I wrote this article months ago for an environmental website.

What if giving up cheeseburgers and fried chicken could help the environment? The truth is that it can. It is a great time for committed environmentalists to eliminate meat from their diets. Evidence shows that the greenhouse gas methane is a big contributor to global warming. The number one source of methane comes from animal agriculture.

Methane contributes to global warming almost as much as all other non-CO2 gases combined. “Methane has a warming effect 23 times as great as carbon,” environmentalist writer George Monbiot states in his book Heat: How to Stop the Planet from Burning. Methane remains in the atmosphere for 9-15 years, according to the Environmental Protection Agency (EPA).

The majority of methane (about 85%) is produced in the digestive tract of livestock. Over 100 million tons of methane is produced by animal agriculture every year. Global meat consumption has increased fivefold in the last 50 years. The Food and Agriculture Organization of the United Nations (FAO) released a report November 2006 about the causes of global warming. Henning Steinfeld, the senior author of the report, said, “Livestock are one of the most significant contributors to today's most serious environmental problems.”

The FAO report found that livestock cause 18% of green-house gas emissions, including nine percent of all CO2 emissions, 37% of methane, and 65% of nitrous oxide. Transportation causes fewer emissions than livestock. The FAO report also noted that between 1970 and 2002 the meat consumption per capita annually in developing countries increased from 24 lbs. to 64 lbs.

Twenty tons of livestock manure is produced in a year for every household in the U.S., according to the Union of Concerned Scientists. The People for the Ethical Treatment of Animals state that animal agriculture produces 130 times the excrement that humans do.

Since 1961 the global livestock population has increased by 60%, according to the Worldwatch Institute (WI). WI also states that the amount of fowl raised for human consumption almost quadrupled from 4.2 billion to 15.7 billion. Beef and pork consumption in the U.S. has tripled since 1970, and in Asia it has more than doubled.

The University of Chicago’s Department of the Geophysical Sciences released a report which concluded that a person consuming a diet of both meat and plant-based food “…causes the emissions of 1485 kg CO2-equivalent above the emissions associated with consuming the same number of calories, but from plant sources. Far from trivial, nationally this difference amounts to over 6% of the total U.S. greenhouse gas emissions.”

Fast food consumption accounts for a part of overall meat consumption. Eric Schlosser noted in his book Fast Food Nation, “Americans now spend more money on fast food—$110 billion a year—than they do on higher education. They spend more on fast food than on movies, books, magazines, newspapers, videos and recorded music—combined.”

The environmentalist organization Earth Save’s pamphlet Our Future, Our Food contains startling statistics concerning U.S. animal agriculture:

• Acres of US land producing hay for livestock: 56 million

• Acres of US land producing vegetables for humans: 4 million

• Amount of U.S. agricultural land used for feed grains and animal farms: 80%

• Amount of land needed to feed a pure vegetarian for a year: 1/6 acre

• Amount of land needed to feed a meat-eater for a year: 3 1/4 acres (about 20 times as much)

• Amount of rainforest needed to produce just one hamburger: 55 square feet

“We definitely take up more environmental space when we eat meat,” noted Barbara Bramble from the National Wildlife Federation. “I think it’s consistent with environmental values to eat lower on the food chain.”