Climate change fuels Himalayan flood risk, experts warn

Scientists warn that climate change is creating conditions that destabilize high-mountain rock and ice, thereby increasing the prospects for disasters such as the recent Himalayan flood that occurred along the Nepal-China border. This event, which involved a massive wall of mud and rock collapsing into a river, resulted in catastrophic floods through towns and valleys, with authorities reporting 165 deaths and nearly 1,500 missing, including many foreigners.

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Climate change is generating conditions that can destabilise high-mountain rock and ice.

While the precise cause of the disaster is still being analyzed, experts suggest it likely originated from a significant ice-rock avalanche on the northern slopes of Nepal's Langtang Lirung peak. This initial collapse triggered a multi-stage hazard chain across borders, damaging at least six major hydropower plants and infrastructure at the Gyirong Port trade hub. The event also altered river channels significantly, extending more than 100 kilometers downstream near the Indian border.

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That in turn makes collapses and cascading hazards of the kind seen this week more frequent.

Experts caution against attributing the collapse solely to climate change as the immediate trigger. However, they emphasize that rising temperatures and melting glaciers likely played a role. Warming trends can reduce ice support on steep slopes, increase meltwater, and alter freezing and rainfall patterns, collectively weakening mountainsides and making large collapses more probable in certain areas. Simon Cox, chief scientist at Earth Sciences New Zealand, noted that climate change generates conditions that make such cascading hazards more frequent.

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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.

This recent event is part of a growing trend of similar, though often smaller-scale, catastrophic surges in the region. These include a 2025 flood at Gyirong, a glacial lake outburst in Nepal's Thame in 2024, and another in India's Sikkim in 2023. The International Centre for Integrated Mountain Development highlights that floods, landslides, avalanches, and droughts are increasing in frequency and ferocity across the Hindu Kush mountain range, posing a major threat to the region's population. Rising mountain temperatures make the cryosphere increasingly vulnerable, according to Farooq Azam, a cryosphere specialist at ICIMOD, who believes heavy snowmelt combined with seismic activity likely triggered the initial avalanche.

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Floods, landslides, avalanches, and droughts are increasing in frequency and ferocity across the Hindu Kush mountain range.