Historical observations indicate a widespread decrease in surface wind speed over continental regions of the Northern Hemisphere mid-and-high latitudes, a phenomenon dubbed “global stilling”. Climate models also project future land surface wind speed decrease under a warming climate. However, the underlying physical drivers of these wind changes remain insufficiently understood, with uncertain roles of large-scale atmospheric circulation changes, versus surface friction effects due to land surface changes, in particular increases in vegetation in a warming, wetter and CO2-enriched world. Here, we analyze the role of vegetation in future projected wind speed changes over land, using idealized climate change simulations, from several climate models, that separate the radiative and physiological effects of CO2 under a quadrupling of atmospheric CO2. In the physiological simulations, only the fertilization effect of CO2 increase on vegetation is simulated (with potential feedbacks onto the atmosphere); radiative effects, and thus global warming and associated large-scale circulation changes, are not included. In contrast, the radiative simulations only include the effects of CO2 increase on large-scale climate (and thus surface winds). Results indicate that projected land wind speed decreases are driven mainly by CO2 physiological effects on vegetation, pointing to the role of surface processes in future wind speed changes - albeit with large inter-model uncertainties. These results are compared with a second line of analysis, which seeks to separate large-scale and surface effects by comparing projected modeled wind speed changes (which include both effects) with geostrophic winds derived from the same models (which only include the former).