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Cows produce planet-warming gases. What does that mean for a beef-lover’s diet?

A man in jeans and a plaid button-down shirt holds a large spool and stakes while standing in a field surrounded by cattle.
Elizabeth Rembert
/
Harvest Public Media
Jim Knopik winds up a twine fence to let his cattle into a new area of pasture for grazing on his central Nebraska ranch. Knopik uses a ranching practice called mob grazing, which aims to improve soil quality and other natural resources through cattle ranching.

Cattle contribute more greenhouse gases than other livestock. The reasons behind that have some ranchers trying to address environmental impacts, while experts say there are also ways for you to curb your plate’s climate footprint.

From her home in eastern Nebraska, Angie O’Brien does what she can to help the environment.

She reduces, reuses and recycles – taking the time to clean out even the messy things like peanut butter jars to make sure it can go in the recycling.

“My husband’s always like ‘You’re using way more water, just throw it away!’” she said. “And I say ‘I know, but I feel like it’s doing good.’”

O’Brien also tries to know where her food is coming from. Like beef, which she often buys from nearby ranchers.

“I’ve always wanted to be more conscious of where my beef is coming from,” O’Brien said. “I’ve figured that if it’s a local cow that’s been in pastures eating grass, that’s probably a little bit better than being brought to a feedlot and fattened up.”

A brown cow reaches down to eat grass in a field, surrounded by other cows in a herd.
Elizabeth Rembert
/
Harvest Public Media
Cattle are agriculture’s biggest source of methane, a powerful greenhouse gas that contributes to climate change.

Beef in particular can drive up a person’s contributions to climate change. In the U.S., beef production is responsible for about 4% of the nation’s planet-warming pollution, according to the U.S. Department of Agriculture.

Some researchers and environmental advocates have suggested that eating less beef could lower emissions. One study published by the American Journal of Clinical Nutrition found that swapping out beef can slash your diet’s footprint in half for that day.

But O’Brien, a native Nebraskan, isn’t looking to cut out the red meat entirely.

“No,” she said, laughing. “We’re in the beef state!”

Beef’s emissions footprint

Most people don’t think about how their diet might be impacting the environment, according to Diego Rose, who leads the nutrition program at Tulane University in New Orleans.

“They typically think about their energy use,” he said. “Do they fly a lot? What kind of car do they drive? How often do they drive? All those questions come ahead of food and diet.”

But his research tallied the emissions footprints of a one-day snapshot of nearly 17,000 people’s diets. Running down the list, most foods clocked in around the same.

“And then all of a sudden, we’d hit one that was like, 10 times more or 100 times more than anything else,” he said. “And invariably, that was beef.”

The burgers, steaks and roasts added up.

“If we could get the top meat eaters down to even just average consumption, we’d save a lot in terms of greenhouse gas emissions,” Rose said. “So much so that it could actually make a small dent in our original commitment to the Paris Accord.”

Beef’s cultural role in the United States can make that hard to pitch, Joshua Specht said. His book “Red Meat Republic: A Hoof-to-Table History of How Beef Changed America” argues beef is tied into the American frontier, affluence, masculinity and more.

“Beef consumption is at the core of what it means to be American. As they were creating America, ranching was a central part of that,” said Specht, a professor at the University of Notre Dame. “Any time we talk about meat consumption today, that’s all kind of in the hamburger as we take a bite.”

Burps drive emissions

Cow burps are a lot of what’s packing the environmental punch, according to Aaron Smith, an agricultural economist at the University of California Berkeley.

“Sometimes people like to say it’s cow farts because it’s more fun or funny to talk about,” he said. “But it really is almost all burps.”

As cows break down grasses and hay, their digestion produces methane. It’s a process that’s unique to animals like cows, sheep and goats – chickens and pigs have a different digestive system.

“It’s one reason they can process foods that we can’t,” Smith said. “If we would eat coarse grasses, they would just go straight through us. But cattle are able to break them down.”

The cow then burps the methane, releasing a powerful gas that contributes to climate change. Methane initially traps far more heat than carbon dioxide, but it doesn’t stay in the atmosphere as long.

“It’s sort of like how much heat is generated from a campfire,” Smith said. “Methane is like a dry twig that burns super hot, so you get a lot of heat coming off it for a short period. Whereas carbon is like a big log that burns steady for a long time.”

Methane lingers in the atmosphere for about 10 years, while carbon dioxide from burning fossil fuels can stick around hundreds and hundreds of years. But methane traps more heat at a time when scientists say emissions must come down drastically to prevent the worst impacts of climate change.

Raising beef with the environment in mind

Some people in the beef industry are thinking of how their cattle impact the environment. Like Jim Knopik, who runs a ranch in central Nebraska.

About 20 years ago, Knopik switched up his ranching strategy. He wanted to take better care of his land, where four generations of his family have raised cows and grown crops.

“What I really want is clean water for the next generation and a good environment and good, clean food,” he said as he checked on his cows on a summer morning.

Knopik used to do conventional grazing – where ranchers let cows loose in large pastures for months – but now he frequently moves his herd to smaller areas within a pasture, sometimes as often as twice a day.

A man in jeans and a plaid button-down shirt walks in a field surrounded by cattle, winding up twine into a large spool and holding stakes.
Elizabeth Rembert
/
Harvest Public Media
Knopik said the soils and grasses in his pastures have improved since he switched to mob grazing. “It was thin and poor quality grass,” he said. “It was sick, because it didn’t have the cattle running on it and tramping down that organic material into the grass.”

It’s called mob grazing — the idea is that the cows help the soil by stamping organic material into the ground and the intervals give grasses time to recover between grazing.

Knopik said he's seen the environmental benefits on his ranch: soil that used to be dry and bare is now healthy pasture, with thick grasses growing even during a years-long drought that withered pastures across Nebraska.

“It’s the sort of thing where you kick yourself for not doing it earlier,” he said. “We’re raising cattle, helping the soil and growing grasses at the same time.”

While most of Knopik’s cattle will eventually end up at a feedlot, some ranchers and researchers say letting cows eat grass their whole lives may reduce the overall impact cattle have on the environment.

Grass-finished beef

Tong Wang is a researcher at South Dakota State University who compared the emissions footprint of various beef operations in North America.

Her research suggests that ranches like Knopik’s – which rotate cows for short grazing sessions and convert cropland into grassland – may be counteracting their methane emissions by sequestering carbon back into the soil.

Wang stresses that more research needs to be done.

“We need to consider the entire system that the cows are raised on, instead of only the cows,” she said. “There is probably no carbon sequestration in a feedlot, but there could be potential in a grass-finishing system.”

The tricky thing, Wang admits, is that it takes longer for cows to gain weight when they only eat grass. So they live longer and emit more methane.

Cattle walk in a field.
Elizabeth Rembert
/
Harvest Public Media
Jim Knopik’s cattle herd ambles toward a new section of pasture in central Nebraska. Most of his cows ultimately end up at a feedlot eating grains, but some researchers think that there may be an opportunity to mitigate environmental impacts and emissions by exclusively feeding cattle grass.

"Strictly from a greenhouse gas standpoint, it’s hard to say grass-finishing cattle is good for the environment,” said Al Rotz, an agricultural engineer and researcher with the U.S. Department of Agriculture. “On the other hand, there are some real benefits to grass-finishing, when it comes to soil quality, electricity reduction and water use.”

Rotz spent about 10 years surveying the U.S. beef supply chain for its environmental impacts. Ultimately, he said substantially lowering the emissions footprint of beef seems like a long shot.

He doubts it can ever become carbon neutral – which means any emissions released from an operation are offset by removing an equal amount.

“There are a lot of things we can do where we can get 5 to 10% reduction in the carbon footprint, which is good. I mean, we need to do something,” Rotz said. “But to get to 50% reduction, or even carbon neutral is a tough, tough job.”

That’s why Diego Rose with Tulane University says the answer is simple.

“If you’re trying to reduce your carbon footprint, eat less beef,” Rose said. “There are ways where you don’t have to give up beef altogether, and you can make a difference. Anything where you’re cutting back or substituting is going to make an impact on the environment.”

Reducing the amount of beef she eats sounds more doable for Angie O’Brien.

“I might cut back a little bit, it’s not like we have beef every night,” she said. “I can go a few days, but then I’m like ‘Oh, a hamburger sounds really good.'”

This story was produced in partnership with Harvest Public Media, a collaboration of public media newsrooms in the Midwest. It reports on food systems, agriculture and rural issues.

Elizabeth Rembert reports on agriculture out of Nebraska for Harvest Public Media.