Swiss glaciers lose record 5% of ice in 2026, threatening water supplies

The Swiss Alps are melting faster than glaciologists thought possible. In the twelve months ending this summer, the country's glaciers shed more than 5% of their remaining ice—a loss so steep that scientists who study these mountains are calling it extraordinary, even as they insist it should no longer surprise anyone paying attention to the climate.

Until recently, losing 2% of glacier ice in a single year was considered extreme. This year, Swiss glaciers disappeared at a rate of 5.5%. "It's really just disastrous," said Matthias Huss, who directs Glacier Monitoring Switzerland, the organization that produced the data. A glaciologist at the University of Bristol, Fabien Maussion, put it differently: ten years ago, he would not have believed such rapid loss was possible. Yet from a climate scientist's perspective, he added, it was entirely to be expected.

The mechanics were straightforward and brutal. Swiss glaciers entered the summer already weakened, blanketed by less snow than usual after a mild winter. Then came the heatwaves—intense ones in May and June—that stripped away what little snow remained, exposing the darker ice beneath. Bare ice absorbs far more of the sun's energy than fresh snow does. The glaciers, now vulnerable, melted faster still when subsequent heatwaves arrived. At the highest elevations, where temperatures are coldest and glaciers should remain snow-covered year-round, researchers found no snow surviving to the end of summer—even at 3,500 metres above sea level. At some sites, four metres of ice vanished where several metres of winter snow should have accumulated.

The immediate consequence was a torrent of meltwater. Between July and September, Swiss glaciers released an estimated 2.2 trillion litres into the water system. This helped ease water shortages during the hot, dry months. The River Rhine, which depends partly on glacier melt, reached record lows in places, disrupting shipping routes and raising transport costs. But the relief was temporary and came at a cost that will compound over time. Every litre of water flowing off during a heatwave, Huss explained, is ancient water—stored in glacier ice for centuries or decades. "It's helping us now but it's unsustainable, so we won't have it at our disposal in the next heatwave."

The long-term threat extends beyond water supply. Smaller glaciers, unable to replenish themselves at the same rate, will struggle to top up water reserves in future droughts. Destabilized mountain slopes pose another danger: as glaciers thin and frozen ground thaws, the risk of landslides increases, potentially triggering flash floods. Nepal experienced this in August when a large area of bedrock and glacier ice collapsed, though scientists note that long-term glacier thinning and thawing ground likely raised the risks rather than caused the event outright.

Some Alpine glaciers have already vanished entirely. Plattalva, in eastern Switzerland, is gone. The physics is simple, Maussion said: "We took an ice cube out of the fridge and it's just melting in front of our eyes." Snow is what glaciers need to survive—it compacts into ice and replaces what melts away at lower elevations. If no snow survives the summer, the glacier starves. It shrinks. It disappears.

Yet the picture is not entirely without hope. Scientists emphasize that sharp cuts to carbon emissions could still preserve much of the world's remaining glacier ice, particularly in the Himalayas and polar regions where most of the planet's frozen water resides. Huss stressed that protecting the climate in these regions could still make a meaningful difference. If those ice masses can be saved or stabilized, global sea levels could be limited—a consequence that would affect billions of people living along coasts. The question now is whether the world will act with the urgency the data demands.