Vegetarianism vs. Meat-Eating and Global Warming

[cross-posted from Ancora Imparo]

Those of you concerned about climate change may already know that one of the more significant changes an individual can make is to reduce the consumption of meat. In an article yesterday (“Meat is Murder on the Environment“), New Scientist reported on a study by Ogino and colleagues in this month’s Animal Science Journal that analyzes, in detail, beef’s environmental impact. It concludes

A kilogram of beef is responsible for more greenhouse gas emissions and other pollution than driving for 3 hours while leaving all the lights on back home.

(It should be noted that the three-hour drive is based on emissions from European cars; the fuel efficiency of American cars is much worse and so the equivalent driving time would be less in the United States.) The greenhouse gas emissions consist primarily of methane from the animals’ digestive systems. Also, transportation and production of the animals’ feed takes a significant amount of energy/fuel. Non-environmental harms—such as the the promotion of antibiotic resistance in humans by the use of (often preventitive) antibiotics in animals—were not considered.Naturally, eating vegetarian food instead still will incur some of the energy costs, but in significantly reduced amounts. As energy flows through the food chain, a significant portion is lost at each step (90% is often cited). This suggests that it would take ten times the plant material to feed a herbivore to provide meat with equivalent energy yield as it would consuming the plants directly. That will require ten times more land to be used, use ten times more water and fertilizers, ten times more fuel for transport (not to mention the cost of transporting the meat, which was not included in the study), and so on. Producing meat requires between twenty-five and two hundred fifty times as much water as producing an equivalent amount of grain (estimates vary by study, but the ratio is probably closer to the higher end).Other publications have discussed the tremendous environmental impact of meat consumption and the potential benefits of switching to plant consumption. In the 9 April 2007 issue of TIME (see also my previous post about this issue), Bryan Walsh wrote

If you switch to vegetarianism, you can shrink your carbon footprint by up to 1.5 tons of carbon dioxide a year, according to research by the University of Chicago. Trading a standard car for a hybrid cuts only about one ton—and isn’t as tasty.

And in March 2007, National Geographic had this to say:

If, like most Americans, you get close to 30 percent of your calories from meat, dairy, and poultry, your diet contributes over 3,274 pounds (1,485.1 kilograms) [of carbon dioxide emitted annually]. Vegetarian diets contribute half that, but you can also replace your calories from red meat with fish, eggs, and poultry, for savings of over 950 pounds (430.9 kilograms).

Of course, these studies tend to focus on switching from meat to a caloric equivalent of plant-derived food. In the developed world, though, obesity has reached epidemic proportions—in the United States, over three-fifths of adults are overweight, and over one-quarter are obese (source, CDC). The environmental benefit of simply eliminating some meat consumption and not replacing it with plant consumption would naturally be even higher than the alternative.Finally, I must note that these benefits are not immediate. Forgoing that cheeseburger today will not reduce global warming tomorrow. Rather, as less meat is consumed, less livestock will be raised, and therefore cause less environmental harm over years and decades.I’d summarize this as follows:

        

  • The consumption of meat (indirectly, in the form of production) results in a tremendous negative impact on the environment.
  • Switching to vegetarianism is probably one of the single most effective lifestyle changes an individual can make in mitigating global warming. However, even if one is not prepared for such a dramatic change, there are several intermediate changes that will also provide significant benefits.
  • Eliminating only mammals (beef, pork, and so on) from one’s diet has a major, beneficial impact.
  • Alternatively, cutting back on meat intake can also be quite beneficial. For instance, depending on one’s meat intake and desire, one could avoid meat one day a week, or perhaps half the week, or even only eat meat one day a week.
  • For those that are overweight or obese, reducing harm to the environment is one more reason to reduce food intake, especially that of meat.
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