As climate risks intensify across the Eastern Himalayas, large hydropower projects once championed as clean energy solutions are increasingly being questioned for amplifying environmental and social vulnerabilities.
A recent commentary by Sharon Sarah Thawaney argues that the rapid expansion of hydropower in the region may be locking fragile mountain systems into long-term maladaptation a term used to describe climate responses that ultimately increase risk rather than reduce it.
Teesta Flood Exposed Structural Vulnerabilities
The debate gained urgency following the devastating 2023 glacial lake outburst flood (GLOF) from South Lhonak Lake in North Sikkim. The flood unleashed an estimated 50 million cubic metres of water, striking the Teesta Stage III dam at Chungthang and breaching it within minutes. The reservoir was reportedly full at the time, compounding the surge downstream.
The disaster left at least 55 people dead, affected nearly 88,400 residents, destroyed over 2,500 homes, and collapsed 31 major bridges. Long stretches of National Highway 10 were washed away, severing connectivity to Sikkim and Kalimpong. Farmland spanning roughly 270 square kilometres was buried under debris, crippling agro-pastoral livelihoods.
Researchers have since confirmed that climate change played a significant role in triggering the event, as warming temperatures accelerate glacial melt and expand high-altitude lakes across the region.
According to recent data from India’s Central Water Commission, glacial lake areas in the country increased by more than 20% between 2011 and 2024. Sikkim and Arunachal Pradesh recorded some of the highest expansions, raising concerns over future GLOF risks.
Fragile Mountains, Expanding Infrastructure
The Eastern Himalayas sit within a seismically active and geologically young mountain system characterised by steep terrain and sediment-heavy rivers. Critics argue that large, static hydropower infrastructure is fundamentally misaligned with this dynamic landscape.
Although many projects are labelled “run-of-the-river,” they often rely on pondage systems that temporarily store and release water in pulses. These artificial surges can intensify erosion, destabilise riverbanks, and heighten downstream flood risks.
Hydropower reservoirs also submerge extensive areas, displacing communities and disrupting fisheries, forests and culturally significant river ecosystems. Environmental impact assessments, experts say, have often failed to fully incorporate evolving climate risks such as intensified rainfall, glacier retreat and unstable moraines.
The Teesta flood, analysts argue, revealed how infrastructure designed around historical hydrological patterns may no longer be adequate in a rapidly warming climate.
Climate Solution or Climate Risk?
The Hindu Kush Himalayan region is estimated to hold more than 3.5 terawatts of renewable energy potential, including nearly 882 gigawatts of hydropower. Governments have promoted this capacity as central to achieving climate goals and driving economic growth.
However, climate change is altering river flow regimes, sediment loads and precipitation patterns faster than infrastructure can adapt. In this context, hydropower projects may transform episodic hazards into systemic disasters by compounding flood intensity and ecological stress.
Experts say the issue is not whether energy development is necessary, but how it is planned. Strengthening basin-scale planning, integrating real-time monitoring, improving early-warning systems for glacial lakes, and ensuring meaningful community participation are seen as critical steps.
Without reforms, observers warn, hydropower expansion in the Eastern Himalayas risks entrenching long-term ecological fragility turning a climate solution into a driver of vulnerability in one of the world’s most sensitive mountain regions.