Climate change raises risk of Himalayan flood disasters, scientists say

Scientists say climate change is creating conditions that can destabilise high-mountain rock and ice, making disasters like this week's Himalayan flood more likely. The flood, which struck along the Nepal-Tibet border, has killed at least 165 people, with nearly 1,500 missing, including more than 800 foreigners.

While the exact cause of the disaster is still being analysed, experts believe it began with a massive ice-rock avalanche from the northern slopes of Nepal's Langtang Lirung peak into the Lhende Khola river on the Tibetan side. The initial collapse triggered a multi-stage hazard chain that damaged at least six major hydropower plants and infrastructure at the Gyirong Port trade hub, and altered river channels more than 100 kilometres downstream near the Indian border.

Simon Cox, chief scientist at the Mountains to Sea programme at Earth Sciences New Zealand, said climate change is generating conditions that can destabilise high-mountain rock and ice, making collapses and cascading hazards more frequent. Warming can reduce ice support on steep slopes, boost meltwater, and change patterns of freezing, thawing and rainfall, which can weaken mountainsides.

Experts caution against describing climate change as the sole trigger for Wednesday's collapse, but say rising temperatures and melting glaciers probably played a role. Farooq Azam, senior cryosphere specialist at the Nepal-based International Centre for Integrated Mountain Development, said heavy snow melt, coupled with seismic activity, likely triggered the initial avalanche.

The region has seen similar catastrophic surges in recent years, though on a smaller scale. These include a 2025 flood at Gyirong, a glacial lake outburst in the Sherpa village of Thame in 2024, and another in India's Sikkim in 2023. Floods, landslides, avalanches, and droughts are increasing in frequency and ferocity across the Hindu Kush range, according to ICIMOD.

The long-term trend is stark. The United Nations said in 2023 that global warming caused Nepal's snow-capped mountains to lose close to one-third of their ice cover in just over 30 years, with glaciers melting 65% faster in the prior decade than the one before.

Benjamin Horton, dean of the School of Energy and Environment at the City University of Hong Kong, said the disaster could be a classic example of a "compound event," where an earthquake interacts with climate-driven changes such as glacier loss, thawing permafrost, and slope instability to create a more complex and damaging disaster than any single factor alone. Understanding these cascading risks will be essential for improving resilience in high mountain regions, he added.