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“Talk to Jim. Jim knows everything.”
That’s what everyone told Woodwell Assistant Scientist, Dr. Jennifer Watts, when she started writing up a research plan to study soil carbon on U.S. rangelands. “And indeed, he does,” Dr. Watts says. “He knows everything about the region, about grazing management, species management, anything having to do with land management on these ranches.”
With his felt Stetson, dusty jeans, and perennial tan, ranch manager Jim Howell looks a bit like the kind of cowboy Hollywood might dream up. And in a way he is—despite looking at home on the range, Howell grew up in Southern California. But he spent his summers out in Colorado’s Cimarron mountains, working on his grandfather’s cattle ranch.
Those summers were Howell’s introduction to the idea that the way livestock are managed can change their impact on the land—a thread that would pull him through a college degree in animal production, towards a career “knowing everything” about holistic ranch management. He was first clued into this concept while walking the fence line separating his family’s property from a patch of public land being used to graze sheep.
“I noticed there were lots of very healthy, perennial, bunch grasses on the sheep side, while our side of the fence had degraded to mostly silver sagebrush, Kentucky bluegrass, and dandelions,” says Howell. “And I just didn’t understand why the differences were so stark.”
Howell’s cattle were stocked continuously on the land, low in number but able to graze year round, while the sheep grazing permit required rotation. There might be a great flock of sheep up there one day and nothing but grass for the remainder of the year. That difference, it turned out, dramatically altered the kinds of plants that could flourish on the land.
“I became aware then that the way that we’d been managing our cows in our country up there was leading to its slow, long-term, ecological degradation. And I didn’t know what to do about it,” says Howell.
There have always been animals grazing the American West—before colonizers, even before native peoples. On the Great Plains there were bison; in the mountains and high altitude deserts of Southwestern Colorado, it was bighorn sheep and pronghorn antelope, as well as elk and mule deer. All three are rare sights now, with populations decimated by overhunting and habitat degradation.
Now, if you see any animal grazing on these ranges, it’ll probably be cattle.
Despite displacing native species, cows can still fill a natural niche in the rangeland ecosystem. Antelope, bison, sheep, and cows all belong to a group of animals called ruminants—animals that can digest grass. Many grasslands have co-evolved with ruminant species; their roaming feasts influence plant growth the same way pruning might affect the shape of a tree. Occasional shearing by a hungry cow stimulates new grass growth. It also creates a more competitive environment that supports a diverse array of plant species.
Grazing also plays a part in cycling nutrients and storing carbon in the soil. In a frequently dry climate like this one, digestion breaks down plant matter much faster than it would decay in the environment. Manure fertilizes new plant growth and returns carbon to the soil. Let this process continue unencumbered for a couple hundred thousand years, and you can build up a valuable carbon sink. And as long as the number of cattle isn’t rising, the oft-cited methane emissions from cow burps are minimal and cycled back down into the plants that grow up after grazing.
Since settlers arrived, however, the land has been put through centuries of abuse. Public lands were, for a long time, left open to unregulated grazing. Many rangelands have been over-stocked and grazed too frequently in order to make a profit and meet growing global beef demand. Land has been ecologically degraded, valuable topsoil was lost, and carbon stores declined as a result.
It would be easy to blame cows for this. But really, they’re not behaving much differently than pronghorn or bison would. They eat what’s in front of them. And they eat the tastier plants first. Howell likens it to a salad bar.
“If you go into a salad bar and there’s some lettuce that has been sitting there for three months, and some of it that’s just been replaced that morning, you take the new stuff. So that’s exactly what the cow does,” Howell says. “If she’s not made to move anywhere new, she’s just going to keep coming back and grazing the regrowth of the good stuff as long as it’s there.”
Pretty soon, perennial grass species, important for their deep roots that help prevent erosion and store carbon and water longer, are grazed into nothing. All that’s left are the sagebrush, dandelions, and other less desirable plants that Howell noticed dotting his family ranch.
“So the whole thing is about how the cows are managed, it’s not the cow itself that is a problem,” says Howell.
But if bad management can degrade the land, then good management should be able to restore it. While studying animal science in college, Howell encountered the concepts of “holistic management”, a term that began to decode this relationship between management practices and the health of the land. Controversial at its introduction a half century ago, holistic ranching has been gaining traction, and Howell and his ranch management company, Grasslands LLC, have helped urge its uptake.
The core principle is to make management decisions that restore lands and keep cattle in balance with the rest of the ecosystem—helping them fill the niche of the ancient grazers. This comes with a host of co-benefits, including water retention and higher plant productivity, that actually end up improving economic profitability for ranches in the long run. Simple adjustments, like lengthening the time between grazing a pasture again and wintering cows on native ranges instead of hay, can turn cattle from an ecosystem destroyer to an ecosystem helper.
“The trick is to let the cows do all the hard work,” says Howell.
Dr. Watts and Woodwell Senior Scientist Dr. Jonathan Sanderman, along with Dr. Megan Machmuller of Colorado State University, are interested in quantifying those co-benefits. Especially carbon storage.
“In the western US on our rangelands, just like in our croplands, we can change how we manage in a way that potentially could become a natural climate solution,” says Dr. Watts. “One where we’re bringing in more carbon than we’re emitting and we’re creating ecosystems that not only are beneficial for carbon sequestration, but also have more biodiversity, offer more habitat for wildlife, and more water conservation.”
In order to prove that value however, scientists need a baseline understanding of how much carbon is currently stored across both traditionally-and holistically-managed rangelands. It’s hard to get an estimate for such a large area (roughly 30% of the U.S. is covered with rangelands), so they are using a remote sensing model, which they verify with strategic on-the-ground sampling.
Howell’s work also created the perfect conditions for the research team to study the long term carbon benefits of altered ranching practices, which is a tricky thing to test empirically. Ranchers must constantly adjust their management techniques to stay profitable.
“In a classical research setting, you try to control all the variables but one, but in real life that’s not what happens,” says Howell. “Nothing is controlled. Day to day, you have to adapt to constantly changing conditions.”
But the ranches Howell’s company works with make those day-to-day decisions based on the principles of holistic management, so tracking carbon on those ranches over time offers the opportunity to generate baseline data on how they differ from more traditionally managed ones.
Howell also brought the expertise of a life spent on the range. He can identify just about any plant growing in the pasture, tell you which are native, which are invasive, and which used to be the preferred food of prehistoric ground sloths. His eye is trained to see diversity even in martian-esque deserts and read the history of the land in the structure of the soil. In May of 2022, Howell guided Drs. Sanderman, Watts, and Machmuller and their teams on a sample collection trip through Southwest Colorado and Utah. The researchers took soil cores, plant samples, moisture and temperature readings, and analyzed carbon fluxing in and out of the pasture.
The ultimate goal is to create a rangeland carbon management tool that will make the soil carbon data model accessible directly to ranch managers. Dr. Watts hopes having that data in hand will enable more ranchers to make management decisions with climate in mind. Dr. Sanderman also notes that it could be useful in eventually helping ranchers get paid for sustainable practices.
“Rangelands haven’t been included in voluntary carbon credit markets like cropping systems have,” says Dr. Sanderman. “Monitoring is a big problem because there’s so much land—How do you keep track of all that? That’s what our tool will be able to offer.”
There are limits to what grazing can accomplish, though. The lands out west aren’t suitable for large-scale cropping, being too dry or too mountainous, which makes them perfect for cattle. But when the animals take up space on land that would otherwise be used to produce crops—or worse, penned into feedlots—their benefits are compromised. Howell also notes that some grazing lands are already as saturated with carbon as they can be. And there remains the fact that ranching will get more complicated as the climate changes.
At the Valdez ranch in Delta, Colorado, Dr. Sanderman and research assistant Colleen Smith unfold a collapsible table in a field of cracking mud, dotted with the brittle stick skeletons of dead grass. Nearby, Dr. Machmuller is assisting Howell in extracting a long metal cylinder from the ground. It was plunged into the soil by a hydraulic corer attached to a pickup truck that’s idling in the field. Howell and Dr. Machmuller lay it out horizontally on the table and slide out the soil core—a 50 centimeter long history of the land beneath their feet.
Howell breaks open a section of the core with his fingers, revealing clusters of white crystals. This is a pasture that has been abused; over-irrigation by previous owners brought salts to the surface. Now nothing will grow here and wind gusts threaten to blow away loose topsoil. It’s a sacrifice zone. The current owners are considering installing solar panels instead.
Water is a big issue for ranchers and it’s threatening to get bigger. The region is constantly dipping in and out of severe drought, and in a place that depends heavily on winter snows for its groundwater and rivers, a warmer, drier climate is a threat.
Agriculture will depend more on irrigation as the climate warms and precipitation patterns change. But this empty pasture is proof that it’s not always a viable solution, and will become less so as climate change advances.
It enforces the urgency of the work Howell and team are doing. The faster we can draw carbon out of the atmosphere, the more successful these ranches are likely to be in the long term. The better managed the ranch, the more resilient it will be in the face of tough conditions.
In the end, Dr. Watts says, the outcome rests in the hands of ranch managers—people like Howell.
“Land managers are the ones that ultimately are going to make or break this country.”
In terms of climate mitigation, forests are like green gold—working overtime to cool the planet, while also supporting a wealth of biodiversity. But we have not been saving them as one would a precious asset. Despite pledges to end deforestation, old growth forests are being cut down at alarming rates. And planting new trees is widely prioritized and incentivized over protecting existing forests. Across the board, standing forests are vastly undervalued. This has to change if we are to stand a chance of limiting warming to internationally agreed targets.
According to a recent study from scientists at Woodwell and the University of Virginia, tropical forests alone are holding back approximately 1 degree Celsius of warming. About 75% of that cooling effect is due to carbon sequestration. Forests grow, trees lock away carbon in their trunks and roots and shunt it into the soil. The other 25% comes from the innate properties of forests that work to cool vast regions of the globe.
Through photosynthesis, plants release water vapor into the air in a process called evapotranspiration. The vapor contributes to cooling near the ground, as well as cloud formation higher in the atmosphere that reduces incoming solar radiation. The shape of the tree canopy also contributes. So-called canopy “roughness” disrupts air flow above the forest. The more uneven the canopy, the more turbulent the air, which disperses heat away from the surface. In the tropics, evapotranspiration and canopy roughness are high, which means that surface temperatures remain relatively low, with the heat dispersed throughout the deep atmosphere.
Forests also naturally produce molecules called biogenic volatile organic compounds (BVOC), which can either contribute to cooling by encouraging the formation of clouds, or to warming by creating ozone and methane. In the tropics, the net effect of these chemicals is cooling.
The cumulative result of these properties is that when forests are removed, the land around them begins to heat up even faster, which can increase the frequency of extreme heat and drought events. Without forests, some regions will become a lot less resilient to sudden shocks. And the release of carbon contributes to global warming which further exacerbates hot, dry conditions.
“Forests act like air conditioners,” says Woodwell Assistant Scientist, Dr. Ludmila Rattis, who studies the impacts of deforestation on agriculture in Brazil. “Deforesting in the face of climate change is like getting rid of your air conditioners before an upcoming heatwave.”
Protecting forests, and maintaining the cooling services they provide, is vital to limiting warming. But, with forests covering 30% of the Earth’s land, prioritizing protection is a massive task. And when it comes to carbon storage, not all forests are equally valuable. Older, healthier forests tend to have a more secure hold on their carbon.
“Mature forests have higher biodiversity and create their own microclimate,” says Woodwell Associate Scientist, Brendan Rogers. “They’re more resistant to drought and other types of disturbance. And because of that, they tend to be more stable in the face of environmental perturbations over time.”
New research from Woodwell and Griffith University has developed a method of identifying high-value forests using satellite imagery. Estimating the metric of “forest stability” through satellite data on the light reflected by vegetation and a water stress index of the tree canopy, researchers were able to determine gradients of stability within forest patches in the Amazon and boreal forests.
Using a gradient of forest stability allows for a better prioritization of forest protection strategies based on their carbon value.
“The first priority is to protect stable forests from further human disturbance,” says paper co-author Dr. Brendan Mackey. “The second priority is to identify forest areas where restoration efforts will be most cost effective.”
But if the state of existing forests is any indication, forest protection continues to be deprioritized. Many wildfires are left to burn unless they threaten human settlements. Governments continue to incentivize deforestation for development or agricultural expansion. Indigenous and local communities are not compensated for their work stewarding their territories and keeping forests safe. And the warmer the planet gets, the more susceptible even protected forests become to drought, fire, and disease.
Research has shown that stewarding standing primary forests, and reviving degraded ones, represents the greatest opportunity for near-term carbon storage and removal. A study of global land-based carbon storage potential found that improved management of existing forests alone could store approximately 215 billion metric tons more than they currently do.
Protecting forests is cost effective, too. For example, in the United States, investing in fire fighting in Alaska’s boreal forests would require just $13 per ton of CO2 emissions avoided. That’s easily on par with other mitigation strategies like onshore wind or solar energy generation.
Effective strategies for protecting forests already exist, they’ve just been suffering from a lack of force—and often funding—behind their implementation. For example, forest carbon markets—where landowners and forest stewards are paid to protect standing forests that are otherwise vulnerable to deforestation—have the potential to keep forests safe while offsetting emissions from other sectors. But nascent carbon markets are inefficient, with weak standards for verifying the quality of credits being sold, and lacking the transparency needed to ensure credits are actually reducing overall emissions, rather than greenwashing carbon-intensive business practices.
Credits are also priced incorrectly for their relative climate value—the market currently values reforestation credits more highly, reducing incentive for landowners to conserve standing, old-growth forests when there is a better livelihood to be made in legally deforesting land for other uses. A truly effective carbon markets system would require large investments in science that can verify credit standards.
Forests are like our global carbon savings accounts—when we cut them down, we’re drawing out money and limiting our ability to collect interest and keep growing our funds. Successful mitigation can’t be accomplished without taking the full value of forests into account and strengthening policies to reflect that. If they aren’t, the planet will pay a far greater price for it as temperatures rise.
“We can’t afford to keep cutting forests. We need to reduce emissions now, and protecting forests is one of our best available solutions. Despite the obstacles, it’s worth the investment,” says Dr. Rogers.
Rangelands occupy more than three quarters of global agricultural land. Many of the world’s native grassland ecosystems have been converted to grazing land for livestock, altering their ecology and changing the flow of carbon on the landscape. However, these lands still have the potential to be a powerful carbon sink if properly managed.
On September 27 and 28, Woodwell Climate Research Center convened a workshop in collaboration with Montana State University (MSU) and Turner Ranches to open discussions on rangeland management in the United States. The workshop took place in Bozeman, Montana, and brought together scientists, ranchers, and conservationists to share their perspectives on rangeland ecology, carbon sequestration, fire management, and herd health, as well as anecdotes from careers spent on the range.
“Montana offers a great location for this conversation because the majority of the state is amazing rangeland including unique grassland and sagebrush steppe environments, in many cases privately held,” said Dr. Stephanie Ewing, an Associate Professor at MSU who co-organized the event. “And because we have a strong academic and extension community at MSU that has been engaged with rangelands and rangeland managers over time.”
Day one began with a series of presentations and panels meant to facilitate discussion about rangeland management. Sessions covered rangeland ecosystem services, rangelands in the American West, management for carbon sequestration, carbon markets, and tools for rangeland monitoring.
For Dr. Jennifer Watts, Woodwell Assistant Scientist, the discussions highlighted the vast untapped potential of rangelands to play a positive part in climate mitigation.
“There’s so much rangeland in the western U.S. and so there is a huge potential for improving ecosystems and improving carbon sequestration and storage,” Dr. Watts said. “But the public doesn’t perceive rangelands with the same reverence that we do with forests or other ecosystems. I think if we start to value them at the national level, and realize the potential for ecosystem services and climate mitigation, that could shape how policy is going to move forward.”
The following day, attendees made site visits to two ranches in the area—Red Bluff Ranch, run by MSU, and Green Ranch, owned by Turner Enterprises—for a hands-on look at the topics they had discussed the day before. They examined soil pits, dug into the grass, and talked about different land management styles.
For Senior Scientist Dr. Jonathan Sanderman, the trip into the field was a catalytic moment in the workshop.
“After just a few hours on the ranches, I felt like a lot of people had lightbulbs go off about how long-term management has affected certain parts of land more than others, and how that feeds back to the soils,” Dr. Sanderman said.
One theme that emerged from the workshop was the need for more and better information on how rangelands could be included in carbon markets. While there was interest from landholders in participating, very few knew enough to get started. Drs. Watts and Sanderman hope future collaborations will allow them to dig deeper into the topic with ranchers.
“A well-functioning carbon market can provide climate benefits and an additional revenue stream, enhancing the economic resilience of ranching communities,” Dr. Sanderman said. “Quantifying and monetizing carbon sequestration from improved grazing management is still in its infancy. This means there is a lot of confusion and few agreed upon standards; but, it is also an opportunity to shape policies and design programs that benefit people and the environment.”
It also became evident that, while many ranchers were interested in carbon storage on their lands, what mattered more to them was the possibility of integrated benefits from holistic range management. Improving carbon storage in the soils can improve water management, nutrient retention, and other ecosystem services.
“Carbon is something that brings it all together,” Dr. Watts said.