Scientists link Nepal-China Himalayan flood disaster to climate change

A new scientific report has concluded that climate change played a significant role in last month's deadly Himalayan disaster near Nepal's border with China. The collapse on 26 August triggered a torrent of water, ice, boulders and sediment that swept through communities along the Trishuli River corridor. The event killed more than 1,300 people and left over 5,000 missing.

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The report, released on Thursday by the World Weather Attribution group, said warming temperatures had thinned glaciers and thawed mountain permafrost in ways that likely destabilised the slope before it failed. A climate researcher at Imperial College London who contributed to the analysis said the disaster was not an extreme weather event, but that the fingerprints of climate change were still visible in long-term changes. The study said the rising freezing threshold was one of the clearest climate-linked shifts, with the altitude at which ground remains consistently frozen moving upward by roughly 100 metres per decade.

Researchers said that exposed rock at higher elevations is now spending longer periods above freezing, weakening the ice and cracks that help hold fractured mountain slopes together. The report also said glacial retreat was another destabilising factor, and that monitoring instruments around 5,000 metres now show some rock and ground no longer remain frozen throughout the year. A geoscientist who has worked in the Himalayan region since 2006 said this means ground that had been sitting below ice for hundreds or thousands of years is now becoming exposed.

The findings add a scientific attribution layer to a disaster with major humanitarian consequences in a remote mountain region where communities are concentrated in narrow river valleys. The report did not determine whether the collapse would have happened without climate change, but said warming intensified several processes that made the slope less stable over decades. It also said the event highlights how climate change can affect not only weather hazards such as heat and heavy rain, but also the stability of mountains themselves.

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The analysis comes as scientists continue to examine how rising temperatures, glacier retreat and thawing permafrost are reshaping risk across the Himalayas. The report said the collapse was not caused solely by climate change, but by a combination of long-term warming and pre-existing geological weakness. It also noted that the release of greenhouse gases from burning fuels such as oil, gas and coal is the underlying driver of human-induced warming.

What remains unclear is how much each factor contributed to the final collapse and whether further assessments will alter the current scientific picture. The immediate focus remains on the missing, the damage and recovery in the affected border region. The report points to a growing risk in high mountain areas where warming temperatures and unstable slopes can combine to produce sudden destructive events.

A new scientific study has concluded that human-induced climate change helped precondition the glacier collapse that triggered deadly floods and landslides on the Nepal-Tibet border last month. The disaster struck on 26 August and left more than 1,400 people dead, with thousands still missing. It also destroyed homes and damaged energy infrastructure across border towns and villages in Nepal and Tibet.

The study, published on Thursday by the World Weather Attribution group, said the event was a compound disaster driven by rising temperatures, thinning glaciers, thawing permafrost and pre-existing geological weaknesses. Friederike Otto, a climatologist at Imperial College London and one of the authors, said there was "absolutely no doubt" that human-induced climate change played a role in preconditioning the disaster. Scientists at the United States Geological Survey said the floods were caused by the collapse of a glacier slope near the peak of Langtang Lirung, on Nepal's side of the Himalayas.

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According to the study, the glacier collapse was powerful enough to register as a magnitude 5.2 earthquake. It said July and August temperatures in the area were about 1.5C warmer because of human influence on the climate. The report also said glaciers in the region have been thinning by about half a metre a year, which may have weakened existing fractures and increased instability.

Heavy snowfall in October and November last year added to meltwater levels early this year, which the authors said may have amplified the event. The findings add a scientific attribution layer to a disaster that has already caused severe humanitarian damage. More than 1,400 people were killed in the floods and landslides, and thousands remain missing.

The destruction of homes and energy infrastructure also points to wider disruption in a remote mountain region where communities are already exposed to landslides, glacier instability and extreme weather. The study said climate change was a destabilising factor acting on a pre-existing geological predisposition, rather than the sole cause of the collapse. It also noted that a magnitude 7.8 earthquake in 2015, which triggered a rock-ice avalanche in the area, could have weakened the underlying rock mass.

However, authorities have said they cannot confirm the exact impact of that earthquake on last month's collapse, leaving some parts of the chain of events still under review. What remains unclear is how much each factor contributed to the final disaster and whether further assessments will change the current scientific picture. The report points to a growing risk in high mountain regions where warming temperatures, unstable slopes and changing snowfall patterns can combine to produce sudden and destructive events.

For Nepal and Tibet, the immediate focus remains on the missing, the damage and the longer-term recovery from one of the region's deadliest recent disasters.

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