Impacts of climate change on virtual water content of crops in China

Looming water scarcity and climate change pose big challenges for China's food security. Previous studies have focus on the impacts of climate change either on agriculture or on water resources. Few studies have linked water and agriculture together in the context of climate change, and demonstrated how climate change will affect the amount of water used to produce per unit of crop, or virtual water content (VWC). We used a GIS-based Environmental Policy Integrated Climate (GEPIC) model to analyze the current spatial distribution of VWC of various crops in China and the impacts of climate change on VWC in different future scenarios. The results show that C4 crops (e.g. irrigated maize with a VWC of 0.73 m(3) kg(-1) in baseline) generally have a lower VWC than C3 crops (e.g. irrigated wheat with a VWC of 1.1 m(3) kg(-1) in baseline), and the VWC of C4 crops responds less sensitively to the CO2 concentration change in future climate scenarios. Three general change trends exist for future VWC of crops: continuous decline (for soybean and rice without considering CO2 concentration changes) and continuous increase (for rice with considering CO2 concentration changes) and first-declinethen-increase (other crop-scenario combinations). The trends reflect the responses of different crops to changes in precipitation, temperature as well as CO2 concentration. From south to north along the latitude, there is a high-low-high distribution trend of the aggregated VWC of the crops. Precipitation and temperature changes combined can lead to negative effects on crop yield and higher VWC particularly in the far future e.g. the 2090s, but when CO2 concentration change is taken into consideration, it is likely that crop yield will increase and crop VWC will decrease for the whole China. Integrated effects of precipitation, temperature and CO2 concentration changes will benefit agricultural productivity and crop water productivity through all the future periods till the end of the century. Hence, climate change is likely to benefit food security and help alleviate water scarcity in China. (C) 2013 Elsevier B.V. All rights reserved.