Swiss glaciers lose more than 5 percent of their ice in a single year

Swiss glaciers lost more than 5 percent of their ice volume in 2026, the Glacier Monitoring Network reported on 1 October. Average thickness fell by 2.5 to 4 metres. Some glacier tongues lost up to 10 metres of ice. The Rhone, Aletsch and Clariden glaciers recorded their greatest melt on record. Two smaller glaciers, Bella Tola in Valais and Griessfirn in Glarus, disappeared completely.

The figures come from the annual mass-balance report of Glacier Monitoring Switzerland, known as GLAMOS, presented with the Swiss Academy of Sciences. The authors are Matthias Huss, Andreas Bauder, Andreas Linsbauer and Martina Barandun. The report, dated 1 October 2026, covers the 2025/2026 balance year. It is the measurement series that has tracked Swiss glaciers for decades, not a model run.

Second only to 2022, and worse on some ice

The network's end-of-summer measurements on 23 reference glaciers put 2026 behind only 2022 for ice loss. The 2022 season remains the worst in the record. This year came close, and on some individual glaciers it passed that mark. Nearly 20 percent of Switzerland's glacier volume has gone in the past five years. A longer cut, 2016 to 2026, shows a 27 percent loss, against 10 percent from 1990 to 2000 and 14 percent from 2000 to 2010. The acceleration is in the measurements, not in the commentary.

The winter of 2025-2026 was among the ten least snowy on record. From May to September the country had hot, dry conditions, with heatwaves on 76 days pushing the freezing level above 4,000 metres. That is more than twice the average and a Swiss record for the length of time the freeze line sat that high. By September no snow remained even at 3,500 metres. Without a snow cover, ice absorbs sunlight directly. That is why a thin winter shows up as metres of ice gone by autumn.

The water that left the ice

From July to September the glaciers released about 2,200 billion litres of water. GLAMOS compares that volume to more than four times the annual drinking-water consumption of Swiss households. The comparison is a scale marker, not a claim that the melt entered the tap. Much of it ran into rivers that also feed hydropower, irrigation and downstream neighbours.

Huss has pointed out the sequence that follows from a shrinking ice area. Meltwater rises at first, because a large ice mass is still there to melt. It then falls, because the area left to melt is smaller. Communities that rely on glacier runoff in late summer, when rain is scarce and snow has already gone, lose that buffer once the ice is gone. The 2,200 billion litres of 2026 are, on that reading, a large withdrawal from a store that will not be refilled at the same rate.

The Great Aletsch, the longest glacier in the Alps, is the reference the network uses against older surveys. Measurements at Konkordiaplatz, the junction of the main Aletsch tributaries, are compared with the average of surveys taken between 1953 and 1983. The 2026 loss on Aletsch, Rhone and Clariden was the largest those glaciers have recorded. Aletsch is also inside the Jungfrau-Aletsch UNESCO site, so the ice loss is visible on a protected landscape as well as in the mass-balance table.

What a vanished glacier means on the ground

Bella Tola and Griessfirn are small. Their disappearance does not move the national volume figure the way Aletsch does. It does remove a named ice body from the map, and with it the late-summer trickle that a high pasture or a small intake used. GLAMOS said several smaller glaciers vanished permanently this year, not only those two. Once a glacier is gone, the rock basin it leaves does not rebuild an ice mass under the winters Switzerland is now recording.

The operational consequence sits with water managers and with the hydropower plants that book glacier melt as summer input. A year that delivers four times household drinking water from ice is a year that also brings high river temperatures, low snow reservoirs for next spring, and a smaller ice area for 2027. The network's next annual report will measure that smaller area. The 1 October release is the number those managers have to plan against: more than 5 percent of the national ice volume gone in one balance year, 2.5 to 4 metres of thickness, and two glaciers that will not appear in next year's table at all.