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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20 comments

  • 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 Cracked.com or The Onion.

    • Daven Hiskey

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

      • 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.

          • DH,
            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.

  • 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.

  • Beano for Bovine?

  • 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.

  • 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

  • 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.

    • 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.

  • 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.

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