We quantify the extent to which net primary production (NPP) of terrestrial ecosystems is water-limited under future atmospheric CO2 enrichment and climate change. Analysis is based on spatially explicit simulations with a Dynamic Global Vegetation Model (DGVM) forced by climate projections from five different General Circulation Models (GCMs) under one emission scenario. We find for many but not all regions that NPP will be less water-limited despite concurrent declines in soil moisture, owing to a frail balance of unfavorable climate effects on soil moisture, reduced transpiration by CO2-induced lower stomatal aperture, and continuous acclimation of vegetation.