Water-stressed Israel realized this year ago when it recognized that its exports of Jaffa oranges were really exporting "virtual water." It took scarce water to grow the orange and when it left the country for overseas markets it was full of water.
Fast forward to 2014 and drought-stricken California. The BBC reports that California farmers are using billions of gallons of incredibly scarce water to grow alfalfa hay destined for China.
The southern Imperial Valley, which borders Mexico, draws its water from the Colorado River along the blue liquid lifeline of the All American Canal.
It brings the desert alive with hundreds of hectares of lush green fields - much of it alfalfa hay, a water-hungry but nutritious animal feed which once propped up the dairy industry here, and is now doing a similar job in China.
"A hundred billion gallons of water per year is being exported in the form of alfalfa from California," argues Professor Robert Glennon from Arizona College of Law.
"It's a huge amount. It's enough for a year's supply for a million families - it's a lot of water, particularly when you're looking at the dreadful drought throughout the south-west."
Why China? It's because of China's one-way trade with the United States. Chinese goods reach the American mainland in ocean shipping containers that then have to go back empty. The glut of empty containers makes alfalfa exports to China cheap, cheap, cheap. It's cheaper to ship Imperial Valley alfalfa to China than to transport it to California's central valley ranchers.
Well, kids, welcome to globalization.
