James Cameron, famed director and well-known climate change activist, has a message for the masses: go vegan to fight climate change. Cameron, who has been vegan for four years, spoke at a climate change summit in Los Angeles earlier this week about the impact of food systems and diet on climate change. In an exclusive interview with Fortune , Cameron explains: [T]he thing that became abundantly clear to us when we met with the experts who are working in nutrition and energy sustainability and climate change is that we can’t actually meet our emission goals if we don’t address animal agriculture, and that’s the thing that’s been left out of the conversation. This message is crucial because many people who care about the environment still have no idea that raising animals for food is so incredibly destructive. Consider some of these facts: Going vegan immediately cuts your CO2 emissions in half It takes 2,500 gallons of water to produce just one pound o