Limited evidence that tropical inundation and precipitation powered the 2020-2022 methane surge.

Atmospheric methane is rapidly increasing, and the role of tropical wetlands in the global methane budget raises concerns about a potential climate-wetland-methane feedback. Here we use Cyclone Global Navigation Satellite System observations to map monthly inundation dynamics across the tropics (37.4°S to 37.4°N) at high resolution (0.01° × 0.01°) over five years (2018-2023), including cloud and vegetation-covered regions. Our results reveal large seasonal and interannual variations in wetland extent not captured in traditional inundation products, with strong El Niño-Southern Oscillation correlations. Tropical wetland models driven by these inundation observations, independent precipitation products, or constrained by total water observations do not show growth in wetland methane emissions from 2020-2022. This suggests the 2020-2022 growth in methane is best explained by other methane source or sink mechanisms, or that non-hydrological controls are more important in tropical wetland methane emissions than currently understood.