Swiss glaciers have suffered a near-record loss of ice in 2026, new data shows, as intense summer heatwaves take their toll on Alpine peaks.
More than 5% of the country's remaining glacier ice has disappeared in the last 12 months, which scientists say is "extraordinary".
They warn that such rapid melting is no longer a surprise given the pace of climate change, but it could threaten water supplies for farming, hydropower and transport in the decades ahead.
The loss of glacier ice can also destabilise mountain slopes and increase the risk of landslides in some places – which can lead to flash flooding in extreme cases, as seen in Nepal in August.
There were multiple factors involved in that event, which was triggered when a large area of bedrock and glacier ice collapsed.
But scientists say long-term glacier thinning and the thawing of frozen ground likely raised the risks.
The notable finding from this latest report is not so much that Swiss glaciers are shrinking – which is to be expected in our warming climate, driven primarily by fossil fuel emissions – but the sheer pace of melting.
Until recently, glaciologists in the Alps considered 2% of ice lost in a single year to be "extreme". This year has seen an estimated 5.5% disappear.
"It's really just disastrous," said Dr Matthias Huss, director of Glacier Monitoring Switzerland, which produced the report.
Swiss glaciers started the summer in an already difficult place, covered by less snow than usual after a mild winter.
And much of that snow disappeared quickly in the early and intense heatwaves of May and June, exposing the glacier ice below.
Bare ice is darker and less reflective than fresh snow, so absorbs more of the Sun's energy.
That left glaciers vulnerable to melting even faster in subsequent heatwaves.
"Ten years ago, I wouldn't have thought that it's possible to lose glaciers so quickly," said Dr Fabien Maussion, a glaciologist at the University of Bristol, who was not involved in the Swiss report.
"What's happened over the summer now is extremely distressing… but at the same time it was to be expected from a climate scientist's perspective," he added.
Meltwater from glaciers can be an important source of water for irrigation, hydropower and even shipping traffic during hot, dry conditions.
Scientists estimate that Swiss glaciers released 2.2 trillion litres of meltwater between July and September.
Although that helped to ease water shortages this summer, it has rapidly diminished the frozen supply.
The loss of ice could pose long-term challenges, Huss warned, with smaller glaciers unable to top up water levels to the same extent.
"Every drop of water that runs off during these heatwaves is kind of old water that's been stocked in the glacier ice centuries or decades ago," said Huss.
"It's helping us [now] but it's unsustainable, so we won't have it at [our] disposal in the next heatwave."
The River Rhine reached record lows in places this summer, affecting shipping navigation routes and increasing transport costs.
One of the most ominous findings is what researchers observed at measurement sites at the highest elevations, where temperatures are lowest and glaciers are typically snow-covered.
Even as high as 3,500 metres above sea level, scientists found no snow remaining at the end of summer.
"At some glaciers we've seen four metres of ice loss at the highest point, where they should be covered by several metres of winter snow at this time of the year," said Huss, from Glacier Monitoring Switzerland.
Snow is like glacier food – and under stable conditions some of it would eventually compact into ice.
But if no snow survives the summer, it cannot replace the ice lost to melting at lower, warmer elevations. The glacier will starve, shrink and eventually disappear.
"Glaciers are complex because they gain mass at the top and they flow downstream, so there is a lot of physics," explained Maussion.
"But in its simplest form, what we see right now is that we took an ice cube out of the fridge and it's just melting in front of our eyes."
Scientists say the climate is now too warm for many Alpine glaciers to survive.
Some, like Plattalva in eastern Switzerland, have already disappeared.
But researchers stress that sharp cuts to carbon emissions can still save much of the world's glacier ice.
This is particularly the case for the Himalayas and the polar regions, where most of the planet's ice resides.
"There we still can make a big difference with protecting the climate," said Huss.
"If these ice masses can be saved or stabilised, we can limit the rise of global sea levels… which could affect billions of people living along the coast."
Additional reporting by Dominic Bailey
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Source: BBC News
