The world is facing a food crisis because it is running out of water to support food production, according to an environmental consultant and author. Speaking at the opening of the Water, Finance and Sustainability 2008 conference in London, Fred Pearce, author of When the Rivers Run Dry, said major changes were needed to find enough water for everyone to use. He said many developed countries have even higher water consumption rates than it first appears because of the global trade in virtual water - the water used to produce food which is exported and imported.