Desert and drought-prone nations increasingly rely on water from other countries and don’t even know it. That's the conclusion of a study in the Proceedings of the National Academy of Sciences that maps the world's water flow.
The problem revolves around a phenomenon that to the uninitiated might sound like a Facebook app or Web game: virtual water. It’s the phrase resource economists are using to describe the amount of water that goes into making a product bound for shipment abroad.
Countries that import food are buying goods made with water. That means they are outsourcing both food production and the environmental and economic risks that can come with overuse of limited water supplies. Food security for these importers may be at increasing risk from water scarcity among trading partners.
The countries most reliant on foreign watersheds are island and desert nations: Malta, which is 92 percent dependent on virtual water, Kuwait (90%), Jordan (86%) and Israel (82%).
Some of the world's most water-rich countries also import vast amounts water. These include the U.S., which imports 234 billion cubic meters a year, Japan (127), Germany (125) and the rain-soaked, umbrella-carrying United Kingdom (77). That's because much of the food they import, or coal in China's case, requires vast amounts of water to produce. The U.S. and China are also the world’s largest virtual-water exporters, at 314 billion and 143 billion cubic meters/year) respectively.
The authors of the paper, Arjen Hoekstra and Mesfin Mekonnen at the University of Twente in the Netherlands don’t propose any direct solutions. They argue that accurately mapping humanity's global water footprint is the first step for nations to avoid finding themselves at the mercy of drought or pollution in a trading partner who might be forced to cut off food exports.