Spatiotemporal Change in Winter-Flooded Paddies Reduces CH4-Associated Climate Footprint in China’s Sichuan Basin

As the second most important anthropogenic greenhouse gas (GHG), methane (CH4) has received wide attention in the mitigation of global climate change. China’s Sichuan Basin has been identified as one of the world’s hotspot regions with very high CH4 emission intensity. Winter-flooded paddies are considered as potential significant sources of CH4 emissions among various cropping systems in Sichuan. However, current studies are limited to the field scale, and there is a lack of research conducted over a large spatiotemporal scale. Here, we simulated CH4 emissions from 1980 to 2023 at region scale using the Denitrification–Decomposition (DNDC) model and evaluated the associated climate impact using the radiative forcing-based climate footprint (RFCF) metric. We found that CH4 emissions have recently decreased, from 0.53 billion tonnes in 2019 to 0.28 billion tonnes in 2023, representing a 47.20% reduction. Moreover, the climate footprint peaked in 2019 at 1.25 mW m−2 and decreased to 1.08 mW m−2 in 2023, and the system achieved net zero increase in radiative forcing (RF) in 2020. This means that Sichuan’s winter-flooded paddies no longer contribute to the additional RF in the atmospheric system. Overall, our findings demonstrate that the reduction in CH4 emissions from winter-flooded paddies has been mainly attributed to a reduction in the cropping area and a decrease in average temperature during the rice growth season. These results provide a scientific basis for region-specific CH4 mitigation policies and demonstrate how these spatiotemporal changes in CH4 emissions from winter-flooded paddies in Sichuan can support sustainable agriculture.