Irrigation cooling effects

By running a climate model with and without irrigation, researchers find that irrigation may cause regional cooling.

The magnitude of the simulated effect varies strongly with season, evidenced by large dry-season decreases in monthly mean and maximum temperatures, but little change in rainy-season temperatures. In their case study of California, which has intense irrigation, Kueppers et al. also show that irrigation-induced cooling may produce changes in regional air circulation. The authors hypothesize that past expansion of irrigation may have masked regional warming signals due to greenhouse gas increases. Many climate recording stations are in areas with irrigated agriculture, they note. Moreover, greenhouse gas emissions and irrigated agricultural area have both increased in the last century.-American Geophysical Union