“glue” that holds mountains together. Higher temperatures mean more landslides and rockfalls, as meltwater penetrates the permafrost and accelerates erosion. Another growing problem: heavy rainfall Climate change has also amplified other natural threats. Apart from drought, the Alps have seen a proliferation of heavy rainfall events. Warmer air can hold more moisture. Due to the topography, major concentrated downpours in the mountain valleys can have fatal consequences. A storm in the upper Maggia Valley in Ticino caused flash flooding in summer 2024. Raging torrents obliterated houses, roads and bridges, claiming the lives of eight people. Officials subsequently expanded the area in the valley that it regarded as risk-prone, meaning that a number of houses near water are now classed as unsafe and had to be vacated. 90 residents had to evacuate their homes in November 2024. With the threat of a huge landslide literally hanging over it, Brienz-Brinzaul has remained off-limits since then. Rockfalls proliferated again this summer after heavy rainfall, although the situation had become a little less acute by the time of our editorial deadline in mid-August. Brienz-Brinzaul will not be vacated for good, the authorities insist. The construction of a drainage tunnel costing 40 million francs is meant to mitigate the risk of landslides. Nevertheless, the villagers are aware that they may yet have to resettle. The Bernese Oberland also has its fair share of crumbling mountains. Landslides have been a topic in Guttannen since 2005 (see “Swiss Review” 4/2022), while officials have been closely monitoring Spitzer Stein, an increasingly unstable peak above Kandersteg, for a number of years. Permafrost thaw has weakened one side of Spitzer Stein, raising concerns that millions of cubic metres of rock could come tumbling down and cause flooding. Dams are currently being built to protect Kandersteg. These will cost 11 million francs. In general, scientists warn of further deterioration in the Swiss Alps. Permafrost temperatures monitored at over 20 sites by the Swiss Permafrost Monitoring Network (PERMOS) have increased significantly in recent years. Permafrost is commonly found above altitudes of 2,500 metres, acting as the Other cantons are also reviewing their hazard maps and investing a great deal of money in dams to prevent flooding and in netting to intercept rockfalls. In total, Switzerland spends around one billion francs a year on shoring up its defences against natural hazards. This includes investing in early-warning systems that save lives by ensuring that communities are evacuated in time. ETH climate scientist Sonia Seneviratne, who is vice-chair of Working Group I of the Intergovernmental Panel on Climate Change (IPCC), believes in the importance of prevention. “But these are no more than sticking-plaster measures in the long run,” Seneviratne told the “Watson” news portal in an interview. We need to be asking a different question: “Should we really be living and building more houses in increasingly exposed areas?” Global warming will further increase the risk of rockfalls, landslides and mudslides in the Alps. It is imperative that we take this into account, stressed Seneviratne. “Unless we dramatically cut carbon emissions and get a handle on climate change, future tragedies are almost inevitable.” Top: In Bondo (Grisons), authorities have invested 50 million Swiss francs in protective structures, including a dam and a catch basin. In 2017, the village was razed by a mudslide. Right: Heavy rainfall in southern Switzerland caused widespread destruction in the summer of 2024. The picture shows a section of the A13 near Lostallo in the Misox Valley that was washed away. Below: In the Grisons village of Brienz, the hillside continues to slide. Whether those evacuated from their homes will be able to return is uncertain. Photos: Keystone Swiss Review / October 2025 / No.4 7
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