Experts say that if food were a country, it would rank second behind the US as one of the biggest greenhouse gas polluters. The reason is the rising demand for meat. Animal farming is responsible for14.5 percent of global greenhouse gas methane(甲烷) emissions(排放). While cows are the worse contributors, pigs, sheep, donkeys and other animals play a part as well.Animal agriculture also causes land to become damaged, water to be polluted and forests to get destroyed. With the world population forecast to rise to 9.8 billion by 2050, things are only looking worse for our already decreasing