The urgency of assessing the greenhouse gas budgets of hydroelectric reservoirs in China

Already the largest generator of hydroelectricity, China is accelerating dam construction to increase the share of hydro-electricity in its primary energy mix to reduce greenhouse gas emissions. Here, we review the evidence on emissions of GHGs, particularly methane, from the Three Gorges Reservoir, and argue that although the hydroelectric reservoirs may release large amounts of methane, they contribute significantly to greenhouse gas reduction by substitution of thermal power generation in China. Nonetheless, more systematic monitoring and modelling studies on greenhouse gas emissions from representative reservoirs are necessary to better understand the climate impact of hydropower development in China.