The Teesta dam and the long shadow of climate change

• An expert committee recommended the rebuilding of the Teesta-3 dam in Sikkim on January 27, 2025, following a devastating glacial lake outburst flood in October 2023.

• The dam and its hydroelectric power generation facility were severely damaged, with over 100 people killed and over 80,000 affected.

• The dam’s slope failure and the resulting landslides were due to a moraine on the South Lhonak lake’s flank.

• The dam’s decision was motivated by its success and commercial viability, and its power-generating equipment was largely intact.

• The committee’s decision has been questioned by environmental activists and hydrogeology experts, who have expressed concerns about large hydroelectric power projects in the Himalayas.

• The new design of Teesta-3 2.0 includes a spillway nearly three times more voluminous, an early-warning system for flooding, and a “worst-case scenario” modelled by the India Meteorological Department.

• Experts argue that climate change is a risk-multiplier, and if the slope failure off the South Lhonak lake had occurred without a lake, there is unlikely to have been a flood.

• The commercial viability of Teesta-3, pre-GLOF, speaks to India’s soaring power demand, but the consequences of climate change should be weighed against the production in specific locales.

• The decision should be made within a framework of priorities led by the need to minimize risk to locals, their property, and their livelihoods and maximize their socioeconomic resilience.

• The cost of these measures should be included in the dam’s hydroelectric power tariff rather than externalising it in the determination of commercial viability.