The devastating deluge that swept through the mountain valleys on the border between Nepal and Tibet in China is a potent reminder of a growing green-energy risk in one of the world’s most hazard-prone areas.Hydropower dams high in the Himalayas seem to be a ready solution for an energy-starved region. Governments see mountain rivers as an answer to rising electricity demand, fossil-fuel dependence and economic underdevelopment. But a changing climate is bringing with it unstable glaciers and unpredictable rain, creating new risks for existing projects and raising the potential cost of those that are still on the drawing board.
“Hydropower is very important for climate change adaptation and the energy transition,” said Holger Frey, a researcher leading a group studying hazards and risks in mountains at the University of Zürich. “This is a dilemma for countries investing in renewables and hydro, and at the same time having to deal with the consequences of climate change.”
The region has already had warnings, including a glacier collapse in the Indian state of Uttarakhand in 2021 that left at least 200 dead or missing, and floods in Pakistan that left a third of the country under water in 2022. The recent catastrophe in Nepal, triggered by a landslide and glacier collapse, is a further alarm bell — hundreds of hydropower workers are among those missing in the aftermath.
The disaster wiped out about 10% of Nepal’s hydropower capacity, striking at the heart of one of Asia’s most ambitious clean-energy buildouts. Nepal, Bhutan, India and China have all dramatically expanded plans for hydropower in recent years.
But all high mountain areas with ice, glaciers and permafrost — the frozen ground that holds rocks together — are at risk, Frey said. “The big difference between countries is the amount of people and the amount of infrastructure close to these sites.”
That includes the European Alps, the Andes and most of all the Himalayas, where the risk is gargantuan. More than 40 gigawatts of hydropower capacity are already operating in the region, with another 200 GW in various stages of planning, according to Global Energy Monitor, enough to power France and Germany combined.
Chain Reactions
Despite the rapid growth of other types of renewable energy generation in recent years, hydrodams remain the world’s largest source of clean electricity, generating over 50% more power than nuclear, wind or solar in 2025, according to data from Ember. It’s also historically been more reliable than other low-carbon alternatives, although increasing frequency of floods and droughts related to climate change has chipped away at that advantage.
In the Himalayas, the terrain that makes these projects possible is undergoing rapid change. Mountains are warming faster than the average for the rest of the planet as greenhouse gases accumulate in the atmosphere. Higher temperatures are melting snow and glaciers, making these environments more unstable and putting at risk billions of people living downstream.
The danger is not simply melting glaciers, but the chain reactions they can trigger, said Rayees Ahmed, a project scientist at the Divecha Centre for Climate Change at the Indian Institute of Science in Bengaluru. “An ice-rock avalanche can interact with a river and generate a much larger downstream disaster.”
As slopes become less stable, the region faces a growing risk of glacial lake outburst floods, landslides, debris flows, ice-rock avalanches and sudden river flooding — several of these hazards have occurred over the last decade just in the area immediately surrounding where the glacier collapsed on Aug. 26.
“Hydropower is particularly exposed because many projects are located in narrow Himalayan valleys and downstream of glaciers, unstable slopes and potential flood pathways,” Ahmed added.
Surveying potential glacial lake outburst floods alone, a 2023 study found that 105 operational or planned hydropower projects were under threat in the Third Pole, an area that encompasses the Himalayas and surrounding mountain regions.
Workers at the Tapovan Vishnugad Hydropower Plant in India’s Uttarakhand state in 2024; photo credit: Prashanth Vishwanathan/Bloomberg
Nepal’s Green Battery
For Nepal, the stakes are especially high because hydropower has become central not only to energy policy but also to the country’s economic future.
The government aims to increase generation capacity more than sixfold to nearly 30 GW by 2035, with more than half of that destined for export. India has agreed to significantly increase imports of Nepalese electricity, while Bangladesh has already begun purchasing power. Electricity exports are generating record revenues, helping policymakers imagine a future in which energy narrows the country’s chronic trade deficit and attracts foreign investment.
“Nepal is the green energy battery store for the region,” said Bhim Prasad Gautam, chief executive officer of the Independent Power Producers’ Association Nepal. “India wants green energy. Bangladesh wants green energy. In the future, they must import green energy from Nepal.”
The recent flood exposed the vulnerability of that vision. Twelve hydroplants, more than 400 megawatts of operating capacity, have been damaged. In total, around 20 hydropower projects are located across the Trishuli River basin, one of the country’s most important energy corridors. Gautam estimates the disaster caused around 130 billion Nepali rupees ($850 million) in damages and may have set back Nepal’s hydropower ambitions by as much as five or six years.
Still, it’s the region’s superpowers that dominate its hydropower ambitions. India and China have the most hydropower capacity in operation and under construction in the Himalayas, respectively, according to Global Energy Monitor. China is pursuing the most ambitious project in the region, the Yarlung Tsangpo dam, which will be the world’s largest power plant when completed. Both countries are also involved in the financing and build-out of dams in countries such as Pakistan and Nepal.
“The Himalayas offer two things hydropower needs and few places have together: enormous vertical drop over short distances, and rivers fed by both monsoon rain and snow and ice melt, so they keep flowing outside the wet season,” said Joe Bernardi, a project manager with Global Energy Monitor.
Both India and China have seen the impact of extreme weather and climate change on their dams. The flood that hit Uttarakhand in 2021, similarly triggered by a rock and ice avalanche, damaged two hydropower plants. This summer, heavy rainfall brought by Typhoon Maysak led to a dam overtopping and breaching in Guangxi Province, leaving at least 26 dead.
The challenge is on Chinese policymakers’ minds. In a five-year plan on climate policy released recently, the government called for population centers, infrastructure and industry to be located in areas at lower risk of hazards and disasters.
The dams in Tibet could face construction delays from extreme weather events, and they might operate more poorly than expected because of reduced ice storage and snowpack in a warmer world, said Yuxi Wang, a senior research analyst with energy consultancy Wood Mackenzie Ltd. Still, there’s little risk of projects being canceled.
“From the government’s side, they’re quite supportive of these hydropower projects,” she said. “They hold strategic importance not only for Xizang’s economy but for China’s national grid,” Wang added, using the name by which China refers to Tibet.
Risks and Costs
Even in Nepal, few people expect dam construction to slow significantly. Alternatives carry their own problems. Shipping fossil fuels in the rocky terrain is difficult and expensive. Solar is promising but competes with scarce agricultural land and provides only intermittent generation — the country’s pipeline for hydro projects is 14 times larger than utility-scale photovoltaics, according to Global Energy Monitor.
“The question is not whether we should continue developing hydropower in the Himalayas,” said Ahmed. “The question is whether we are developing it based on the Himalayan conditions of the past, or the much more dynamic and uncertain conditions of the future.”
Going forward, projects may need to be redesigned to be more resilient, likely adding to construction costs. Powerhouses should be built underground rather than beside rivers, while tunnels should be equipped with fast-acting gates to prevent debris from entering critical infrastructure, said Hitendra Dev Shakya, the recently retired head of the Nepal Electricity Authority.
Costs of insuring projects may also increase as the recent flooding events “are likely to make insurers more cautious and the market for hydropower risks may harden further,” said Benjamin Ng, Asia power leader for Aon.
The disaster in Nepal will be a turning point for how projects are built and upgraded, said Christian Huggel, a professor at the University of Zürich advising multilateral development banks and development agencies on how to adapt hydropower projects to growing risks in the Himalayas.
“This event will change a lot,” Huggel said. “And I hope so, because otherwise billions of dollars in investment will be lost and so many more lives will be lost across the Himalayas.”
Top photograph: The Tapovan Vishnugad hydropower plant being built in the Indian Himalayas near Joshimath, Uttarakhand in 2024; photo credit: Prashanth Vishwanathan/Bloomberg
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