Global vegetation production may decrease in this century due to rising atmospheric dryness.

Previous projections from Earth system models have suggested that rising atmospheric CO2 concentrations would stimulate global vegetation production through the CO2 fertilization effect. Here we show that increased atmospheric dryness driven by climate warming will substantially counteract this effect. Using measurements from global eddy-covariance sites and a process-based model, we project that global vegetation gross primary production (GPP) will peak around the middle of the twenty-first century and subsequently decline. The peak of global GPP is projected to increase by only 5.4 ± 0.5% compared with the present. The stalled increase in GPP is more prominent in tropical regions. Additionally, the increased atmospheric dryness resulting from two non-CO2 greenhouse gases (CH4 and N2O) plays an important role in GPP changes. These gases induce climate warming and atmospheric dryness but, unlike CO2, lack a fertilization effect. This study underscores that climate warming-induced atmospheric dryness markedly reduces terrestrial vegetation production, potentially limiting the terrestrial carbon sink in the future.