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.