Climate change helped destabilize deadly Nepal slope collapse, scientists find

Decades of human-caused warming thinned glaciers and thawed permafrost deep within the Himalayas, very likely helping to destabilize the mountain slope that collapsed on August 26 and killed more than 1,300 people in Nepal, according to a scientific assessment released Thursday by World Weather Attribution.clickorlando+1

The report, produced by roughly two dozen international researchers, represents one of the first comprehensive scientific evaluations of the disaster on Langtang Lirung mountain near Nepal's border with China. While cautioning that climate change was not the sole cause — a magnitude-7.8 earthquake in 2015 may have weakened the rock years earlier — the scientists concluded that warming intensified several processes that made the slope progressively less stable over decades.dw+2

How Warming Primed the Mountain

The analysis found that rising temperatures have pushed the altitude at which ground stays permanently frozen upward by roughly 100 meters per decade, exposing rock at increasingly high elevations to thawing and fracturing. The Langtang Lirung glacier itself has retreated about half a kilometer since the 1990s, with retreat accelerating sharply after 2010, stripping away ice that once supported the rock wall above.japantimes+2

About 116 million cubic meters of rock and ice initially broke away — roughly five times the volume of the 2021 Chamoli disaster in India — and plunged more than 1,400 meters to the valley floor, releasing energy equivalent to a magnitude-5.2 earthquake. The resulting debris flood reached the Nepal-China border crossing 20 kilometers downstream in approximately seven minutes, traveling at speeds around 170 kilometers per hour.dw+2

July and August 2026 were the warmest such months on record locally, with climate change contributing approximately 1.5 degrees Celsius to regional temperatures. Unusually heavy snowfall in late 2025 added further meltwater that likely seeped into cracks and weakened the slope in the months before the collapse.wincountry+1

Limits of Adaptation

The researchers said the disaster exceeded what Nepal's early warning systems could handle. The first mass SMS alert went out about 38 minutes after the initial collapse — but the flood had already swept through the border area within seven minutes. "When warming destabilizes the roof of the world, no amount of local adaptation can fully shield vulnerable people downstream from this scale of destruction," said Friederike Otto, a climate scientist at Imperial College London and co-founder of World Weather Attribution.climatechangenews+2

More than 5,000 people remain missing. Nepal estimates recovery costs at $4.8 billion — over 11 percent of its GDP — and has requested $20 million, the maximum allowed, from the United Nations Fund for Responding to Loss and Damage. The fund's board met informally on Wednesday but took no decision. Nepal, which contributes less than 0.1 percent of global greenhouse gas emissions, has framed the request as a matter of climate justice rather than aid.nationalgeographic+1

A Warning for the Himalayas

Scientists warned that the conditions driving such collapses are already locked in for decades. "All these drivers that we've talked about, permafrost melting, glacial melting, etc., will just become worse," Otto said. "And that means that events like this become more frequent".ksat+1