Probing Question: Are cow burps contributing to global warming?

Mar 04, 2011 By Solmaz Barazesh Spence
Credit: Credit photos.com

When people think about sources of greenhouse gas emissions, they think of oil refineries, smokestacks and trucks spewing out thick black smoke. They don't usually think of cows.

But recently, the idea that could be a source of greenhouse gas has been attracting attention. It turns out that the belches of cows, and other livestock animals contain substantial amounts of , a particularly that has about 25 times the global warming potential of .

Are cows emitting ?

"Yes — in fact, the Environmental Protection Agency estimates that cattle belching and manure management contribute about 28 percent of all anthropogenic methane emissions in the United States," Alexander Hristov, Penn State professor of dairy nutrition, said. "However, in the big picture of global , cows are a relatively small player."

Methane gas is a natural by-product of the complicated bovine digestive process, Hristov explained. As cattle feed makes its way into the largest compartment of the cow stomach, called the rumen, it is feasted upon by microbes and begins to ferment. The fermentation process breaks down the fibrous cattle feed, helping cows get nutrition from otherwise indigestible grass and hay — but also produces lots and lots of gas in the process. Methane makes up somewhere between 20 and 40 percent of the mix.

The bubbling of ruminants' stomachs isn't a new concern, Hristov added. "Millions of buffalo were emitting methane for thousands of years in North America before the white man replaced them with cattle," he explained. And the type of food that farmers give their cattle may not be to blame, either. "Wild ruminants such as deer, elk and moose also emit methane as a result of fermentation. Other herbivore animals, horses and elephants for example, also produce methane from a similar type of fermentation occurring in the large intestine, but in much smaller quantities."

But is all this hot air enough to contribute to global warming?

Despite methane's potency, "As a proportion of all greenhouse gases emitted in the United States, livestock belches only contribute about 2.2 percent," noted Hristov. "The emissions from the energy and transportation sectors are much larger. In fact, looking at methane emissions alone, there are other human activities with larger methane footprints than livestock, such as emissions from landfills, for example."

That's good news, because research into methods of cutting down the amount of methane that emit is only just beginning. "There are a number of technologies that animal scientists are working on, but no 'magic bullet' yet," Hristov explained. "It is likely that none of these technologies will produce revolutionary reductions in methane emissions, and society has much better opportunities to mitigate environmental impacts, for example by developing more efficient methods for producing energy," he added.

The EPA's Greenhouse Gas Inventory Report concluded that fossil fuel combustion produced 78 percent of all greenhouse gases emitted in the United States.

In light of this huge number, "Farm animals are a relatively small player in the big picture of greenhouse gas emissions, particularly in the developed world," said Hristov.

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User comments : 10

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apex01
not rated yet Mar 04, 2011
I'm gonna go run for a few miles and contribute to global warming.
kaasinees
1 / 5 (3) Mar 04, 2011
Nobody fart, we wil die by global warming!
*Person spontaneously combusts*
Everybody fart moderately!

From southpark.
zevkirsh
not rated yet Mar 04, 2011
for every pound of meat that a person eats, they fart x and the function of X that is how much the cow farts per pound of edible meat it has is Y. so x + y is a lot of farts. but x+y is delicious.
ryggesogn2
1 / 5 (4) Mar 04, 2011
Ruminants convert high fiber grass and fodder, like the corn plant, humans can't eat into food humans can eat.
peteone1
2.3 / 5 (3) Mar 04, 2011
(I'm gonna go run for a few miles and contribute to global warming.)
That sounds like a GREAT idea...anything to help my rightwing, capitalist, corportate-fascist, Christian-Imperialist brothers to melt the ice caps, drown the polar bears, and destroy mother earth! ;-)
apex01
4 / 5 (1) Mar 04, 2011
(I'm gonna go run for a few miles and contribute to global warming.)
That sounds like a GREAT idea...anything to help my rightwing, capitalist, corportate-fascist, Christian-Imperialist brothers to melt the ice caps, drown the polar bears, and destroy mother earth! ;-)


It sounds like you have some anger peteone1. Try not to have a stroke. Oh and how would you know if i'm a "rightwing, capitalist, corportate-fascist, Christian-Imperialist" yada yada yada, etc. anyway ??? Kinda jumping to conclusions and stereotyping aren't you?
fixer
5 / 5 (1) Mar 05, 2011
Kangaroos have the same diet but have a slightly different bacteria in the GI tract and they don't fart!
I believe work has been done to modify the bacteria to make it compatible with cows to address this problem.
Don't hold your breath...
bluehigh
1 / 5 (2) Mar 05, 2011
Fart gas is a vector for contagious diseases. Ban farting in enclosed spaces. Could I get a grant to investigate the health impacts of farting ... shit, many researchers get grants for pointless research. I could even come to a conclusion that enables a new tax to save public health!
#winner

Skeptic_Heretic
5 / 5 (1) Mar 05, 2011
for every pound of meat that a person eats, they fart x and the function of X that is how much the cow farts per pound of edible meat it has is Y. so x + y is a lot of farts. but x+y is delicious.

You think human and cow farts mixed together are delicious?

(check your labels:)
Could I get a grant to investigate the health impacts of farting ... shit
Unintentionally hilarious.
bluehigh
1 / 5 (2) Mar 06, 2011
I find no reputable reference that substantiates the idea that Kangaroos do not fart. Although some suggestions are made that Kangaroos do fart but the fart methane gas is at low levels. To suggest that digestion occurs completely absent of any out gassing is rather odd and if theres no farting or belching them its gonna be a big bang for Skippy.

I find suggestions that it is the decomposing faeces that releases the major amount of methane. So just get the pooper scoopers out and dispose of the cow, sheep and pig crap properly.