Swiss glaciers lost an estimated 5.5% of their remaining ice over the past year, a near-record decline that scientists describe as disastrous. The unusually rapid melting, driven by intense heatwaves and a mild winter with little snow, is a sign of the pace of climate change and could put future water supplies at risk.

Glaciers released about 2.2 trillion litres of meltwater between July and September, easing shortages this summer but drawing down water stored over decades or centuries. Even at 3,500 metres, researchers found no snow left at the end of summer, leaving little to replace melting ice; the Rhine also reached record low levels in places, disrupting shipping. Continued glacier loss could affect farming, hydropower and transport, while thinning ice and thawing ground can make mountain slopes less stable.