Fig. 2: Change in global mean annual land air temperature and individual climate forcing induced by vegetation physiological response to increasing atmospheric CO₂.

a Global annual area-weighted temperature change of vegetated land induced by total CO₂ physiological forcing (PHY_all) and the direct CO₂ physiological forcing (PHY_dir) in response to increasing atmospheric CO₂ concentration. Shaded areas are the standard errors of the six Earth System Models (ESMs) used, and the thick curves are their multi-model means. For each atmospheric CO₂ concentration in panel (a), values are based on smoothing using a twenty-year running window (to match with the decomposition results in panel (b). The final temperature change induced by PHY_all and PHY_dir effects under 4 × CO₂ are further marked on the righthand side, with the “+” markers indicating multi-model means. b PHY_all-induced climate forcing associated with changes in albedo, aerodynamic resistance (r_a), evapotranspiration (ET), downwelling shortwave radiation (SW) and near-surface air emissivity (ɛ_a). Again, the shaded areas are the standard errors of the models, and the mean is the thick continuous lines. The changes in these variables are calculated using a moving average with a 20-year window. The resulting values under 4 × CO₂ are plotted on the righthand side.