Tracking grid-level freshwater boundary exceedance along global supply chains from consumption to impact

Consumption behaviours exert pressure on water resources both locally and globally through interconnected supply chains, hindering the achievement of Sustainable Development Goals 6 (Clean water and sanitation) and 12 (Responsible consumption and production). However, it is challenging to link hotspots of water depletion across spatial scales to final consumption while reflecting intersectoral competition for water. In this study, we estimated the global exceedance of regional freshwater boundaries (RFBs) due to human water withdrawal at a 5-arcmin grid scale using 2015 data, enabling the identification of hotspots across different spatial scales. To reduce uncertainty, we used average estimates from 15 global hydrological models and 5 environmental flow requirement methods. We further attributed the hotspots of exceedance to final consumption across 245 economies and 134 sectors via the multi-region input–output model EMERGING. Our refined framework revealed previously unknown connections between regional hotspots and consumption through international trade. Notably, we found that 24% of grid-level RFB exceedance (718 km3 yr−1; 95% confidence interval of 659–776 km3 yr−1) was outsourced through trade, with the largest flows (52 km3 yr−1; 95% confidence interval of 47–56 km3 yr−1) from water-stressed South and Central Asia to arid West Asia. The demand for cereals and other agricultural products dominated global consumption-based RFB exceedance (29%), while the exports of textiles and machinery and equipment exacerbated territorial exceedance in manufacturing hubs within emerging economies. Our methodology facilitates the tracing of global hotspots of water scarcity along supply chains and the assignment of responsibilities at finer scales.