A catastrophic glacier collapse on Nepal's Langtang Lirung mountain on 26 August was driven by a compound crisis of geological and climatic forces, with decades of human-induced warming having critically destabilised the landscape before the disaster struck, according to the first scientific study of the event. More than 1,300 people were killed and around 5,000 remain missing after a section of overhanging glacier and rock measuring roughly 200,000 square metres broke away, fell nearly 1,400 metres, and triggered flash floods that tore through valleys on both the Nepali and Tibetan sides of the border at speeds exceeding 180 kilometres per hour.

The study, conducted by the World Weather Attribution (WWA) group — a collaborative research initiative led by scientists at Imperial College London — found that several intersecting factors, many of them worsened by climate change, created the conditions for the collapse. Temperatures in the Himalayan region during July and August reached approximately 5°C above the 30-year average, levels not seen in 55 years of records. Of that anomaly, an estimated 1.5°C is attributable to climate change, while cumulative warming across the broader region since pre-industrial times amounts to roughly 2°C. The freezing threshold in the Himalayas has also crept upward by about 100 metres per decade since the 1980s, steadily thawing the permafrost that holds mountain slopes together. Glaciers in the area have been thinning by roughly half a metre per year since 2000, removing the stabilising ice that once buttressed the rock wall. Unusually heavy snowfall last October and November added further meltwater once temperatures rose, likely increasing pressure on the already weakened slope. A 7.8-magnitude earthquake that struck Nepal in 2015 may also have fractured the underlying bedrock, though researchers could not precisely quantify its contribution.