Elevated CO2 concentrations play an important role in determining future yields in general and have the potential to beneficially affect plant water use efficiency . The elevated CO2 effects are projected to be most prominent for rain-fed C3 crops . Combined results from field experiments and global crop models show that CO2 fertilisation could reduce consumptive water use by 4-17% . To account for uncertainties, global agricultural models provide output with and without account for CO2 fertilisation effects, though recent progress on reducing model uncertainty indicates that non-CO2 model runs may no longer be needed for adequate projections of yield impacts .
IPCC
Climate Change 2022: Impacts, Adaptation and Vulnerability
IPCC Report