KATHMANDU, SEPTEMBER 18 An international team of scientists has found that decades of warming in the Himalayas pre-conditioned the catastrophic rock-ice avalanche that struck Nepal's Bhotekoshi and Trishuli corridors on August 26, though they stopped short of directly attributing the collapse to climate change. The findings, published today by World Weather Attribution (WWA) - a scientific initiative run through Imperial College London - represent the first systematic, multi-country scientific assessment of the disaster's causes. Although the report has not undergone peer review, WWA utilises established peer-reviewed methodologies to evaluate extreme weather and climate events. The report cautioned that climate change was not the sole trigger. Analysis suggests that the major 2015 Nepal earthquake likely weakened the mountain's rock structure years prior to the failure. 'This disaster was not an extreme weather event, but the fingerprints of climate change are still clear to see in longterm changes,' said Ben Clarke, a climate researcher at Imperial College London who contributed to the study. As of today, the disaster has resulted in at least 1,410 confirmed deaths in Nepal, with only a small fraction of victims identified and returned to their families. According to National Disaster Risk Reduction and Management Authority (NDRRMA) data, over 6,000 people remain missing, roughly 13,700 have been rescued, and more than 8,600 have received medical treatment. Around 3,400 displaced individuals are staying in holding centres. The disaster has affected an estimated 84,270 people across 17 local administrative divisions in six districts: Rasuwa, Nuwakot, Dhading, Gorkha, Chitwan and Tanahun. The government has officially declared 15 municipalities as crisis-hit zones for a threemonth period. Climate scientists noted that rising temperatures across the Himalayas are accelerating glacial retreat and thawing the permafrost that binds fractured high-altitude rock. As a result, climate change affects not only meteorological hazards like heavy rainfall and heatwaves, but also the structural stability of mountain slopes, directly threatening communities in downstream river valleys. While researchers could not conclusively determine if the collapse would have occurred without anthropogenic warming, they concluded that climate change intensified multiple long-term processes that destabilised the slope. The study clarifies that the seismic signal recorded on August 26 was generated not by tectonic activity, but by the sudden collapse of approximately two square kilometres of rock wall and glacier ice from Langtang Lirung at an elevation of 5,150 metres. The mass fell roughly 1,400 metres to the valley floor, releasing energy equivalent to a magnitude-5.5 earthquake, according to data from the US Geological Survey (USGS) and Nepal's Centre for Hydrology and Water Resources Research (CHWRR). As the avalanche surged downward, mechanical friction melted substantial volumes of glacial ice. Upon hitting the valley floor, the mass incorporated buried ice and water, transforming into a massive debris flow - a dense mixture of rock, ice, sediment and water moving with the destructive force of wet concrete. The flow reached the Rasuwagadhi border crossing - 22 kilometres downstream - in just seven minutes, achieving an average speed of 188 kilometres per hour. Over the next 15 minutes, it destroyed border infrastructure and submerged the towns of Timure and Syabrubesi, overwhelming pilgrims, border staff and local workers. Within 45 minutes of the initial collapse, the flood reached Betrawati in the Trishuli valley, tearing through Betrawati and Trishuli Bazaar while carrying large boulders and sweeping multi-storey buildings into the river. The flood travelled 200 kilometres downstream to Devghat in under seven hours, where peak discharge on the Trishuli River more than doubled to approximately 5,850 cubic metres per second. An estimated 20 million cubic metres of excess water passed through in under four hours before crossing into India. In total, the event deposited roughly 30.5 million cubic metres of sediment and debris across farmland, towns, and energy infrastructure. At Galchi, 88 kilometres downstream, river levels rose by 8.5 metres. HIGH MOUNTAIN SLOPES WEAKENED The report identified the upward migration of the freezing elevation as one of the clearest physical impacts linked to climate change. Warming has pushed the altitude of permanently frozen ground upward by approximately 100 metres (328 feet) per decade. This exposes high-elevation rock faces to prolonged above-freezing temperatures, melting ice within structural joints and destabilising the rock face. Glacial retreat has acted as another primary destabilising factor. Regional glaciers have been thinning at an average rate equivalent to over half a metre of ice loss annually for decades. The Langtang Lirung glacier has retreated nearly half a kilometre since the 1990s, removing structural support from adjacent rock walls. The Himalayan region holds the largest volume of ice outside the polar poles. More than 63,000 glaciers feed 10 major Asian river systems, supporting water, food, and energy security for billions of people. However, studies indicate that 78 per cent of this glacial area - situated between 4,500 and 6,000 metres above sea level - is highly vulnerable to rising temperatures. UN data shows that between 2000 and 2019, regional glaciers lost an average of 267 billion metric tonnes of ice per year. Unusually high temperatures preceded the collapse, with July and August 2026 recorded as the warmest such period on record locally. LIMITS OF ADAPTATION The report highlights that hazards originating in high-mountain environments can exceed the structural and operational limits of existing early warning systems and adaptation frameworks. While Nepal has expanded its disaster risk reduction infrastructure, the sheer scale and velocity of the collapse overwhelmed existing safety measures. Unlike meteorological floods that afford hours or days of lead time, catastrophic high-altitude slope failures occur with minimal warning and remain difficult to forecast. The report concludes that while improved high-altitude monitoring and earth-observation systems can mitigate risk, adaptation faces inherent limits in narrow valleys where settlements, roads and hydropower facilities remain concentrated along river beds. Because permafrost and glaciers respond to thermal changes over decades-long timescales, significant mountain instability has already been locked in.