How Melting Ice Buried a Village in Nepal

Mountain glaciers are disappearing and threatening local settlements in their way

Thame River flood damage. Credit: Nepal Police/The Kathmandu Post

* * * A version of this article first appeared on The Southern Winds.

The Event

On August 16, 2024, a swift-moving flood along the Thame River buried a large portion of a village in the Khumbu Pasang Lhamu Rural Municipality in Solukhumbu District, Nepal. According to Mingma Sherpa of Thamechho Kydug, the glacial structure containing Thengbo Lake near Tashi Lapcha Pass burst, releasing the contents of the lake into the river virtually all at once. This sudden deluge raced downstream, crashing over the village, also called Thame.

Subsequent analysis indicated that a second glacial lake discharged simultaneously. At elevations above the Khumbu area, there are (were) five glacial lakes. Two gave way, causing this flood event; three more remain. Chief District Officer Devi Pandey Khatri of Solukhumbu warned that two of the remaining three appear unstable and still pose a threat to the areas downstream.

What befell the village of Thame was the result of what is known as a Glacial Lake Outburst Flood (GLOF). These events occur when lakes high up in the mountains breach their containment barriers and suddenly force copious amounts of water into riverways not particularly suited for such enormous added volume. Below, I discuss how climate change contributes to the development of glacial lakes, the basic structure of the two primary types, and why they explosively discharge.

Before that, however, as a part-time resident of Nepal and one who works toward mitigating the effects of all kinds of natural disasters, I wanted to know how the Thame villagers faired.

To find out, I reached out to my friend Kami Rita Sherpa for some details. He is from there. Kami Rita is the current world record holder for summitting Mount Everest more times than any human ever (click the story below to read about our first conversation from which we became friends). He is one of several famous sherpas, the “guardians of Everest,” who call this village home. Here is what he told me:

The disaster happened in the daytime, so thankfully no one was hurt. If it happened at night, who knows what would have happened, but it would have been much worse. I urge the climbing community and anyone else to consider supporting the residents of Thame. We need your assistance to recover and rebuild.

A Global Trend: Degrading Mountain Ice

Over the last few years, the public has become increasingly aware of the problem of the planet’s rapidly retreating glaciers. The concern seemingly almost always focuses (in the layperson sphere, anyway) on the great ice shelves of the polar north and south. This is understandable, given the sheer size and visual attractiveness of the landscape there. Moreover, when people think about glaciers or harsh tundra generally, undoubtedly the polar regions come to mind foremost.

Yet, lesser-noticed but equally important masses of ice are also at risk, and the implications are no less concerning. Mountain glaciers across the world are rapidly melting, in many cases faster than the ice at the poles.

Snowpack and glaciers at the highest elevations provide critical resources for at least three billion people globally. Cyclical melting and refreezing once followed a consistent pattern, fostering agriculture and industry. These natural patterns provided predictability in regional weather and river flows, allowing people to organize their societies based upon them. Moreover, these factors enabled the production of electricity by hydropower, an unquestionably cleaner form than fossil fuels. These are all now facing calamity and chaos.

Disruptions in these millennia-long patterns have readily foreseeable disastrous results. Every mountain range in the world is undergoing chaotic change, including glacial melting. And in nearly every one of these places the speed of the melt exceeds any comparable rate over the last thousand or more years. Smaller glacial zones face near to total disappearance in just a few decades.

In a recent piece, Ricky Lanusse illustrated what is happening in the Andes Mountains. He explained:

Another research from May 2024 reveals that the central range of Peru, near Lima, could lose 84 to 98% of its glaciers by 2050, with complete disappearance expected by 2056. This troubling projection comes as Peru, home to approximately 68% of the world’s tropical glaciers, has already seen over half of them vanish in the last 60 years, according to a recent government report published in October 2023.

Alpine ice is fairing no better. In a previous piece, I wrote:

Using AI modelling coupled with satellite and other inputs… research indicates about a 34% decrease in ice volume with a reduced coverage area [of] around 32% [so far]… At the worst, alpine glaciers could see an abatement of ice by over 65% between now and 2050.

In Africa, the IPCC predicts the total loss of glaciers on the Rwenzori Mountains and Mount Kenya by 2030. A similar consequence is expected for all of the smaller glacial masses in mountain ranges across the world over the next half century or so. These include those in the European Alps, Pyrenees, Caucasus, North Asia, Scandinavia, tropical Andes, Mexico, eastern Africa, and Indonesia.

South-facing view of Kalinchowk’s Kuri Village in Dolakha District, Nepal. I took this photo about 11 miles south of the Nepal-China border and the Himalayan Ganesh Himāl sub-range.

Himalayan Ice Loss

The loss of Himalayan ice poses a problem of greater significance than that of any other mountain range in the world. The problems are the same as those outlined above, but the difference is in the number of people they will affect.

Himalayan mountains feed (either directly or indirectly) some of the most important rivers in the world, including the Indus, Ganges, Brahmaputra, Yangtze, Yellow, Mekong, Salween, and Tarim. As many as two billion people rely on them for drinking water and farming; the agriculture of many surrounding areas receives as much as three-quarters of their total irrigatable water from mountain runoff.

Warming temperatures have drastically altered weather patterns in the Himalayas. Snowfall rates and snowfall coverage area (meaning where it snows) directly affect snowpack depth. All three have decreased in recent decades across most of the Himalayan Mountains (with the slight exception being the Karakoram area). Snowpack provides insulation against warming by reflecting approximately 90% of incident radiation back into the atmosphere. As snowpack diminishes, it exposes larger sections of both glacial ice and surface rock. These exposures intensify glacial melt.

A study of South Col Glacier, the highest in the world, found that decades’ worth of mass accumulation is now being lost each year. These researchers added that because the highest-elevation glaciers typically host smaller snowpacks, lower snowfall rates can increase glacial ablation by a factor of twenty. Changing winds and atmospheric humidity exacerbate this degradation.

The South Col Glacier is but one example of a trend across the entirety of the Himalayan Mountains. One group of researchers reconstructed 4,798 Himalayan glaciers from the Little Ice Age — 400 to 700 years ago — to the present. They concluded:

The ten-fold acceleration in ice loss we have observed across the Himalaya far exceeds any centennial-scale rates of change that have been recorded elsewhere in the world.

Glacial melt is the primary generator of glacial lakes. As these bodies of water become more prevalent, the risk of catastrophic GLOFs rises. About a year and a half ago, I wrote a detailed article about the impact of climate change in Nepal. In that piece, I discussed GLOFs:

Glacial melt results in the formation or expansion of new glacial lakes, which increases the chance of glacial lake outburst floods (GLOF). According to research conducted by the International Centre for Integrated Mountain Development (ICIMOD), four GLOF events have occurred since 2003 that resulted in significant damage or casualties. ICIMOD also determined that there are currently 47 glacial lakes that pose a significant risk to lower-lying populations based on their volume, location and geological damming. Faster melting glaciers will undoubtedly compound this danger for the affected populations in the years to come.

The rapid glacial melt in the Himalayas directly contributes to the growth in the number and size of glacial lakes. Other factors associated with climate change and human activity generally worsen the chances of a GLOF event, causing considerable property damage, injuries, or deaths. These include the urbanization of at-risk areas, which leads to the destabilization of natural protections against flooding.

The Anatomy of the Glacial Lake

Glacial lakes form when glaciers retreat from the glacial till — the rocky debris fields culminated from repeated glacial advances and withdrawals over eons. Meltwater pours into low-lying areas either between the till and the ice-front of the glacier or in geological depressions carved out from glacial erosion.

The latter of these are called moraine-dammed glacial lakes. When the retention of water depends upon the ice front itself, they are referred to as ice-dammed glacial lakes. In other words, the water collects in the low topographies but is held there by ice from the glacier itself. Both ice- and moraine-dammed lakes are dangerous, but for somewhat different reasons.

This image shows a glacier lake with lateral moraines on the right and left. The glacier till is still visible at top. The ice dam is below (outside of the picture). (Credit: ICIMOD)

Moraine-dammed lakes become GLOFs when the water breaches the surrounding earthen or stone structural barriers. This usually occurs when a sudden, large mass is added to the lake body. Examples include rockslides or calving of adjacent glaciers. The effect is the same as dropping too many ice cubes into a cup of water, causing the water to pour over the edges. Less common causes include exceedingly heavy rainfall or rapidly melting snowpack or glacial ice, both of which create excessive volume, or earthquakes that disrupt the physical structure of the moraine.

Ice-dammed lakes also become GLOFs because of excessive volume. These can occur suddenly or from a build up over long periods. Because the retaining wall(s) is made of ice, when the water reaches sufficient volume to support the bulk of the ice dam it will float upward. This allows for the rapid release of lake water beneath. After a substantial amount of water escapes, what remains can no longer support the weight of the ice dam allowing it to resettle upon the stone bed and shut off any further outflow. Warmer temperatures weaken ice dams by diminishing their mass, rendering them more susceptible to floating, while adding to the liquid volume of lakes.

In either case, the implications downriver can be severe because an enormous volume of water is instantly added to an existing riverbed. At high elevations, riverbeds tend to be narrow and surrounded by steep topography, so the water has nowhere to go but downstream. Moreover, like a landslide, the water can carry with it massive amounts of debris.

Moraine GLOFs are more dangerous in the short-term because they typically comprise higher discharge volumes than ice-dammed GLOFs (Clague and Evans, 2000). Upon an outburst, however, moraine damming tends to be destroyed eliminating the possibility of the lake reforming. Ice-dammed GLOFs release smaller amounts of water, but because they “reseal” following the discharge they can cause repeated floods from the same glacial lake. In either case, the water often accompanies debris like mud, boulders, or sediment.

GLOF Risks in The Himalayas

The International Centre for Integrated Mountain Development’s (ICIMOD) GLOF dashboard provides data on historical and contemporary incidents, marking 703 events resulting in 7,008 fatalities going back nearly two centuries. Of these, 23% involved the same lake body on at least two occasions. Avalanches, rockfalls, and landslides caused 54% of all incidents. Heavy rainfall was responsible for 18% of them. ICIMOD identifies the Karakorum range of the Himalayas as the region where GLOFs represent the greatest risk.

The frequency of GLOF events has increased since 1980, but especially in Southeastern Tibet and the China-Nepal border since 2010. One study estimates that approximately 6,353 square kilometers of land currently lie at risk of exposure to a GLOF event. According to these researchers, that comprises 55,808 buildings, 105 hydropower projects, 194 square kilometers of farmland, 5,005 kilometers of roads, and 4,038 bridges.

A case study articulated the damage of one event, the 2016 Bhote Koshi River GLOF in Nepal, as follows:

20 concrete houses, a boarding school and parts of a customs office were swept away, and dozens more buildings were damaged. Large stretches of roads fell apart, including along a highway that links Nepal to China; a hydropower plant was severely impacted. Rapid evacuations and rescue missions prevented deaths, but the economic damages were estimated at about $70 million.

Nepal endured twenty-six GLOF events between 1977 and 2020, with nearly half of them originating outside the country. This statistic highlights a key challenge in monitoring and managing them. Because the Himalayas feed rivers that span multiple countries, GLOFs can start in one but cause significant damage in another. A study of glacial lakes determined that one in six of them posed a risk to at least two countries. It anticipated a three-fold increase in the danger over the next few decades. Another study estimated that at least 15 million people globally live in very high-risk areas.

Damage from a flood in Kagbeni, Mustang, Nepal, in 2023. Credit: Volunteer Corps Nepal.

Mitigating GLOFs

Unfortunately, not a lot of solutions exist to mitigate the current societal and economic impact. Many areas most at risk of catastrophic damage simply lack the resources to conduct any large-scale projects that are probably needed to be effective. Even then, effective here means mitigating potential damage; no one has devised a way to prevent GLOFs altogether. Nonetheless, smaller, community-centered efforts are underway in many localities.

In Bhutan, government and private sector organizations have engaged in campaigns to educate people on what GLOFs are and under what conditions they are likely to occur. The same is true in Nepal. My organization, the EALS Global Foundation, works closely with Volunteer Corps Nepal (VCN) to provide information about GLOFs to villagers living along rivers who are potentially exposed to GLOFs.

Another path toward reducing the loss of life from GLOFs is the implementation of early warning systems. In many areas of the Hindu Kush Himalaya region, ICIMOD has launched its community-based flood early warning system (CBFEW). This program recruits volunteers to monitor areas for evidence of flood potentiality. When conditions meet a certain threshold, these volunteers alert communities downstream to provide them time not only to flee but to take with them livestock and other items critical to their livelihoods. EALS Global is working to buttress this system through the use of advanced technology that can monitor and notify harder-to-reach locations.

Wilfried Haeberli and Alton C Byers recently proposed other mitigation ideas in the Nepali Times. These include standardizing how scientists evaluate glacial lakes for stability or the level of hazard they pose. Another is to expend more resources on studying the melting of permafrost layers in the mountains. On this, they note:

Thawing frozen mountains means softening them, making them less resistant against gravity, leading to breakage of small to large sections, resulting in rock falls, rock avalanches, and landslides.

Relatedly, they suggest improving early warning systems at the site of glacial lakes. This would include not only installing reliable detection measures, but increasing training for locals to understand what to do with the subsequent information to best ensure that communities can escape any effect from GLOFs.

Finally, they encourage enhanced facilitation of communication among scientists. This is especially necessary for breaking down some of the boundaries that are artificially created by the structure of funding in both the scientific and nonprofit world.

None of these are perfect solutions. For the time being, however, perhaps no perfect solutions exist. Until the world takes climate change more seriously, these events will not only persist, but they will inevitably rise in number.

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For more on the dangers of melting ice, click below.

I am a Certified Forensic Computer Examiner, Certified Crime Analyst, Certified Fraud Examiner, and Certified Financial Crimes Investigator with a Juris Doctor and a Master’s degree in history. I spent 10 years working in the New York State Division of Criminal Justice as Senior Analyst and was a firefighter before that.

Today I work both in the United States and Nepal, and I currently run a non-profit that uses mobile applications and other technologies to create Early Alert Systems for natural disasters for people living in remote or poor areas. In addition, I teach Tibetan history and culture, and courses on the environmental issues of the Himalayas both in Nepal and on the Tibetan plateau. For more content, head over to my Medium page.