Last January, as wildfires engulfed the Los Angeles area, People for the Ethical Treatment of Animals (PETA) mailed Governor Gavin Newsom a matchbox. Accompanying the gift was a message from Tracy Reiman, PETA’s executive vice president, who had just fled her LA home. “My city burns,” she wrote—and one of the reasons, she claimed, was the cows.
iStock photo by Adam Kaz
Methane from cattle, Reiman argued, was heating up the planet and helping fuel the fires. She demanded Newsom pull the plug on subsidies for the state’s beef and dairy industries. “The choice is yours,” Reiman warned. “Cows’ milk or California?”
California is cow country. With hundreds of thousands more dairy cows than Wisconsin, the state is home to the nation’s biggest dairy industry. Better known for its fruits and vegetables, the state’s number one agricultural commodity is, in fact, milk. California is also among America’s top beef producers. Although Americans have been eating less beef since consumption peaked in the 1970s, livestock still graze on one-third of California’s land. In 2023, the state produced nearly $13 billion worth of dairy and beef—outstripping Hollywood’s entire domestic box office revenue for that year by billions of dollars. To activists like Reiman, though, cows have long been the enemy.
The battle against cows in California can be traced to the beginnings of the environmental movement. In the 1970s, the Sierra Club fought against cattle grazing in protected areas including Sierra Nevada meadows. They claimed cows polluted streams and devoured native plants. By the 2000s, the battlefront had shifted to methane emissions, with the 2014 documentary Cowspiracy turning cows into poster creatures for climate chaos.
The critics have a point. Methane is a dangerously potent greenhouse gas. Although it remains in the atmosphere for a short time relative to carbon dioxide, over a twenty-year span it traps around 80 times more heat than CO2. And cows produce a great deal of it.
“Around half of California’s methane emissions come from livestock, primarily through cow burps—which is a very hard problem to solve—and via the microbes that break down their manure,” says Aaron Smith, an agricultural economist and the Gordon Rausser Distinguished Chair in Agricultural and Resource Economics.
“Cows and other grazers can help native wildlife and enhance biodiversity, and reduce the risk of fires starting and continuing to burn.”
— Lynn Huntsinger
But Lynn Huntsinger, a rangeland ecologist and professor in the Department of Environmental Science, Policy, and Management (ESPM), says that figure only tells part of the story. When adjusting methane to carbon dioxide equivalents, which considers the larger impact of methane on warming, all of agriculture (including crops that rely on fossil fuels, cows, and manure) contributes only 8 percent of the state’s emissions, according to the California Air Resources Board. And even then, the ranchers and scientists who study California’s rangelands—which Huntsinger says make up more than half of the state’s land area—will tell you that cows interact with the environment in a multitude of ways.
To them, cattle and other grazing animals are not environmental villains, but rather crucial players in what have now become messy and volatile ecosystems, where invasive and native plants compete for dominance. Unlike, say, the Amazon rainforest, where more than 800 million trees have been felled in the last eight years to create cattle farms, California’s rangelands—areas where the dominant vegetation is composed of grasses and grass-like plants—have evolved together with grazing animals. What if the problem wasn’t too many cows, asks Huntsinger, but rather, not enough properly managed grazing animals in the right places?
Scientists like Huntsinger help manage rangelands using ecological methods to control invasive species, protect watersheds, and reduce wildfire risk. And as Huntsinger has shown, grazing animals can play an important role in each of these domains, as a partial corrective to a long history of human disruption.
“Cows and other grazers, like sheep and goats, are not native to California, but can help make our landscapes more like the one that our native flora and fauna evolved with,” says Huntsinger. “Grazers can help native wildlife and enhance biodiversity, and reduce the risk of fires starting and continuing to burn.” It’s a radical rethink for some. But in a state wracked by increasingly intense wildfires, perhaps it is high time, says Huntsinger, to listen to those who work in and help manage its most combustible areas.
Grazing for Good
Over the last two centuries, invasive species have come to blanket a large proportion of California’s rangelands. From wild oats and medusahead to ripgut brome and barb goatgrass, annual grasses from Europe and the Mediterranean basin have flourished in California’s similar climate since the earliest days of European colonization, outcompeting native perennial species—including purple needlegrass, the state’s official grass—and reshaping its rangelands.
As soon as the seeds of non-native grasses and grass-like plants made it onto California soil, the outcome was mostly sealed. Many endemic species did not stand a chance of maintaining dominance. Each year, Huntsinger grows native and non-native grasses together so her students can see the stark difference for themselves. “The natives are always half as tall, with half the root volume,” she says. “Plus, the invasives are tough as nails. They live underground for a while as seeds and then come back as soon as it rains—they are also extremely resilient to fire and grazing.”
Left: Limnanthes bakeri (Baker’s meadowfoam), a rare plant endemic to Mendocino county that has higher abundance in grazed areas. Middle: A soil knife used by researchers to reference plant size. Right: Nassella pulchra (Purple needlegrass), the state’s official grass, is drought and heat tolerant and grows from the Oregon border to Baja California. Photos courtesy of Justin Luong
As they spread across the state, these newcomers transformed the land. They clogged vernal pools. They overwhelmed animal species, like the burrowing owl, which prefers to make its home among short grasses. They swiftly pushed aside the types of flowers that feed pollinators. “Non-native plants have profoundly changed the types of wildlife habitat the state has to offer,” says Huntsinger. It was an ecological disaster. But although these plants have naturalized and will never be eradicated, their impacts can be controlled. It turns out that cattle—another non-native species, in fact—have a penchant for non-native plants. “Domestic livestock—goats, sheep, and especially cows—much prefer to eat the tall, non-native grasses,” says Huntsinger. “Our common grazing animals were first domesticated in the Fertile Crescent around 10,000 years ago, and that’s where the grasses evolved too.” Huntsinger notes that research has shown that ceasing grazing can lead to the decline of threatened pollination plants and their pollinators.
Cattle’s benefits go well beyond controlling invasive species. The native plants in California’s rangelands evolved with disturbances from cultural burning and wild grazing animals like tule elk and pronghorn. Now, many wildflowers need disturbances to germinate. It’s a role that the hooves of cattle play very well in certain contexts, says rangeland ecologist Justin Luong, an assistant professor of working lands for people and the environment.
“Moderate, well-managed grazing can be important for promoting higher carbon storage,” says Luong, who joined Rausser College this July. The practice has been shown to stimulate root growth, and bigger roots mean more carbon stays in the soil, helping to mitigate climate change.
“Moderate, well-managed grazing can be important for promoting higher carbon storage.”
— Justin Luong
But life on the range is not what it once was. While California remains a major dairy and beef state, ranching is in decline. Facing economic pressures and recent droughts, many ranchers are scaling back. Some are reducing their herds. Others are selling their land altogether—often to developers.
Huntsinger works closely with the California Rangeland Trust, which gives ranchers an alternative. To protect their open spaces, landowners can partner with the Trust to create conservation easements that permanently conserve the land, prevent development, and ensure responsible stewardship of the land while allowing it to remain a working landscape.
For Huntsinger, preventing the paving over of open space is personal. She grew up in Southern California, watching the grasslands she loved turn into suburbs. In her twenties, craving proper open spaces, Huntsinger spent three transformative summers working as a cowhand in the Sierra.
One day, as she rode alongside a fellow ranch hand, he mentioned he recently earned a master’s degree in range management. Huntsinger hadn’t known such a field existed, but quickly realized it was exactly what she wanted to do. “I decided to go back to graduate school and get a degree that would let me ride around the mountains chasing cows forever,” she laughs.
As an undergraduate at UC San Diego, Huntsinger had helped develop and teach a course on wilderness and human values. But in Berkeley’s range management graduate program, she encountered a different idea: On most of the planet, there’s no such thing as untouched landscape. A Native American speaker hammered it home at a symposium. “Wilderness—that’s a term invented by the white man,” Huntsinger recalls him saying. “To us, it’s a home, a garden.”
Since then, Huntsinger has dedicated her career to working lands—studying the ecology of rangelands and partnering with ranchers who manage their properties for biodiversity, fire resistance, and habitat restoration. California’s ecosystems have been thrown off balance in multiple ways, says Huntsinger, and grazing can be part of the solution.
Left: Huntsinger’s undergraduate class hearing from Tim Koopman, who manages his family’s multigenerational ranch for food and to foster habitat for wildlife like the California tiger salamander, California red-legged frog, and callippe silverspot butterfly. Middle: Summer in Rancho Jamul Reserve and Hollenbeck Canyon Wildlife Area, located in San Diego County. Right: Larry Ford, MS ‘86 Range Management; PhD ‘91 Wildland Resource Science, sampling grassland at Rancho Jamul as part of a UC Berkeley project evaluating the effects of cattle grazing on wildlife habitat and fire hazard reduction. Photos courtesy of Lynn Huntinger and Felix Ratcliff
“I was just visiting Napa,” she says. “What used to be beautiful open grasslands and oak woodlands are now filling in with shrubs like coyote brush.” That plant is native—but without traditional burning or grazing to keep it in check, the brush overtakes the land, turning open landscapes into highly flammable thickets. In the Bay Area, non-native broom plants add to the tangle of flammable fuels.
Grazing, Huntsinger’s research has shown, can complement prescribed burns—which are notoriously difficult to approve and implement—in keeping vegetation under control. Cattle can help reduce fire hazards on rangelands by up to half. A 2022 study by a group of Huntsinger’s former students found that California’s cattle removed nearly 12 billion pounds of flammable vegetation from rangelands.
“Grazing can do wonderful things. But people are still stuck in that old mindset,” Huntsinger says. “It’s like convincing people that not all fire is bad. We’re at the same point now with grazing animals.” Reducing fire risk also helps curb greenhouse gas emissions, of course. And as Huntsinger points out, wildfires contributed nearly 25 percent of California’s total emissions in 2020.
Methane Matters
Huntsinger stresses the importance of putting agricultural emissions—especially methane—into perspective. She notes that while CO2 stays in the atmosphere for hundreds or even thousands of years, methane has a relatively short lifespan of 7-12 years in the atmosphere. “And the relationship between grazing animals, plants, and methane has been one that has been a part of our planet’s ecosystems for millions of years,” she says.
Still, methane remains a thorny issue. Environmentalists have long focused their ire on large livestock operations, and California’s farms are large contributors of the potent world-heating gas. It’s a difficult problem to solve. But that hasn’t stopped policymakers and researchers from searching for solutions.
“Around half of California’s methane emissions come from livestock, primarily through cow burps and via the microbes that break down their manure.”
— Aaron Smith
California’s 1.7 million dairy cows produce 30 million gallons of manure a day. Lagoons filled with the manure produce nearly a quarter of the state’s methane. So, in 2016, state lawmakers decided to act. They set an ambitious target: cut methane emissions by 40 percent by 2030.
The obvious fix, says Smith, would have been to charge farmers methane fees. But California officials worried that piling on new expenses would accelerate the current exodus of dairy farmers to cheaper states like Arizona and Nevada while raising prices at the grocery store. Instead, they performed some clever policy alchemy. They turned methane into fuel.
California began including dairy methane in its Low Carbon Fuel Standard, a program designed to clean up transportation fuels. “Now,” says Smith, “the state essentially subsidizes the capture of methane from manure, which is cleaned and put into pipes to be used as a transportation fuel in place of fossil natural gas.”
The roundabout strategy works like this: Farmers cover their manure lagoons with anaerobic digesters, which trap the methane and convert it to renewable natural gas that powers school buses, Amazon delivery trucks, and other vehicles. But the system is controversial. Environmentalists argue that it essentially turns farms into poop factories, encouraging farmers to generate more manure to create more of the powerful greenhouse gas.
“It’s the cobra effect,” says Smith. “The idea that, if you offer a bounty for dead snakes, pretty soon people start breeding them.” For now, though, Smith—who has studied the effects of the policy in detail—says there’s no solid evidence of increased production triggered by the methane incentives.
Still, he’s critical of the policy for different reasons. California has a long tradition of paying farmers for creating environmental benefits through practices such as maintaining plants that attract pollinators or reducing erosion through soil management. (At the national level, agricultural incentives were essential to recovery from the Dust Bowl and have continued as a strategy through the Natural Resources Conservation Service.) In offering these incentives, California is counting on farmers to not pass on the cost of these environmental improvements to customers. But, says Smith, shielding consumers from important knowledge—namely, the true cost to the environment of the foods they eat—can lead to further problems down the line. “The policy as it stands is not really sustainable,” he says.
Belches pose a trickier problem still. Methane from manure can be trapped. Cow burps, on the other hand, are much harder to capture, but that may soon change.
Researchers at UC Berkeley’s Innovative Genomics Institute (IGI) are collaborating with experts at UC Davis to reprogram the microbes inside the cow’s gut that produce the methane. The effort is part of a larger project focused on the microbiome and CRISPR gene editing, funded by a $70 million gift through TED’s Audacious Project that’s overseen by IGI founder Jennifer Doudna and Jill Banfield, IGI director of microbiology and a professor in ESPM. Inspired by studies showing that feeding cows red seaweed could slash methane emissions, the group of researchers—led by UC Davis professors Ermias Kebreab and Matthias Hess—are working to harness CRISPR gene-editing techniques to disable the methane-making genes inside those gut microbes. The goal is a one-time treatment for calves that could curb their lifetime methane output.
“This project represents a transformative opportunity to tackle one of the livestock sector’s biggest climate challenges,” said Kebreab. “By using cutting-edge science to target methane-producing microbes in the cow’s gut, we aim to deliver a one-time, practical solution that farmers everywhere can adopt to make cattle production more sustainable.”
