Sorry, you need to enable JavaScript to visit this website.

Assessing a Rain-Fed Switch

03:01AM Feb 12, 2014

Limited freshwater for irrigation, coupled with pro­jected climate change, could hurt crop production much more than previously thought.

Computation Institute’s Center for Robust Decision Making on Climate and Energy Policy research scientist Joshua Elliott and colleagues say a lack of water could force farmers globally to switch between 50 million and 150 million acres of irrigated land back to rain-fed production.

The study, "Constraints and Potentials of Future Irrigation Water Availability on Agricultural Production Under Climate Change," is expected to improve the accuracy of future research because it uncovered differences in the way hydrological models integrate processes, including crop water productivity and the carbon cycle, compared with agricultural models.

Additionally, the study attempts to quantify the caloric value of food that could be lost through water scarcity. Climate-change models have suggested a loss of 400 and 2,600 petacalories per day. (One petacalorie equals 10 to the power of 15 calories.) The new report notes that water scarcity could cut between 600 and 2,900 petacalories more.

But it isn’t all bad: Some places might have a water surplus that could limit the effect of climate change on food production by as much as 57%, assuming it were allocated properly. That would help geographies anticipated to become short on freshwater, including the western U.S., India and China.