‘No doubt’ of climate change’s role in deadly China-Nepal flood, say scientists

Climate change was a core factor in last month’s deadly glacial mountain collapse on the China-Nepal border that killed more than 1,400 people and left at least 6,600 missing, scientists said Thursday.

However, scientists from the World Weather Attribution (WWA) group said the disaster was not caused by a single extreme weather event but rather a “compound crisis” shaped by long-term warming, glacier retreat, permafrost thaw and geological instability.

“Relentless warming has lifted the altitude of the freezing threshold on the high Himalaya, exposing ice and permafrost deep in the bedrock to higher and longer thaw temperatures, weakening mountain slopes,” a WWA report said.

A massive section of rock and glacier broke away from Langtang Lirung mountain on Aug 26, triggering a huge flood of water, ice and debris that swept downstream, destroying communities and infrastructure.

Report co-author Walter Immerzeel, a mountain hydrologist at Utrecht University, said the region was undergoing “fundamental, irreversible shifts”, with glacier retreat and permafrost degradation undermining mountain stability.

“We conclude that this was a geologically vulnerable slope, potentially weakened by the 2015 earthquake, but it was destabilised further by glacier retreat and permafrost fall,” Immerzeel told reporters.

Nepal, a largely rural nation of 30 million people, contributes a fraction of global greenhouse gas emissions compared to industrialised nations.

The study found that July and August 2026 were the warmest months locally recorded, while heavy snowfall in late 2025 contributed to increased meltwater before the collapse.

A magnitude 7.8 earthquake in Nepal in 2015 may have further weakened the slope, although its precise role remains uncertain, the report said.

Last month’s disaster has also raised concerns about the limits of adaptation.

Prime Minister Balendra Shah will take his first foreign trip as Nepal’s leader to address the UN General Assembly on the urgent issue next week.

Nepal estimates the reconstruction bill after deadly floods sparked by a glacial mountain collapse last month will amount to US$4.78 billion.

“There is no doubt that climate change is one of the drivers, and therefore obviously it needs to be discussed in the context of loss and damage,” Friederike Otto, a professor of climate science at Imperial College London, told reporters.

Nepal’s disaster authority said Wednesday it had sharply revised up the number of people considered missing to 6,150, following data collection and verification in affected districts.

The number of bodies retrieved stands at 1,403 bodies, 105 of which had been identified, according to the disaster agency.

In China, the toll is 43 dead and 519 missing, according to state media.

The combined toll from both nations now stands at 1,446 people dead and at least 6,669 missing.

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