Transition from positive to negative indirect CO2 effects on the vegetation carbon uptake

Elevated atmospheric CO2 concentration (eCO2) has substantial indirect effects on vegetation carbon uptake via associated climate change, but their dynamics remain unclear. This study investigates how the impacts of eCO2-driven climate change on growing-season gross primary production (GPP) have changed globally during 1982–2014, using satellite observations and Earth system models, and evaluates their evolution until 2100. The initial positive effect of eCO2-induced climate change on vegetation carbon uptake has declined recently, shifting to negative in the early 21st century, particularly in high latitudes. This is linked to a decrease in the direct CO2 physiological effect, resulting in a sharp reduction of current growth benefits from climate warming and CO2 fertilization. Land drying partially contributes to this weakening indirect CO2 effect, and it's expected to worsen under global warming.

Zefeng Chen, Weiguang Wang, Giovanni Forzieri, Alessandro Cescatti