Critical impact of vegetation physiology on the continental hydrologic cycle in response to increasing CO ₂

Significance Predicting how increasing atmospheric CO 2 will affect the hydrologic cycle is of utmost importance for a wide range of applications. It is typically thought that future dryness will depend on precipitation changes, i.e., change in water supply, and changes in evaporative demand due to either increased radiation or temperature. Opposite to this viewpoint, using Earth system models, we show that changes in key water-stress variables will be strongly modified by vegetation physiological effects in response to increased [CO 2 ] at the leaf level. These results emphasize that the continental carbon and water cycles have to be studied as an interconnected system.