Methane Emissions from Wetlands in China and Their Climate Feedbacks in the 21st Century.

Wetlands are large sinks of carbon dioxide (CO) and sources of methane (CH). Both fluxes can be altered by wetland management (e.g., restoration), leading to changes in the climate system. Here, we use multiple models to assess CH emissions and CO sequestration from the wetlands in China and the impacts on climate under three climate scenarios and four wetland management scenarios with various levels of wetland restoration in the 21st century. We find that wetland restoration leads to increased CH emissions with a national total of 0.32-11.31 Tg yr. These emissions induce an additional radiative forcing of 0.0005-0.0075 W m yr and global annual mean air temperature rise of 0.0003-0.0053 °C yr, across all future climate and management scenarios. However, wetland restoration also resulted in net CO sequestration, leading to a combined net greenhouse gas sink in all climate management scenarios, except in the highest restoration level combined with the hottest climate scenario. The highest climate cooling was achieved under medium restoration, with the climate scenario consistent with the Paris agreement target of below 2 °C, with a cumulative global warming potential of -3.2 Pg CO-eq (2020-2100). Wetland restoration in the Qinghai-Tibet Plateau offers the greatest cooling effect.