Published on: 2026-08-29
Source: United Nations – Объединенные Нации –
An important disclaimer is at the bottom of this article.
Fabrice Robinet
August 28, 2026 Climate and Environment
Just a day before a giant wall of ice, rocks, and mud descended onto the Himalayan valleys near the Nepal-China border, climatologist Dipesh Chapagain was discussing with a colleague the scale of the disaster that such an event could cause.
For a 40-year-old researcher who grew up on the hills of eastern Nepal and is now working at the United Nations University branch in Bonn, this topic is not only professional but also deeply personal. The changes threatening the region are happening right before his eyes.
“When I was a child, everything was different,” he shares. “Neither my parents nor my grandparents faced threats on such a scale.”
Disasters are happening more frequently
On Wednesday at 8:37 a.m. local time, part of a mountain massif collapsed in the Himalayas. The rocky base beneath the glacier gave way, and a colossal mass of ice and rock fell down, covering about 1200 meters vertically.
The disaster was so massive that seismic instruments recorded an impulse equivalent to a magnitude 5.2 earthquake.
A torrent of water, sediment, and boulders poured into the riverbeds. It swept away several settlements along one of the most important trade routes connecting Nepal and China. At one of the hydrological stations, the water level rose by nine meters in just half an hour.
© United Nations University/O. Gonzales Dipesh Chapagain at the United Nations University in Bonn, Germany.
By Friday, the death toll in Nepal and Tibet exceeded 500 people, with more than 1,500 reported missing, including hundreds of foreign tourists.
The Chapagain family was not harmed, but this news resonated with pain in him.
“Every time, it is unbearably hard to receive such news from home,” he says. “And these disasters are happening more often and becoming increasingly destructive.”
What happened is a harsh confirmation of climate scientists’ fears. The icy structure of the Himalayas is rapidly changing, and millions of people are left defenseless against the force of nature, whose behavior is becoming increasingly difficult to predict.
How a mountain landslide turned into a deadly flow
Scientists continue to reconstruct the chronology of events on Wednesday. Analysis of satellite images shows that the bedrock beneath the glacier lost stability, causing a mass of ice and rocks to collapse into Lhende-Kholu — a tributary of the Bhote-Kosi River. This triggered a cascade of destruction.
The disaster mechanics differ from glacier lake outburst floods, which Dr. Chapagain studies within the mountain regions research program at the United Nations University Institute for the Environment and Human Security. Chapagain and his colleagues focus on the Hindu Kush-Himalaya region.
According to the program’s data, covering the period from the beginning of observations up to 2024 (a total of 493 cases), the frequency of lake breaches since 1950 has increased approximately fivefold – from seven to 34 cases per decade.
Such floods usually occur when meltwater accumulates in bodies of water near retreating glaciers, often held back by unstable ice or loose mountain rocks and bottom sediments. When such a natural dam breaks, a huge volume of water is released almost instantly.
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However, on Wednesday the scenario was different. “This time there was no intermediate stage,” explains Chapagain.
Instead of a gradual accumulation of water in the lake, there was a sudden collapse of a rock and ice mass. Researchers are currently testing the hypothesis that the debris may have briefly blocked the river, creating a temporary dam that subsequently broke under the pressure of the water (this version has not yet been officially confirmed).
For specialists, the difference in mechanics is fundamental, although the outcome downstream looks equally catastrophic: a giant flow of water, ice, and debris squeezed through a narrow channel instantly engulfs settlements.
It is too early to say whether the climate factor was the cause of the collapse. However, global warming is rapidly changing the high-mountain environment: glacier melting and permafrost degradation destabilize rock masses, and meltwater washes away the slope, reducing its strength.
The consequences extend far beyond the high mountain villages. The Hindu Kush-Himalayan massif feeds the 10 largest river basins in Asia, on whose resources 2.1 billion people depend.
At risk
Not only the mountainous landscape is changing – the geography of human settlement is also changing. Dipesh Chapagain recalls that in his childhood, residential houses in the mountainous regions of Nepal were traditionally built higher up on the slopes, while the lowlands near rivers were used for growing rice. His family’s house stood on the top of a hill, and the plots for growing rice were located below, by the water.
Over time, infrastructure – roads, businesses, hotels, and hydroelectric power plants – began to concentrate in river valleys: it’s easier to build and conduct business there. Additionally, sources of drinking water located at high altitudes gradually dry up, forcing people to move lower.
This has led to a dangerous trend: as warming destroys mountains, populations and key infrastructure assets are concentrated directly in the path of potential mudflows and water streams.
© UNICEF/L. Prasad-Ngahusi Buildings and streets in the settlements of Nepal’s Bagmati Province are covered in mud.
The valley affected on Wednesday is a vivid example of such development. Along the Bhotekoshi–Trishuli transport corridor leading to Kathmandu, there are hydropower plants, bridges, hotels, and residential neighborhoods. The flood destroyed energy facilities and disrupted transportation and communication throughout the region.
The potential danger was obvious; disasters had happened before: just a year ago, a glacial lake outburst in the same river system took the lives of nine people, and another 24 went missing.
When every minute counts
Wednesday’s events revealed another problem – the imperfection of the early warning system.
The Nepalese authorities learned about the approaching flood only when the flow was already nearing the border. Alerts were transmitted via SMS, social networks, calls, and emergency notifications on phones.
According to Chapagain, the risk of floods can only be reduced by implementing a set of measures at the earliest stages: continuous monitoring of glaciers and unstable slopes using satellites is necessary, expanding the network of meteorological and hydrological stations, as well as implementing early warning systems that give people time to evacuate.
Given the transboundary nature of rivers and glaciers, China, Nepal, and the downstream countries must establish operational data exchange.
But there is a deeper problem. Even if greenhouse gas emissions are sharply reduced, glaciers will continue to lose mass for several more decades due to the inertia of the climate system. Humanity can still influence how much ice will be preserved in the long term, but scientists are unable to prevent the processes that will occur in the coming years.
This means that adapting to new conditions is not preparation for a distant future. For the residents of the Himalayas, that future arrived already on Wednesday.
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