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Climate change fingerprints found in catastrophic Nepal mountain collapse, say scientists – EnviroNews
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The catastrophic collapse of rock and ice from Langtang Lirung mountain in northern Nepal, which killed more than 1,300 people and left over 5,000 missing, was driven by a complex combination of climatic and geological factors, according to a rapid scientific assessment by an international team of glaciologists and climate scientists.
The August 26, 2026 disaster triggered a massive flood of water, ice and debris that swept downstream, destroying communities and causing widespread devastation along the Bhote Koshi area.
Scientists said the tragedy was not the result of a single extreme weather event but a compound mountain crisis in which long-term warming, glacier retreat, permafrost thaw, increased meltwater and geological instability combined to undermine the high-altitude landscape.
The analysis found that decades of atmospheric warming, primarily driven by the burning of fossil fuels, have significantly altered the Himalayan environment.
According to the scientists, warming has pushed the freezing threshold, or 0°C isotherm, upward by approximately 100 metres per decade. This has exposed previously stable ice and permafrost within mountain rock to warmer and longer periods of thaw, weakening the geological structures that help hold steep mountain slopes together.
At the same time, glacier retreat has removed stabilising ice around the collapse site, while increased meltwater may have contributed additional pressure and instability.
The scientists said a massive magnitude 7.8 earthquake that struck Nepal in 2015 may also have further preconditioned the slope for failure, although its specific contribution to the 2026 collapse cannot yet be confirmed.
The conditions immediately preceding the disaster were particularly severe.
July and August 2026 were reportedly the warmest months on record locally, while unusually high snowfall during October and November 2025 provided substantial additional snow and ice that subsequently contributed to meltwater in the months before the collapse.
An attribution analysis conducted as part of the assessment found that climate change had increased temperatures in the collapse region by about 1.5°C during July and August, compared with pre-industrial conditions. On an annual basis, climate change has increased temperatures in the region by approximately 2°C.
Dr Ben Clarke, Extreme Weather and Climate Change Researcher at Imperial College London, said the disaster demonstrated how climate change is transforming high-mountain environments even when a catastrophe cannot be attributed to a single weather event.
“This disaster was not an extreme weather event, but the fingerprints of climate change are still clear to see in long-term changes,” Clarke said.
He said climate change was altering several environmental factors that could contribute to mountain instability, thereby increasing risks in a region already exposed to significant seismic activity.
Professor Walter Immerzeel, Mountain Hydrologist at Utrecht University, said the Himalayas were undergoing fundamental changes as warming continued to affect glaciers and permafrost.
He explained that the upward movement of the freezing line was exposing permanently frozen ground and bedrock to increasingly warm and prolonged thaw conditions.
“When you combine high-elevation permafrost degradation with glacier retreat and record summer heat, the structural integrity of these mountain walls is compromised,” Immerzeel said.
Professor Bethan Davies, Professor of Glaciology at Newcastle University, similarly warned that continued warming was melting snow and ice, reducing glacier coverage and thawing permafrost, thereby contributing to greater instability on mountain slopes.
She called for urgent action to reduce greenhouse gas emissions to slow further warming and limit future risks.
Adaptation limits exposed
Beyond the immediate loss of life, the disaster has raised concerns about the ability of vulnerable mountain communities to adapt to rapidly changing climate conditions.
Scientists noted that Nepal has early warning systems and disaster-response plans, but said the scale of the catastrophe had exceeded the country’s physical adaptation limits.
Madhab Uprety, Senior Technical Advisor and Asia-Pacific Focal Point at the Red Cross Red Crescent Climate Centre, described the loss of life as a devastating indication that communities were already encountering the limits of climate adaptation.
He called for deeper global emissions reductions alongside international support for countries facing unavoidable climate-related losses and damage.
“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,” Uprety said.
Manjeet Dhakal, Director of Climate Analytics South Asia, said the catastrophe was a warning about the increasingly complex hazards emerging across a rapidly warming Himalaya.
He called for stronger monitoring and early-warning systems, greater investment in understanding cascading mountain risks, climate-resilient development and increased international climate finance for vulnerable countries.
Warning beyond Nepal
The scientists said the implications of the disaster extend beyond Nepal, pointing to the longer-term consequences of warming across high-altitude regions worldwide.
Glaciers and permafrost respond to temperature changes over decades. This means warming that has already occurred may continue to influence mountain stability in the future, even if temperatures were to stop increasing immediately.
Professor Friederike Otto of Imperial College London said the event illustrated the climate justice dimension of climate-related disasters, particularly when vulnerable communities experience the consequences of emissions generated elsewhere.
“When warming destabilises the roof of the world, no amount of local adaptation can fully shield vulnerable people downstream from this scale of destruction,” Otto said.
She urged faster action to transition away from fossil fuels, warning that continued warming could increase the likelihood of disasters involving multiple interacting hazards.
The scientists stressed that the precise contribution of individual factors to the Langtang Lirung collapse requires further investigation. However, they said the evidence clearly demonstrates that climate change is reshaping the physical conditions of the Himalayas, potentially increasing the interaction between glacier loss, permafrost degradation, extreme heat, meltwater and geological hazards.
For Nepal and other high-mountain countries, the catastrophe underscores the growing need to combine climate mitigation with stronger early-warning systems, risk monitoring, resilient infrastructure and international support for communities facing climate-related loss and damage.