That meat production has a large carbon footprint is an article of faith among folks who keep track of these things. The problem is that the people who keep track of these things often don't know shit from shinola about farming in general, or meat production in particular.
The website of Science News recently ran a report on the effects of human diets on greenhouse gas emissions. In a nutshell, Ulf Sonesson of the Swedish Institute for Food and Biotechnology told the American Association for the Advancement of Science's annual meeting that beef is a powerful greenhouse gas emitter, and that pork and poultry are less so, and that vegetable based proteins, such as soy, are the best for the climate.
Sonesson looks at the beef industry from a pretty standard set of assumptions: the cattle that produce our beef are fed large amounts of corn in centralized feedlots, where the feed is trucked in, large amounts of methane are produced, cattle are trucked out to slaughter, beef is frozen, trucked around the country, and stored in large industrial freezers. All of these steps of transportation, feeding, and storage require the burning of energy, which emit greenhouse gasses. The production of the corn that feeds the cattle in the feedlots also emits greenhouse gasses.
These are all very valid points, and, unfortunately, are true for the vast majority of beef that's produced in the US.
It appears that Sonneson makes some further assumptions about the production of beef, however, that are simply untrue. Primarily, that every part of the beef production cycle is like the feedlot. It's not.
The beef industry has two very distinct components: the cow-calf operations and the feeding operations. The cow-calf operations are almost entirely grass based, using pasture and range as their main source of nutrition for the cattle. Ranchers and farmers who run these operations have herds of cows that deliver calves every year, and it is these calves (minus replacement heifers) that go on to the feedlots after they are weaned. There are also several types of operations that specialize in taking calves from relatively light weaning weights to the sizes that feedlots typically take in; many of these are also grass based operations.
What difference does that make? Tons. Millions of tons, and perhaps billions, actually. Every acre of managed pasture and range absorbs greenhouse gasses. Grass based farming increases the organic matter in the soil, and this organic matter is largely carbon. The carbon comes from decaying plants, which obtained carbon by taking it out of the atmosphere in the form of carbon dioxide, one of the most powerful greenhouse gasses. The management of cattle on pasture or range requires very little in the way of fossil fuel input. Pasture and range is generally not treated with chemical fertilizer. Low-horsepower vehicles (actual horses, in many cases) are used to check and round up cattle. Perhaps most importantly, the soil is not tilled.
When soil is exposed to the air, as it is when it is tilled for the production of grains and oilseeds, it loses carbon into the atmosphere. Native prairie soils are black; this is carbon -- those decomposing plants again. In places where prairies have been put to the plow, the soil turns brown, or a sickly anemic gray as carbon is released. Compared to the amount of carbon lost through oxidization, the emissions of tractors used to do the plowing is almost trivial.
The models that condemn beef production as an emitter of greenhouse gasses -- as far as I can tell -- do not give beef credit for the millions and millions of acres of carbon sequestering grasslands that underpin the admittedly wretched feedlot business.
While swine and poultry are much better converters of grains and oilseeds into human food than beef cattle (cattle are ruminants and not ideally suited to processing high levels of starch), they do not have any grassland components to their industry. They are essentially all feedlot, all the time, as the models incorrectly assume the beef industry is.
The normally thoughtful Epicurious ran a blog posting this week under the heading "Eat Soy, Save the Planet" based on the Science News article. The author admits to having her tongue in her cheek when she wrote it, but it is the take-away message that so many of these analyses seem to promote. I was heartened that my comment there was not a voice in the wilderness on this issue.
Soy as a source of human protein is also not without its environmental costs. Deforestation of the Amazon basin for soy production is a huge source of carbon emission. Every acre of land that produces soy is tilled, and loses carbon to oxidation. Most commercial soy production relies heavily on chemical fertilization, herbicide application, and is causing the loss of topsoil at a rate that is several orders of magnitude higher than that of the grass-based component of beef production.
As interesting as it would be to look at the carbon footprint of the beef industry as it actually is, it would be even more interesting to look at the carbon footprint of grass-fed beef that is processed and consumed within a 100-mile radius of where it is grown. I suspect that it would be a winner.
And lamb? Lamb is seldom even discussed in these analyses, because it represents such a tiny slice of our diet. But grass-fed lamb would require even less carbon than grass-fed beef, as the carcasses would require less energy to chill, and the production generally requires less machinery. In my own farming operation, I know that I am increasing organic matter in the soils that I graze -- I have soil tests to prove it. Organic matter is mostly carbon, mostly from carbon dioxide taken from the atmosphere by plants. I wouldn't be surprised if an analysis of my operation showed that I am either carbon neutral, or perhaps have some carbon credits to sell.
Pastured poultry still requires some grain, and most pastured pork does as well. For the very reasons that poultry and pork are better at converting grain into meat than ruminants, they are worse at converting grasses and forbs: they don't have a rumen to break the cellulose down. While local, pasture-raised pork and poultry are wonderful, I suspect they are less carbon-friendly than red meat produced from locally-raised grass fed ruminants.
I'm hopeful that we can start to see some more nuanced carbon-footprint analyses of human diets that flow from an actual understanding of how food is produced, not from faulty assumptions. It's time for science to start catching up with reality, and perhaps offering some models for how farmers can reduce the carbon footprints of their operations.