Balancing food production within the planetary water boundary

Abstract

Freshwater use is recognized as one of the nine planetary boundaries. However, water scarcity is a local or regional phenomenon, meaning that the global boundary must be spatially downscaled to reflect differences in water availability. In China, as in most countries, irrigation is the major freshwater user, closely linking food security to the freshwater boundary. To provide evidence supporting environmentally sustainable water use in China’s food production, this study explores how a grain production shift affects the national water-scarcity footprint (WSF) and the potential to reach sustainable water use limits while maintaining the current grain production level. We found that the historical breadbasket shift towards water-scarce northern regions has increased the WSF by 40% from 1980 to 2015. To operate within the boundary, national irrigation needs to be reduced by 18% in hotspot regions, with implications of a 21% loss of grain production. However, this loss can be reduced to around 8% by closing yield gaps in water-rich regions. It demonstrates the high potential of integrating crop redistribution and closing yield gaps to achieve grain production goals within freshwater boundaries. This Chinese case study can be representative of the challenges faced by many of the world’s countries, where pressures on land and water resources are high and a sustainable means of increasing food supply must be found.