The Economist, September 18, 2008 - “Most people may drink only two litres of water a day, but they consume about 3,000 if the water that goes into their food is taken into account. The rich gulp down far more, since they tend to eat more meat, which takes far more water to produce than grains. So as the world’s population grows and incomes rise, farmers will—if they use today’s methods—need a great deal more water to keep everyone fed: 2,000 more cubic kilometres a year by 2030, according to the International Water Management Institute (IWMI), a research centre, or over a quarter more than they use today. Yet in many farming regions, water is scarce and likely to get scarcer as global warming worsens.” Read more.