Beef has become one of the central villains of the climate crisis. Many environmentalists limit their cow consumption or eat entirely from lower levels of the food chain. But though it's true that global figures on beef's carbon hoofprint are worrisome, they perhaps also gloss over the complex system that these cows are a part of. There are many, many ways of producing burgers and steaks—and some ranchers argue cattle can actually be a force for good. In fact, cattle might play a surprising role in mitigating climate change. If done right, grazing can heal grasslands and enable them to stow away more carbon from the atmosphere, even becoming carbon-negative systems.
At Ranney Ranch in central New Mexico, the cattle herd moves between about 33 smaller pastures within a larger 18,000-acre ranch on rocky mesa grassland. The cows graze down one pasture at a time for a period of a few days to three weeks in what’s called adaptive multi-paddock (AMP) grazing. Then, the ranchers move the ruminants to the next patch, and the just-grazed area has at least six months to rest. In the 16 years since she adopted this grazing plan, Nancy Ranney says she’s increased the number of cattle while at the same time building soil carbon and increasing the biodiversity of native grasses sprouting across the ranch. “Not only is it a viable alternative,” she says, “it’s a necessary management practice if you want to keep grasslands healthy and you want to have healthy soils.”
Cattle production is inseparable from grasslands. Most beef cows—both grass- and grain-fed—start their lives on a pasture, explains Ermias Kebreab, a professor of animal science at the University of California, Davis. After about a year to a year and a half, cows are either sold to a feedlot or continue grazing until slaughter. Feedlot cows are fed a high-calorie, often grain-based, diet on which they fatten quickly. Finishing cows on grass takes about three to six months longer, since grass is less calorie-dense.
Often during the pasture stage, cattle are free to roam about entire ranches, nibbling on whatever patch of grass they like, whenever they want. But especially with large numbers of animals, this continuous grazing can erode the grassland ecosystem. Uninterrupted trampling can reduce a once-vibrant prairie to patches of scraggly, weedy plants and bare, compacted soil. And with that erosion and loss of plants goes the ability of the soil to store carbon in organic matter, a key function of grassy regions.
This bleak picture might lead you to question beef’s sustainability. But the grazer-grassland relationship is not inherently destructive; native ruminants and plants evolved together, and they have a mutually beneficial relationship in natural ecosystems. Millions of bison once roamed the United States, and they instinctively moved between pastures, giving plants and soil a chance to recover.
If done carefully, Kebreab says livestock grazing can mimic this natural function. Additionally, he notes, "the thing that people might not consider is that a lot of these cattle occupy land that's considered to be marginal—you can't really do anything apart from growing grass." So, when considering the amount of land used to produce beef, which many environmentalists cite as a negative impact, it's important to realize that that grazing land can support way more than cows. As long as the operation takes places on a natural rangeland—as opposed to the destructive practice of chopping down a forest to produce pasture—there's potential to foster a healthy ecosystem and store carbon in addition to producing beef.
Rotational grazing, including the AMP approach Ranney uses, seeks to mimic those historic herds of bison and other grazers that once trod the land, creating a microcosm of this ecological relationship. In it, a ranch is divided with fencing to create many smaller paddocks. The herd will chow down on one small area for as little as a few hours before ranchers move them to a new spot. Then, the mowed-down spot gets a long rest, usually at least a couple months. "This adaptive multi-paddock grazing is a way to manage [cattle] in a way that emulates large native herds of wildlife," says Steven Apfelbaum, an ecological consultant with Applied Ecological Services, Inc.
Even just a few cattle, if grazing uniformly and nonstop, can degrade a grassland. That’s because they’ll preferentially feed on certain tasty plants, and thus eliminate these grasses. High-speed rotational grazing avoids this by keeping cows on a patch just for a short time. Then, the long rest allows the grasses to grow back—all while enjoying the extra nutrients from cow patties.
Many ranchers say this approach leads to more productive grasses, which in turn support more food for cows and even wildlife like birds. Those grasses also feed a bustling microbial community and add organic matter into the earth, improving soil qualities like its ability to hold and infiltrate water. Cooper Hurst, who runs the Hunt Hill Cattle Company in Mississippi with his wife Katie, says that switching to restorative ranching practices including AMP grazing has ended their need for synthetic fertilizers and fostered a diverse community of forage plants, providing nutritious feed for the cattle—which he says has lowered healthcare costs for the animals, too.
Managed grazing can transform a degraded area, a net carbon source, into a net carbon sink, according to Richard Teague, a range ecologist at Texas A&M University. Based on data he collected "across the fence" between Texas ranches, he calculated that AMP grazing could store a ton of carbon per hectare of land per year in a site that previously was continuously grazed. For wetter climates where plants grow faster, that rate is likely even higher.
Another study found similar results for the Southern Great Plains region. In a life cycle assessment, it considered all the emissions the cows generate as well as the carbon that the grassland could sequester. While AMP emissions resulted in higher greenhouse gas emissions per cow than continuous grazing, those emissions were far outweighed by the carbon stored. Converting a field from heavy, continuous grazing to AMP grazing led to a negative net carbon emissions of just over 2000 kilograms per year. According to the assessment, that effect lasts for decades as the ranch slowly approaches capacity in carbon storage.
Now, Teague and a team of researchers from around the country are studying the soils, biodiversity, and profits in side-by-side pairs of ranches in Kentucky, Tennessee, and Alabama. He’s reluctant to share preliminary findings, which he plans to release as part of a film, but says they’re getting “some pretty decent results.” Apfelbaum, a member of the team, does describe one surprising insight: “We believe we’re measuring in real-time that the methane being emitted by the cattle is being sequestered by methanotrophs, being eaten up by methane-consuming bacteria in soil very quickly … And that’s not what we’re measuring in the conventionally grazed, degraded grasslands.”
Right now, each burger patty is estimated to produce 3.7 kilograms of CO2 equivalents in warming potential—far more than other sources of meat or vegetable protein. But there's huge potential for curbing those emissions with advances like managed grazing.
While cows produce methane, a potent greenhouse gas, through their digestion, a well-managed grassland is still a carbon-neutral system. That's because methane gets converted back to CO2 after about 10 to 12 years, and it can then be reabsorbed by plants, which are then eaten by cattle, and so on, forming a closed-loop of carbon, says Kebreab. "As long as you don't increase the number of animals in a certain area, then you will keep that carbon balance," he says. "You're not adding carbon into the atmosphere."
In a 2018 study in Agricultural Systems, the authors did life cycle assessments for grass-fed beef on AMP grazing and conventional, grain-finished beef. While feedlot-produced beef had less emissions over its life cycle (because the cows fatten up faster, releasing less methane), AMP-grazed beef emissions were totally offset by soil carbon sequestration.
In an assessment prepared for White Oak Pastures in Georgia, which uses AMP grazing, environmental consultants found that beef from the ranch was actually carbon-negative. While a kilogram of conventional beef produced 33 kilograms of emissions, the net emissions from White Oak Pastures were -3.5 kilograms per kilogram of beef. Previous estimates of beef's carbon footprint had failed to include grassland carbon storage, therefore missing "the full carbon story for regenerative agriculture systems," write the authors.
More and more ranchers are becoming like White Oak Pastures. Rotational grazing (a broad term that includes AMP and other methods of moving cattle about the land) is on the rise. "I think that rotational grazing is becoming the gold standard now, making sure that [grazing] leaves enough time for the soil to recover," says Kebreab. In a survey of California and Wyoming ranchers, two thirds reported using rotational grazing. While in many ways our agricultural system incentivizes efficiency over sustainability, preserving the land is still in ranchers best interest. "There are some really smart ranchers out there who've been doing great stuff for a long time," says Derek Scasta, an herbivore interactions ecologist at the University of Wyoming. "We have some ranches in Wyoming in phenomenal condition because we have 30 years of really good grazing management—there's rest for pastures, [and] they're adjusting adaptively as conditions are changing."
Still, Scasta adds that intensive rotation methods aren’t feasible for everyone. For one, many ranchers in the West are moving their cattle between private and public land, and timing of that might not be compatible with AMP grazing. Also, moving cattle everyday between fenced areas takes more labor, demanding additional time and money from ranchers.
Moreover, making a wholesale transition to rotationally-grazed, grass-finished beef may not be feasible if we want to continue producing the same amount. Even though the AMP method maintains better forage quality and thus may lead to faster-growing cattle than animals finished on a continuous grazing system, it still uses more land than grain-finished livestock. That’s because grass finishing simply requires the cattle to be on the pasture longer, lengthening the turnover time per area of land compared to grain-finished cattle.
There are compromises, though. Ranney in New Mexico sells her cattle for slaughter right after weaning, around seven months. Though the cows are smaller, she’s had no trouble selling the beef. And Hurst in Mississippi moves most of his cows to a feedlot to finish on a grain-based diet.
The potential of grazing to mitigate our climate impact is still unknown, but it could be sizable. A 2016 review in Nature Climate Change found that carbon sequestration through grazing management had the greatest potential among several mitigation strategies to reduce the carbon footprint of animal agriculture (here's the specific figure).
Importantly, the carbon-sucking potential of a piece of land depends on its starting condition. If a grassland is already thriving, adding managed grazing won’t change much, says Scasta. “It depends on the starting point for reach individual pasture, each individual ranch, to see how they might move the needle on organic matter.”
But given how degraded the world's grasslands are, there's a lot of room to improve carbon stores through grazing management. Right now, as the IPCC reports, a quarter of the Earth's ice-free surface faces degradation. All that land is a source of carbon rather than a sink. But grasslands make up about a quarter of the Earth's land surface, and store tons of carbon in their extensive roots and soil. One study found that in California, grasslands are more reliable carbon sinks than forests because they're more resilient to the rising temperatures, drought, and wildfires brought on by climate change; the results could be similar for other semi-arid regions. With the U.S. comprising 19 percent of the world's beef production, and much of that beef being produced on continuously-grazed lands, there's to be a lot of potential to build up soil carbon stores. It's certainly not going to make much of a dent if we continue to burn fossil fuels, but it could at least reduce our burgers' footprints.
Unfortunately, as a consumer making a smarter choice for the planet isn’t as simple as choosing grass-fed, because those cattle may well have been raised on continuously-grazed pasture that doesn’t necessarily provide ecosystem and carbon-sequestering benefits. Instead, because those cattle are hanging out and burping methane for more time than grain-fed animals, grass-fed can even be worse for the environment, says Kebreab.
But if you want to support healthy grasslands, it's still possible with a little more research. The Audubon, for example, has a "bird-friendly" certification, which indicates that the beef is from a pasture that supports bird habitat. Birds are a good indicator for the health of an ecosystem, so a grassland that makes birds happy probably also has productive grasses and carbon-rich soil.
While beef production as a whole isn’t doing the planet a favor, managed grazing proponents say we can’t give up on cattle. “We have huge, huge volumes of carbon we can put back in the soil by improving soil health,” says Apfelbaum. “So cattle can be viewed as a tool, whether you eat meat or not—we need the relationships that have evolved for millions of years between grazing animals, native plants, and soil microbes in grasslands.”
