How can virtual water trade reshape water stress pattern? A global evaluation based on the metacoupling perspective

With water scarcity increasingly becoming a growing global risk, it is prevalent to explore water supply-demand interaction within and beyond national borders driven by global virtual water trade and its effects on water sustainability. However, there is little study on system integration of differential environmental impacts of various types of trade. Based on metacoupling framework highlighting human-nature interactions across spacewithin a place (intracoupling), between adjacent places (pericoupling), and between distant places (telecoupling), this study quantified the linkages and intensities of three kinds of coupling processes during global virtual water trade for the first time. Correspondingly, water stress changes under a set of trade scenarios were evaluated based on the indicator of UN SDG 6.4.2 to distinguish the influence of trade taking place on different spatial scales. Results show that during 2005-2015, local water resources supported 80% of global water consumption. Distant virtual water import was about 5 times in volume as large as adjacent virtual water import, alleviating 99.8% of global average water stress. Virtual water trade reduced water stress in 86% of developed countries and increased that in 71% of developing countries in 2005. Owing to trade, water stress in many countries with poor water resources endowment declined while that of many with relatively good endowment went up from 2005 to 2015. Our findings can help to systematically understand the influence of virtual water trade on water stress change and provide scientific guidance for sustainable water management and regional regulations.