Methane Emissions in Asian Wetlands During 2010–2020: Insights From an Online‐Coupled Microbial Functional‐Group‐Based Model

Wetland ecosystems are the dominant natural source of atmospheric methane (CH 4 ) in the global methane cycle, yet significant uncertainties remain. Along with the warming climate system, CH 4 emissions from these ecosystems are projected to increase, presenting challenges for accurate CH 4 budget accounting and climate mitigation efforts. This study assessed CH 4 emissions and controlling factors in wetlands across East, South, and Southeast Asia (EA, SA, and SEA) for 2010–2020, using a regional Earth system model coupled online with a microbial functional‐group‐based CH 4 model (RegESM‐Microbe). The results from the RegESM‐Microbe model were evaluated against 11 offline wetland models from the Global Carbon Project and revealed consistent hotspots for wetland CH 4 emissions, including the Yangtze River floodplain, the Ganges and Brahmaputra River basins, and the Mekong River basin. The annual total wetland CH 4 emissions in Asia estimated (34.69 ± 2.55 Tg CH 4 yr −1 ) by the RegESM‐Microbe model was close to the bottom‐up wetland model ensemble (36.66 ± 1.19 Tg CH 4 yr −1 ). The time series of emissions showed a decreasing trend before 2014. Meanwhile, the weakening of anaerobic CH 4 oxidation between 2014 and 2020 contributed to increased CH 4 flow in the three transport sub‐processes, driving the enhanced CH 4 emissions. Most wetlands in the region exhibited an upward trend in CH 4 emission, with precipitation and radiation as the primary driver, followed by rising atmospheric CO 2 . Our study highlighted the critical role of climate change‐induced wetland CH 4 emissions in shaping long‐term greenhouse gas mitigation strategies.