Is it possible to raise a carbon-neutral cow?
In the rolling hills along a rural stretch of the California coastline south of San Francisco, researchers plunged small probes into the soil last year, took samples, and sent them to a lab to measure the carbon stored in the dirt. Three years earlier, they’d done the same thing. Over time, they found, the amount of carbon in the soil had grown. The hypothesis: A herd of cattle grazing on the land may be fighting climate change by helping sequester extra carbon from the air into the ground.
Is it possible for a burger to be carbon-neutral? It’s well known that cattle—and by extension, beef and milk and cheese and ice cream—have a large carbon footprint. A 2018 study found that Americans need to eat 90% less beef and 60% less milk to keep global warming under 2 degrees Celsius. But another recent study suggests that if farmers manage grazing using specific techniques called regenerative agriculture, the final stage of beef production could actually sequester more carbon than it produces.
Regenerative agriculture practices could store carbon on farms growing other crops, and if it happened across the industry, some experts predict that the impact could be substantial. If the quantity of carbon in soils on farms increases 0.4% each year, says the European “4 Per 1000” initiative, it could offset the 4.3 billion tons of CO2 emissions that humans pump into the atmosphere annually. Another study from the National Academy of Sciences put the figure at 3 billion tons.
The possibilities are especially intriguing to food companies that are trying to lower the emissions that are required to grow their products. “We’ve come around to the understanding that our biggest opportunity to make an impact not just on reducing emissions but potentially trying to turn agriculture into a solution for a climate change rather than a part of the problem really lies in improving soil health,” says Britt Lundgren, director of organic and sustainable agriculture at Stonyfield Farm.
For companies with cows in their supply chain, the potential to alter the emissions calculus for animal agriculture is especially interesting, as plant-based dairy and meat startups are growing quickly, in part because of their environmental claims. But it’s not that simple: Behind the eye-popping numbers from pro-regenerative agriculture studies, there’s some deep scientific controversy about exactly how much carbon it will actually cut—and if it’s just a way for a polluting industry to argue that it can continue to expand at a time when emissions need to radically fall.
THE CARBON HOOFPRINT
Cows are an issue for the climate in a few ways. When they eat, the microbes in their stomachs also produce methane, a potent greenhouse gas, which cattle belch at a rate that’s almost as polluting as the natural gas industry in the United States. Their manure is another source of emissions. But the cows themselves are just one piece of their total carbon use: In the last stage of life, before cattle go to slaughterhouses, they’re often sent to feedlots and fed grains to fatten them up, and the fertilizer used to grow the grains is also a large source of emissions. And in countries like Brazil, huge swaths of rainforest continue to be cut down to make room for cattle or to grow crops to feed them. Deforestation is one of the largest causes of climate change.
Overgrazing—when too many animals are on the same pasture for too long, eating plants down to the ground and exposing bare soil—is yet another source of emissions. But the argument of regenerative agriculture is that when grazing is well managed, animals can actually help with carbon sequestration. Soils are a natural carbon sink, since plants suck in CO2 as they grow and then push extra carbon into the earth through their roots. The world’s soils currently contain an estimated 2,500 billion tons of carbon. Typical farming techniques, including plowing land and leaving soil bare between crops, releases that carbon. Overgrazing does the same thing. Farmed soils around the world have lost 50-70% of the carbon they once contained.
But when cattle graze just enough, the regenerative argument goes, they can help plants grow faster, pushing more carbon back into the ground. Other techniques, like planting trees and shrubs or spreading compost on pasture, can also help farms and ranches absorb more carbon.
IS ANY GRAZING GOOD?
The techniques employed by regenerative agriculture are mostly just older ones that have been supplanted by modern industrial farming, and the hard science supporting their efficacy—particularly relating to cows and other animals—is in the early stages. A 2018 study, for example, found that grass-fed beef, produced from cows that grazed in a regenerative way, could be carbon-neutral or carbon negative for the last stage of the animal’s life (from the point after a calf is weaned from its mother until it’s “harvested”), but it followed other studies showing that this isn’t the case. The studies didn’t examine the whole life cycle of the animal and focused on one particular region. It’s not clear what may happen differently in different areas, or how carbon sequestration happens over time. More research is needed. “The science is completely unsettled,” lead author Paige Stanley wrote in an email. “There’s some very interesting results set to come out in the next year or two that will add a lot more to the conversation, but we definitely need more research. There [certainly] seems to be enough evidence to suggest that [well-managed grazing] can sequester a lot of carbon, but we need to understand exactly how much, under what management, with what soil types, and over what time frames.”
There are other challenges. Carbon that’s captured in the soil can later be lost if something changes on a farm, and after a few decades, when there’s an equilibrium between carbon entering and leaving the soil, it will also stop sequestering extra carbon from the air entirely (while animals continue creating new emissions.) Finishing cattle on pasture is also less productive than feedlots—less meat per acre—which can mean more emissions as production spreads to more farms. A large new report on the future of food from the nonprofit World Resources Institute concluded that the potential for carbon sequestration in soil was limited. Princeton researcher Tim Searchinger, who authored that report, argues that better management techniques can be helpful but not as much as many think, and that the term “regenerative” is so vague that it risks becoming greenwashing. Another study, from the Food Climate Research Network in the U.K., found that better management of livestock only sequesters carbon under some conditions and even then may be temporary and not necessarily large enough to offset the negative impact of raising the animals.