As a multiyear drought grinds on in the Southwestern United States, many wonder about the impact of global climate change on more frequent and longer dry spells. As humans emit more carbon dioxide into the atmosphere, how will water supply for people, farms, and forests be affected? A new study from the University of California, Irvine and the University of Washington shows that water conserved by plants under high CO2 conditions compensates for much of the effect of warmer temperatures, retaining more water on land than predicted in commonly used drought assessments.