Food Exports Can Drain Arid Zones: Trade in Agricultural Products Can Increase Water Stress
Milius, Susan, Science News
About a fifth of the water that humankind now uses gets exported from one country to another--though rarely as anything that can splash into a glass.
Understanding the big blue picture of water resources means getting over the notion that water is wet. Ninety-two percent of water used planetwide goes into agricultural production, according to the latest accounting from Arjen Hoekstra and his water research group at the University of Twente in the Netherlands. So for 1996 through 2005, Hoekstra and colleagues tracked "virtual water," a combination of actual liquid and the shares of water used in industry and in growing wheat, beef and other products.
This accounting highlights the various degrees to which nations depend on foreign water. Some arid countries take a whopping portion of their virtual water from outside their borders (Israel, 82 percent; Kuwait, 90 percent). But so do relatively watery places such as the United Kingdom (75 percent) and the Netherlands (95 percent), the researchers report online February 13 in the Proceedings of the National Academy of Sciences. The United States, which exports more virtual water than it imports, still reaches outside its borders for 20 percent of its consumption. …