One might say that the United Nations' timing in proclaiming 2025 as the international year for glacier conservation was exceptional. The season of uncontrolled melting has not yet begun — the streams full of milky water rushing down the valley, the crevasses exposed to solar radiation, the freezing level shooting above the summit of Mont Blanc — and yet we have already witnessed the terrifying collapse of a glacier that buried an entire village. On 27 May, Blatten was a small municipality in the Canton of Valais, Switzerland, home to fewer than three hundred souls. The following day, it ceased to exist geographically, buried under tonnes of rock, ice and debris.

What happened

A large portion of the Birch Glacier, in whose shadow and presence the village of Blatten stood, broke away at 3:30 pm on 28 May. Fortunately, the event did not come without warning. The ice had been under close surveillance for weeks, and the worsening situation had prompted authorities to evacuate the area, fearing the worst.

In the days leading up to the collapse, the glacier had been advancing towards the valley at roughly ten metres per day as a result of a landslide dynamic that had begun in May. It is normal for glaciers to move — they do so because gravity acts on large masses of ice — but in this case the speed was exceptionally high.

The glacier's history

The flank of Kleins Nesthorn overlooking the Lötschental had been monitored by researchers for some time: for years it had given rise to collapses and flows — surface phenomena that nonetheless led to an accumulation of material on the glacier below (the Birch). From mid-May, the situation had changed, because the landslide dynamics had begun to involve the slope at depth, causing a genuine upheaval of the mountain's topography between 19 and 20 May. A volume of rock estimated at millions of cubic metres shifted dramatically, causing an entire ridge section to drop by almost a hundred metres and depositing tonnes of material onto the glacier. The pressure of the landslide on the glacier caused it to move rapidly downvalley for several days, until the catastrophic event of 28 May, when an enormous portion of it broke away and began its descent towards the valley floor.

One hazard after another

The prompt evacuation of the area at the critical moment meant that this disaster resulted in the burial of an entire village, its infrastructure, possessions and memories — but not its people. Can we breathe a sigh of relief? Unfortunately, not yet. The subject of close scrutiny now is the Lonza river, which flows (or would flow) along the valley floor. The enormous mass of debris from the collapse has blocked its course, causing the formation of a makeshift lake where Blatten once stood — a development considered highly alarming by local administrators and experts, given the risk of flooding downstream of the newly formed lake and landslide. Reports coming from the Lötschental in recent hours indicate that the river has managed to carve a path through the two kilometres of debris, and that the reservoir located along its downstream course has been emptied to accommodate the flow and prevent further damage. The situation is evolving rapidly, and with it the risk to which the valley's residents are exposed.

The glue of the Alps

In high-profile, significant cases such as this one, taking a moment to bring order to events and listen to the experts is essential — even if in our minds the connection between this disaster and climate change has by now become almost automatic.

That global warming has innumerable and substantial impacts on high-altitude terrain is undeniable: from permafrost degradation to glacier retreat, mountains are literally crumbling above our heads. Permafrost, in fact, is what might be called the "glue" of mountains — a layer formed of ice, rock and soil that maintains a temperature at or below 0°C and that literally holds together high-mountain and polar regions.

What is happening to the permafrost of the Alpine mountains in this century is described in a study published a few months ago in Nature, which reports that permafrost temperatures in European mountain regions are rising very rapidly. When permafrost degrades due to above-zero temperatures, it destabilises not only the surface: water infiltrates and penetrates into cracks and fissures that have opened up. The increased water pressure causes new fissures to open, and the water penetrates even deeper into the bedrock, in a self-reinforcing cycle that weakens the mountain from within.

The connection between climate change and landslides specifically in the Swiss Alps has been investigated and studied in depth by a team of researchers from the Institute for Climate Change Impacts and Risks in the Anthropocene in Geneva, who demonstrated that permafrost degradation contributes to slope instability and rockfall. The findings of the study, published last year in Nature, were obtained using palaeoclimatic techniques and a continuous time series of rockfall activity at Täschgufer spanning from 1920 to 2020.

The Environment @theEcoglobal

𝕏

Birch #Glacier collapsed into the #Swiss #Alpine village of Blatten. Swiss officials linked the catastrophe to accelerated glacier melt driven by #climatechange.
#Switzerland

30 mag 2025 · Apri su X →

Extreme events and long-term trends

Although the connection between slope instability and global warming is clear and scientifically demonstrated, it is also true that in the case of large-scale events — such as the one that occurred just days ago in Blatten — it is wise to exercise patience and allow experts the time to carry out the necessary analyses and account for all the variables involved (as was done in Italy following the collapse of the Marmolada glacier in July 2022).

Drawing a direct link between rising temperatures and landslides of this magnitude may indeed be premature, as there are other geological variables to consider in the equation. In particular, as explained by Daniel Farinotti and Christophe Lambiel, researchers and university lecturers specialising in the study of permafrost and glaciers, it is not yet known whether the collapse was triggered by external factors or by internal reactions within the glacier. Time, and expert analysis, will help us reconstruct with precision the causes of what happened.

How do you live on a mountain that is crumbling above your head

While we await the verdict of the "autopsy" of this disaster, the fact remains that the instability of high-altitude terrain confronts those who live there with new and complex challenges. How, then, can we avoid being caught unprepared? Satellite imagery, radar and sensors installed in the ground now make it possible to monitor ground movements along mountain slopes with great precision. When anomalies are detected, early-warning systems can be activated in time, allowing authorities to secure the affected areas. In this respect, Switzerland stands out as a leading country in monitoring the Alpine arc: its system is built on close collaboration between decision-making bodies, companies specialising in advanced detection technologies and the research community, which is continually testing and validating new tools.

Moreover, when unstable phenomena are known and under observation, it is possible to implement effective preventive measures: reinforced concrete barriers, embankments and other nature-based engineering interventions can offer protection to settlements exposed to the risk of floods or debris flows. However, where the volumes of material in motion are very large or located in areas that are difficult to access, intervention becomes complex, both technically and economically.

The hazards posed by climate change in the Alps

Climate change is introducing new risks to mountain regions, adding to those already known. The accelerated melting of glaciers and the degradation of permafrost are undermining slope stability and increasing the frequency of landslides and debris flows. Rising temperatures and shifts in precipitation patterns are encouraging the proliferation of parasites such as the bark beetle, which has been devastating forests across several Alpine regions for years. On top of these come extreme weather events set to become ever more frequent, such as violent storms and prolonged periods of drought. Faced with this rapidly evolving scenario, it becomes essential and urgent to develop adaptation and land-use planning strategies that take into account the interconnection between these phenomena, in order to guarantee the safety of mountain communities and the resilience of Alpine ecosystems — on which, in reality, we all depend.