Mike Muller seems to imply that destroying natural wetlands in the course of hydropower development is a cost worth bearing because it will reduce methane emissions (Nature 566, 315–317; 2019). I disagree: intact riparian systems are crucial for climate adaptation.

Large dams are typically subject to weak impact assessments, murky finances, and poor operations and maintenance (A. Ansar et al. Energy Pol. 69, 43–56; 2014). With lifetimes extending over a century, they can also become unworkable in the face of climate shifts — as seen in Australia, Zambia, Venezuela, the United States and southern Asia.

Clear trade-offs between mitigation and adaptation must be negotiated. Damaging the water cycle for the benefit of the carbon cycle provides no net gain for water-dependent economies and ecosystems. We should therefore protect and enhance carbon-sink wetlands (W. R. Moomaw et al. Wetlands 38, 183–205; 2018).

Climate-sensitive water management balances the resilience of ecosystems, infrastructure and land-use patterns with carbon-related and economic benefits. Through better-informed decisions, we can sustain and value wetlands and hydropower together.