French ski resorts are being forced to spend millions reinforcing cable car supports and other structures being weakened by subsidence as climate change causes ice to melt. Chamonix has spent £1.3 million shoring up cable car supports this year. Les Deux Alpes and Val-Thorens have also had to reinforce structures in danger of collapse because they are built on permafrost — layers of ground under the surface that remain permanently frozen, which are shrinking at an increasingly rapid rate. Concern is growing for the future of France’s lucrative ski industry and resorts facing shrinking glaciers and diminishing snow cover are struggling to preserve the fragile Alpine environment from the consequences of pollution. Climate change has caused permafrost to thaw in recent years so that it can no longer serve as a natural cement. Cable car supports and foundations of mountain shelters have started moving and structures above the ground have begun to weaken and crack. Chamonix has been forced to shore up its Bochard cable car supports by consolidating the ground to compensate for thawing and rebuilding stronger foundations. The supports have been fitted with detectors to warn of subsidence or movement. Thibauld Guyon, the resort manager, said: “With the permafrost deterioriating, rocks were destabilised and the structure was being pulled downwards little by little.” Pierre-Allain Duvillard, a scientist specialising in high altitude structures, said other resorts had also been affected since 2010. “Les Deux Alpes had subsidence under a cable car terminal and Val-Thorens had to consolidate a ski lift pylon.” A recent survey of 947 resort structures built on permafrost found that 45 ski lifts, six shelters and one tunnel were at high risk of “destabilisation”. Ludovic Ravanel, another scientist, said the future of the ski industry was “worrying”. “If we experience an average temperature rise of 4 degrees Celsius by the end of the century, that will mean an 8-degree rise in the Alps,” because of the warming effect of melting glaciers. Chamonix is now lobbying the authorities to restrict the number of cars allowed into the Chamonix Valley in an effort to cut pollution. Éric Fournier, the mayor, warned: “Mountainsides are collapsing.”