Climate change impacts on global agricultural water deficit

Abstract

This paper assesses the change in crop water deficits (the difference between crop evapotranspiration and precipitation that is effective for crop growth) of 26 crops (including rainfed and irrigated) under current (1961-1990) and projected climates (2070-2099). We found that despite the universally rising mean temperature, crop water deficits are likely to decline slightly at the global scale, although changes vary by region. While the increasing precipitation and changing intra-annual precipitation distribution in many areas can lead to more effective rainfall for crop growth, the declining diurnal temperature range will play a key role in offsetting the warming effect at the global scale. Regionally, Africa and China are likely to benefit from lower water requirements, but the impacts on other regions, including Europe, India, South America, and the United States, are subject to the land-use types (rainfed or irrigated) and the uncertainty involved in the assessment approaches. Key Points With global warming, crop water deficits may decline slightly at global scale Declining diurnal temperature range is vital in offsetting the warming effect Regional impacts vary significantly. ©2013 American Geophysical Union. All Rights Reserved.