Cows are a big part of the climate problem — but can be part of the solution, too

A secret weapon to curb global warming even faster than cutting carbon emissions from fossil fuels is lying — and chewing — in plain sight: the cows. Don’t be fooled by their peaceful manner. They are heating up the climate with every breath, belch, fart and poop — but especially breath.  

The good news is, researchers around the world are working on ways to reduce methane emissions from cows. The stakes are high because methane is a far more potent greenhouse gas than carbon dioxide but much less persistent in the atmosphere, which means we would see the benefits of curbing methane faster.

“So if we decrease methane today … it will have an impact in the near future,” says Karen A. Beauchemin, a global authority on bovine methane emissions who recently retired as a federal research scientist in Canada. 

There’s a lot of confusion about the role of cows in climate change, so here are some questions and answers to clear the air: 

Why are experts so worried about cows and climate change?

There are very good reasons why the global debate over how to curb climate-warming greenhouse gas emissions has focused on carbon dioxide. CO₂ contributes more to human-induced global warming than any other gas by far, simply because so much of it is released by human activities, especially by the burning of fossil fuels. 

But other gasses contribute to planetary warming, too, especially methane, which is over 80 times more potent than carbon dioxide over a 20-year time span because it can trap more heat.

Some sources of methane are natural, including wetlands and rotting vegetation, but two-thirds of global methane emissions are due to human activities. Agriculture is the second-largest source of atmospheric methane — and manure, and digestive releases from livestock, account for about one third of all agricultural emissions. Cows rank the highest in this sector: they can produce: 250 to 500 liters of methane a day. That’s a lot of natural gas, enough to run a stove for more than an hour at medium heat. 

Why do cows make so much methane?

Cows are ruminants that chew their food long after the meal is over, thanks to their special digestive system consisting of four compartments. They usually chew their meals at night or in the afternoons, preferably in total peace and on their left side, since it’s their best position to chew comfortably. Usually the process takes 30 minutes to an hour, but they will chew less if feeling stress, hunger or pain.

Unlike humans who have multiple nutrient options, cows rely on fiber from grass and other plants — and fiber is hard to digest. “All [of] the diet of a cow is primarily fiber,” says Beauchemin. “So they wouldn’t get any energy out of it if they couldn’t digest it and they need to digest it very slowly.” 

During this slow and chewy process, a lot happens. To digest the fiber, a cow launches an army of stomach microbes, including bacteria, fungi, protozoa and methanogens. Then comes fermentation, a process that produces a lot of carbon dioxide and hydrogen as unwanted byproducts. 

“You’ve got to get rid of those byproducts or there will be a buildup, right?” Beauchemin says. While a cow can only exhale some of the CO₂, the rest gets combined with hydrogen and turned into methane. Most of the methane is expelled through a cow’s breath, with the rest going out via pooping and farting.

Can’t we solve this problem by just having fewer cows?  

This wouldn’t be easy to achieve. The number of cows around the world topped 1.5 billion recently and is still growing. 

Why? A major reason is that people love meat so much that they eat too much of it. High-income countries are consuming way more meat than recommended by health experts, and many low- and middle-income countries seem likely to follow this path in the coming decades. Meanwhile, intake of fruits, vegetables and plant-sourced protein is only about half of the recommended levels.

Studies suggest that for the sake of our health and the planet’s, we should transform our diet and food system. But that will be very difficult, especially because the human population is projected to reach 9.7 billion by 2050, with the greatest growth in developing countries that are ramping up meat consumption. If current diet trends continue, more people will mean more cows — and more methane.

While we can cut fossil-fuel emissions of carbon dioxide by substituting greener sources like solar and wind, it’s much trickier to replace animal sources of methane in agriculture. “We’re producing food for people and we can reduce, but we can’t totally replace,” Beauchemin says.

Are there other possible solutions, without having to give up meat?

Yes, there are alternatives. Researchers are working on various ideas to reduce methane emissions from cows and other livestock. There are four main strategies: production intensification, dietary manipulation, rumen manipulation and selection of low-methane-producing animals, according to Abubeker Hassen, who studies the issue at the University of Pretoria in South Africa.

With many farms being family-based or small-scale, making they are more sensitive to cost and return, Hassen thinks this strategy is a potential win-win, generating both financial and environmental benefits. If a high-performing cow can produce as much income as three low-performing ones, then methane emissions are reduced by two-thirds while income rises.

Increasing the amount of beef produced per acre — in other words, production intensification — would be the fastest and most feasible strategy because it will improve profitability for the farmer. “The intervention can pay for itself,” Hassen says.

Dietary and rumen manipulation both involve supplements and additives. They involve either changing the food the cows are eating or altering the chemical reactions occurring within a cow’s digestive system. Potential dietary additives to accomplish this include saponin, biochar and nitrate, all of which cut bovine methane emissions by over 20%, according to Hassen’s recent study.

There are some promising supplements, too, according to Hassen’s study. And some of them, including oils and 3-NOP, showed promise for both methane reduction and increased profitability.

Genetic selection is also an area where there has been a lot of activity. “A lot of money [is] being invested to identify low methane emitting animals and incorporate that knowledge into breeding programs,” Beauchemin says.

Why hasn’t all this research paid off yet? 

All of the strategies have been tried only on small scales so far. The $436 billion global cattle industry is so vast and so diverse — covering everything from huge factory farms in the American Midwest to farmers in Africa who own just one or two cows — that scaling up these measures will be extremely difficult. “Farmers hardly make any money already. It’s very difficult for them. So who’s going to pay for that?” Beauchemin asks.

Beyond the expense, there’s a critical need to educate farmers about the benefits of lower-methane cattle, she says. “It’s very difficult everywhere. Farmers want to reduce emissions. If you tell them about it, they say, ‘Oh, okay, we can help with that.’”

There needs to be much more communication, Beauchemin says, between policymakers, consumers, farmers, processors, retailers and wholesalers — all of whom will play a role in cutting methane emissions. “It has to be a discussion all the way through,” she says.