after a major landslide enveloped the Swiss town of Blatten, researchers at ETH Zurich have already given their insight as to what caused the catastrophe. Experts at the university concluded that climate change likely had its part to play in boosting the destructive power of the slide.
The incident itself began on May 14, 2025, when the first signs of instability were spotted high in the mountains. Rocks from the Kleiner Nesthorn had fallen onto the flank of the Birch Glacier, triggering the first small avalanche above the town of Blatten.
Between May 17 and 19, all residents of the town of Blatten were evacuated as parts of the mountain had already slid 17 metres in three days. A major collapse soon occurred on May 19 and 20, when 1,5 million cubic metres of rock slid down the Kleiner Nesthorn and settled on the glacier. By May 27, nine million tons of debris had collected on the glacier’s icy surface.
The situation came to a head on May 28, when a large section of the Birch Glacier gave way under the weight and pressure of the rockfalls. Debris and ice buried 90 percent of the town of Blatten, with ice forming a large lake where homes once stood.
Further rockslides in the region remain likely, while there is a risk of flooding along the River Lonza. Though everyone was evacuated, a farmer is missing after he was spotted checking his flock of sheep 300 metres outside the evacuation zone. The emergency services have confirmed that a search is still underway.
In a fact sheet on the collapse, ETH Zurich noted that the Blatten landslide is a “remarkable” and “historic” event. “The sheer scale, the amount of material that was moved there, is something you don't see every day, every year, or every decade in Switzerland,” glaciologist Daniel Farinotti noted.
They went on to argue that the Birch Glacier has been unstable since a snow and ice avalanche in 1993. However, “human-induced climate change” also “played a role in this event”. Last year, for example, Switzerland saw temperatures 2,9 degrees above the pre-industrial average.
“This event could certainly have occurred without climate change…Establishing a direct link between individual events and climate change is very difficult, if not impossible. But rising global temperatures are indeed leading to drastic changes in high mountain regions," the paper wrote.
They added that climate change is stripping Alpine regions of permafrost. This, they explained, acts “like glue”, which can hold rock formations together. When this thaws during periods of high temperatures, these rocks can separate and fall, causing major landslides.
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