%0 Journal Article
%T Hydrologic implications of vegetation response to elevated CO2 in climate projections
%J -
%D 2018
%R https://doi.org/10.1038/s41558-018-0361-0
%X Climate model projections using offline aridity and/or drought indices predict substantial terrestrial drying over the twenty-first century1,2,3,4,5,6,7,8,9,10,11. However, these same models also predict an increased runoff12,13,14,15. This contradiction has been linked to an absence of vegetation responses to an elevated atmospheric CO2 concentration [CO2] in offline impact models12,14,16,17. Here we report a close and consistent relationship between changes in surface resistance (rs) and [CO2] across 16 CMIP5 models. Attributing evapotranspiration changes under non-water-limited conditions shows that an increase in evapotranspiration caused by a warming-induced vapour pressure deficit increase18 is almost entirely offset by a decrease in evapotranspiration caused by increased rs driven by rising [CO2]. This indicates that climate models do not actually project increased vegetation water use under an elevated [CO2], which counters the perception that ¡®warming leads to drying¡¯ in many previous studies1,2,3,4,5,6,7,8,9,10,11. Moreover, we show that the hydrologic information in CMIP5 models can be satisfactorily recovered using an offline hydrologic model that incorporates the [CO2] effect on rs in calculating potential evapotranspiration (EP). This offers an effective, physically-based yet relatively simple way to account for the vegetation response to elevated [CO2] in offline impact models
%U https://www.nature.com/articles/s41558-018-0361-0