Seven minutes to disaster: How climate change exposed a Himalayan blind spot

(Edited and refined by Grace Chong, with the assistance of AI translation.)

A section of a Himalayan glacier in Nepal collapsed on 26 August, triggering a catastrophic mudslide. The cross-border disaster involving China and Nepal not only caused significant loss of life and property, but also highlighted the new and increasingly complex risks posed by extreme mountain hazards in a warming world.

A growing threat in a warming world

Experts say the number of highly dangerous flash flood events worldwide has risen significantly over roughly the past decade. The source of this disaster was in a monitoring “blind spot”: neither China nor Nepal, nor the international scientific community, had previously identified the site as being at risk of becoming unstable.

The Wall Street Journal reported that high-altitude ice around the world is rapidly melting or collapsing, making frozen soil and mountain slopes increasingly unstable and raising the risks of landslides, glacial collapses and floods. As temperatures rise, those risks are intensifying for high-altitude communities across Asia, Europe and North America. Meltwater from Alaska’s Mendenhall Glacier has become an annual threat, while the Swiss Alps experienced a glacial collapse and subsequent landslide last year that virtually destroyed an entire village.

According to Agence France-Presse, Ludovic Ravanel, a geomorphologist at the French National Centre for Scientific Research, said the Alps experienced an exceptionally hot summer this year, with rockfalls reaching a record high. Some of them resulted in fatalities.

Koji Fujita, a professor of glaciology at Nagoya University in Japan, said the scientific community broadly regards glacial retreat as an accelerating global trend, particularly since 2020. It is estimated that between 2022 and 2023 alone, the Swiss Alps lost ice equivalent to about 10% of their total volume — roughly the same amount lost over the 30 years from 1960 to 1990.

Ecosystems face mounting uncertainty

At the same time, uncertainty within ecosystems is increasing. A study published in Nature Communications on 21 August found that model projections for 2025 to 2100 suggest that variations in water availability across the Tibetan Plateau could widen, hydrological buffering capacity could weaken, and system entropy could increase, pushing the overall system towards greater disorder.

The researchers stressed that this does not mean the Tibetan Plateau will inevitably undergo a “tipping point”-type collapse. Rather, under continued warming, the stability and resilience of its hydrological system may decline.

The South China Morning Post reported that Chen Xiaosong, the study’s lead author and a physicist at Beijing Normal University’s School of Systems Science, said on 27 August that, from now until the end of the century, “the increase of soil water and the intensification of glacier melting [in the Tibetan Plateau] will constantly trigger such geological disasters”.

Tenzing Chogyal Sherpa, a Nepalese glaciologist at Utrecht University in the Netherlands, said climate change is not the sole cause of every landslide or ice-rock avalanche, “but it is increasingly changing the conditions in which these events happen”.

More people are exposed to high-risk areas

Climate is not the only factor. Greater human exposure in high-risk areas is also amplifying the impact of disasters.

The New York Times reported that Nepal’s Rasuwa district has undergone significant economic development over the past decade, with China-Nepal trade, border crossings, Chinese-backed hydropower projects and tourism all expanding and drawing more people into the area. At the same time, it is one of the parts of Nepal most vulnerable to natural disasters.

Residents along the Nepal-China border in Tibet received no warning before the mudslide struck on 26 August, highlighting the limitations of monitoring and early-warning systems in extremely high-altitude areas.

Sherpa said the Hindu Kush Himalaya region, which spans eight countries across Asia, is home to more than 60,000 glaciers. Monitoring such a vast area presents an enormous challenge, particularly for poorer countries.

A disaster that unfolded in minutes

The speed at which the disaster unfolded made early warning even more difficult. Liu Qiao, a researcher at the Institute of Mountain Hazards and Environment of the Chinese Academy of Sciences and the Ministry of Water Resources in Chengdu, told Sanlian Lifeweek Magazine (《三联生活周刊》) that meltwater generated by melting ice, together with the air blast created by its high-speed movement, reduces friction and provides lift for all the material carried along by the flow.

As a result, the entire mass moved extremely quickly. It took only about seven minutes for the ice-rock avalanche to reach Gyirong Port after it occurred, leaving an extremely short window in which to issue a warning and too little time for people to evacuate.

An analysis published by the US think tank Stimson Center said the source area of the disaster was in a genuine monitoring blind spot. China, Nepal and the international scientific community had not previously identified the site as an emerging risk. The analysis stressed: “No one held back any information. The speed and intensity of this event were overwhelming for all.”

The article said more than a dozen extreme flooding events had occurred in the Himalayan region over the past decade. With the exception of the 2023 South Lhonak Lake outburst in Sikkim, all originated at locations that had not previously been monitored.

Existing early-warning systems rely primarily on weather stations and river gauges and were established to monitor monsoon flooding and known glacial lake outbursts. When sudden ice-rock avalanches and high-speed floods occur, there is often insufficient time to monitor the event, confirm what is happening and issue a warning.

Closing the monitoring gap

The Stimson Center recommended combining satellite remote sensing with seismic, meteorological and river monitoring, while also making use of local people, such as herders and mountaineers, to identify unusual activity. It also called for stronger information sharing between China and Nepal and greater transboundary risk analysis.

CCTV reported on 29 August that China’s Ministry of Water Resources’ emergency hydrological monitoring team said the barrier lake formed upstream by the mudslide on the China-Nepal border had resumed normal natural outflow and was essentially drained.

Rescue workers, about 1 kilometre from Gyirong Port, used large excavators and other equipment to excavate the mountainside and advance towards the port. Their progress, however, was constrained by factors including the high-altitude canyon terrain, the limited working area in the Gyirong Tsangpo valley and rainfall.

Xinhua News Agency separately reported that rescue teams continued searching the site of the mudslide disaster at Gyirong Port, carrying out sweeping inspections and grid-based searches of key areas.

This article was first published in Lianhe Zaobao as “中尼边境泥石流：气候变暖加剧风险 预警存盲区”.

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