Do Cow Farts Really Significantly Contribute to Global Warming?

Shawn asks: Do cow farts really significantly contribute to global warming?

cow-backsideThere are currently approximately 1.3 to 1.5 billion cows grazing, sleeping, and chewing their cud at any given time on planet Earth. And these 1,300 pound (average weight for both a beef and dairy cow) animals eat a lot. Much like humans, when they eat,  gas builds up inside of their guts and has to be expelled. (See Why Beans Make You Fart) Cows fart and burp… a lot.  The result is a large amount of methane being introduced into the atmosphere.

In a 2006 United Nations’ Food and Agricultural Organization report, it claims that the livestock sector, most of which are cows, “generates more greenhouse gas emissions as measured in CO2 equivalent – 18 percent – than transport.” According to a Danish study, the average cow produces enough methane per year to do the same greenhouse damage as four tons of carbon dioxide.  So is this significantly contributing to global warming?

Let’s start with how and why cows produce so much methane gas. Cows, sheep, goats, giraffes, and deer belong to a class of mammals called ruminants. Most ruminants have four stomachs, two-toed feet, and store their food in the first chamber of the stomach, called the rumen, before regurgitating it. This regurgitated food is called “cud” and the animals chew it again to help further break it down to make it easier to digest. Inside of the rumen, over four hundred different kinds of microbes exist that also play a critical role in the digestion process. Several of these microbes create methane gas as a byproduct. Due to the sheer number of cows on the planet, along with the large size per cow, our tasty friends produce more methane gas than all other ruminants combined.

Why could this potentially be bad? Methane is twenty one times more potent at trapping heat from the Sun than carbon dioxide. Though it is less prevalent in the atmosphere than carbon dioxide, it is, by unit, the most destructive of the greenhouse gases. Since the turn of the 19th century, methane gas emissions have increased by 150%, according to NASA’s Goddard Institute.

Methane gas, like all other greenhouse gases (which includes water vapor), acts like a blanket around our planet, trapping heat. The right amount and the planet has an average temperature of a life-supporting 59 degrees Fahrenheit. Too little and the greenhouse effect becomes weak, like on Mars. Too much and the surface of the planet becomes so hot “it can melt lead,” like on Venus.

Livestock is the largest source of methane gas emissions worldwide, contributing over 28 percent of total emissions. Wetlands, leaks from oil refineries and drills, and landfills also contribute methane gas to the atmosphere. In fact, unlike the ratios on a global scale, in the United States livestock is only the third largest contributor, behind the mining and transportation of natural gas and rotting landfill waste.

In actuality it’s not as much the farting that’s the problem, cows’ burping and manure contribute more methane gas than flatulence. According to researchers at New Zealand’s largest Crown Research Institute, AGResearch, up to 95 percent of the emissions comes from the cow’s mouth rather than its behind. It’s estimated, through whichever orifice, that each individual cow lets out between thirty and fifty gallons of methane per day.  With an estimated 1.3 to 1.5  billion cattle in the world today, this adds up fast.

Exactly how significant this it to our global environment isn’t something that anyone can easily put a number on, but the EPA, NASA, various global agriculture organizations, and the United Nations all recognize that this is a real problem. In recent years, several different solutions have been proposed. Scientists and experts have experimented with cows’ diets to see if that could help cut down on the amount of methane gas. For instance, Welsh scientists studied the effects of putting garlic into cows’ feed. According to BBC News, “Garlic directly attacks the organisms in the gut that produce methane.” So far, results have been positive.

Researchers have also studied adding plants that are high in tannins to the diet, which are believed to lower methane levels in ruminants. Another branch of study focuses on not lowering the amount of methane gas, but figuring out a way to contain it and repurpose it. Some farms have experimented with having their livestock live in a plastic bubble, which takes the expelled gas and converts it into electricity. But this process is both expensive, inefficient, and considered somewhat inhumane, forcing animals to live inside an artificial bubble.

Methane gas emitted by cows and other livestock does have a significant impact on the amount of greenhouse gases in our atmosphere, which are the main culprits behind climate change and global warming. While farts aren’t the only way cows are expelling methane, it is, at least, accurate to say that cow farts play a part in our planet’s climate growing hotter.

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Bonus Facts:

  • In 2010, the United Nations proposed a “global levy on livestock methane emissions,” or as the press dubbed it, “the fart tax.” This didn’t pass… but it is something that has continued to be discussed.
  • According to the Food & Agriculture Organization of the United Nations, livestock also cause phosphorus and nitrogen over contamination. This contributes to biodiversity loss in marine ecosystems, most dangerously at the moment in the South China Sea.
  • In the early to mid-20th century, dairy farming started becoming big business in America, England, Australia, Argentina, and New Zealand.  The number of cows in the world first doubled, then tripled. In order to feed this massive influx of cows that natural growing grass and flowers could no longer handle, pastures were reseeded with perennial ryegrass. This grass lacks the nutrients and is difficult digest, which causes even more methane gas to be expelled from cows.
  • Feeding cows maize silage and fermenting corn shuckings can mean a thirty three percent decrease in methane gas emissions.
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  • James

    If the population of cattle has increased so significantly in recent years and thus the amount of methane gas produced, why hasn’t the mean temperature of the earth increased in over 17 years? Your ending paragraphs that suppose that man-made global warming (aka AGM) is fact are in error. AGM is a theory much in doubt and your claims to the contrary show that this site is no more based in truth than or The Onion.

    • Daven Hiskey

      @James: “why hasn’t the mean temperature of the earth increased in over 17 years” It has.

      • FriedFish

        You are using Wikipedia as your source? THAT’S funny. You should’ve busted out the hockey stick graph or some East Anglia emails to really cement your position.

        • Daven Hiskey

          @FriedFish: Wikipedia is nearly as accurate as Encyclopedia Britannica. Would you say the same about it, arguable one of the most accurate general knowledge compilations in human history? The important thing with Wikipedia is simply to check their sources and, as with any source, never trust a single one implicitly. Nobody bats a thousand. For example, I’m no etymologist, but have found numerous errors in even the likes of the OED over the years studying the origins of words and phrases, but it doesn’t change the fact that they are a phenomenally accurate source on the whole, perhaps the best in human history when it comes to language. So bottom line, attack the information on its merits (or lack thereof), not the source. Everybody’s inaccurate sometimes- it’s impossible not to be as the state of human knowledge progresses. And even chain emails occasionally have a kernel of truth.
          But if you still don’t like that answer, the above linked graph is courtesy of data from a NASA news release, and the lengthy references backing what is said/shown in the preceding link are here.

          • FriedFish

            Follow the money on that one. If you want to use a NASA reference; good.

            “A prominent scientist and former NASA researcher has added his voice to those who challenge the “scientific fact” that manmade carbon emissions are causing global warming.

            Dr. Leslie Woodcock is a professor emeritus of chemical thermodynamics at the University of Manchester in England, with a Ph.D. from the University of London, and served as a senior research consultant at the Wright-Patterson Air Force Laboratory in Ohio.

            In an interview with Britain’s Yorkshire Evening Post, Woodcock declared: “The theory of ‘manmade climate change’ is an unsubstantiated hypothesis.”

            Climate change is called the seasons; spring, summer, fall and winter. Happens every year.

    • AquinoMeloCastro

      Every month is a new historic record of heat

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  • Ms Kew

    1.3 – 1.5 Billion cows worldwide – and you expect me to believe that these animals produce more methane than the estimated 30 – 50 billion bison that roamed the Americas prior to the arrival of Europeans?

    • Daven Hiskey

      @Ms Kew: Kudos to you for correctly calling them “bison” rather than buffalo, which they are not, contrary to popular belief. 🙂 But your estimates are a bit high there. At their peak, it’s estimated there were about 100 million American Bison which actually happened after the Europeans arrived. Evidence suggests that the bison population in the Americas was kept in check thanks to the Native Americans. Once the vast majority of the natives rapidly died out from European diseases, the bison population exploded and, indeed, they became one of the most numerous wild mammals on Earth for a very brief time, but nowhere near 30-50 billion.

    • Crash

      Uhhh…how much methane do the 7 BILLION HUMANS produce?! Plenty. Oh, also, humans exhale ten times more carbon dioxide per year than all cars, factories, mines, and oil fields combined. All we know is that the temperature has gone up, STOP PRETENDING THAT YOU KNOW WHY. You don’t have the first clue. Maybe the sun is a little hotter (and it is btw), maybe the Earths orbit has perturbed a bit (does anyone know the error margin on the distance between earth and the Sun? Hint: it’s measured in miles.) Hell, for all we know, maybe the recovering ozone layer (that’s right, the hole is closing) is trapping more and more “greenhouse gases”…lol it cracks me up that water counts as a greenhouse gas, oh god, these gases are everywhere!! Ahhh stop believing the fear mongers and go look this shut up for yourself, you might learn something.

      • Tony

        I figuratively laughed at you here Crash, not literally, because it was too sad of a comment to actually laugh at. The fact that you looked stuff up only looking for anything and everything that may support your opinion is sad. You threw random facts that you probably didn’t know whether or not had factual backing to them and then laughed at information that actually did have factual backing. If anyone here doesn’t know what they are talking about, it is you Crash. Maybe you should take your own advice and stop pretending like you do. Climate change is being accelerated by human activities. It is accepted by 97% of all climatologists and even NASA. The only people who choose to deny it are people like you who use things like scare tactics, conspiracy theories and singled out non-evidential results that don’t have scientific backing to try and defend their conservative standpoints.

  • Ralph

    Beano for Bovine?

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  • Jack Ryan

    I used to believe that you were an especially reliable source for facts. This post tells me I have been too generous to you and frankly I am very disappointed.

    “Methane gas emitted by cows and other livestock does have a significant impact on the amount of greenhouse gases in our atmosphere, which are the main culprits behind climate change and global warming.” – Sorry, there is no man-made or cow-made climate change.

    Our climate has been changing since the earth was formed. There are factors too numerous to mention that contribute to the variability with tremendously greater impacts than anything humans or animals could do. But to forestall the ignorant from saying that I’m just making it up I will cite solar activity, vulcanism, and cosmic radiation as just three.

    The other fallacy that your comment perpetuates is that “greenhouse gasses”, (generally taken to mean carbon dioxide), “cause” global warming. A careful look at climate records (both historic and prehistoric) shows that carbon dioxide levels increase after – not before – temperature increases. The pseudo-scientists that preach the dogma of “climate change”, (previously known as “global warming” in the 90’s and “global cooling” in the 70’s), deliberately misread correlation as causation in order to buttress their arguments.

    I hope that this was just an isolated lapse in judgement and that you will do some in-depth research and correct your error.

    By the way, the graph you cited from Wikipedia is from “Hansen et al. (2006)” – Hansen, still, refuses to allow access to the underlying data for this graph to other (or should I say “real” scientists) to examine. Hansen has also publicly and in writing has claimed he is a “Nobel Prize winner” – he is not. Veracity of the source should be considered. Also you might notice that the graphs that NASA publishes, as is the case with the vast majority of “global warming” enthusiasts, only goes back at most to 1880. Why stop there? It’s not like that is the beginning of human based temperature records and certainly not the beginning of scientifically measured temperature records via ice, tree rings, or geological evidence. The answer is simple – the data doesn’t fit the “climate change” narrative – it contradicts it. It is also more difficult to “manipulate” that data than it is to manipulate the electronically generated data available since the 70’s.

    Also NASA is in no way a credible or unbiased source. Like NOAA, NASA routinely “corrects” raw data – to match their models. They are routinely called out by scientists that are not on the “climate change” gravy train and, sometimes, they even correct their “mistakes”, but bury them and re-swizzle the data in another way to again match their models. And as a check to your use of “lengthly references” as evidence – think about the 1950’s tobacco companies “lengthy references” that smoking was safe – even if you hold open the possibility that there was limited clinical evidence, they still allowed for no doubt that smoking was safe – why? Follow the money. The same is true here – in spades. Government largess (with our money) is heaped upon those departments that investigate and then show (manufacture?) evidence of “climate change”.

    You really should try to utilize the scientific method regarding the “climate change” theory – which is all that it is, not the BS “settled science” that some sycophants proclaim – and evaluate the raw data and alternative viewpoints from non-governmental sources (which includes most universities since they receive, to a greater or lesser extent, grants and funding from governments). You would quickly come to the conclusion that the “climate change” theory is at a minimum full of holes, or more likely complete rubbish.

  • ron

    Maybe climate change is a cyclical thing.maybe there are other factors at work that haven’t been fully considered. But are you guys seriously going to deny that mankind and mankind byproducts haven’t had a major and detrimental impact,particularly over the last century and a half? Cmon,the Ice caps are indisputably shrinking,polar bear pencils are losing their leads,and weather patterns have been increasingly violent and extreme.I don’t care what wikipedia and NASA got right or wrong;real evidence, if required,can be had just by opening your eyes and ears to the world around you and interpreting what you can you can see and hear for yourself

    • Crash

      There’s no way to know why, you can point to anything you want and say “see! Global warming, humans’ fault!” Btw that’s exactly what the lobby “scientists” are doing. “look, a dead animal! See?! Clearly no species ever went extinct due to climate issues until just now…wait, dinosaurs…ice age? Nope, men killed them too. Global warming.”

      I’ll admit that maybe we are having an impact, but there’s no way we could possibly know it with our current “scientific” understanding of atmospheric chemistry. We noticed the temp going up yes, nobody is arguing that, we’re arguing that we shouldn’t torpedo the economy (EPA wants 44 trillion over the next 50 years, over a hundred billion per year – for perspective, it would only take $2 billion per year to provide the globe with clean water). We’re saying, okay okay, it’s hotter, but Jesus Christ we have more important shit to deal with right now!

    • fchap

      Science is about coming up with a theory, predicting what would happen if that theory were true and then making accurate measurements to test whether the predictions are correct. That’s what climate change scientists have been up to all these years. It is not about cyclical changes. The computer models show the difference between having so many tonnes of greenhouse gases in the atmosphere and not having them. The increase in greenhouse gases is marching in step with measurable climate change.

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  • jay harris

    So many other environmental problems exist which are conveniently ignored, like the mountains of plastic and nappy garbage, the economies of scale not supporting solar energy prices to be more affordable and fully self sufficient, the towns that get the ass end of cities, i.e. stinky sewerage plants, the industrial wastes like the cancerous by-products of plastics, nuclear energy dangers and nuclear testing where people in these areas end up birthing babies with gross defects, mercury poisoning from contaminated fish in polluted waters and I’m going to be concerned about cows’ methane output? PUH-LEASE! I think it’s crazy trying to change the cow, better off looking after the atmosphere by controlling the man made factors contributing to global warming.

    • rebuck1020

      This IS a man-made factor. Without our insatiable desire for beef, there would be significantly fewer cows in the world – and the ones that still existed would be able to eat flowers and grass, as they always had before the population exploded.

      This is one of the most devastating causes of our changing climate, but few environmental groups, if any, make cutting meat consumption one of its core goals. It’s simply too unpopular. So instead, we’ve got people buying hybrid cars and throwing up their hands saying, “well, I’ve done my part!” But we’d be much better off with a nation of vegans driving Hummers than we are with the current situation – a docile population gleefully consuming 9 ounces of meat every day.

      • wskadavis

        I have read that if we all became vegetarians tomorrow that would do more to end climate change than anything else we could do.

  • Subodh kumar

    Cows are definitely making contribution to methane and carbon dioxide. But so are human also.
    The fact is overlooked that cows dung & urine dropped in to the soil gets converted in to manure. One Kg of Cow manure has the capability to to lock 9 liters of rain water in the form of soil moisture. Thus cow droppings protect forests from desertification by natural water harvesting and promoting greenery. The contribution of cows to preventing global warming by ensuring natural greenery far out weighs the methane emission that is put forward against cow population.
    In fact as discovered by environmental biologists headed by Allan Savory more coes will mean less global warming and natural reclamation of waste lands.

    • Em

      Your forests are being obliterated to grow food to feed all these cows.

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  • Sharon

    Cows are meant to eat grass. If cows these days are producing an excess of noxious gasses, I suspects it’s mostly the ones in factory farms that are fed corn and other things that are not their natural diet. If we got rid of factory farms and went back to pasture raising them, I suspect this would no longer be an issue. It would also slow down the rate of bacteria becoming antibiotic-resistant.

  • Katrin

    If asking everyone to become vegetarian is too far fetched then if everyone reduced their meat consumption to a quarter of what they eat now the planet would be in such a happier place. There are so many sources indicating on the destructive nature of the cattle industry, something has to be done!

    • AquinoMeloCastro

      You don’t need to become a vegetarian in order to prevent more cow burping, just eat more fish and white meat and probably the cow industry will shrink

      • Em

        Overfishing is a massive problem for the planet. The last thing we need is everyone to start eating more fish. And chicken farming is horribly cruel. It’s honestly not that hard to eat a plant-based diet these days and truly enjoy it.

  • Pete E

    If you also go to Wikipedia and query “Ice Age” you will discover that we are currently living in one now and have been for the past 2.3 million years. This current climate cycle named the Milankovitch Cycle consists of ice ages of about 120,000 years followed by brief warming periods of 10-12 thousand years. Since the cycles are governed by cosmic factors like earth’s orbit, precession, solar temperature and other factors beyond man’s control scientists can say with great certainty that the next major climate change will be down into an ice age starting anywhere from now to 8000 years from now. The earth has largely been a frozen rock 90% of the time for the last 2.3 million years and cow farts are not going to change that.

    • Daven Hiskey

      @Pete E: Your conclusion is not supported by your premises, regardless of any accuracy of those suppositions.

  • Caine

    Global temperature varies in 60 year cycles between warming and cooling. There have been 3 such cycles since 1850 while CO2 was steadily increasing.

    On every time scale from seasonal to multi-millennial CO2 increases after the oceans and earth warm, never before. While CO2 increased 57% in the last 8,000 years, the earth has cooled 1.5C. It was warmer 1, 2, 3, 4 and 8,000 years ago while CO2 was much less. (Vostok Ice Core and over 90 other proxies)

    Catastrophic Anthropogenic Global Warming (CAGW) alarmists have not been able to refute the empirical results of real world studies by scientists in different countries.

    Extensive, recent independent research by scientists in different countries reveals that each step in the speculated CO2 CAGW process fails. It takes only one negative result to prove a hypothesis false. Here is one of many:

    EXAMPLE: Water evaporation from warm tropical oceans falls as rain, cooling and drying the tropical troposphere and stratosphere providing a negative global warming feedback contrary to the CAGW hypothesis.

    As the CO2 CAGW hoaxers have NO empirical evidence to point to, they will cite models and consensus. The average of 102 CMIP5 models for a 33 year simulation show a 200% error on the warm side. ALL consensus polls have been totally destroyed by various researchers using the pollsters own criteria. Never mind that computer models and “consensus” is not empirical evidence.

    • fchap

      Sorry you have your science wrong here. Science is based on predictions and the ability to predict a change due to certain circumstances. The climate change models that scientists have been using have been predicting the global warming we are seeing. It’s not just random fluctuations otherwise it would not be predictable.
      Also you have to ask yourself if it were a hoax what would be the purpose? There is far more reason for oil companies to want this not to be true than there is reason for anyone to make it up.

  • Vijesh

    what about cow relatives in the wild??

  • Eccles

    If we stopped eating meat and had to replace all that protein with more veg how much greenhouse gas would we produce? Surely to get the same amount of energy we would produce a similar amount of gas? Vegetables need transporting to. So what would the saving really be if we stopped farming livestock?