International trade of scarce water

- Current assessments of virtual water flows do not differentiate flows originating from regions of severe water scarcity.
- We use a global multi-region input-output table to evaluate embodied water flows between 187 countries.
- We identify top flows of scarce water, e.g. scarce water used to grow cotton in Pakistan used for clothing bought in USA.
- The composition of top exporters in terms of total water versus scarcity-weighted water is strikingly different.
- Future assessments of virtual water should take scarcity into account.

Recent analyses of the evolution and structure of trade in virtual water revealed that the number of trade connections and volume of virtual water trade have more than doubled over the past two decades, and that developed countries increasingly import water embodied in goods from the rest of the world to alleviate pressure on domestic water resources. At the same time, as demand continues to increase and climate change threatens to alter hydrological cycles, water scarcity is a growing problem. Does research into virtual water trade need to consider water scarcity and differentiate flows out of water-scarce regions from flows out of water-abundant regions? Previous studies sum and compare virtual water volumes originating in countries experiencing vastly different degrees of water scarcity. We therefore incorporate water scarcity into an assessment of global virtual water flows. We use input-output analysis to include indirect virtual water flows. We find that the structure of global virtual water networks changes significantly after adjusting for water scarcity.