Monday, February 02, 2009

More Meat

As it turns out, eating meat has a curious little environmental side effect: it contributes to the release of prodigious amounts of greenhouse gas (GHG).

A 2006 report by the United Nations Food and Agriculture Organization (FAO) concluded that meat produces more of the GHGs carbon dioxide (CO2), methane, nitrous oxide, and the like than either transportation or industry. The FAO report found that current global production levels of meat contribute between 14 and 22 percent of the 36 billion tons of "CO2-equivalent" GHG the world produces every year.

Producing half a pound of hamburger releases as much GHG into the atmosphere as driving a 3,000-pound car nearly 10 miles. Producing the annual beef diet of the average American emits as much GHG as a car driven more than 1,800 miles.

Pound for pound, beef production generates GHGs that contribute more than 13 times as much to global warming as do the gases emitted from producing chicken. Compared to potatoes, the multiplier is 57. At McDonald's, the world would be better off if you just ate the fries.

In fairness, every food we consume incurs hidden environmental costs in transportation, refrigeration, and fuel for farming. Growing just half a pound of asparagus in Peru emits greenhouse gases equivalent to 1.2 ounces of CO2 as a result of applying insecticide and fertilizer, pumping water, and running heavy, gas-guzzling farm equipment. To refrigerate and transport the asparagus to an American dinner table generates another two ounces of CO2-equivalent GHG, for a total CO2 equivalent of 3.2 ounces.

But that is nothing compared to beef. Depending on the production method, cows emit between 2.5 and 4.7 ounces of methane for each pound of beef they produce. Because methane has roughly 23 times the global-warming potential of CO2, those emissions are the equivalent of releasing between 3.6 and 6.8 pounds of CO2 into the atmosphere for each pound of beef produced.

Raising animals also requires a large amount of feed per unit of body weight. Producing a pound of beef protein for the table requires more than 10 pounds of plant protein, with all the emissions of GHG that grain farming entails. It has been calculated that producing a pound of beef in a feedlot generates the equivalent of 14.8 pounds of CO2 pound for pound, more than 36 times the CO2-equivalent greenhouse gas emitted by producing asparagus.

Even other common meats cannot match the impact of beef; it has been estimated that producing a pound of pork generates the equivalent of 3.8 pounds of CO2; a pound of chicken generates 1.1 pounds of CO2-equivalent greenhouse gases.

Interestingly, beef produced in America and most other first world countries is several times less GHG intensive than the world average. That's because we no longer destroy carbon sinks to feed cattle, whereas many poorer parts of the world still do. But worldwide beef consumption is rising rapidly, both as populations increase and as people eat more meat. Eating less beef is a good idea, but most of the damage is from land-use change for grazing and feeding cattle for and by poor people who can now afford to eat more of it. But if the U.S. and the rest of the developed world ate less meat, particularly beef, we'd all be better off.


GreenSmile said...


GreenSmile said...

and livestock has recently taken over as the largest US source of anthropogenic methane.