Scientists report that climate change is producing conditions that can weaken high-altitude rock and ice, raising the risk of disasters such as this week’s Himalayan flood along the Nepal–China (Tibet) border, which claimed 547 lives.
At least 800 foreign nationals are among the nearly 1,500 people reported missing, authorities said on Thursday, one day after a huge mass of mud and rock crashed into a Himalayan river, unleashing devastating floods across nearby towns and valleys.
"Climate change is generating conditions that can destabilise high-mountain rock and ice," said Simon Cox, chief scientist at the Mountains to Sea programme at Earth Sciences New Zealand.
He added that this, in turn, increases the likelihood of collapses and cascading hazards of the sort witnessed this week.
Although the precise cause of Wednesday’s catastrophe is still under investigation, scientists believe it likely started with a huge ice and rock avalanche cascading down the northern slopes of Nepal’s Langtang Lirung peak into the Lhende Khola river on the Tibetan side.
A cross-border sequence of hazards set off by the initial collapse damaged at least six major hydropower plants and infrastructure at the Gyirong Port trade hub.
It also reshaped river channels over 100 km (62 miles) downstream, close to the Indian border.
Although specialists warn against identifying climate change as the single, direct cause of Wednesday’s collapse, they acknowledge that increasing temperatures and retreating glaciers likely contributed to the catastrophe.
Warming can reduce ice support on steep slopes, boost meltwater, and change patterns of freezing, thawing and rainfall, which can weaken mountainsides and make large collapses more likely in some spots, Cox added.
Comparable devastating upswings have shaken the region in recent years, though on a lesser scale.
These events span from a 2025 flood in Gyirong on the Tibet–Nepal border to a glacial lake outburst in the Sherpa village of Thame in 2024, which followed a similar incident in India’s northeastern state of Sikkim in 2023.
Across the Hindu Kush mountain range, floods, landslides, avalanches, and droughts are occurring more often and with greater intensity.
The Nepal-based International Centre for Integrated Mountain Development warns that the rapid transformations affecting water, land, and air present a significant danger to people living in the region.
Increasing temperatures in mountain regions are making the cryosphere—the ice-covered portions of the Earth’s surface—significantly more vulnerable than before, said Farooq Azam, senior cryosphere specialist at ICIMOD.
He stated that he believed substantial snowmelt, combined with seismic activity, likely set off the initial rock and ice slide that led to Wednesday’s downstream flash flood.
The long-term pattern is striking, with the United Nations reporting in 2023 that global warming has led Nepal’s snow-covered mountains to lose nearly one-third of their ice over a little more than three decades.
It added at the time that glaciers in Nepal had melted 65% faster in the prior decade than in the preceding one.
Benjamin Horton, dean of the School of Energy and Environment at the City University of Hong Kong, said Wednesday's catastrophe may represent a textbook "compound event."
This occurs when an earthquake combines with climate-related changes—such as melting glaciers, thawing permafrost, and unstable slopes—to "produce a more complex and destructive disaster than any single factor would cause on its own," he explained.
Horton added that grasping these cascading risks will be crucial to strengthening resilience in high-altitude mountain areas.