| A guest post by Maine farmer Eliot Coleman over at Grist got under my skin today. With a provocative title -- "Debunking the meat/climate change myth" -- and a maddening lack of focus and specificity, he eventually comes to the point that it isn't meat that adds to the climate crisis, but the industrial agriculture system. Although much of the piece drove me crazy, I can't argue with his overall conclusion that much of the meat's climate change impact can be placed at the feet of industrial agriculture and our nation-spanning food system. Items like the production of soy and corn using chemical fertilizer (emission of N2O), transporting feed and animals (emission of CO2), use of machines (CO2), and so on, contribute a significant amount to the carbon footprint of meat. |
We can get a ball-park estimate of the industrial contribution using an excellent academic paper from Weber and Matthews. The paper, which was published in Enviromental Science and Techonology last year, provides some life-cycle estimates for various categories of food produced in the standard American manner (e.g. CAFOs for meat, heavily fertilized corn & soy feed, monocultures, etc.).The analysis considers nearly all impacts of production, including delivery, freight, wholesale/retail, and production. For the average household, the "red meat" category (beef, pork, lamb), contributes 2.5 metric tons (mt) of CO2-equivalent emissions per year out of a total of 5.5 metric tons. Of this 2.5 mt CO2-equivalent contribution from red meat, 7% is from delivery, freight, wholesale/retail (mostly as CO2), with the remaining 93% of the impact is from production (i.e., growing the feed, raising the animals, slaughter, processing). The production category can be further broken down into CO2 emissions, nitrous oxide emissions (mostly from synthetic fertilizer) and methane emissions (mostly from the digestive systems of ruminents like cows and sheep). The CO2 portion of the production category is 24% of the red meat contribution, the nitrous oxide portion is 36%, and the methane portion is 33%. Thus, about 2/3 of the greenhouse emissions are related to the production methods, and 1/3 is directly from the animals. Clearly this is a rough estimate because decomposing manure emits N2O, and there is a certain baseline amount of CO2 needed for even the greenest beef operation (e.g., transportation). It would be interesting to break this down more carefully to get a better estimate, but now is not the time for such an undertaking. Returning to the post at Grist, Coleman writes: If I butcher a steer for my food, and that steer has been raised on grass on my farm, I am not responsible for any increased CO2. The pasture-raised animal eating grass in my field is not producing CO2, merely recycling it (short term carbon cycle) as grazing animals (and human beings) have since they evolved. In terms of CO2, this statement might be true, but when you consider methane and nitrous oxide, I doubt that it is. Steers and other ruminents emit methane as part of their normal digestion -- even when eating grass (see this article in New Scientist, for example) -- and methane is far a more potent warming agent than CO2 (25 times more potent, according to the IPCC Fourth Assessment Report). And thus, when a cow converts a carbon atom from a plant into a methane molecule instead of a CO2 molecule or a part of their body, the climate impact of that carbon atom is increased by 25-fold. However, when we take a step back and include the pasture ecosystem in the calculation, the answer might change. It is conceivable to me that a steer that eats only grass from naturally fertilized pasture could have a carbon footprint that is minimal or even negative. The reasons: the roots of grasses (especially perennials) and the soil itself can act as carbon sinks, thus sequesters enough carbon to make up for any methane emitted by a steer. It is also conceivable that manure decomposes differently on pasture than at the CAFO. I'd love to see some serious research about this subject -- I'm sure that someone is doing the measurements, modeling and math. Coleman concludes his piece with this: Targeting livestock as a smoke screen in the climate change controversy is a very mistaken path to take since it results in hiding our inability to deal with the real causes. When people are fooled into ignorantly condemning the straw man of meat eating, who I suspect has been set up for them by the fossil fuel industry, I am appalled by how easily human beings allow themselves to be deluded by their corporate masters.
Unfortunately, the vast majority of meat produced in the U.S. is from an industrial system that has an enormous carbon footprint, and so when people target "livestock" because they read that livestock constitutes 9% of total U.S. greenhouse gas emissions, they are really targeting the livestock produced by the current greenhouse-gas-intensive system. But if it turns out to be true that pasture-raised beef is indeed climate neutral or climate positive, the discussion about beef and climate change might split into two discussions: one about increasing access to pasture-raised beef, and one about changing the predominent industrial food system. (note: I also left a comment on the Grist post under the username mm510, and so some of the sentences might match) |
