Warmer temperatures increase water loss to the atmosphere, leading to drier soils. In contrast, higher CO₂ levels cause leaf stomatal pores to partly close, lessening the amount of water vapor that escapes and the amount of water plants draw from soil. This new study finds that CO₂ does more to counterbalance warming-induced water loss than previously expected. In fact, simulations of levels of warming and CO₂ predicted for later this century demonstrated no net change in soil water, and actually increased levels of plant growth for warm-season grasses.

See the USDA news release here.

This result should not be surprising to anyone except climate alarmists who have long predicted global warming will increase evapotranspiration and decrease soil moisture. However many laboratory and field studies found that rising carbon dioxide reduces evapotranspiration and leads to higher soil moisture content, results similar to the USDA study. The USDA study was conducted on warm-season grasses. Other studies were conducted on a wide range of grasses, beans, sorghum, scrub oak, forbs, and food crops.

See also:

Drought in the West

Water Supply and Demand in Tucson