How Much Do Cattle Really Contribute to Greenhouse Gases/Climate Change?

The dogma that eating meat is killing the planet seems to rest on shaky grounds

(This was originally posted on my blog in 2021. Since then, the push to save the planet by eating plants has greatly intensified.)

Recently I've been pondering the effects of what humans eat on our planet. With a few exceptions, I've steered clear of politically charged issues on The Skeptical Cardiologist and tried to focus on issues relevant to cardiovascular health, especially ones espoused by mainstream guidelines which lack a solid scientific basis (e.g. dairy fat is bad for you.)

In the diet wars, I am a neutral observer, although I can be a keto-friendly cardiologist I also advocate prioritizing whole fruit and vegetable intake to my patients.

I've written extensively on the lack of science underlying vegan diet claims to prevent or reverse coronary heart disease but also recognize the pseudoscience that purveyors of the carnivore/bullet-proof/paleo diets on the far end of the meat-centric spectrum spew. For an excellent discussion on the nuttiness on both ends of the dietary tribal wars I recommend episode 401 of the Sigma Nutrition podcasts which inducts Dr. Michael Greger, Eric Berg DC, and Paul Saladino, aka the Carnivore MD into their Quack Asylum

When it comes to fat consumption the scientific evidence does not tell us we should be eating less of the saturated fat that comes from dairy products. In addition, I'm not convinced by vegan arguments of cruelty to cows because I've seen how cows can be treated like members of the family on well-run dairy farms.

One argument that has captured my attention is that by switching from dairy and meat consumption to a completely plant-based diet we can reduce greenhouse gas emissions.

The Dogma on Climate Change: Eating Meat is Killing the Planet

Professor Google answers my titular question with this factoid from an article on Inside Climate News, versions of which pop up in most articles on diet and climate change and which most journalists in the climate change arena accept unquestioningly:

Emissions from livestock account for about 14.5 percent of total greenhouse gas emissions, globally, and roughly two thirds of those emissions come from cattle — mostly from methane burped by cows, growing feed and clearing land for grazing and feed crops.

Even more depressing for we omnivores, Inside Climate News also tells us that "Air Pollution From Raising Livestock Accounts for Most of the 16,000 US Deaths Each Year Tied to Food Production, Study Finds"

Substituting poultry for meat could save 6,500 lives and if everyone converted to veganism even more lives would be saved according to this

The Canadian website Let's Talk Science, aimed at promoting STEM learning in youths, ends a piece on cows, methane and climate change by telling kids that eating less meat will mitigate climate change.

But as you have just learned, methane gas emissions from livestock are a huge problem. So driving less may not be the most important thing we can do to help mitigate climate change. Many experts now believe that eating less meat would actually have a bigger impact.

From Let's Talk Science: How burps and farts of methane are produced

Marion Nestle' Piles on the Anti-Beef Wagon Then Reconsiders

The beef industry thinks the 14.5% number is wrong and has attempted to counter the prevailing wisdom that beef consumption is nonsustainable. Marion Nestle, at Food Politics wrote a post critical of a beef industry ad that claimed that American beef contributes only 2% of greenhouse gases.

From Food Politics courtesy of Lisa Young, Ph.D

Two of her readers objected to her use of the widely quoted figure of 14.5% and argued for a correction.

The first was Stephen Zwick, who writes a blog that advocates "regenetarianism" and is independent of industry interests. The notes he sent Nestle are summarized in a subsequent blog post and include these points

-The 14.5% figure comes from a study that included land-use change, “specifically in Brazil at peak deforestation rates from 1998 to 2004,” and just for OECD countries.

-In North America, deforestation isn’t a large issue. The 2014 UN Climate Change Conference numbers from countries where land change is not a big factor total 8.1% for all agriculture. Of that, only a quarter is from enteric fermentation (cattle methane burps). Adding in manure management, brings it to about 40% of 8.1% or a bit over 3%.

-These global or regional numbers also don’t account for soil sinks or tropospheric sinks, a topic he covers in these 3 blog posts,

• WTF happens to all that methane?

• Methane: Accounting for both sides of the scale

• Ruminations: Methane math and context

Zwick concludes

"Ruminants and other sources of biogenic methane aren’t the problem. Thermogenic sources (fracked gas, coal bed gas and other fossil fuels) of GHG’s are. Enteric methane is a distraction. Poor land management destroying soil sinks and reducing photosynthesis via desertification, deforestation and ocean acidification are also a huge problem. And yes, cattle and palm oil are part of the problem in tropical regions as I noted in this more recent blog post, The Deforestation Process... Cattle is a very conspicuous driver, though it’s not really the primary driver. Human greed is."

Elsewhere Zwick has written an excellent piece entitled "Life and Death from the soil food web on up" which begins with this quote:

“Part of living is killing. I don’t care if you eat vegan or you eat meat, you are responsible for death. I would argue that if you’re vegan, you are responsible for way more death than if you eat a healthy, regenerative diet with grass-fed meat. As a regenerative rancher, it’s part of our responsibility to give more life than we take. We understand—because we understand nature—that every part of eating is killing, no matter what it is. A plant doesn’t have a heart or lungs; you’re right. But that crop field growing crops was once life to a huge diversity of plants, and animals, and birds, that are now gone. You are responsible for that patch of cropland killing that habitat, and killing all of those animals that could be living there—living there alongside your grass-fed steer, or living alongside your diversified agriculture crop.”

Doniga Markegard, author of Dawn Again: Tracking the Wisdom of the Wild

and is followed by this intriguing paragraph

"Meats versus plants is a false dichotomy. Doing the least harm, causing the least amount of suffering and creating the most diversity is more a matter of balance than absolutism. So for any type of food, whether from plants, animals or fungi, there are a wide array of ways to grow, catch or raise that food ranging from very bad to very good. This is especially true in regards to overall impacts on ecosystems and other sentient beings. So the HOW and appropriateness of WHERE any particular food is grown, raised or caught often matters as much or more than the WHAT that’s raised, grown or caught."

Does Beef Do More Damage Than Transportation?

Frank M. Mitloehner, a Ph.D. Professor of Animal Science at UC Davis has studied the ways in which animal agriculture affects air quality and climate change for 20 years and convincingly argues that meat's bad rap on GHG is undeserved.

In 2006, the United Nations Food and Agriculture Organization published a study titled “Livestock’s Long Shadow,” which received widespread international attention. It stated that livestock produced a staggering 18 percent of the world’s greenhouse gas emissions. The agency drew a startling conclusion: Livestock was doing more to harm the climate than all modes of transportation combined. .This latter claim was wrong and has since been corrected by Henning Steinfeld, the report’s senior author. The problem was that FAO analysts used a comprehensive life-cycle assessment to study the climate impact of livestock but a different method when they analyzed transportation.

Even if Americans eliminated all animal protein from their diets, they would reduce U.S. greenhouse gas emissions by only 2.6 percent. According to our research at the University of California, Davis, if the practice of Meatless Monday were to be adopted by all Americans, we’d see a reduction of only 0.5 percent.

Defending Beef

After researching this topic, I don't think we should be teaching kids that eating less meat would have a bigger impact on climate change than driving less. I don't think the science is settled on whether switching from dairy and meat consumption to a completely plant-based diet will significantly reduce greenhouse gas emissions.

While pondering this topic, I listened to a podcast that featured Nicolette Hahn Niman, a former vegetarian and environmental activist who married a cattle rancher. Before writing the book, Defending Beef she was the senior attorney for the environmental organization Waterkeeper Alliance, where she was in charge of the organization's campaign to reform the concentrated livestock and poultry industry, and before that an attorney for the National Wildlife Federation.

I have purchased her book Defending Beef: The Ecological and Nutritional Case for Meat, which argues for the benefits of regenerative beef production. She believes and I agree that

the problem with our food system is industrialization, and [fake meat is] an industrial food. It’s produced on an agricultural level, industrially, almost universally, and it’s a highly processed food before it gets to your plate.

Animals are essential in her mind as they

add an element that cannot be replaced with chemical amendments to the soil. That’s been done for decades and didn’t work. What regenerative agriculture is all about is understanding relationships and connected connections between living things, and trying to foster life. And to me, that is absolutely the direction that farming has to go and whether it’s on a small scale or large scale.

In the meantime, although I'm a huge advocate of minimally processed vegetables, nuts, pulses and fruit, I see no compelling reason from an environmental or nutritional perspective to eliminate beef from my diet or from the diet of my patients who have documented coronary artery disease.

Antifartinogenically Yours,

-ACP

N.B. I’m not a climate change denier, and I strive to minimize my personal negative impact on the environment. I drive an electric car, am actively vermicomposting, avoid buying plastic water bottles, and recycle compostable materials that my worms can’t eat.