Global threat to food supply as water wells dry up, warns top environment expert by John Vidal | 8 Jul 2013 food crisis | China | Saudi Arabia | United States Grain harvests are already shrinking as US, India and China come close to 'peak water', says the Global Policy Institute's Lester Brown Grain harvests are already shrinking as US, India and China come close to 'peak water', says the Global Policy Institute's Lester Brown