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Post comparing bison and cattle methane emissions does not pass smell test | Fact check

Nate Trela   Paste BN

The claim: Post implies methane emissions from cattle have no environmental impact because bison gas did not cause climate change

An Aug. 3 Facebook post (direct link, archive link) shows an image of a bison and questions how much of an impact its ancestors had on the environment.

"In the early 1800s, there were roughly 60 million buffalo residing in America. There are currently 9.4 million dairy and 31.7 million beef cows in America. You either have to prove cow farts are more destructive to the environment than buffalo farts … or admit that cow farts really aren't something we should be worried about," reads the post.

A July 31 Facebook post using the same image was shared more than 3,000 times in five days before it was deleted.

"I heard about the ’big stink’ over livestock manure, etc. The people who churn out that tripe really need to get a grip and go after the real culprits!!! They must think we are totally clueless!!" one commenter replied to the deleted version of the post.

Similar posts were shared on Facebook.

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Our rating: Missing context

The implied claim here is wrong. While cows aren't the biggest source of greenhouse gases, they do still release methane into the atmosphere. However, limited research suggests bison in the 1800s may have released a similar, though possibly lower, amount of methane than cattle today.

Cattle generate greenhouse gases, but not a top source

Cows are the leading agricultural source of greenhouse gases worldwide, although they and other large ruminants – herbivores with four-chambered stomachs – only produce about 4% of greenhouse gases in the U.S., Frank Mitloehner, director of the CLEAR Center at the University of California, Davis, told Paste BN.

That’s not an insignificant amount in an industry considered the second- or third-largest contributor of greenhouse gas emissions, as Paste BN previously reported.

“Livestock contribute to (greenhouse gas emissions), and mitigating emissions from livestock is important, but it’s not what drives us over the top,” Mitloehner said.

Petroleum products remain the largest source, he said.

The post tries to dismiss the effect of bovine emissions on the environment by claiming tens of millions of buffalo in the 1800s should have had an equal, if not greater, impact. The term "buffalo" is technically incorrect because buffalo are native to Asia and Africa. The word is commonly used to refer to bison, their North American cousins.

The focus on the animals' rear ends also misses their most potent source of methane, Mitloehner said. The anatomy and digestive habits of cattle and bison cause almost all of the methane to escape from their mouths, a process known as enteric emission.

But the question raised in the post has actually been examined by multiple studies.

Mitloehner referenced a 2012 paper that tried to estimate methane emissions from bison and other wild ruminants before European settlement on the North American plains. It suggests total methane emissions were similar to the amount currently being emitted by cattle and other livestock.

Fact check: False claim Bill Gates and AOC said a cow produces ‘more pollution’ than a car

A 1998 paper hinted at a larger gap. The researchers found bison fed a diet of sun-cured alfalfa pellets emitted about 30 kilograms of methane each year, far less than the roughly 100 kilograms per year emitted by cattle. A 2021 paper says wild bison could have produced even less methane, noting that their diet on the prairie would involve eating forage that would lead to less gas. That same paper also notes the difficulty of measuring bison methane emissions "due to their mobile grazing habits and safety issues associated with measuring non-domesticated animals."

If the figures in the 1998 paper are correct, bison in the 1800s generated far less methane than cattle today. At 30 kilograms of methane per bison every year, 60 million bison would produce about 1.8 billion kilograms. But at 100 kilograms of methane per cow every year, the 42 million cows referenced in the post – a low estimate, according to Mitloehner – would produce about 4.2 billion kilograms. 

Paste BN reached out to the social media user who shared the meme for comment but did not immediately receive a response.

Lead Stories also debunked the claim.

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