Recent Sharp Increase in Greenhouse Gas Emissions from Chinese Reservoirs exacerbated by Climate Change

Reservoirs are increasingly recognized as significant sources of greenhouse gas (GHG) emissions, yet their long-term emission trajectories remain poorly constrained, particularly at national scales. Here we compile a comprehensive dataset comprising 5,054 measurements of CO2, 2,679 of CH4, and 1,184 of N2O concentrations to quantify monthly GHG emissions from reservoirs across China during 2000–2020. By integrating machine learning based upscaling with monthly reservoir surface area dynamics, we show that total reservoir GHG emissions increased continuously over the past two decades, at a mean rate of 0.76 ± 0.07 Tg CO2 eq yr⁻¹. Emission growth accelerated markedly after 2010, culminating in peak emissions of 52.6 ± 11.2 Tg CO2 eq in 2020. Spatially, southeastern China emerged as a hotspot of emission intensification, driven primarily by rising air temperatures and declining precipitation. Given projected climate warming and hydroclimatic shifts, GHG emissions from reservoirs are likely to further intensify. Our findings highlight an increasingly important and previously overlooked role of reservoirs in the regional and global carbon cycle