Climate change, water availability and future cereal production in China

Climate scenarios from a regional climate model are used to drive crop and water simulation models underpinned by the IPCC A2 and B2 socio-economic development pathways to explore water availability for agriculture in China in the 2020s and 2040s. Various measures of water availability are examined at river basin and provincial scale in relation to agricultural and non-agricultural water demand and current and planned expansions to the area under irrigation. The objectives are to understand the influences of different drivers on future water availability to support China's food production. Hydrological simulations produce moderate to large increases in total water availability in response to increases in future precipitation. Total water demand increases nationally and in most basins, but with a decreasing share for agriculture due primarily to competition from industrial, domestic and municipal sectors. Crop simulations exhibit moderate to large increases in irrigation water demand which is found to be highly sensitive to the characteristics of daily precipitation in the climate scenarios. The impacts of climate change on water availability for agriculture are small compared to the role of socio-economic development. The study identifies significant spatial differences in impacts at the river basin and provincial level. In broad terms water availability for agriculture declines in southern China and remains stable in northern China. The combined impacts of climate change and socio-economic development produce decreases in future irrigation areas, especially the area of irrigated paddy rice. Overall, the results suggest that there will be insufficient water for agriculture in China in the coming decades, due primarily to increases in water demand for non-agricultural uses, which will have significant implications for adaptation strategies and policies for agricultural production and water management.