July 20, 2010

Cattle Burps and Climate Change: What About Bison? A Response to Joel Salatin

Brent Kim

Brent Kim

Project Officer, Food Production & Public Health

Center for a Livable Future

In a recent Mother Jones article, writer Kiera Butler asks the experts if eating responsibly raised meat can actually be good for the planet.  One of the responses comes from Joel Salatin, star of Food, Inc., Fresh and a personal hero of mine.  Joel makes some strong points that uphold the merits of an ethically- and environmentally-sound diet that includes animal products.  However, one of his arguments struck me as unsound:

“…far more herbivores (bison) existed in the Americas 600 years ago than exist today: The notion that methane from burping herbivores causes climate change is both unscientific and ridiculous.”

With all due respect to Joel, here’s why I think he’s missing the mark.

“…far more herbivores (bison) existed in the Americas 600 years ago than exist today.”

True, there are fewer bison alive today, and I don’t have numbers on the total numbers of herbivores then and now.  But if we’re talking about climate change, large ruminants – animals with multiple stomachs and a penchant for belching large amounts of methane, a potent greenhouse gas – are the animals we’re concerned about.

The best historical estimates put the number of bison roaming the Great Plains at 30 million (1,2,3).  In 2008, the USDA reported the U.S. cattle inventory at 96 million head (4).  That’s three times as many large ruminants alive in the U.S. today (not accounting for moose and their ilk).

“The notion that methane from burping herbivores causes climate change is both unscientific and ridiculous.”

Not so.  Burping ruminants have contributed to climate change throughout history, and the dominant large ruminants in the U.S. currently contribute roughly three times as much as they used to.  The 30 million bison roaming the Great Plains are estimated to have released 46 Tg CO2e enteric methane emissions annually (3), compared to the 140 Tg CO2e methane released in 2008 by U.S. beef and dairy cattle (about 85% of which are grazing at any particular point in time, the rest are in feedlots) (5).

These are rough comparisons.  They don’t account for other ruminants like deer, sheep and goats, though these smaller animals contribute far fewer methane emissions than cows and bison (6).  Moose may be another story, though I suspect the number of cattle (wild and domestic) in the U.S. has far outweighed moose populations.  The data are limited to enteric methane emissions (belching only) and exclude greenhouse gas emissions from manure and other sources.  Further, no one knows exactly how many bison roamed the U.S.  Still, the available data strongly suggest that our current livestock production model produces far more annual greenhouse gases than Great Plains bison ever did.

These finer points don’t detract from Joel’s other arguments, and I still hold that raising livestock under certain conditions can have numerous ecological benefits.  Still, it’s important to set the record straight about red meat, dairy and climate change.  To satiate the U.S. demand (and to a lesser degree, the international demand) for meat and dairy, we raise far more large ruminant animals than would otherwise naturally occur, and the effects on climate change are heavy.

Brent Kim


1. D. Flores (1991) Bison Ecology and Bison Diplomacy:  The Southern Plains from 1800 to 1850. The Journal of American History 78 (2).

2. H. Epp and I. Dyck (2002) Healthy Human-Bison Population Interdependence in the Plains Ecosystem.  Great Plains Research 12 (2002).

3. F. M. Kelliher and H. Clark (2009) Methane emissions from bison-An historic herd estimate for the North American Great Plains.  Agricultural and Forest Meteorology 150 (3), pp. 473-577.

4. USDA ERS Newsroom.

5. US EPA (2010) 2010 U.S. Greenhouse Gas Inventory Report.

6.  N.M. Swainson et al. (2008) Comparative methane emissions from cattle, red deer and sheep.  Proceedings from the New Zealand Society of Animal Production 68.


  1. Posted by Bert McDert

    But let us not forget, either, that bison weren’t confined to the Great Plains. There were woodland bison all down the eastern seaboard, tho they are now confined to the northernmost end of their original range. Joel’s math may still be suspect, but either way it’s not primarily the fault of ruminants that we are fouling the air in myriad ways. Or even that they exist in such high numbers, or that their current form is optimized not for ecological function but rapid growth, or that they eat the wrong sorts of food for their metabolism, or that their raising is so petroleum-dependent and otherwise ecologically devastating. How we come to eat ruminants matters, as does the scale on which we do so. But there’s in all likelihood no way to feed this many people that wouldn’t also destroy the landbase. Taking our diet down a rung or two on the would certainly slow down the carnage, but the population that’s most significantly out of control is our own, hands down.

  2. Posted by Bert McDert

    on the … ? I was gonna say on the food chain, thereby mixing my metaphor. Instead I omitted a necessary noun clause. Oh well. My poor grammar is also not why the Earth is dying.

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  4. Two points:
    1) there are more things to consider than just methane.
    a) Livestock are responsible for 65% of nitrous oxide, which is now the single greatest cause of expansion of the ozone, which in turn has also been linked to the expansion of sub-tropical zones, creating more arid, drought prone areas.
    b) It is estimated that by 2030, 1/3 of all US counties will face water stress, and 1/3 of the world. We can feed far more people a vegan diet than a meat diet. According to Univ. of Calif-Davis, it takes 1238 gallons of water to grow one serving of beef in Califonia, 330 gallons to grow one serving of chicken, but only 98 gallons to grow one complete, nutritionally balanced diet of one grain, one protein (from legumes) and two veg in the state of california. We will not be able to feed the population if people keep eating animal products, only if we eat vegan.

    2) Methane from livestock has caused cliamte change before. We had mega fauna (camels, mammoths, etc) 13,000 years ago as richly diverse as Africa here in the Americas, but within about 1000 years, humans hunted them to extinction. The rate of decrease of methane coorlating with this decline in mammals was enough to put the planet into a small ice age — the Younger Dryas Ice age. At that time methane levels were much lower than today. So today, if we decrease the methane from the livestock, hopefully we will cool enough to balance out the climate.


  5. Posted by Rick McCallion

    First the hypothetical ideal: lowest impact is living from what is naturally produced in your local ecosystem with no intervention: hunting and gathering, building with what is available be it rock, wood, mud, or grass.
    This will only happen in small tribes in undeveloped nations so move on.

    Next, clearly, moving up the food chain for our sustenance increases the energy and land base needed to feed us. Assuming best practices (recycling nutrients and energy, using renewable energy, etc) for whichever form of agriculture, the same area of land needed to feed 100 people meat and vegetables, grains and legumes and fruit, will feed several hundred people if you simply drop the (even ethically raised, organic, free range) animals.
    The only exception to this would be the hypothetical first choice – a population hunting and gathering in a natural forest ecosystem who then convert the forest to fields to grow plants and become vegan… even though this would support more people on the same land area the loss of carbon sink would probably result in a net increase in carbon footprint.

    Furthermore it’s not even clear that organic free range meat production is less ghg producine than factory farming due to certain efficiencies in factory farming.

    Regardless of which meat production method has lower ghg emissions than the other, it’s impossible for either to match the efficiency of plants in converting solar energy to human food. Herbivores live on plants. How can you have them walking around, heating themselves, mooing and doing their thing, without subtracting all of the energy needed for those activities and other costs of their lifetime from the final product on your plate once slaughtered?

    Yes i know that the hooves breaking up soil allow some carbon capture from the air to the soil.
    Plants do that better too.

    I’m no expert, simply using what logical reasoning is at my disposal. Any corrections invited and welcomed.
    thank you

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  9. Do you understand that the CO2 that is released from “burping herbivores” comes from the process of the sugars in the plant material breaking down? That is a process that WILL occur no matter how that plant material is broken down. Whether it’s from herbivores, omnivores, ruminents, rodents, primates, BACTERIA, or anything else, those sugars will be broken down and CO2 will be a by-product. It’s a natural cycle that keeps the planet breathing. In living plants CO2 is absorbed to create sugars and give off O2 as waste. When plants decay, the organism “eating” the plant absorbs O2 to break down the sugars and give off CO2 as waste. It is a zero-sum equation. That plant matter that those burping herbivores are eating would have decayed from some other process that would have produced equal amounts of CO2 and those plants being devoured makes way for new plants to grow which will then again absorb equal amounts of CO2 and give off O2.

    The reason CO2 is constantly increasing for us is because when trees evolved there was nothing that could consume them, there weren’t even any bacteria that were adapted to eating the dead trees. So they did not decay. They were left in the earth for millions of years under pressure and that’s where fossil fuels come from. All that CO2 that was abosrbed by those trees was never released back out into the atmosphere. Now that we are burning them, that is exactly what is happening. And since bacteria and animals have evolved to beable to eat trees, we’re never going to have all that CO2 packed away buried in the Earth again.

  10. Hi Nick,

    Thank you for your thoughtful comment. The primary gas of concern associated with ruminant belching is actually methane, not CO2.

    I’m not entirely sure i follow your other points about CO2. By “zero-sum equation” are you suggesting that the carbon cycle keeps atmospheric CO2 levels in balance?

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  12. Posted by Mark Shoalts

    I haven’t looked at 2010 when you originally posted this but the cattle numbers that you quote are about double what there actually are in North America today; obviously this has a huge impact on your assumptions. It is unfortunate that you don’t understand Nick’s comments. That puts another dent in your authority for speaking on the subject. Carbon in plants oxidizes at different rates depending upon the mechanism at play, but the net result is the same. A rotting tree is the same as a burning tree, except for the time period. A grazed prairie, burned prairie, or composted prairie is the same thing. This is not to say that we are not without influence and are not doing terrible things to our planet, it’s to say that facile arguments do more damage than good to the cause of educating people about living responsibly.

  13. After reading how polluted much of CA is, I’m not as comfortable buying food grown there! Not to mention the hormone disrupter in Roundup. Something is wrong and Medicare is horrible insurance who won’t cover costs of diagnosis for over a decade. I want to go back to work and can’t! Waste of a college degree and it’s really annoying. I think I have to switch to all organic foods, even though I can’t afford it. Try to buy free range and the rare times I eat meat, make sure it’s raised properly and without antibiotics. The overuse of them has already put us at the brink of another Dark Ages if the Pharm industry doesn’t find new ones soon! Stay out of hospitals unless you are dying.

  14. Oh and I’d to add that all these fires being set in Canada on purpose, as well as Indonesian and Tasmania, is causing a lot of the soot in the air to land on the Greenland ice sheet and is turning it darker, and therefore absorbing more warmth and accelerating melt. Waters are already rising and noticeable on islands. I wish people and the world wake up and stop this from happening. I thought Canadians were supposed to be environmentally very conscious, yet it’s their tar sands that have led to so much destruction. Shut that crap down! Stop pipelines! We ALL must demand that it’s time for wind, solar, wave, tidal, etc. to replace fossil fuels.

  15. People forget that we humans also poop and produce methane. Watch the docu by VICE- You Don’t Know Sh*t. Very interesting and I wondered how much methane HUMANS are putting into the air.

  16. Posted by Jerry Brosius

    Not sure where you are getting your numbers but I get 60 million bison before 1600?

  17. Think it is closer to 60 million bison…and add other ruminant animal population, I am pretty sure you would reach that 100 million mark. I think you should check on what the lack of all our grasslands and how that grazing actually helped the environment. Now we have feed lots and our grasslands are rapidly disappearing

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