Climate crisis could be destabilising mountain areas like Nepal, experts warn

Glacier Collapse on Langtang Lirung Triggers Catastrophic Flood Along Nepal–Tibet Border

Wanderstayfinder.com – A wall of ancient ice broke free from the north face of Langtang Lirung — a 7,000-metre (23,000-foot) peak straddling the Nepal–Tibet border — and sent a torrent of mud, water, and shattered rock racing down the Bhotekoshi River valley on Wednesday. The resulting flash flood tore through border communities, sweeping away buildings, roads, and entire neighbourhoods. At least 360 people have been confirmed dead, and roughly 1,400 remain missing as rescue operations continue under difficult terrain conditions.

The event has sharpened a growing scientific consensus: the climate crisis is actively destabilising the geology of mountain and polar regions worldwide, putting millions of downstream inhabitants at escalating risk.

What Actually Triggered the Collapse

In the hours after the disaster, a magnitude 4.4 earthquake was widely cited as the likely cause. That explanation has since been overturned. Seismologists at the US Geological Survey re-examined long-period wave data and concluded the seismic signature matched a glacial collapse and debris flow rather than tectonic movement. The impact of the ice mass striking the slope registered a magnitude of 5.2 on seismographs — a figure that initially confused early assessments.

“Additional analysis of long-period seismic waves indicates that the seismic energy was instead generated by a glacial collapse and debris flow,” the US Geological Survey said.

The ice-and-rock avalanche hurled boulders and fragmented debris into the Lhende Khola River, a tributary feeding the Bhotekoshi. Within roughly 30 minutes, water levels in downstream reaches surged by between seven and nine metres, according to the International Centre for Integrated Mountain Development, an intergovernmental scientific body focused on mountain-region challenges. That velocity of rise left communities with almost no time to evacuate.

A Perfect Storm of Heat and Water

Scientists are still piecing together the precise mechanics of the failure, but several converging factors appear to have created the conditions for collapse. Two days before the event, ground temperature at the site reached its highest reading in two years, according to Dr Hamish Pritchard, a glaciologist with the British Antarctic Survey whose team maintained sensors approximately six miles (10 km) from the location.

“These high temperatures would have weakened the snowpack, filled crevasses with water and thawed the bonds between ice and rock that hold these glaciers in place,” Pritchard told the Science Media Centre.

The detachment occurred amid an unusual heat spell that likely melted the ice acting as a structural adhesive between splintered bedrock fragments. Layered on top of that thermal stress was the monsoon season, which had already saturated surrounding soils and swollen river channels. A series of intense heatwaves has struck the region since early this year, mirroring patterns observed across multiple continents.

A Warning Written Years Ago

The broader trajectory was not a surprise to the climate-science community. In 2023, the United Nations’ principal scientific advisory body issued a stark warning that previously ice-bound landmasses — from permafrost tundra to high-altitude glaciers — would grow increasingly unstable as temperatures continued to climb.

“Every increment of warming will multiply and intensify future hazards from cryosphere regions,” the Intergovernmental Panel on Climate Change observed in its sixth synthesis report. “Floods, landslides and freshwater shortages from glacier retreat and snow loss pose a serious threat to mountain regions across the world.”

That language has moved from academic caution to operational reality. Average global temperatures are edging closer to 1.5 °C above preindustrial levels, and alpine and polar zones are warming even faster because the disappearance of snow and ice strips away the thermal insulation that once moderated surface heating.

Why Mountains Are Becoming More Fragile

Dr Richard Waller, a senior lecturer in physical geography at Keele University, frames the problem in structural terms. As snowpack and glacier ice retreat, the exposed surface becomes less reflective and absorbs more solar energy, accelerating local warming in a feedback loop.

“The progressive loss of snow and glacier ice results in the surface being less reflective, so it absorbs more solar energy and heats up. In combination with atmospheric warming, this is leading to the melting of mountain permafrost,” Waller explained. “Think of the high mountains like this as shattered bedrock glued together by ice-filled joints. As the permafrost and the ice-filled joints melt, then there’s the potential for these types of catastrophic failure.”

The thaw is reshaping the landscape in visible ways — altering colour, texture, and solidity of terrain, spawning or enlarging glacial meltwater lakes, and, over longer timescales, threatening the very headwaters of major river systems. In much of South and East Asia, hundreds of millions of people rely on rivers such as the Ganges and the Brahmaputra, whose flows originate in Himalayan glaciers. A sustained retreat of those ice bodies would compress seasonal water availability and intensify both flood and drought extremes.

A Pattern Across Continents

Scientists assign high confidence to the conclusion that glacier retreat is driven by human-induced global heating — the combustion of gas, oil, and coal. Collapse events are no longer confined to one range: documented failures have occurred from the Alps to the Andes. In the Langtang catchment area of Nepal specifically, a peer-reviewed study found that glacier loss rates have accelerated by more than fourfold since 1964, a trajectory that has already contributed to multiple loss-of-life events.

The Bhotekoshi corridor is not new to such disasters. A smaller flood struck the same river system in July 2025. In 2015, an earthquake-triggered avalanche on Langtang Lirung obliterated the village of Langtang, killing hundreds and leaving the community in ruins. Each event has been treated in isolation; the accumulating record now points to a systemic vulnerability that will worsen as warming continues.

For the communities living along the Bhotekoshi and its tributaries, the question is no longer whether the next failure will occur, but how quickly infrastructure, early-warning systems, and land-use planning can adapt to a mountain environment that is, in measurable and accelerating ways, losing its structural integrity.