‘Compound crisis’ behind Nepal disaster, scientists report
Climate change combined with suspected geological weakening identified as UN highlights risk of similar events in areas from the Andes to the Alps
The consequences of climate change that caused glaciers to thin and permafrost to thaw, combined with suspected geological shifts, were blamed for a disastrous rock and ice collapse in Nepal, a preliminary scientific report found.
Rather than a single extreme weather event, the report by international glaciologists and the World Weather Attribution group of scientists said the disaster in August was a “compound crisis”.
The scientists behind the report, which is yet to be peer reviewed, said there was certainty about the role of climate change, while the geological weakening role played by the 2015 earthquake was likely but their research could not yet confirm it.
Accelerated global warming had hastened the glacier and permafrost melt, it said, and an abnormal previous season of high snowfall had been followed by rapid thawing during unusually hot weather.
Walter Immerzeel, mountain hydrologist at Utrecht University, said the earthquake in 2015 likely made the mountainside less stable but it was the accumulation of climate change effects that had set in motion the catastrophe.
More than 1,300 people were killed and some 4,000 estimated missing after a section of an overhanging glacier and rock fell from Langtang Lirung mountain on August 26, unleashing a massive flood of water, ice and debris.
“There is absolutely no doubt that human-induced climate change played a role here in the preconditioning of the disaster,” said Friederike Otto, professor of climate science at Imperial College London and an author of the report.
Climate change had pushed the warming point, which marked the freezing threshold, upwards by about 100 metres of altitude per decade in the area, the report concluded.
This resulted in the substantial glacier retreat and the thaw of permafrost within rock fissures, which typically hold high mountain walls together. The loss of ice destabilised the mountainside and increased meltwater.
The area had also been hit with abnormal snowfall in October and November last year, adding large amounts of meltwater, while the temperature before the collapse in July and August was the warmest on record for the Langtang Valley.
Otto said the daily maximum temperature anomaly was more than 5C above the average in the three-day period preceding the collapse.
“When you combine high-elevation permafrost degradation with glacier retreat and record summer heat, the structural integrity of these mountain walls is compromised,” said Immerzeel. “The catastrophic impacts of what can then happen are clear for all to see.”
The region had experienced long-term warming of about 2C above the pre-industrial level, the researchers said, far ahead of the global level of about 1.4C.
Scientists have long warned that the Himalayas are deeply vulnerable to climate change.
Madhab Uprety at the Red Cross Red Crescent Climate Centre said the cost of recovery from this disaster would be “substantial”.
“For a nation that’s done virtually nothing to contribute to this problem, it underlines the need to find fairness in helping climate-vulnerable nations cope with the problems they have not unleashed,” he said.
Nepal has requested help from the UN’s so-called loss and damage fund, set up to help countries deal with the effects of climate change. The vehicle, however, has a severe funding shortage.
A separate report from the UN’s World Meteorological Organization released on Thursday outlined widespread glacier loss in 2025 across all regions of the world for the fourth consecutive year.
In the three years to the end of 2025 alone, glaciers lost mass of 1,400bn tonnes, roughly equal to the water required to fill about 560mn Olympic-sized swimming pools, or about one-third of annual freshwater withdrawals, it said.
It identified Asia and Africa as the regions most affected by water-related disasters, and the WMO’s cryosphere or frozen water expert highlighted the risk of similar events to the Nepal catastrophe in places from the Andes to the Alps.