Climate change probably weakened the glacier whose collapse triggered catastrophic flooding across Nepal and Tibet last month, killing more than 1,300 people, according to the first scientific assessment of the disaster.
Researchers found that unusually high temperatures preceded the collapse, which released an estimated 110 million cubic metres of snow and ice into the valley below. The resulting avalanche generated powerful flash floods that struck downstream communities with little or no warning.
“Communities in Nepal are paying with their lives for a crisis driven by fossil fuel emissions thousands of miles away,” said Dr Friederike Otto, a climate science professor at Imperial College London, which carried out the study.
“When warming destabilises the roof of the world, no amount of local adaptation can fully shield vulnerable people downstream from this scale of destruction. Without much faster action to transition to zero fossil fuel emissions we will inevitably see more disasters of this scale occurring in the years to come.”
More than 1,300 people were killed and over 5,000 remain missing following the August 26 disaster. A vast section of overhanging glacier and rock, covering approximately 200,000 square metres, broke away from Langtang Lirung mountain and plunged about 1,400 metres into the valley.
The impact was so powerful that it registered as an earthquake. Ice was rapidly liquefied, producing a freezing torrent that surged downstream at speeds exceeding 110mph.
The flood carried water, ice, rock and sediment through the valley, destroying homes, settlements, roads, bridges and other infrastructure. Entire families were swept away, while surviving communities were left isolated from emergency assistance.
“Rock avalanches of this size are rare, with annual frequency estimates of approximately one event this size every 1,000–10,000 years,” the study said. “This event shows that limits to adaptation are already being reached.”
The research differed from previous assessments conducted by Otto and the World Weather Attribution group, an international collaboration involving Imperial College London and other climate specialists.
Rather than linking the catastrophe to a single extreme weather event, the scientists examined a combination of conditions that may have destabilised the mountain.
Their findings suggest that decades of atmospheric warming caused by greenhouse gas emissions intensified several underlying risk factors. Dr Ben Clarke, an Imperial researcher specialising in extreme weather and climate change, said the long-term changes surrounding the glacier carried clear “fingerprints of climate change”.
Temperatures in the region have risen by approximately 2C since pre-industrial times, while average temperatures during July and August have increased by about 1.5C. July and August 2026 were the warmest recorded locally, with temperatures reaching as much as 5C above the 30-year average shortly before the collapse.
The Himalayan freezing threshold has also climbed by around 100 metres per decade since the 1980s. Researchers said higher temperatures and longer periods of thawing had weakened mountain slopes formed around permafrost.
Rising temperatures had already caused substantial glacial retreat, removing ice that previously helped stabilise the collapse site and increasing the amount of meltwater in the surrounding area.
Scientists also examined the possible influence of the powerful 7.8-magnitude earthquake that struck Nepal in 2015, although its precise role in the August disaster could not be established.
The research team stopped short of identifying climate change as the sole or fundamental cause of the collapse. Instead, the scientists described global warming as a destabilising force that had compounded the area’s existing geological vulnerabilities.
Clarke said: “We found that climate change is transforming the high mountain environment, influencing many of the possible drivers of this collapse.”
Nepal has formally requested financial assistance from the United Nations’ loss and damage fund to support recovery efforts. Accessing the funding requires the country to demonstrate a connection between the destruction and the global climate crisis.
Foreign Minister Shisir Khanal has also called on major emitting countries, including China and India, to “wake up” and acknowledge their shared responsibility for the disaster.
Madhab Uprety, a senior technical adviser at the Red Cross Red Crescent Climate Centre, which participates in World Weather Attribution, said major reductions in global emissions were necessary to address the mounting losses suffered by vulnerable communities.
He added: “In addition to the human tragedy on an unimaginable scale, the cost of recovery for this disaster is 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.”
