The Himalayas are the world’s youngest and one of its most geologically unstable mountain ranges. Earthquakes, landslides and glacier melt are deeply interconnected here. The glacier-related disaster along the Nepal–Tibet border on August 26, 2026, highlights climate change as one of the key factors behind the growing risks in the region.
Climate change, rising temperatures and shifting monsoon patterns have created or intensified conditions that are destabilising the Himalayan ecosystem. The immediate trigger, however, was the collapse of a glacier or an avalanche involving ice and rock, followed by a massive debris flow.
One important point needs to be understood: climate change does not necessarily produce a “flood” directly every time. Instead, it first changes the entire structure of risk.
On August 26, a large section of a glacier in the upper reaches of the Lhende Khola River in Nepal’s Rasuwa region fell from an altitude of around 5,200 metres to nearly 1,200 metres below. It carried ice, rock and debris with it, suddenly generating an extremely powerful flow in the river. This was followed by flooding in the Bhotekoshi and Trishuli river systems. In some locations, water levels rose by as much as nine metres within approximately 30 minutes.
The flood devastated towns located along the riverbanks, destroyed more than 10 hydropower projects in its path, and washed away more than 50 kilometres of highways and 30 bridges.
Initially, an earthquake was considered a possible cause. However, subsequent satellite and seismic analyses indicated that what was initially interpreted as an earthquake signal was actually a seismic signal generated by the large-scale collapse of a glacier or rock mass. The United States Geological Survey (USGS) has described the incident as a sudden glacier collapse associated with a debris flow.
A Fragile Mountain System Under Pressure
Rising temperatures in the Himalayas are causing glaciers to retreat rapidly and lose ice mass. The rate of glacier loss across the Hindu Kush–Himalaya region has accelerated. Nepal’s glaciers have lost roughly one-third of their ice volume over the past three decades.
This does not mean that every glacier will collapse. But it does mean that the structure of glaciers and the geography surrounding them are changing. Melting ice does not merely increase the amount of water; it can also weaken the mountains themselves.
In the high Himalayas, ice frozen between rocks and soil—known as permafrost—acts like a natural “cement”. As it thaws, mountain slopes can become increasingly unstable.
It is therefore inadequate to describe these disasters simply as “natural disasters”. The hazard may be natural, but the scale of a disaster is often shaped by the combined effects of climate change, fragile geological systems and growing human activity in river valleys.
Uttarakhand is widely seen as a state of snow-covered peaks, dense forests and rivers. Yet the character of its land has changed rapidly over the past three decades. Between 1992 and 2022, snow-covered areas declined, natural vegetation decreased, while the built-up area increased nearly thirteenfold.
Unplanned and unscientific development is further increasing climate vulnerability. Roads that are unnecessarily widened by cutting into the lower sections of mountain slopes, large-scale hydropower projects, rapidly expanding military infrastructure, settlements and other construction are spreading through extremely fragile Himalayan valleys and river corridors.
These are precisely the areas that are highly vulnerable to catastrophic floods and landslides.
At the same time, changes in rainfall and temperature patterns are becoming increasingly evident.
In India’s Himalayan regions, particularly Uttarakhand and Sikkim, three major and devastating glacial lake outburst flood (GLOF) events have been recorded in recent years, killing hundreds of people.
The experience of Sikkim provides a particularly important example.
When a Known Risk Is Ignored
In 2013, scientists at India’s National Remote Sensing Centre (NRSC) assessed the risks associated with South Lhonak Lake. Their findings were alarming: the study estimated a 42 per cent probability that the lake could breach.
The danger was therefore documented in government records and known nearly a decade before the disaster occurred.
Yet directly downstream of the lake stood the 1,200-megawatt Teesta-III hydropower project at Chungthang, one of Sikkim’s largest hydropower projects. Over the following decade, the lake continued to expand while the dam continued to operate normally.
Despite the known risk, no comprehensive plan was put in place to evacuate people to safer locations. No necessary structural modifications were made to the dam, nor were adequate safety arrangements established commensurate with the threat.
Then, in the intervening night of October 3–4, 2023, the lake breached in precisely the manner anticipated by the earlier assessment.
The resulting flash flood destroyed the dam within hours. Fifty-five people died and 74 went missing. More than 7,000 people from 1,756 families were rendered homeless in Sikkim, while more than 2,000 houses were completely destroyed across the districts of Mangan, Gangtok, Namchi and Pakyong.
The matter took another startling turn about 14 months later. Regulators approved the reconstruction of a dam at the same location. This time, the proposed dam is 118.64 metres high—almost twice the height of the original structure.
Some important technical approvals related to the project are still pending, and construction has not yet begun. A petition challenging the matter has also been filed in the Supreme Court.
Ignoring risks while pursuing hydropower development is therefore not climate resilience. It is contributing to disaster.
In fact, until comprehensive climate-risk assessments are completed, there is an urgent need to put a halt to large hydropower development in the Himalayas.
The Warning From Glacial Lakes
According to India’s disaster management authorities, of the approximately 7,500 glacial lakes across Jammu and Kashmir, Ladakh, Himachal Pradesh, Uttarakhand, Sikkim and Arunachal Pradesh, 189 could potentially become major sources of disaster. Around 56 of these are classified as extremely dangerous.
This places nearly 30 million people at significant risk.
The lakes formed by melting glaciers are not merely an ecological concern. The water released from these lakes can dramatically alter river flows. When a lake fills to capacity or its natural retaining barrier fails, the resulting flood can cause catastrophic destruction in downstream areas.
This is therefore a major warning for Sikkim, Uttarakhand, Himachal Pradesh and the entire Himalayan region.
The issue is not simply that glaciers are melting. The deeper concern is the destabilisation of the entire mountain system.
Development Must Work With Nature, Not Against It
Protecting the Himalayan ecosystem requires a fundamentally different approach to development—one based on sustainability, ecological limits and long-term risk assessment.
The Government of India has taken several important steps to monitor and provide early warnings for natural hazards in the Himalayan region, including landslides, flash floods and glacial lake outburst floods.
Modern Doppler weather radars, automatic weather stations and automatic rain gauges have been installed in Uttarakhand and other high-risk areas to improve the accuracy and availability of weather information.
In states such as Uttarakhand, vulnerable glacial lakes are being identified, while advanced sensors and early-warning systems are being deployed to detect and help mitigate the risk of flash floods.
Satellite-based monitoring and the use of artificial intelligence are also being expanded to monitor water levels in catchment areas and identify cloudburst events.
But the Himalayas do not end at national borders.
It is now time for the countries of the Himalayan region to work together to establish real-time monitoring, tracking and early-warning systems across the mountain range.
This is a message that needs to be raised more widely and more forcefully.
India and Pakistan need greater cooperation on flood-related issues. India and Bangladesh likewise need stronger coordination. More broadly, South Asia needs comprehensive regional cooperation to confront the climate crisis.
The Himalayas are not a mountain range confined within the borders of any one country. The rivers and lives of hundreds of millions of people across South Asia—including India, Nepal, Bhutan, China and Pakistan—are connected to this mountain system.
Sharing real-time data on glaciers, weather and river levels; developing joint disaster-warning mechanisms; and coordinating river and flood management are no longer optional. They are a necessity.
If the Himalayas are severely damaged, India, Nepal, Bhutan and Tibet will not be the only regions to suffer. China and Pakistan will also face enormous losses of lives, property and resources. Nepal, Bhutan and large parts of northern and northeastern India could face devastating consequences.
The Himalayas are warning us repeatedly.
The question is not whether the next disaster will come. The question is how seriously we take the warning before it does.
Alongside global efforts to address and mitigate climate change, we must fundamentally change the way we think about development in the Himalayas. Development that challenges and disregards nature can ultimately become one of the greatest threats to human security.
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*With Bargi Dam Displaced and Affected Association
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