Fig. 6.

Future changes in evapotranspiration, gross primary productivity and above ground biomass under RCP 8.5. a Earth system model (ESM) mean and inter-quartile range of historical (blue) and future (green) evapotranspiration (ET) dependency on precipitation (P) The grey line and shading represent the mean and range, respectively, of estimated breakpoints across tropical forest locations globally²¹. b Historic and future gross primary productivity (GPP) dependency on P, coloured for ESMs as in a. The magenta line represent the empirical GPP dependency on P scaled with the ESM ensemble increase in ecosystem water use efficiency (eWUE; 1.31). c Historic and future dependency of above ground biomass (AGB) on P. The eWUE-induced increases seen for GPP do not translate to similar increases in AGB, and are limited to a narrow P range in the radiation-limited regime. In the water-limited regime, AGB does not change, indicating that CO₂ effects on eWUE do not affect AGB in the water-limited regime in the ESMs