Human-caused climate change likely contributed to destabilising a rock-and-ice slope whose collapse triggered the deadly Nepal-Tibet disaster on August 26, according to a scientific assessment of the event.
The study linked decades of warming to thinning glaciers, thawing permafrost and increasing rainfall replacing snowfall, conditions that weakened the mountain slope before its collapse.
“There’s absolutely no doubt that human-induced climate change played a role here in the preconditioning of the disaster through permafrost thawing, through thinning of the glaciers, through having more rainfall instead of snow,” said Friederike Otto, a climatologist at Imperial College London and co-author of the World Weather Attribution study.
A cascading disaster
Researchers described the event as a cascading disaster rather than a conventional flood.
Around 2 square kilometres of rock wall and glacier ice collapsed from Langtang Lirung at an elevation of about 5,150 metres. The mass plunged approximately 1,400 metres before transforming into a debris flood.
Water, rock, ice and sediment then travelled around 22 kilometres to Rasuwagadhi in approximately seven minutes, leaving downstream settlements with almost no warning.
The study found that long-term warming had pushed freezing levels higher, exposing previously frozen rock and permafrost to prolonged thawing. This weakened the material that helps bind steep mountain slopes together.
July and August were exceptionally warm, with researchers estimating that human-caused climate change contributed around 1.5°C to temperatures during the period.
Heavy snowfall in late 2025 may also have supplied additional meltwater. Researchers noted that Nepal’s 2015 magnitude-7.8 earthquake could have weakened mountain slopes, although they were unable to quantify its contribution to the disaster.
Growing need for Himalayan monitoring
Priyanka Vadrevu, an independent researcher specialising in climate adaptation and disaster resilience, said rising temperatures were changing the risks faced by Himalayan communities.
“Rising temperatures are thinning ice, thawing permafrost and weakening frozen material that helps hold steep slopes together. Preparedness in the Himalayas can no longer focus only on rainfall and conventional flood forecasting. We need integrated monitoring of glaciers, permafrost, slopes, rivers and weather conditions,” Vadrevu said.
Nepal now hopes to seek around $20 million (£15 million) from the UN Fund for Responding to Loss and Damage, which supports countries facing climate-related destruction.
The study could strengthen Kathmandu’s case by linking global warming to environmental conditions that contributed to the slope failure.
Nepal seeks greater climate financing
The findings are also expected to contribute to Nepal’s diplomatic efforts on climate vulnerability and financing.
Prime Minister Balendra Shah is scheduled to travel to New York from September 22 to 26 for the UN General Assembly, marking his first foreign trip since taking office.
The Nepalese government has said he will highlight the August 26 disaster, the vulnerability of the Himalayan region and the need for greater climate justice and financing for countries experiencing disproportionate losses from global warming.
