Fig. 2.

Estimated trends in global gross primary production (GPP) and water use efficiency (WUE) and their drivers over 1982–2011. a, b Annual mean anomalies and its standard deviation (shown as error bars) of global GPP in Pg C per year (n = 84) and global WUE in g C mm⁻¹ H₂O (n = 12) during 1982–2011, respectively. The green line in a and blue line in b represent the linear trend over the past three decades. c Contribution of E and WUE to total global trends in GPP (Total). d Contributions of four factors to the total increase in global WUE (Total). C _a, D, L and $f_{E_{\mathbf{i}}}$ refer to contributions from atmospheric CO₂ concentration, vapour pressure deficit, leaf area index and fraction of canopy interception to total ecosystem water use, respectively. The error bars in all the subplots represent one standard deviation