Prairie land under a blue sky
SPLT land (Trent Davis Bailey for The Atlantic)

Trees Are Overrated

Preserving the world’s great expanses of grass could be essential to combatting climate change.

Updated at 1:10 p.m. on July 29, 2022

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Once upon a time, not a blade of grass could be found on this planet we call home. There were no verdant meadows, no golden prairies, no sunbaked savannas, and certainly no lawns. Only in the past 80 million years—long after the appearance of mosses, trees, and flowers—did the first shoots of grass emerge. We know this in part because a dinosaur ate some, and its fossilized poop forever memorialized the plant’s arrival.

Grass then was still an odd little weed, vying for a spot on the forest floor. It took ages for grasses to grow in numbers that might constitute a grassland. And grasslands only started to occupy serious real estate in the past 10 million years—basically yesterday. They now cover roughly one-third of Earth’s land area.

We humans arrived in the midst of grass’s heyday, and it is doubtful we would exist otherwise. Homo sapiens evolved in and around the savannas of Africa, then spread around the world, often following grassy corridors. With the invention of agriculture, many societies fed themselves on domesticated grasses like wheat and corn, and on livestock that turned wild grasses into edible protein. We are, many of us, grass people.

But for all grass has done for us, we haven’t done much for grass lately. Grasslands rank among the most imperiled and least protected biomes on Earth. They are disappearing even faster than forests, and much of what remains has suffered varying degrees of damage. Their decline threatens a huge chunk of the planet’s biodiversity, the livelihoods of roughly 1 billion people, and countless ecological services such as carbon and water storage. Yet these losses don’t register with the same force as deforestation. Perhaps because we do not notice, or perhaps because we do not care.

The tendency to overlook and undervalue grasslands is a product of their reputation as degraded and thus disposable landscapes—a misperception rooted in centuries of scientific confusion and cultural bias. It reflects a deeply held preference for forests, mainly among people of European descent, that has warped global grassland science and policy. Some scholars have described the problem as “arboreal chauvinism.” Joseph Veldman and his colleagues have called it the “tyranny of trees.”

Veldman is an ecologist at Texas A&M University. Tall and athletic, with a low, booming voice and a voluble disposition, Veldman earned his Ph.D. in 2010 by studying the tropical forests of Bolivia. Then, as now, scientists feared that logging and fires were turning the Amazon into savanna. But when Veldman began looking at true savannas—which are just grasslands with more trees—he learned that they were distinct ecosystems governed by a completely different set of rules. And they did not deserve to be maligned as run-down forests.

So Veldman proposed the term old-growth grassland to differentiate ancient, intact grasslands from those that form after humans clear a forest or abandon farmland. In a 2015 paper, he and his co-authors explained that old-growth grasslands, like their forest counterparts, take centuries to develop biological diversity and build up carbon stores, and that they are effectively irreplaceable once lost. (Coincidentally, the word veld refers to a common type of grassland in southern Africa.)

When I visited Veldman in April, we set out on a blustery, overcast morning in search of a rare old-growth grassland near the Gulf Coast. After a short unplanned detour (Veldman refuses to use Google Maps), we arrived at an inconspicuous field on the side of a rural highway. Waist-high golden grass waved toward a distant tree line, concealing a carpet of fresh green growth underneath.

To the untrained eye, Nash Prairie looks like an unkempt pasture. To Veldman, it is a treasure—a 250-acre relic of the coastal prairie that once stretched from Mexico to Louisiana. As soon as he parked his truck, he tromped off to inspect the tangle of prairie grasses and wildflowers, as giddy as a kid at an amusement park. Through Veldman’s eyes, places like this do not seem degraded and disposable, but deeply worthy of protection—for their own sake and ours.

Veldman standing in a field of grass with blue sky above
Veldman, photographed at Texas A&M Ecology and Natural Resources Teaching Area (Callaghan O’Hare for The Atlantic)

Veldman and almost every other grassland scientist I talked with were quick to say that they have nothing against trees. Protecting the world’s forests is crucial to stabilizing the climate and to conserving the diversity of life and human cultures. Trees also have an innate allure. “My wife and I planted a tree when we married,” says William Bond, a retired biologist at the University of Cape Town who recently produced a seven-minute educational video that is essentially a promotional trailer for grasslands. “It grew into a big tree; it was lovely,” he says. But, as Bond declares in the video—speaking from the perspective of grasses, naturally—forests have been “our main adversaries.”

On an ecological level, grasslands and forests have been duking it out for a long time. Grasses prevail when, for one reason or another, conditions are inhospitable to trees; trees prevail when they grow dense enough to shade out grasses. In many places, grasslands and forests coexist in a slow-motion tug-of-war.

Humans have played a part in this struggle for millennia. Many Indigenous peoples, likely noting the benefits of wildfires for hunting and foraging grounds, intentionally burned the landscape, helping to maintain and possibly expand grasslands and savannas. But in Europe, powerful civilizations took root in forested terrain. And centuries later, when these cultures began exploring and colonizing the rest of the world, they chose trees over grass.

Across Africa, French foresters diagnosed naturally treeless landscapes as severely deforested and colonial governments seized control of the land from locals in the name of restoration. In Madagascar, a former French colony, it’s taken centuries to overturn the narrative of human destruction. “We’ve been told from primary school that Madagascar was covered in forests,” Cédrique Solofondranohatra, a Malagasy botanist, says. Then, supposedly, people came, cut down the trees, and set fire to the landscape, creating vast, artificial grasslands that few scientists even bothered to study. Over the past 15 years, however, work by Solofondranohatra, Bond, and others has uncovered evidence that grassy ecosystems existed on the island long before humans arrived.

This possibility did not concern colonial foresters in Africa and elsewhere, who set about planting trees in the belief that it would not only restore the landscape but also elevate its inhabitants. “The ultimate goal was to make both colonized people and the environment more European, since Europe was the alleged center of civilization,” the researchers Diana Davis and Paul Robbins wrote in a 2018 article. Veldman puts it more bluntly: “It’s not just about Europeans valuing trees. It’s also that trees provide a nice pretext to justify colonialism.”

Colonial forest practices had an extractive dimension too. In India, for instance, British foresters came looking for timber, so when they encountered stands of trees with a grassy understory, they decided to call them forests. Now scientists know them to be savannas. “They are sister landscapes to what you see in Africa,” says Jayashree Ratnam, the director of wildlife biology and conservation at the National Centre for Biological Sciences in Bangalore.

It didn’t help that the nascent field of ecology also had a pro-tree bent. The influential German naturalist Alexander von Humboldt observed that vegetation patterns followed climate patterns, laying the foundation for an abiding belief that if a landscape was capable of supporting forests, it ought to. That idea culminated in the 20th-century concept of succession, which held that ecosystems tend to evolve toward a climate-dependent “climax” state. In many depictions, grasslands appear as an early stage in this progression that will—given time and barring outside interference—eventually sprout trees. The model worked well enough in forested ecosystems, but for a variety of reasons, it struggled to explain the existence of many long-lived grasslands except as stunted landscapes held back by human meddling.

The perception of grasslands as degraded landscapes has largely kept them off international conservation agendas, says Karina Berg at the World Wide Fund for Nature. She leads the organization’s Global Grasslands and Savannahs Initiative, which launched in 2020 to address this oversight—and to correct for the conservation movement’s role in perpetuating it. “We contribute to this kind of constant reinforcing of, ‘Oh, trees are the ones that are going to solve our problem,’” Berg says. (A case in point: Of the 50 founding initiatives of the UN Decade on Ecosystem Restoration, which began in 2021, only two involve grasslands and savannas.)

Researchers, particularly in the tropics, are weary of fighting these misperceptions, which still shape global policy. “I don’t mean to blame my colleagues from Europe,” says Fernando Silveira, an ecologist at the Federal University of Minas Gerais in Brazil who studies the Cerrado, a critically threatened Brazilian savanna. “I just want them to understand.” To register their frustration and highlight the problem, Silveira and colleagues from around the world, including Veldman, recently gave the phenomenon a name: “Biome Awareness Disparity,” or BAD.

closeup of a hands holding a strand of grass outside
Paspalum plicatulum, commonly known as brownseed paspalum (Callaghan O’Hare for The Atlantic)

At Nash Prairie, our hosts Jeff Weigel and Susan Conaty call Veldman back from the grass, and he reluctantly returns to the line of parked cars. Weigel is the director of strategic initiatives for the Texas chapter of the Nature Conservancy, which owns the property, and Conaty is a local volunteer who championed the prairie’s protection.

For most of the preceding century, this land belonged to Kittie Nash Groce, a rancher and Houston socialite who whizzed down local roads in a pink Cadillac. When she died, she left part of her estate to St. Mary’s Episcopal Church in nearby West Columbia. Conaty’s late husband happened to be the congregation’s priest, and when she discovered that the ranch contained a slice of coastal prairie, the couple devoted themselves to saving it, ultimately persuading the church to sell the land to the Conservancy in 2011.

This pocket of old-growth grassland owes its survival to “dumb luck,” Conaty says. Just 1 percent of Texas’s prairies remain intact. (Nationally, about half of native grasslands have already been converted to cropland or consumed by development, and millions more acres are lost each year.) As far as anyone knows, Nash Prairie was never plowed, fenced, fertilized, or seeded. Local farmers mowed it for hay, but that actually helped maintain the prairie. “It was accidentally well managed,” Weigel says.

Veldman is wonderstruck by the results. In fact, after chatting for half an hour, he can’t restrain himself on the periphery any longer. Under cottony clouds, we follow him back into the tall grass—a mix of switchgrass, little bluestem, and other perennials—where he narrates what he finds, possibly for my benefit and possibly because, in his professorial way, he can’t help it. He stumbles over the genus of one plant, not yet in bloom. “Texas coneflower,” Conaty offers. “Rudbeckia texana.” She points out green milkweed, a trailing pink mimosa, and a tiny lily called yellow star grass.

Despite their apparent simplicity, grasslands are bastions of biodiversity. They support everything from large, charismatic megafauna (think lions and elephants) to humble pollinators and rare wildflowers. The Cerrado, for instance, is home to more than 12,000 plant species, a third of which occur nowhere else on Earth. And a mountain grassland in Argentina holds the world record for the most plant species found within a square meter of land: 89.

But just as second-growth forests lack the complexity of old-growth stands, ancient grasslands lose much of their diversity after they’ve been plowed or planted. In 2020, Veldman and one of his graduate students, Ashish Nerlekar, published a study showing that secondary grasslands contain an average of 37 percent fewer plant species and require centuries or even millennia to approach former levels of biodiversity. (Secondary grasslands can have conservation value too, but Veldman and Nerlekar’s work shows what’s lost in conversion.)

The results suggest that grasslands take just as long to mature as forests, which qualify as old growth after about 150 years. But forests age more impressively. “We can see time embodied in that large tree in a way that we don’t very easily with most grasslands,” Veldman admits. In grasslands, time manifests visibly as an abundance of slow-growing perennial flowers—and, invisibly, in the considerable biomass that accumulates underground as plants grow bulbs and tubers, set roots that can plunge 20 feet deep, and feed bacteria and fungi a steady diet of carbohydrates.

Indeed, grasslands are gigantic reservoirs of carbon. Scientists estimate that, worldwide, they contain about a third of all the carbon stored on land, mostly in their soils. Scientists also know why: After enduring millions of years of extreme drought, frequent fire, and hungry herbivores, grassland organisms have evolved to stock up and hunker down. Some grasslands even host “underground forests”; to survive frequent burns, certain tree relatives grow subterranean branches and sprout only small stalks of leaves to capture sunlight.

Savanna trees that grow above ground can tolerate fire. Regular disturbances hold back other woody invaders, even in places where climate and soil conditions might otherwise support forests. But while the theory of succession saw disturbances as interrupting the natural progression from grass to trees, many scientists now view them as stabilizing grassy ecosystems. “Fire for the savanna is like rain for the rain forest,” Veldman likes to say.

Ironically, this dependence on disturbance makes grasslands highly vulnerable to modern forms of human interference, like the disruption of natural fire cycles and the replacement of wide-ranging native grazers with dense herds of sedentary livestock. In many landscapes, these actions—together with a changing climate—have shifted the advantage from grass to trees and shrubs, which quickly take over. That means protecting grassy ecosystems won’t suffice if we don’t actively maintain them. In Texas, Veldman and others repeated a mantra of sorts: Today, grasslands are often a choice.

The day before we visited Nash Prairie, Veldman and his students affirmed this choice by burning a restored prairie owned by Texas A&M. The grassland is far from pristine—decades ago, it was mined for fill to expand the airport runway—but fire still nourishes the ecosystem. It also serves as a teaching exercise for Veldman’s class, and a public demonstration of a practice that once constituted a felony in the state.

Before a few dozen onlookers, the crew worked its way across the large field, using drip torches to light a trail of fire. As the invading mesquite trees erupted in flames, the dry grasses sizzled and popped, writhing as they flared and then burned themselves out. This is what they evolved to do.

At Nash Prairie, the Nature Conservancy also conducts prescribed burns every year or so. In 2021, someone dropped a lit cigarette, likely from a car, and torched most of the property. “I call it fire by idiot,” Conaty says. Still, it saved the organization some trouble. As it recovered, the prairie transformed into a sea of technicolor green flecked with outrageous displays of flowers. Veldman can hardly imagine what it must look like. “Glorious is the word,” Weigel says.

As we prepare to leave, I ask Veldman what he sees in a landscape like this. He gives a rather clinical assessment of the character and condition of the vegetation. I explain that what I really want to know is how it feels to be here. Veldman falls uncharacteristically quiet, and his eyes redden. “It actually makes me emotional to talk about it,” he says, his voice creaking. “The last time I felt this way, I was at Iguazu Falls”—a roiling amphitheater of plunging cascades in South America—“and it caught me completely off guard that I would just feel kind of overwhelmed.”

He recovers. “It has to do with thinking about what it must have been like to see it,” he says. To see this grassland long ago, uninterrupted and alive with bison and mammoths. “To think, you know, there’s just so little of it left.”

A lone tree on in a field of grass
Grasslands are part of the post-oak savanna, which was once widespread across east-central Texas. (Callaghan O’Hare for The Atlantic)

The two-hour drive back to College Station would once have cut across sweeping prairies and oak savannas. Instead, we traverse a checkerboard of farms, ranches, and strip malls. Here, as in many parts of the world, grasslands have disappeared because their rich soils make them ideal for growing crops and the lack of trees to clear makes them easy targets for development. We see grasslands as empty, and therefore available for human use.

Now, scientists like Veldman are alarmed by the prospect of tree planting as an all-purpose restoration and carbon-trapping strategy. The Bonn Challenge, a partnership between Germany and the International Union for Conservation of Nature, aims to restore 860 million acres of degraded and deforested land by 2030, largely by increasing tree cover. More ambitious still is a billionaire-backed project run through the World Economic Forum that seeks to “conserve, restore and grow” 1 trillion trees by the end of the decade. It was inspired by a controversial 2019 study that found trees could suck up one-third of the carbon dioxide released by humans.

Already, governments and companies have made substantial tree-planting commitments under these programs, and the practice enjoys wide public support. Even President Donald Trump, who called climate change a hoax, signed the U.S. up to join the trillion-tree initiative and planted a maple tree on the White House lawn. The problem, at least for grasslands, is that people aren’t always particular about where they put trees.

While there’s plenty of truly deforested land in need of reforestation, grasslands offer an appealing place to plant trees precisely because they appear empty and available. Several global assessments have also suggested that grasslands could support more trees. For example, in 2014, the Washington, D.C.–based World Resources Institute (WRI) posted an online map that classified many grassy ecosystems, including parts of the African Serengeti, as suitable for forest restoration. Likewise, the 2019 study estimated that, of all the world’s biomes, tropical grasslands held the greatest potential for tree-carbon storage.

Veldman, Bond, and others have pointed out that adding trees to old-growth grasslands is ecologically inappropriate. But neither the WRI nor the scientists behind the 2019 study have amended their products to set aside grassy ecosystems. Thomas Crowther, an ecologist at the Swiss Federal Institute of Technology in Zurich and the senior author of the tree study, says that, in their case, the issue is partly cosmetic: The map presented in the paper highlighted every scrap of land that could support 2 percent or more tree cover, including grasslands that could only accommodate a few scattered trees. He plans to distinguish grassy landscapes more clearly in future work. Crowther also laments that media coverage overwhelmingly cast the study as promoting mass tree planting even though it focused on the potential of natural forest recovery. (He calls that miscommunication “the greatest failure of my career.”)

WRI representatives say that they don’t support planting trees in ancient grasslands, and that the map, which was based on fairly coarse satellite data, is meant to highlight the overall potential of forest landscape restoration, not guide on-the-ground efforts. “What we really need is a global map of natural grasslands,” Katie Reytar, a senior research associate, says.

At the moment, the fervor for tree planting shows little sign of abating, despite the lack of clear guidance on where trees should go. Institutions from grassroots environmental groups to multinational corporations have embraced the movement. There’s even a credit card that promises to plant a tree for every purchase.

To Veldman, the whole enterprise carries a whiff of colonialism: Many of the countries most responsible for climate change are now promoting tree-planting campaigns as a climate solution, primarily in tropical nations and sometimes without regard for local ecosystems or livelihoods. “We have the idea that, you know, these are well-intentioned people who just want to help the tropics get its forest back,” he says, but “they are very well continuing on a legacy that has a really ugly past.”

And in grasslands, the climate benefits aren’t straightforward. Researchers know that protecting and restoring natural forests trap carbon, but they have also identified drawbacks of planting trees in non-forested landscapes. For starters, it can release the carbon held in soils, reduce water supplies, and warm the local environment by replacing light-colored grass with dark, heat-absorbing foliage. In addition, the end product is often a commercial plantation—a monoculture of young, typically nonnative trees that offer few ecological benefits and store far less carbon than natural forests. (As of early 2019, nearly half of the area pledged for restoration under the Bonn Challenge was slated for commercial tree plantings.)

Scientists say that banking carbon in trees instead of grasslands carries risks too, because trees face increasing threats from drought, pests, and wildfires. Grasslands burn, of course, but the soil and its carbon remain mostly untouched by fire, and rapid regrowth captures most of the carbon released by the burning of biomass. In fact, grassland fires might actually store additional carbon by turning a fraction of the plant matter into charcoal, which likely locks up the element for centuries. One recent analysis based on global climate models estimated that, in the long run, grasslands and savannas may save more carbon through fire than forests lose.

Grasslands store less carbon per acre than forests, on average, but in a volatile climate, they can often store it longer. “That’s what we need to really get our minds wrapped around,” says Benjamin Houlton, a climate scientist and a dean at Cornell University. It’s “the tortoise-and-the-hare sort of thing.”

a woman stands outside her car with the door open and her hands on the window
Nicole Rosmarino on SPLT land (Trent Davis Bailey for The Atlantic)

Deep in the short-grass prairie of southeast Colorado, down miles of poorly marked dirt roads, a compound of buildings sits perched on the edge of a curving mesa dotted with juniper. I arrive to find Nicole Rosmarino, the executive director of the Southern Plains Land Trust, picking up the remains of a dilapidated yurt that was destroyed in a recent windstorm. This is the heart of Dust Bowl country, and traces of old homesteads still dot what has become the Heartland Ranch Nature Preserve. Now, among other purposes, the ranch is a place to corral carbon.

Heartland sprawls across nearly 70 square miles of native grassland. Rosmarino and her partner, preserve manager Jay Tutchton, live on it alongside Heartland’s prairie dogs, pronghorn, birds, and butterflies. SPLT (pronounced “split”) has also introduced an assortment of other animals, including two herds of bison, a posse of longhorn cattle, a band of wild horses, a pace of donkeys, a few wayward cows, and the couple’s dog, cat, and two parrots. (One of the bison herds is made up of genetically “pure” animals that are allowed to reproduce, but the rest—even the parrots—are nonbreeding rescues that Rosmarino and Tutchton couldn’t turn away.)

Rosmarino, who has a sun-weathered face and long brown hair, came west from New York to earn a Ph.D. in political science at the University of Colorado Boulder. After graduating, she worked for the nonprofit WildEarth Guardians, pursuing legal protections for endangered species. Eventually, she decided that she wanted to protect a piece of land and the animals living on it. “There’s that famous saying about environmentalism that all the victories are temporary and all the defeats are permanent,” she says, paraphrasing the conservationist David Brower. “Here, all victories are permanent.”

In 1995, Rosmarino visited the Comanche National Grassland, near the Oklahoma border, and it awakened a latent love for the prairie. “There’s something so romantic about these windswept plains,” she says. Soon after, Rosmarino, her sister Bettina, and several others founded SPLT and started buying acreage in this part of the state, focusing on properties with relatively intact prairie.

SPLT uses many financial tools to acquire more land, but one stands out: It is among the first landowners in North America—and the world—to sell carbon credits from grasslands.

Carbon credits are generated by projects that either remove carbon from the air or prevent it from being emitted, and they are purchased by polluters to compensate for carbon emissions elsewhere. They have become a mainstay of mandatory carbon-trading systems, like California’s cap-and-trade program for industrial emitters, where credits sell for about $30 per metric ton of carbon dioxide, and of voluntary carbon markets designed for both companies and individuals, where they typically go for much less. Forest-based credits are common, because trees store large amounts of carbon in an obvious way, but credits from grasslands have lagged. They, too, store ample carbon, but they hide it out of sight.

a landscape of the Colorado prairie
SPLT land (Trent Davis Bailey for The Atlantic)

From SPLT’s compound, Rosmarino leads me to a nearby vantage, where Heartland’s prairie unfurls below us, still clothed in winter gold. It’s a wide, undulating landscape straight out of a Western; I can almost hear the orchestral music swelling. Rosmarino calls my attention to our feet, which stand on a dense mat of blue-green buffalo grass. Though its gnarled blades stand only a few inches tall, its roots burrow down four to six feet. That’s where the carbon is. “I call the short-grass prairie the inverse of the rain forest,” Rosmarino says. In fact, acre for acre, some North American grasslands hold as much carbon in their soils as tropical forests store in vegetation.

But for grasslands to help stop climate change, they have to remain grasslands. Globally, exhausted soils and rising crop prices have driven farmers to plow ever more land, releasing much of the carbon in grassland soils. Protecting grasslands thus offers a significant and relatively cheap climate solution, particularly in places with large, threatened grasslands like the U.S. There’s growing support for it here, including the expected introduction of a North American Grasslands Conservation Act, but until recently, the only financial incentives were a smattering of tax breaks and payments from government conservation programs. Now, carbon credits have joined the list.

In 2016, with support from the Environmental Defense Fund, SPLT helped pilot a grassland offset protocol developed by the nonprofit Climate Action Reserve. Under the protocol, SPLT must protect the land from plowing for at least 100 years after issuing its last credits and monitor the condition of the grassland at least once every six years.

As of 2022, SPLT’s carbon-credit sales have brought in approximately $1.2 million and sequester more than 15,000 metric tons of carbon dioxide per year—about as much as burning 16 million pounds of coal emits. (Landowners can sell credits annually for up to 50 years, since that’s how long a converted grassland typically releases carbon.) Companies like Microsoft, Stonyfield Organic, and Vail Resorts have bought SPLT’s credits. “Carbon has been a big deal for us,” Rosmarino says, adding that “we’re gonna use all those dollars to preserve more grasslands.”

Conservation groups aren’t the only ones interested in selling carbon credits. The Lower Brule Sioux Tribe, which has been buying back and restoring ancestral lands in South Dakota, is working with the National Indian Carbon Coalition to develop its own grassland carbon project. “I remember having this ‘Aha!’ moment, like, ‘We don’t have to plant trees to help with climate change,’” says Shaun Grassel, a wildlife biologist with the tribe. “We can just keep restoring grasslands.”

Credits have also found their way to working grasslands like the May Ranch, a family cattle operation about an hour from the Heartland preserve. Cows shoulder a lot of blame for climate change; livestock account for about 14 percent of human-caused greenhouse-gas emissions. But in the Great Plains and elsewhere, ranching is one of the few economic forces keeping grasslands intact, Dallas May, the ranch’s gentle-mannered patriarch, says. “If it wasn’t for cattle, the place you’re looking at today and all the wildlife species and the wildlife habitat we have would’ve been gone decades ago,” he told me when I stopped by. Black cows browsed across the prairie, sharing the land with prairie dogs, burrowing owls, and beavers.

Numerous independent audits and conservation awards attest to the excellent ecological condition of the Mays’ land, as does the decision by Colorado Parks and Wildlife to reintroduce endangered black-footed ferrets here in 2021. The property shows that ranching can be compatible with grassland preservation; the challenge is making it profitable, too. May’s family runs roughly half the cattle that their 15,500 acres of grassland could support, leaving plenty of room for native wildlife. To compensate for the foregone income, May and his family rely on carbon credits and a number of other environmental incentives, including a bird-friendly certification from the Audubon Society. He’s heard from more and more ranchers who want to steward the environment while also raising cattle. “It’s not all or none,” May said. “You can do both.”

The credits sold by SPLT and the May Ranch simply promise to keep grasslands as they are. But scientists and entrepreneurs also hope to boost the carbon-trapping capacity of grassland soils. Promising techniques include spreading compost and planting a diversity of species when restoring prairies. Ranchers and investors have also expressed keen interest in the potential benefits of better grazing practices, although estimates of their impact range wildly, from modest to world-changing (the most bullish claims suggest that it could completely reverse climate change). Jonathan Sanderman, a soil scientist at the Woodwell Climate Research Center, says that while there are plenty of reasons to improve livestock management, “the jury is just totally out on how much we can actually change carbon levels.”

Carbon markets aren’t waiting for a verdict. A recent report by the nonprofit Ecosystem Marketplace, which tracks voluntary markets, found a 7,200 percent increase in grassland- and rangeland-related credit sales between 2020 and 2021—a trend that makes Sanderman nervous. “There is a large, growing unease in the scientific community about how fast this is moving forward,” he says. The process by which carbon credits are minted and traded is often murky, and the term wild west comes up a lot. (A new billion-dollar climate initiative from the U.S. Department of Agriculture could fund analyses of existing protocols, helping farmers and ranchers participate more effectively in carbon markets.)

The very concept of carbon credits divides climate activists. Proponents argue that credits can help the world reduce emissions quickly and economically. But many critics oppose them on the grounds that they allow polluters to keep emitting. Credits also suffer from problems like leakage—where preventing emissions in one location simply increases them elsewhere—and have been criticized for exacerbating environmental injustices. In some cases, creditors claim to protect carbon that was never even at risk of release. (The Climate Action Reserve’s protocol requires evidence that a grassland actually faces the threat of conversion, and sets aside a portion of every project’s credits to compensate for leakage.)

To many environmentalists and observers, using income from credits to fund conservation represents a virtuous cycle, but to Veldman, it looks like a twisted bargain. “I feel like we’re just stuck in this scenario where everything has to be economically justified,” he says, “and basically, the only mechanism is to get carbon-polluting industries and companies to pay for conservation, to, you know, atone for their sins.”

He and other scientists also worry that focusing too heavily on carbon obscures the many other benefits of grasslands, like storing and filtering water, cooling the planet with their reflective color, and providing resilient habitat to humans and other species. Grasslands evolved to survive and even thrive on wildfires and extreme weather, so they’re relatively well prepared for a future under climate change. Grassland residents are remarkably flexible too. Little bluestem, a widespread prairie grass, grows from Mexico to Canada, and bison can tolerate temperatures ranging from –40 to 120 degrees Fahrenheit. As Margaret Torn, a biogeochemist at Lawrence Berkeley National Laboratory, puts it, grasslands are “bring-it-on landscapes” that offer a measure of stability in an unpredictable world.

A buffalo runs across the Colorado prairie
Buffalo on SPLT land (Trent Davis Bailey for The Atlantic)

On my last day in Colorado, Rosmarino is busy with meetings, but she agrees to let me explore another SPLT preserve, called Raven’s Nest. I wind my way there on empty roads through a mosaic of native grasslands, plowed fields, and feedlots before finally arriving at the designated GPS point. (The preserves are unmarked except for a few generic signs banning hunting and unauthorized entry.) I park on a rise and step out to take in the landscape around me.

Early white visitors used words like barren and desolate to describe the plains, and maps once labeled the region the Great American Desert. Flat and uniform, concerned with their own internal and mostly subterranean affairs, grasslands make little effort to impress us. Their transformations from brown to green, dull to flamboyant, follow the rhythms of rain and fire, not the predictable march of the seasons. Caught on the wrong day, they can be hard to love.

Rosmarino attributes these missed connections to a refusal to “meet the prairie on its own terms.” And I am guilty of this too. After months of reporting and weeks of touring grasslands, I knew a lot about their ecology, but still hadn’t really felt their power.

I walk down the road and turn off onto an overgrown path leading into a broad bowl of prairie. Without trees, my sense of distance crumples, and soon, the rental car has shrunk to a blue speck. There are no fences in sight. The only signs of humans are a few abandoned water tanks and a far-off cell tower. It’s one thing to see a grassland from a car or a roadside, I realize, and quite another to experience it alone and on foot.

Once I’ve immersed myself, I discover a rustling, vibrating, three-dimensional world. The wind whips my face as a pronghorn bounds across the path, then turns to watch me from a safe remove. Cloud shadows tumble over the rolling terrain, alternately conjuring awe and dread. I finally understand that the essence of the prairie is inseparable from its scale—which is increasingly difficult to experience and exceptionally hard to communicate. (When I get home and look at my photos, I am deeply underwhelmed.)

At last, I have an inkling of what Veldman felt at Nash, and what Rosmarino means when she says that “these landscapes will make your heart sing.” I stand knee-deep in the dancing blue grama and sand dropseed listening to grasshoppers buzz. A meadowlark trills. Prairie dogs skitter between burrows, chirping in alarm. I spy a train on the horizon, so far away it looks like a caterpillar crawling along the ground. It takes forever to inch out of view.

This Atlantic Planet story was supported by the HHMI Department of Science Education. Reporting was also supported in part by a Knight Science Journalism Project Fellowship at MIT.

This story originally misstated the amount of coal that would emit 15,000 metric tons of carbon dioxide, if burned.