Food securityFreshwater loss compounds climate change’s detrimental effects on agriculture
A warmer world is expected to have severe consequences for global agriculture and food supply, reducing yields of major crops even as population and demand increases.Agricultural models estimate that given the present trajectory of greenhouse gas emissions, climate change will directly reduce food production from maize, soybeans, wheat, and rice by as much as 43 percent by the end of the twenty-first century. Now, a new analysis combining climate, agricultural, and hydrological models finds that shortages of freshwater used for irrigation could double the detrimental effects of climate change on agriculturedue to the reversion of twenty to sixty million hectares of currently irrigated fields back to rain-fed crops.
A warmer world is expected to have severe consequences for global agriculture and food supply, reducing yields of major crops even as population and demand increases. Now, a new analysis combining climate, agricultural, and hydrological models finds that shortages of freshwater used for irrigation could double the detrimental effects of climate change on agriculture.
A University of Chicago release reports that given the present trajectory of greenhouse gas emissions, agricultural models estimate that climate change will directly reduce food production from maize, soybeans, wheat, and rice by as much as 43 percent by the end of the twenty-first century. Hydrological models looking at the effect of warming climate on freshwater supplies project further agricultural losses, due to the reversion of twenty to sixty million hectares of currently irrigated fields back to rain-fed crops.
“It’s a huge effect, and an effect that’s basically on the same order of magnitude as the direct effect of climate change,” said Joshua Elliott, a research scientist with the Computation Institute’s Center for Robust Decision Making on Climate and Energy Policy (RDCEP), Argonne National Laboratory, and lead author of the paper. “So the effect of limited irrigation availability in some regions could end up doubling the effect of climate change.”
The research was led by Elliott and colleagues from the Agricultural Model Intercomparison and Improvement Project (AgMIP), as part of the Inter-Sectoral Impacts Model Intercomparison Project (ISI-MIP). The paper is among twelve featured in a special feature dedicated to ISI-MIP research in Proceedings of the National Academy of Sciences, published online 16 December.
Agricultural models and hydrological models both incorporate the influence of climate, but are designed by different scientific communities for different purposes. While agricultural models simulate how temperature, precipitation, and other climate factors may alter the yield for various crops, hydrological models seek to estimate water-related characteristics such as stream flow, water availability, and storm runoff.
The two types of models overlap in estimating the amount of water used for agricultural irrigation, by far the largest human use of freshwater in the world. When Elliott and colleagues fed each type of model with the same climate model forecasts, however, the models produced dramatically different predictions about the future demand for freshwater irrigation
