Recent methane surges reveal heightened emissions from tropical inundated areas

Record breaking atmospheric methane growth rates were observed in 2020
and 2021 (15.2±0.5 and 17.8±0.5 parts per billion per year), the highest since the
early 1980s. Here we use an ensemble of atmospheric inversions informed by
surface or satellite methane observations to infer emission changes during
these two years relative to 2019. Results show global methane emissions
increased by 20.3±9.9 and 24.8±3.1 teragrams per year in 2020 and 2021,
dominated by heightened emissions from tropical and boreal inundated areas,
aligning with rising groundwater storage and regional warming. Current
process-based wetland models fail to capture the tropical emission surges
revealed by atmospheric inversions, likely due to inaccurate representation of
wetland extents and associated methane emissions. Our findings underscore
the critical role of tropical inundated areas in the recent methane emission
surges and highlight the need to integrate multiple data streams and modeling
tools for better constraining tropical wetland emissions.