When examining the issue of water shortages and water usage, most of the emphasis is on domestic utilization. Rarely is the issue posed in terms of the impact of trade on water usage. However, such an analysis poses an alternative, and interesting, methodology to think about and examine water utilization.
About a fifth of the water that humankind now uses gets "exported" from its original country to another, but not in liquid form. Approximately 92% of water used planetwide goes to agricultural production. To see if it is "exported", researchers assessed the share of water used in industry and in growing wheat, beef, and other agricultural products. The result of the assessment is, not surprising, that some arid countries (e.g., Isreal, Kuwait) take a huge portion (80-90%) of their "virtual water" (water used in industry and in agricultural goods that are imported) from outside their borders. But, then so do some relatively wet places (e.g., UK, 75%; Netherlands, 95%). The U.S. exports more virtual water than it imports, but still sees 20% of water consumed manifest from imported goods.
The worldwide trend toward eating more animal products and processed foods may increase the demand for water. Producing a gram of protein in the form of milk, eggs, and chicken typically requires half again as much water as delivering a gram of protein from legume protein. Creating a half liter of soda uses between 170 and 310 liters of water (95% of this usage goes to growing and processing ingredients; the amounts vary with the type of sweetner produced).
Industrial usage is dwarfed by agricultural usage. The researchers are assessing that sector now.
Reports on this topic can be found at http://www.pnas.org/content/early/2012/02/06/1109936109 and http://www.springerlink.com/content/p470u310l0850478/.
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