Monday, February 16, 2009

Beefy statistics

For those of you feeling good about yourselves by eating grass-fed beef rather than the corn-fatted variety, some bad news from the recent meeting of scientists in Chicago (from an article in Science News):

From a climate perspective, beef is in a class by itself.

Many environmentalists have argued that finishing up the fattening of beef cattle on corn is worse for the environment than cattle that are raised solely on pasture grass. An analysis finds that at least from a climate perspective, the opposite is true. “We do see significant differences in the GHG intensities [of grass vs grain finishing]. It’s roughly on the order of 50 percent higher in grass-finished systems.”

When an audience member questioned whether he had heard that right, that grass-fed cattle have a higher carbon footprint, Nathan Pelletier of Dalhousie University in Halifax, Nova Scotia, reiterated, “higher. Yes.” The reason: “It’s related to the much higher volumes of feed throughput and associated methane and nitrous-oxide [GHG] emissions.” He added that most pastures were highly managed, and subject to “periodic renovations and also fertilization.” Finally, with grass-fed cattle “there is also a high [grass] trampling rate. So the actual land area that you need to maintain magnifies that [GHG] difference,” Pelletier said.

It takes a lot of energy and other natural resources to produce cattle feed, manage the animals’ manure (a major emitter of methane, a potent GHG), get the livestock to market, slaughter the animals, process and package the meat, dispose of the greater part of the carcass that won’t be human food, market the retail cuts, transport them home from the store, refrigerate them until dinner time, and then cook the beef.

Tally the GHG emissions associated with all of those activities, and you’ll find it’s the global-warming equivalent to spewing 19 kilograms of carbon dioxide for every kg of beef served. At the other end of the spectrum are veggies. The climate costs associated with growing, marketing, peeling and boiling up a kg of potatoes, by contrast, is just 280 grams.

Another factor contributing to cattle’s particularly egregious carbon footprint is their relative fecundity, if you will, says Pelletier. In her lifetime, a mother fish, particularly in protected aquaculture settings, may give birth to hundreds — if not thousands — of surviving offspring. A hen could certainly produce hundreds of chicks. Even a sow can give birth to eight piggies per litter. But a cow: She tends to issue a single calf every year for maybe 10. And while she’s in gestation and then waiting to become pregnant again, farmers have to care for her and perhaps a bull — which are both big, hungry manure factories.

Currently, although beef accounts for only about 30 percent of the world’s meat consumption, it contributes 78 percent of meat’s GHG emissions. Pork, at 38 percent of consumption, contributes only 14 percent of meat's GHGs. Another 32 percent of the meat consumed worldwide comes from chicken, but getting these birds from farm to fork contributes only 8 percent of meat’s global carbon footprint. By shifting some share of beef and pork production to chicken over the next four decades, the increase in meat’s GHG emissions by 2050 might be held to just 6 percent higher than today, Pelletier said, even as the human population grows by another quarter-million each day.

Although meat's overall carbon footprint is projected to grow only a little over the next 40 years, the global goal is to cut emissions in every sector. Pelletier offered some suggestions on how to do that. Some were considerably more appetizing than others.

For instance, substituting all beef production for chicken would cut meat’s projected carbon footprint by 70 percent, he said.

Want to find out the carbon footprint of what you're eating? Go to

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