San Francisco Frontiers - Scorching summer triggers record rockfalls in Alps, scientist says

This year "will undoubtedly be a record year" both in terms of the frequency of rockfalls and the sheer volume of rock breaking away from the mountains on an almost daily basis, the research director at CNRS, France's national scientific research centre, told AFP.

The area around Mont Blanc -- nicknamed the "roof of Europe" -- has been particularly hard hit.

At the end of a summer punctuated by extreme heatwaves, the number of rockfalls recorded in the Mont Blanc massif alone is expected to reach 450, Ravanel said.

"That is an absolutely staggering figure, given that just 10 or 20 years ago, there were only a few dozen," the geomorphologist added.

The previous record stood at 300 and was set in 2022, another year marked by heatwaves.

"A large majority (of the rockfalls) can be attributed to the climate crisis," Ravanel said, noting that rising temperatures are degrading and reducing the permafrost.

For several thousand years, "invisible" ice has been lodged in cracks in the rock, where it "acts as a kind of cement holding the mountains together", he said.

With high temperatures, the ice can melt and rocks break loose, causing rockfalls.

Rockfalls are also caused as glaciers melt, when the stabilising pressure they exert on rock walls eases as the glaciers "lose thickness", he added.

Temperatures are expected to drop at high altitudes in coming days.

However, it doesn't mean the return of stability, as "even if the surface freezes over again, the enormous amount of heat from the summer of 2026 will continue to penetrate the ground until November, December, or even as late as January", Ravanel said.

"We're expecting the biggest rockfalls to happen this autumn," Ravanel predicted, though they are likely to be less frequent.

- Precautions -

The rock destabilisation poses risks to mountaineers, and several climbers have died since the start of the summer season.

In July, two Czech tourists were killed in a rockfall on the most commonly used route up Mont Blanc. In August, a 31-year-old man also died in a rockfall in the Mont Blanc massif.

Authorities closed two shelters used to climb Mont Blanc, a precaution also taken in 2022.

But Ravanel doesn't believe access to the high mountains should be completely restricted, describing them as "above all, a place of freedom".

"The mountaineering community regulates itself" and "does not put itself at greater risk during a heatwave than during a cooler summer", he said.

In his view, there is therefore "no surge in accidents" caused by rockfalls.

Rather, the increase in accidents reflects the growing popularity of mountain resorts and villages among holidaymakers, leading to higher visitor numbers overall.

L.Nguyen--SFF