Ensemble estimates of global wetland methane emissions over 2000-2020

Due to ongoing climate change, methane (CH₄) emissions from vegetated wetlands are projected to increase during the 21^st century, challenging climate mitigation efforts aimed at limiting global warming. However, despite some reported emission trends, a comprehensive evaluation and attribution of recent changes is still lacking. Here we assessed global wetland CH₄ emissions from 2000 to 2020 based on an ensemble of sixteen process-based wetland models. Our results estimated global average wetland CH₄ emissions at 158±24 (mean ± 1) Tg CH₄ yr^-1 for the period 2010-2020, with an average decadal increase of 6-7 Tg CH₄ yr^-1 compared to the decade of 2000-2009. The increases in the four latitudinal bands of 90°S-30°S, 30°S- 30°N, 30°N-60°N, and 60°N-90°N were 0.1-0.2 Tg CH₄ yr^-1, 3.6-3.7 Tg CH₄ yr^-1, 1.8-2.4 Tg CH₄ yr^-1, and 0.6-0.8 Tg CH₄ yr^-1, respectively, during the two decades. The modeled CH₄ sensitivities to temperature show a reasonable consistency with eddy covariance-based measurements from 35 sites. Rising temperature was the primary driver of the increase, while precipitation and rising atmospheric CO₂ concentrations played secondary roles with high levels of uncertainty. These results suggest climate change is driving increased wetland CH₄ emissions.