Glacial melting in Switzerland was once again enormous in 2025. A winter with low snow depth combined with heat waves in June and August led to a loss of three per cent of the glacier volume. This is the fourth largest level of shrinkage since measurements began. Consequently, the ice mass reduced by one quarter in the last ten years. This was reported by GLAMOS, the glacier monitoring network in Switzerland, and the Swiss Commission for Cryosphere observation (SCC), in which the WSL Institute for Snow and Avalanche Research SLF is also represented.
Even the United Nations International Year of Glaciers' Preservation has seen further massive melting of glaciers in Switzerland. A winter with little snow was followed by heat waves in June 2025 that saw glaciers nearing the record levels of losses of 2022. Snow reserves from the winter were already depleted in the first half of July, and the ice masses began to melt earlier than had rarely ever been recorded. The cool weather in July provided some relief and prevented an even worse outcome. Nevertheless, almost a further three per cent of the ice volume was lost across Switzerland this year, and this is the fourth greatest shrinkage after the years 2022, 2023 and 2003. 2025 therefore importantly contributed to the decade with the most rapid ice loss. Glaciers all over Switzerland have lost a quarter of their volume since 2015. Over 1,000 small glaciers have already disappeared.
In particular, glaciers below 3,000 m above sea level have suffered considerably in 2025. Snow from the winter disappeared there up to the summit level. As a consequence, the ice thickness on, for example, the Claridenfirn (Canton of Glarus), the Plaine Morte Glacier (Canton of Bern) and the Silvretta Glacier (Canton of the Grisons) reduced by over two metres. For glaciers in the southern Canton of Valais, such as the Allalin Glacier or Findel Glacier, the loss was less at around one metre.
Too little snow in winter ¶
In the winter of 2024/2025, the combination of less precipitation and the third warmest six months of winter (October to March) since measurements began led to very low snow depths, as shown by measurements taken by the WSL Institute for Snow and Avalanche Research SLF. For example, less fresh snow fell in parts of the northern and central Grisons than ever before. For this reason, around 13 per cent less snow was evident on the glaciers at the end of April when compared to the period from 2010 to 2020. The second warmest June since records began led to rapid melting of snow right up to the highest altitudes. Following a somewhat cool and damp July, August brought a heatwave with a high zero-degree line recorded in part at over 5,000 metres. In combination, this weather led to above-average temperatures in the summer. Between July and September, a few cold fronts resulted to individual days with fresh snow over 2,500 m above sea level, but this only remained for longer periods in high mountains.
"The continuous diminishing of glaciers also contributes to the destabilising of mountains," says Matthias Huss, Director of GLAMOS. "This can lead to events such as in the Lötschental valley where an avalanche of rock and ice buried the village of Blatten."
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The Claridenfirn (GL) was completely free of snow in September 2025. (Photo: M. Huss)
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Glaciologists on the Great Aletsch Glacier (VS). This year, snow from the winter remained in the upper part of the glacier. However, the shaded tongue has once again melted significantly. (Photo: R. Moser)
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Ice loss at Konkordiaplatz, Great Aletsch Glacier (VS), between 2022 and 2025 compared with the average measurements between 1953 and 1983. (Photo: M. Huss)
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The ice cave at the Vadret da Morteratsch (GR) is enormous, but unstable due to collapsing ice blocks. (Photo: L. Hösli)
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Drilling of a stake to determine the mass balance on the Glatscher da Medel (GR). (Photo: L. Hösli)
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Installation of a stake to determine the mass balance in the upper part of the Glatscher da Medel (GR). (Photo: L. Hösli)
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In southern Valais, as here at the Findel Glacier near Zermatt, winter snow remained above about 3300 metres, allowing the high-altitude glaciers to form some new ice. (Photo: M. Huss)
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The Gries Glacier (VS) once again suffered greatly in 2025. The glacier tongue is collapsing in on itself. (Photo: M. Huss)
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By the end of June 2025, many glacier tongues were already snow-free, as here at the Vadret da Morteratsch (GR), and ice melt began exceptionally early. (Photo: M. Huss)
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In various places in the Alps, impressive ice caves have formed within the glaciers. (Photo: M. Huss)
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Ice caves display fascinating colours, but they are a sign of internal decay processes in the glaciers and are often at high risk of collapse. (Photo: M. Huss)
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The former glacier at the Diavolezza (GR) disappeared completely about 15 years ago. It is now the only Swiss “glacier” preserved for skiing solely thanks to snow farming and covering, in an artificial form. (Photo: A. Linsbauer)
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Countless small glaciers are vanishing. At Lai Verd, near the Lukmanier Pass (GR), only a tiny remnant of what was once a sizeable glacier remains, which still reached the lake in the 1990s. (Photo: L. Hösli)
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The torn and bulging tongue of the Birch Glacier (VS), a few months before the rock–ice avalanche that buried Blatten. (Photo: L. Hösli)
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The measurement stake on the Claridenfirn (GL) has been maintained in the same place for 111 years – a record length of observations unrivalled anywhere in the world. Because of abundant snowfall, the site was almost always within the glacier’s accumulation zone. Significant losses occurred only in 2022, 2023 and 2025. (Photo: M. Huss)
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The lake in front of the Rhone Glacier (VS) is expanding rapidly due to retreat. (Photo: M. Huss)
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Operation of the artificial ice grotto at the Rhone Glacier (VS) had to be abandoned this summer: the ice block, protected with covers and long since detached from the glacier, became too small. (Photo: M. Huss)
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Drilling of a stake to determine the mass balance on the Vadret dal Murtèl. (Photo: M. Huss)
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Measuring installation to determine snow depth and melt in real time beneath Piz Palü on the Vadret Pers (GR). (Photo: A. Linsbauer)
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Retreat of the Gries Glacier (VS) between 1919 and 2025. (Photo: swisstopo / VAW-ETH Zurich)
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Disappearance of the Pizol Glacier (SG) between 2006 and 2025. (Photo: M. Huss)
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Retreat of the tongue of the Rhone Glacier (VS) between 2022 and 2025. (Photo: enlaps / VAW-ETH Zurich)
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Disappearance of the Vadret da Triazza (GR) between 1936 and 2025. (Photo: swisstopo / VAW-ETH Zurich)
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Landscape changes between 1927 and 2025 in the Lötschental following the collapse of the Birch Glacier (VS). (Photo: swisstopo / VAW-ETH Zurich)
The Swiss Commission for Cryosphere observation (SCC) ¶
The Swiss Commission for Cryosphere observation (SCC) of the Swiss Academy of Sciences (SCNAT) documents changes in the Alpine cryosphere. It coordinates the long-term Swiss monitoring networks created for snow, glaciers (GLAMOS) and permafrost (PERMOS). The Swiss Commission for Cryosphere observation (SCC) therefore represents those institutions that look after national monitoring networks, such as the Swiss Federal Institute for Forest, Snow and Landscape Research WSL, the WSL Institute for Snow and Avalanche Research SLF, the Swiss Federal Office for Meteorology and Climatology (MeteoSchweiz), the Swiss Federal Institute of Technology in Zurich (ETH Zurich), the Universities of Zurich, Fribourg and Lausanne and the University of Applied Sciences and Arts of Southern Switzerland (SUPSI), or who contribute financially to long-term safeguarding, such as the Swiss Federal Office for the Environment (FOEN), the Swiss Federal Office for Meteorology and Climatology (MeteoSwiss), in the context of the Swiss Global Climate Observing System (GCOS), the Swiss Academy of Sciences (SCNAT) and the Swiss Federal Office of Topography (swisstopo).
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