How does eating meat harm the environment?

When land is used to raise animals instead of crops, precious water and soil are lost, trees are cut down to make land for grazing or factory-farm sheds, and untreated animal waste pollutes rivers and streams. In fact, it has such a devastating effect on all aspects of our environment that the Union of Concerned Scientists lists meat-eating as one of the biggest environmental hazards facing the Earth. Globally, animal agriculture is responsible for more greenhouse gases than all the world’s transportation systems combined. No wonder, when you consider facts like these:

Cows must consume 16 pounds of vegetation in order to convert them into 1 pound of flesh. Raising animals for food consumes more than half of all water used in the U.S. It takes 2,500 gallons of water to produce a pound of meat but only 25 gallons to produce a pound of wheat.
Producing just one hamburger uses enough fossil fuel to drive a small car 20 miles. Of all raw materials and fossil fuels used in the U.S., more than one-third are devoted to raising animals for food.
A typical pig factory generates the same amount of raw waste as a city of 12,000 people.
Of all agricultural land in the U.S., 87 percent is used to raise animals for food. That’s 45 percent of the total land mass in the U.S. About 260 million acres of U.S. forest have been cleared to create cropland to produce feed for animals raised for food. The meat industry is directly responsible for 85 percent of all soil erosion in the U.S.
More than 80 percent of the corn we grow and more than 95 percent of the oats are fed to livestock. The world’s cattle alone consume a quantity of food equal to the caloric needs of 8.7 billion people—more than the entire human population on Earth. According to the Worldwatch Institute, “Roughly 2 of every 5 tons of grain produced in the world is fed to livestock, poultry, or fish; decreasing consumption of these products, especially of beef, could free up massive quantities of grain and reduce pressure on land.”