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Orgo-Life the new way to the future Advertising by AdpathwayA catastrophic landslide on 28th May 2025 resulted in devastating damage to the village of Blatten in Switzerland. About 90% of the village was destroyed or covered with debris, resulting in a major catastrophe.
Seeing Blatten buried again and again, from every angle… Properly staggering! 😮😱
The damage is pretty catastrophic.
These are approx. 3 M m3 that collapsed from the Birch Glacier! 🧊🌊 The deposit spans 2.3 km of the Lötschental valley floor!
You can explore Blatten here:
So what happened? Was this because of climate change?
Developing Landslides
Well, we know that this event was anticipated. Which means that the 300 inhabitants of the village of Blatten were evacuated on 19th May, and the inhabitants, bar one person missing, were moved to safety. This is because a rock slope failure was developing on the mountain side of “Petit Nesthorn” (“Kleines Nesthorm”) above Birch Glacier (Birchgletscher), above the valley floor village of Blatten, and a large avalanche of rock and ice was identified as a risk.
A large landslide then occurred around or shortly before 20th May. You can view the landslide here:
Nice timelapse showing the moving rock mass of the Klein Nesthorn landslide yesterday! 😱 Source Geopraevent
This was a major instability, with a highly mobile rock mass, generating a huge volume of rock falls and rock dust as the mass deformed.
Webcam image of the deforming slope at Blatten in Switzerland, from Dave Petley’s Landslide Blog. Overloading Birch Glacier
Landslides continued over the following week, with a series of smaller rockfalls. These rockfalls largely landed on the Birch Glacier surface, which became loaded with glacier debris. Up to 81 m of debris was reported on the glacier surface. This increased the pressure at the base of the ice.
Lidar survey of Klein Nesthorn landslide 🏔️ 🚁 📷 The results acquired last friday by #HelimapSystemSA and #Terradata show that the Klein Nesthorn has lost 101 m in elevation and that 81 m of debris have accumulated on Birch Glacier ! 1/
On 26th May, the SRF reported that up to 9 million tonnes of debris was sitting on the glacier surface, also reported by ETH.
Glacier acceleration
The Birch Glacier was overloaded with rockfall debris, with the glacier accelerating to move at up to 10 metres per day by the 26th May, according to the SRF. This is a marked acceleration. Lots of cracks started to form in the ice, which is on a steep slope, a sign of the tension in the ice.
Glacier collapse on 28th May
The night of 26th May was warm, and on the 28th May at 15:30 CEST the glacier catastrophically collapsed under the weight of the rock debris that had accumulated on its surface, generating the massive landslide that impacted the village of Blatten. Essentially, the weight of the rock load on the ice surface overcame the resistive basal friction and longitudinal tension that holds the glacier onto the mountain, causing lots of cracks and catastrophic failure of the ice. The increased pressure on the ice surface may also have contributed to more ice melting under pressure at the base of the ice, reducing basal friction. Additional water input from rainfall and the mechanical action of the rockfall on the glacier may have contributed to the destabilisation of the glacier.
As the glacier was on a steep slope, the ice and rock mixture cascaded down the mountain, gathering momentum and more material as it went.
Thus this was a cascading disaster that impacted the village. Evacuating the village was a good call.
Absolutely stunning frontal views of the entire path of the #Blatten event! 😮 Numerous debris flow run through the avalanche fan! 🌊 Shot by @ABettmeralp in early afternoon 🙏
Debris is reported up to 240 m on the facing valley side, showing the dramatic power of the event.
Developing flood risk
To add to the hazard, the rock-debris and ice mixture of the landslide dammed the Lonza River, resulting in the damming of a growing lake in the valley. This is flooding the village of Blatten, but if the dam fails, could impact downstream communities. As a result, they have had to be evacuated.
See again the useful update from Melaine Le Roy:
Aerial view westward over the Blatten deposit and the newly formed lake upstream! 🧊🌊 📷Via Christian Petit/Linkedin
Solidarity to the inhabitants of Blatten who have lost their home, and I grieve for their catastrophic loss.
Was this due to climate change?
Birch Glacier collapsed, causing the devastating landslide that impacted Blatten village, because it was overloaded with debris, rather than due to climate change causing more melting. Although glacier detachments do occur as a result of warming resulting in more meltwater reaching the bed of steep mountain glaciers, the situation here is more complex.
However, mountain landslides are becoming more common in a warming climate, and so more large events like this are happening. A warming climate can lead to increased rainfall, melting permafrost and change the number of freeze-thaw cycles, and this can exacerbate landslides.
In summary, climate change can lead to large landslides and major mountain hazards like this becoming more common. Although it is simplistic to claim that this specific event occurred due to climate change at the moment, these catastrophic events are more likely in a warmer world.
Shrinking glaciers in a warming world
Climate change is causing dramatic changes in mountain glaciers in Europe, and elsewhere. Record glacier melt occurred globally in 2023, according to the WGMS, and Sweden showed the highest melt levels in 80 years of observations. In 2024, the melt from glaciers was again very high. At least one third of European Alps glacier loss will be lost by 2050, even without further warming, and if current emissions continue, two thirds of glacier ice will be lost. The rapidly changing cryosphere, and mountains above mountain glaciers, may result in rapid changes in mountain hazards.
More details and data are available in the 2024 State of the Cryosphere report: https://iccinet.org/statecryo24/
This ongoing glacier recession, firmly attributed to climate change due to increased temperatures driving more glacier melt, had already resulted in the along-flow disconnection between the lower and upper parts of the Birch Glacier. The glacier became disconnected, or separated, in ~2000 AD, and the lower glacier started to advance by about 50 m since 2019, and the ice velocity and terminus thickness increased. This is likely due to the periodic input of the rockfall from above, insulating the glacier from melting and increasing the mass of the glacier through adding rock material. The separation of the glacier may have made it more susceptible to catastrophic detachment, by removing the longitudinal stresses that can support steep mountain glaciers.
This anomalous behaviour, associated with glacier shrinkage, meant that the Birch Glacier was preconditioned to be hazardous, and regularly monitored.
Furthermore, a warmer climate can also increase glacier detachments by encouraging more surface and basal melt in steep mountain glaciers, which can result in catastrophic glacier detachments. More basal meltwater means more lubrication and reduced basal friction.
In summary, climate change likely contributed to a number of factors that preconditioned the glacier to collapse, and made the large scale rock slope failure more likely. However, attributing the specific incidence of the rock fall onto the glacier surface and the resulting ice-rock avalanche down valley, is simplistic.
Further reading:
Dave Petley’s Landslide Blog: excellent, informative and vital source of information.
Big thanks to Melaine Le Roy for daily informative updates! Follow him on Bluesky.
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