Do Humans Fart More Methane Than Cows?
In the annals of climate activism, cows get gassed. Yes, that’s two puns, but it’s also deadly serious, more than we imagined.
It wasn’t me.
Do you breathe, burp or fart? If so, you’re contributing to climate change. Just like Dad, we point the finger at someone else — cows. Do cows deserve to be the pariahs of climate change? The answer is no. Humans are unequivocally at fault, but it is complicated.
If you’ve heard of methane, you probably read about burping cows. Unlike most other animals, ruminants like cows, sheep, and goats produce methane in their stomachs in the process of digestion. Enteric methane production is then released through flatulence, excrement, but mostly belching. Cows produce 250 to 500 L of methane per day. Collectively, the earth’s 1.5 billion cows emit 120 million metric tons per year, responsible for roughly 2% of climate change. That’s just a small part of how cattle propagation contributes to climate change (setting aside land use, water use, and nutrient efficiency).
Methane lingers. The earth filters break it down over a period of 120 years. The bad news is, the troposphere and stratosphere break down methane into CO2, also a greenhouse gas. During the first 20 years, methane’s contribution to climate change is 80 times more powerful than carbon dioxide. That’s why scientists keep the focus on methane and why activists raise a stink about cows.
By comparison, humans produce a paltry 1 L of flatus per day, only 7% of which is methane, and we don’t burp methane. As a species, humans emit 73 metric tons of methane and 1000 metric tons of carbon dioxide per day. As a species, we produce about half of one million metric tons per year.
But wait, bad news for vegans! According to a recent study, all-plant diets result in seven more farts per day.
Cows produce far more methane than humans… in their bodies. Outside of biology, the human impact dwarfs ungulates. Humans contribute 60% of annual methane emissions, contributing to 25% of annual global warming. One-third results from processing fossil fuels, another third from agricultural practices, and a final third from decomposing waste and biomass burning. The majority of nature’s contribution comes from wetlands, and we’ll get back to that in a moment.
What no one seems to ask, though, is this: does methane from cows actually contribute to climate change?
Cows instead of deer
There used to be a lot more ruminants on earth. At their peak, 60 million bison roamed North America. Beside them foraged 62 million white-tailed deer. Add at least as many million for antelope, caribou, and moose. Throw in a few million more for other large animals like bears, wolves, and beavers and you’ve got a 200 million strong menagerie of burping, shitting, farting creatures roaming the forests. Now, most of those herds have dwindled to a fraction, in some cases almost extinction.
Did they burp and fart as much as modern ruminants? Those bison, deer, and moose lived on natural, free-range diets. Science tells us they may have emitted up to 20% more methane than modern animals.
By comparison, there are currently 98.8 million beef and dairy cows in North America, 65 million pigs, and 5 million sheep. The earth is carrying fewer total animals than before. We’ve already done a lot to stop climate change — by killing off all the large animals. We could in fact have a deficit of greenhouse gases in the atmosphere, as far as cows are concerned, were it not for our other contributions and the lack of sequestration.
The earth’s atmosphere can easily absorb the methane belched out of our beef. For that reason, we should focus instead on the fossil fuel industry as the biggest culprit. We could forget cows altogether, if not for a tangential problem. When methane breaks down in the atmosphere, it becomes CO2. Back when wild animals roamed the earth, that CO2 was sequestered in the thick forests and grassy plains of a fertile earth. Now North American ruminants stand in their own CH4 emitting shit surrounded by a thousand miles of monoculture. That’s a problem.
Is there something we can do about it? Scientists discovered that feeding cows seaweed appears to make an impact. Cows fed Asparagopsis taxiformis emitted over 80% less methane. In addition, a 2019 study focused on methane-producing bacteria in the cow’s stomach found that altering the bacteria mix also reduces methane production. That may require a genetically-modified cow, specially bred for certain diets.
That’s good news for climate change, but not very good news for cows. Cows are rarely spotted diving for red seaweed. Modern North American feedlot cows require a heavy dose of hormones and anti-bacterial medication to keep them healthy on artificial diets of barley and corn. Introducing a non-grass food source may lead to other unintended consequences. There may not be enough seaweed in the ocean to feed all our cattle without dire marine consequences. On the plus side, as climate change worsens and the oceans rise, we’ll have more places to farm it.
So maybe cows aren’t as big a problem as we think they are, but they point to something even worse.
The human factor
When you look up “human sources of methane”, you’re going to get natural gas, leaks from petroleum production, agriculture, and, of course, cows. You don’t get “farting”.
There is a deeper reason for this. This isn’t because our contribution is too small. Human wastewater represents 14–20% of total methane emissions. It’s because we don’t think of it. We don’t consider ourselves as biological creatures, as part of the ecosystem. Some humans have a hard time accepting anthropogenic climate change at all, much less that our daily defecations may doom us.
Humans have exceeded the earth’s carrying capacity, not cows, hence “anthropogenic” not “bovinogenic” climate change. As our population grows from ten million in wilder times to 7.8 billion today to 9.7 billion in a few decades, we need to take a harder look at ourselves. Not just what we eat and how much gas our bodies produce, but everything we do around the food we put in our mouths. Methane gas is produced by enteric bacteria in 30–62% of humans, so maybe we could use some seaweed, too. Let’s try that before we start genetic modifications.
Until then, give the cows a break, at least as far as methane is concerned. We can and must continue to investigate land use and deforestation and the myriad of related climate perils our meat industry creates. But when it comes to greenhouse gasses, keep the focus on oil, gas, and coal industries, the biggest overall contributors to climate change. Keep the message simple.
I also write for the podcast Replace Remove Recover. For a whole new perspective on climate change and what we can do to fix it, listen here or wherever you get your podcasts:
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