Fig. 2: Global distribution of wetland δ13C-CH4 and its latitudinal and long-term gradients simulated by isoTEM.

a Modeled global wetland δ13C-CH4 for wetland grid cells with static inundation data49. b Mean latitudinal distribution of δ13C of POM (yellow), produced CH4 (red), and CH4 emitted to the atmosphere for all grid cells (blue) and flux-weighted grid cells (purple). c Long-term trends of global mean wetland δ13C-CH4 with and without incorporating long-term trend in δ13C-POM (blue and purple, respectively). The shaded area in (b, c) represents one standard deviation determined from 20 ensembles of simulations where the optimized parameters were varied.