From scarcity to risk - Propagation of green water stress through the food system due to agricultural trade

Water resources are increasingly shaped by global teleconnections. Through international trade, particularly in agricultural commodities, water is imported and exported as virtual water, linking distant regions via shared dependencies on freshwater resources. While virtual water trade can alleviate local water scarcity and enhance food security, it also amplifies systemic vulnerabilities within global supply chains. Even though the majority of global agricultural production depends on green water resources (soil moisture derived from precipitation), existing research has predominantly focused on blue water resources (surface and groundwater) and the redistribution of blue water stress due to trade. This study addresses this gap by explicitly linking export-side green water stress to import-side water-related risks within the global food system. We integrate a national-scale green water stress assessment, simulated using the LPJmL dynamic global vegetation, crop, and hydrological model, with international trade data from the CWASI database for selected primary crops. This combined framework enables a systematic analysis of the propagation of green water stress through the global food system via trade relationships. For this, we develop and analyze distinct categories of green water scarcity risk at country level: First, risk associated with domestic agricultural production; second, risk arising from the reliance on imports sourced from water-stressed regions; and third, risk that emerges in a country due to its export-oriented production. Using this categorization, we follow and map water-related risks from producers to consumers. Our results demonstrate that dependence on distant green water resources creates a complex and often opaque network of vulnerabilities, whereby local water stress can translate into risks far beyond the region of origin. By revealing how green water stress is embedded in global trade flows, this study underscores the need to move beyond local perspectives on water management. A more holistic, teleconnection-aware approach is required to sustainably govern global water resources and to reduce systemic risks in an increasingly interconnected world.