Fig. 3. BU and TD models exhibited substantial uncertainties in the magnitude and trend of wetland CH₄ emissions over the Boreal–Arctic region.

a, The multimodel ensemble median (50th percentile) of wetland CH₄ emissions estimated by TD (blue line) and BU (orange line) models, compared with the upscaled wetland CH₄ emissions (red line). The darker shaded areas represent 25th to 75th percentiles and the lighter shaded areas represent the ranges of wetland CH₄ emissions. b, The mean annual magnitudes and trends of wetland CH₄ emissions estimated by TD and BU models, compared with those of the upscaled wetland CH₄ emissions (red circle). For TD models, dark-blue markers indicate that the trends are significant, that is, P < 0.05, and light-blue markers indicate that the trends are not significant, that is, P > 0.05. For BU models, orange markers indicate that the trends are significant, and yellow markers indicate that the trends are not significant. The P values can be seen in Supplementary Table 5, obtained from a two-sided t-test.