On August 16, 2024, Thame, a village in Nepal experienced a disastrous event. Thame, at an altitude of 3,800 meters in the Everest region, was affected by a sudden outburst of water from a glacial lake. In just 30 minutes, the water destroyed the whole village as the village was converted into mud. Everything was destroyed – homes and schools. Fortunately, the people were safe. They had either gone to Kathmandu or Namche Bazar for bathing and shopping. Sadly, less than a year later, the same incident was repeated in July 2025. Another glacial lake on the Purepu glacier burst. This time, the consequences were very sad. Some people lost their lives, dozens went missing, and an important international bridge was completely destroyed (Lord, 2025).
What is a GLOF?
The increase in temperatures due to climate change has caused glaciers to melt extensively to produce a lot of meltwaters which then gets collected behind dams made of rocks, ice, and sand. These dams can break easily, and it is not hard for the break to happen/occur.
There are a few ways the dam can break can happen:
- An avalanche can happen and put a lot of weight on the dam, causing it to break
- A landslide occurring close to the dam can cause changes in the rocks supporting the dam
- The pressure of the water on the dam due to the rising water levels can cause the waters to break free.
When the dam breaks, water, rocks, and mud mixes and gets pushed down the valley, causing destruction in its path. Melting glaciers have created more than 25,000 glacial lakes across the Himalayan region. Of these, Nepal has been particularly affected; at least 24 of its glacial lakes have already drained or burst in past events, and ICIMOD has flagged 47 more as highly dangerous (International Centre for Integrated Mountain Development [ICIMOD], 2020; United Nations Development Programme [UNDP], 2020).
The Hidden Danger of Small, Unmapped Lakes
Scientists used to focus their efforts on satellite tracking of major glacial lakes in the region for a number of years. However, the recent tragedies reveal that it was a huge mistake, since small lakes can be equally dangerous.
Take a look at the case of the Thame flood, for example. It turned out that the lake that burst was extremely small and was only 0.05 square kilometers in area. Nevertheless, when it burst, the water came out with a staggering peak speed of 800 cubic meters per second. To make things worse, the flood reached the village within just 22 to 32 minutes after the burst of the lake (Khadka et al., 2026).
The water source that was responsible for the tragedy at Another striking example comes from Rasuwagadhi, the site of the Purepu glacier lake, burst. The water source responsible for this tragedy is still a mystery today; it only appeared on satellite maps a few months before the disaster. The mapping specialists from ICIMOD explain that such tiny ice ponds are rapidly and inexplicably increasing their size, transforming into an invisible danger in the mountains.
Downstream Destruction and Cultural Loss
The destructive power of these glacial lake floods travels far beyond the mountains. The floods devastate the regions along the way. One flood hit Nepal's 80-kilometer river span. Another flood in Upper Mustang wiped off the map 35 kilometers of river. Scientists predict that in 2050, the Hindu Kush Himalaya ecosystem will reach its highest point of glacial hazard, the point at which accelerated glacier melt produces the greatest number of unstable, flood-prone lakes, before glacier volumes eventually shrink enough to slow new lake formation. When that happens, floods will happen thrice as often and cause damage worth billions by destroying dams, roads, and fields. Besides money and buildings, floods target entire communities. UNESCO noticed this vulnerability and initiated a project aimed at documenting the impact of floods on the cultural heritage (UNESCO, 2026).
The Race to Mitigate Risk
Nepal has taken proactive measures to counter this issue. Following the Thame tragedy, the country received assistance from the United Nations Development Programme and the Green Climate Fund. The agencies have provided funding worth $36 million to help Nepal strengthen its flood protection systems (United Nations Development Programme [UNDP], 2025). Some of the initiatives designed today include different measures aimed at keeping these lakes empty before they become full artificially low before they can reach dangerous volumes done through methods like siphoning or cutting controlled drainage channels, similar to the ongoing lowering of Tsho Rolpa Lake in Nepal alongside installing early warning systems for downstream communities and using satellite monitoring to catch changes in these water bodies early, installing early warning systems to warn downstream communities, and using satellite systems to catch any potential changes occurring in the water body. However, the biggest challenge lies in locating these famous minute lakes before they cause havoc.
Crossing Borders: The Dharali Disaster in Uttarakhand
The crisis is evident across borders. The natural disaster results from climate change and weak natural barriers in the Indian Himalayan region. On August 5, 2025, flash floods hit the Kheer Gad region, wiping out the village of Dharali in Uttarkashi district in Uttarakhand. The tragedy resulted in the death of at least 5 people and left more than 50 missing. While the media reported this incident as a natural flood at first, geological analysis proved otherwise: a naturally occurring moraine dam situated 4700 meters above sea level near Srikanth Parbat had broken down. As it turned out the disaster happened as a result of the complex mix of heavy rains, quick melting of glaciers, and the presence of a dangerous natural dam (Nainwal et al., 2026). The geologists pointed out one more serious factor: human activity. The construction of roads, hydropower plants, and the absence of regulation of tourism development have destabilized the area. At the end of the day, the example of Dharali is a reminder of the fact that there is a shared danger for mountainous regions of both India and Nepal.
A Himalayan Reckoning
Climate change is glaringly evident in the mountains, particularly through glacial lake outburst floods (GLOFs). These floods can change the tranquil, frozen landscape into destruction almost instantly. From the Himalayas, the river systems are crucial for many ecosystems and around 260 million people, or almost a quarter of the world's population, living downstream. With so many lives depending on these waters, comprehending and preventing such sudden occurrences has become a global issue, not merely a local one.
References
International Centre for Integrated Mountain Development & United Nations Development Programme (ICIMOD). (2020). Glacial lakes and GLOF risk in the Hindu Kush Himalaya. In Moving Mountains: Preventing glacial lake outburst floods in the Third Pole (COP27 Brief). ICIMOD.
Khadka, N., Pandey, V. P., Watson, C. S., Zheng, G., Wu, T., Sharma, K., Rawlins, L. D., Allen, S., & Gouli, M. (2026). The 2024 cascading glacial lake outburst flood in the Thame Valley of Everest region, Nepal: process, impacts and implications [Preprint]. EGUsphere. https://egusphere.copernicus.org/preprints/2026/egusphere-2026-2011/
Nainwal, H. C., Pandey, A., Shah, S. S., Kneib, M., Sati, M., Tripathi, U., Chauhan, A. S., & Adhikari, L. (2026). Hydro-meteorological analysis of the Dharali-Uttarkashi flash flood event of 05 August 2025. Landslides, 23(7), 1951–1965. https://doi.org/10.1007/s10346-026-02747-4
Lord, A. (2025, August 7). Investigating an emerging climate hazard: Transboundary glacial floods on the china-nepal border • stimson center. Stimson Center. https://www.stimson.org/2025/investigating-an-emerging-climate-hazard-transboundary-glacial-floods-on-the-china-nepal-border/
United Nations Development Programme (UNDP). (2025, July 3). Green Climate Fund approves $36.1 million to help Nepal protect lives and livelihoods from glacial flood risks. https://www.undp.org/press-releases/green-climate-fund-approves-361-million-help-nepal-protect-lives-and-livelihoods-glacial-flood-risks
UNESCO. (2026, June 26). After catastrophe in the Himalayas, UNESCO and Thame's community rebuild resilience through living heritage. https://www.unesco.org/en/articles/after-catastrophe-himalayas-unesco-and-thames-community-rebuild-resilience-through-living-heritage