Extended Data Fig. 4: Robustness of SC-CH4 distributions to wider prior assumptions, and posterior methane cycle parameter relationships.
From: Equity is more important for the social cost of methane than climate uncertainty
a, SC-CH4 distributions for FUND (solid line) and DICE (dashed line) depicting the main results (red) and a sensitivity analysis that uses wider prior parameter distributions during the model calibrations (blue). The SC-CH4 distributions correspond to a constant 3% consumption discount rate under RCP 8.5 and pool the SC-CH4 estimates of each IAM across the four climate models. Coloured circles show the estimated multi-model mean SC-CH4 for the two scenarios. b, Posterior parameter relationship between natural methane emission rates and the initial value for the time-varying tropospheric lifetime of methane in the S-MAGICC climate model. c, Posterior relationships between the uncertain methane cycle parameters depicted in b with the estimated SC-CH4 of S-MAGICC for RCP 8.5 under a constant 3% consumption discount rate. Different sized diamonds and circles identify the initial tropospheric lifetime of methane for DICE (blue) and FUND (red). Both b and c depict 5,000 randomly selected posterior estimates, with loess-smoothed curves (white lines) helping to illustrate the relationship between x- and y-axis values.
