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How Much Does U.S. Livestock Production Contribute to Greenhouse Gas Emissions?

By: Ralph Loglisci

A round of applause for Washington Post reporter Ezra Klein for pointing out last week the undeniable fact that meat production is a major contributor to global warming, and that consumers can make a difference by cutting out their meat consumption just one day a week. How big a difference in greenhouse gases reduction it would make in the United States has long been a topic of debate, and something I’ve wanted to clarify for quite a while. Before I explain why, I want to make it clear that there is more than enough evidence that shows reducing meat consumption nationwide would lead to dramatic improvements in environmental degradation, widespread public and personal health risks, animal welfare and environmental and social justice issues.

First off, I’m pleased to see that mainstream media outlets are finally increasing their coverage of food systems’ effects on climate change. Believe it or not, it’s taken a while for the news gatekeepers to catch on. Last year Johns Hopkins Center for a Livable Future’s research and policy director Roni Neff published a paper in the journal of Public Health Nutrition that found U.S. newspaper coverage did not reflect the increasingly solid evidence of climate change effects due to current food systems.

It’s not just burps from livestock that are to blame for the greenhouse gases (GHG) attributed to food animal production. Don’t forget that the vast majority of the grains we grow in the U.S. go to feed livestock. A 12-year-old Cornell study found that livestock, “consume more than five times as much grain as is consumed directly by the entire American population.” (The amount of fresh water used in animal production is even more shocking.) When you consider the GHG emissions from all that grain production including transportation and the fossil fuels used to make artificial fertilizers you start to get the picture of just how resource intensive industrial food animal production can be. Klein’s article does a fair job of trying to explain all the contributing GHG factors…

According to a 2006 United Nations report, livestock accounts for 18 percent of worldwide greenhouse gas emissions. Some of meat’s contribution to climate change is intuitive. It’s more energy efficient to grow grain and feed it to people than it is to grow grain and turn it into feed that we give to calves until they become adults that we then slaughter to feed to people. Some of the contribution is gross. “Manure lagoons,” for instance, is the oddly evocative name for the acres of animal excrement that sit in the sun steaming nitrous oxide into the atmosphere. And some of it would make Bart Simpson chuckle. Cow gas — interestingly, it’s mainly burps, not farts — is a real player.

… but like most issues, it’s a lot more complicated than that. As a communicator I have a difficult time deciding just how much information I should dump on a reader before the message I’m trying to convey becomes too muddied and convoluted.

The UN report that Klein mentions by the Food and Agriculture Organization of the United Nations entitled Livestock’s Long Shadow is a well done and important document, which I hope will influence climate change policies in countries around the world. However, I’ve always been a little uneasy when reporters throw around the 18% number without making it crystal clear that the percentage represents global GHG emissions due to food animal production. To be fair, Klein did say “worldwide,” but he would have been more clear if he wrote that, while the total amount of GHG emitted by livestock in the United States is massive, compared to other GHG emitters in the U.S. the percentage may be lower here. Always looking for a technicality to exploit, food industry spin-machines are screaming foul over Klein’s article. They claim Livestock’s Long Shadow, “has thoroughly been debunked,” pointing to EPA data that suggests the percentage of GHG emissions from all agriculture production in the U.S. is only 6%.

I’d like to “debunk” their misleading claim. First off, the percentage used by Livestock’s Long Shadow is not comparable because UN researchers were looking at global numbers and they included data that the EPA accounts for in other categories. Regardless, industry groups are trying to confuse the American public by focusing on percentages rather than hard numbers. Even if the percentage is actually lower, that doesn’t mean that the total GHG emissions are any less. The fact that the U.S. spits out so much more GHG through its power plants, fossil fuel powered vehicles and factories than most other countries, it’s not surprising that the percentage number is lower. The U.S. is arguably the number one GHG emitter in the world. Although recent data suggest China just earned the top distinction, climate experts say all the GHG created by Chinese factories spitting out products for American consumers should count towards our total. But I digress. Another contributor to a lower percentage number may include that we’ve already deforested the majority of our land, unlike less developed countries.

Because the EPA does not break out a livestock number in its GHG inventory report, we can only assume that if they used the same data, their number would be less than 6%. A while ago I called up the EPA to find out why their numbers were so different. One researcher told me it’s because their figures omit many of the factors that Livestock’s Long Shadow takes into account. If you read the executive summary of the EPA’s 2009 U.S. Greenhouse Gas Inventory report you’ll see that, unlike Livestock’s Long Shadow, when EPA researchers determined U.S. agriculture’s contributions they were not looking at GHG emissions from fuel combustion or CO2 fluxes due to land use.

The Agricultural chapter contains anthropogenic emissions from agricultural activities (except fuel combustion, which is addressed in the Energy chapter, and agricultural CO2 fluxes, which are addressed in the Land Use, Land-Use Change, and Forestry Chapter).

So what exactly did Livestock’s Long Shadow include in its computations that the EPA did not? Here’s what I could determine:

• Carbon dioxide emissions from: Nitrogen in fertilizer production, on farm fossil fuel related to feed and livestock, deforestation, desertification of pasture, cultivated soils due to tillage and liming, processing and transport.

Again, I think it’s misleading for industry to even try to compare the 6% number, because as you can see the EPA did not take the holistic approach of computing the data that the UN did. As far as I know, no one has crunched the numbers to determine a comparable GHG emissions number for U.S. livestock. But there is a strong study out of Carnegie Mellon University that took the first comprehensive look at GHG and food production systems in the U.S. The study entitled Food-Miles and the Relative Impacts of Food Choices in the United States yielded some data that could help me come up with relatively close figures. So I reached out to one of our scientists already researching the life-cycle impacts of food production for CLF, Brent Kim, for assistance. Here’s what we came up with:

Red meat + dairy + chicken/fish/eggs = 58% of diet-related emissions (Christopher L. Weber and H. Scott Matthews)

Total U.S. per capita diet-related emissions (animal products only): 3.1 x 0.58 = 1.78 t/year (EPA)

Percentage of total U.S. footprint: 1.78/20.67 = roughly 9%*

* There is one caveat, since the authors’ data grouped together all animal products including fish, dairy and eggs, the number may be a little less comparable, but it should be fairly close.

While much less than the 18% worldwide estimate, 9% still remains a significant number. And in real numbers, not percentages, U.S. livestock production’s GHG contribution could still be the largest in the world. Our friends across the pond are seeing similar GHG percentages. A 2009 report by the respected Food Climate Research Network based at Surrey University determined that livestock generated between 7- 8% of the United Kingdom’s GHG emissions and that substantial reductions in animal based food consumption are needed to cut GHG emissions. However, the author claims if you’re looking to significantly reduce your GHG footprint, you should cut out all animal products like milk, butter and cheese, because dairy production, while its contribution to GHG is less than beef cattle, is a large source of GHG. It’s also fair to note that poultry produce less GHG than ruminants and swine.

Not surprisingly, industry is trying to come up with high-tech band-aids to tackle the GHG issue. Some are trying to breed cows that burp less, others are working on less gassy feed, and don’t forget about the anaerobic digesters that can turn animal waste into electricity; think Mad Max: Beyond the Thunderdome. I may be biased, but I prefer the more sustainable alternatives, like organic meat production and farming, that have the potential to reduce GHG emissions and sequester carbon while at the same time addressing all of the other negative effects of industrial food animal production. It should be noted that while sustainable food animal production contributes less GHG than the conventional industrial model its contribution could still be significant.

In the meantime, I agree with people like Dr. Rajendra Pachauri, Chair of the United Nations Intergovernmental Panel on Climate Change and journalist and author of Omnivore’s Dilemma Michael Pollan who say one of the best ways we can help the environment and our health is to stick with a vegetarian diet once a week. I would add that you might want to cut out all animal products that day if you’re looking to reduce your GHG footprint even more. Regular readers of the LivableFutureBlog know that CLF has long promoted the benefits of a Meatless Monday. Ezra, if you’re reading this, please feel free to spread the word about the national campaign that was created in association with the Johns Hopkins Bloomberg School of Public Health.

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