Global spread of water scarcity risk through trade

Water scarcity is increasingly perceived as a great challenge to the sustainable development of human society. The economic output loss due to water scarcity is defined as water scarcity risk (WSR), which constitutes local water scarcity risk (LWSR, local economic output loss in water-using sectors due to water scarcity) and virtual water scarcity risk (VWSR, the spread of LWSR through trade systems). However, the traditional water stress index used in the existing WSR assessment research is limited in its accuracy and descriptiveness. Here we address these limitations by quantifying the LWSR with the consideration of environmental flow requirement, water intensity, economic output, and further assessing the VWSR. Results show that the WSR of the world is around 2.7 trillion US dollars in 2016. We also identify the hotspots of WSR at the national and sectoral levels. Our findings help lay the foundation for nations to develop strategies for mitigating WSR.