Assessment of greenhouse gas emissions and mitigation potential in global degraded wetlands

Wetland is one of the ecosystem types with the largest density of organic carbon pool. The threat of declining wetland water level to carbon pools and the resulting greenhouse gas (GHG) emissions have attracted much attention. However, an assessment of emissions from degraded wetlands containing the three major greenhouse gases is still lacking. We compiled a global GHG exchange dataset that shows the non-linear water-heat pattern of GHG emissions. Combined with the Wetland Extended Trends Index, we estimated that the total GHG emissions from global degraded wetlands are 276.4 Gt CO₂eq during 1950-2020. The emissions of carbon dioxide, methane, and nitrous oxide are equivalent to 10.8%, - 0.5%, and 30.5% of anthropogenic sources, respectively. Under the historical trend of wetland degradation, the emissions may increase by 1.5 times from 2021 to 2100, reaching 408 Gt CO₂eq. Accordingly, wetland restoration can reduce anthropogenic carbon dioxide emissions by 10%.