India's population of cows and buffalo—the largest in the world—has a significant impact on the environment. India's cows and buffalo are the largest global livestock emitters of methane, a greenhouse gas that's at least 20 times more powerful than carbon dioxide. India's cows and buffalo also require significant amounts of feed and water, resources already under considerable pressure given India's large and growing human population. According to the World Bank, by 2020, India's land, water and air will be under more strain than anywhere else in the world. Part 2 of 2.