26 Mar 2008

Virtual Water

Professor John Anthony Allan of the University of London won the 2008 Stockholm Water Prize for introducing the concept of "virtual water," which captures the amount of water is takes to produce a (food product). Examples:
  • Cup of coffee: 140 liters of water to grow, produce, package and ship the beans.
  • One kg wheat: 1000 liters
  • One kg beef: about 15,000 liters
Bottom Line: A kg of rice will use more water if it relies on irrigation, uses lots of other inputs (fertilizer, etc.) or is grown in a hot, dry climate (e.g., California versus Thailand). Since food exports are also water exports, we should worry about growing food for export in water-poor areas. We should worry a lot if that water is subsidized and/or the food crop is grown for nationalist purposes (e.g., wheat in Saudi Arabia).