In reports of rising CO2 levels, it's easy to get the impression that the carbon-and-oxygen molecule is a kind of toxin, some alien vapor coughed up by a century-plus of heedless industrialism now coming back to haunt us. But on closer inspection, it seems that the problem isn't the carbon itself—it's that there's too much in the air and not enough in the ground.

When we consider our CO2 predicament, we tend to fault our love affair with the car and the fruits of industry. But the greater culprit has been agriculture: since about 1850, twice as much atmospheric CO2 has derived from farming practices as from the burning of fossil fuels (the roles crossed around 1970). Over the past 150 years, between 50 and 80 percent of organic carbon in the topsoil has vanished into the air, and seven tons of carbon-banking topsoil have been lost for every ton of grain produced.

So, how do we get that carbon out of the air and back into the soil? Some suggest placing calcium carbonate or charcoal (aka "biochar") directly into agricultural soil (see "Black Is the New Green," Conservation, Summer 2010). But a growing number of soil and agricultural scientists are also discussing a low-tech, counterintuitive approach to the problem that depends on a group of unlikely heroes: cows. The catalyst for reducing CO2 and restoring soil function and fertility, they say, is bringing back the roving, grazing animals who used to wander the world's grasslands. The natural processes that take place in the digestive system and under the hooves of ruminants might be the key to turning deserts back into grasslands and reversing climate change. In other words, a climate-friendly future might look less like a geo-engineered landscape and more like, well, "Home on the Range."

Perhaps the most steadfast advocate of this future is Allan Savory. A 76-year-old native of Zimbabwe, Savory has the relaxed, weathered look of a lifelong outdoorsman more attuned to the etiquette of the bush than that of the boardroom. In the 1960s, as a young wildlife biologist in what was then called Southern Rhodesia, he noticed that, when livestock were removed from land set aside for future national parks, "almost immediately, these wonderful areas suffered severe loss of both plant and animal species." Cattle, he began to realize, could play—if properly managed—the crucial role in grassland ecology that used to be occupied by herds of wild herbivores. They could help prevent and even reverse land degradation and the desertification of grasslands, combating in the process both human poverty and the disappearance of wildlife. Over the course of several eventful decades—during which he was elected to the parliament, served as an opposition leader against Rhodesia's white-minority government, and spent four years in political exile—Savory developed a program to put these ideas into action.

Savory's singular insight is that grasslands and herbivores evolved in lockstep with one another. This means that to be healthy, grasses need to be grazed. Animals eat plants and stimulate their growth; they cycle dead plants back to the surface, which allows sunlight to reach the low-growing parts; their waste provides fertilizer. When a predator—say, a lion—comes into this bucolic scene, the animals bunch together and flee as a herd, their hooves breaking up and aerating the soil. Then, on a new patch of land, the process starts again. This way all plants get nibbled, but none are overgrazed. And none are overrested, which leads to accumulated dead plant material that blocks sunlight and hinders new growth.

To Savory, the conventional wisdom that grazing degrades the land is an oversimplification; what matters is how livestock are applied. He readily acknowledges that the confined animal feeding operations usually associated with large-scale cattle ranching are problematic, and he opposes cramming cattle into lots on industrial farms. But he contends that this degradation by overgrazing is a matter of time rather than numbers; he's fond of saying that one cow continually foraging in one spot will do damage where a hundred moving from place to place will not. Where feedlots will harm the land, he claims, herds of well-managed grazing animals, nibbling on native grasses and roaming from spot to spot to elude predators and seek fresh pasture—managed in a way that mimics their behavior in the wild—will restore the land's natural dynamics.

For years, many in the academic and ranching establishment dismissed Savory as a gadfly, someone outside the agricultural and scholarly mainstream who did his research in the open air and presented his counterintuitive conclusions in unscientific language. Undeterred, Savory continued to refine his framework and expand his training programs, and today his successes have become hard to ignore. Farmers, ranchers, and other land stewards who have attended his training programs have brought land back from the brink across Africa, Australia, New Zealand, and the U.S. In 2010, his Zimbabwe nonprofit, the Africa Centre for Holistic Management, received a $4.8 million grant from the United States Agency for International Development (USAID) to expand its work in Africa. More recently, Savory won the 2010 Buckminster Fuller Challenge prize, a prestigious award that supports a proposal with "significant potential to solve humanity's most pressing problems."

The centerpiece of Savory's work is the 2,630-hectare Dimbangombe Ranch in northwestern Zimbabwe near Victoria Falls, home to his Africa Centre for Holistic Management. In the hot, dry, depleted landscape of this region, "the rains are not what they used to be" is a frequent refrain. But Dimbangombe looks as though it's been uniquely favored by the rain gods. It has lush, varied grasses, flowing rivers and streams, and thriving livestock—some four times the number of neighboring ranches. Thanks to the renewed flow of the Dimbangombe River, elephant herds no longer have to travel to pools but can water on the river. Women who used to walk as much as five kilometers daily for water now have it available in their communities. Dimbangombe has become productive and vibrant while its neighbors, and similar environments around the globe, are turning to desert. How? "Two things: we brought in increased cattle numbers with holistic planned grazing, and [we] minimized the fires," says Savory.

The Dimbangombe experiment began in 1992, when Savory donated land he had purchased in the 1970s to develop the ranch as a nonprofit demonstration site. (A larger parcel of land owned by Savory is now the Kazuma Pan National Park, part of the five-nation Transfrontier Conservation Area.) In the early days, when funds were tight, he generally camped on the land. Even now, Savory and his wife, Jody Butterfield, director of development at the Centre, live in a mud-and-thatch hut on the riverbank. Savory says this is "not a hardship, as I have lived much of my life like this and simply enjoy living amongst Africa's big game and wildlife more than in a house."

As the ranch grew, Savory and his colleagues ran cattle on the land, beginning with what they could afford. "We also invited farmers in the neighboring community who had run out of feed to add their cattle to the herd," Butterfield says. "They needed to keep their animals alive, and we needed numbers to restore the land. Sometimes we had 600 cattle, sometimes 300. We kept them constantly on the move."

The other key intervention, creating firebreaks, put a stop to uncontrolled clearing fires and to fires set by animal poachers, who sometimes torch the grass to obliterate their tracks. These woodland and grassland fires, Butterfield says, can go on for hundreds of miles. "Africa is burning to death, many parts of it," adds Savory. "809 million hectares of grassland are burned annually. The reason we're burning them is that there are not enough herbivores to keep the grass alive." What he means is that fires are used to clear decaying plant material and promote fresh growth—functions that grazing herbivores are uniquely equipped to do better. Savory contends that planned grassland fires cause numerous problems, including leaving exposed soil (which oxidizes and leads to runoff) and promoting fire-dependent plant species over the more diverse and soil-enriching grasses that animals eat. Another result of grassland fires is added atmospheric CO2. In one hour, says Savory, a half-hectare fire pumps as much CO2 and other pollutants into the air as 4,000 car trips.

With these strategies applied in Dimbangombe, "each year things got better and better," Butterfield recalls. "Gradually over the years, the grass was thickening up and the ground would close in, covered with plants. Then we started noticing, 'oh, the wetlands are expanding along the upper reaches of the river.' We started seeing sedges and reeds growing many yards up from the riverbanks and could now see a huge swath that was becoming wetland. In the past few years especially, it's been quite dramatic."

Allan Savory, in his laconic way, makes it all sound elementary. "All we've done really is make the rainfall more effective." Parched and unproductive regions throughout the world are not necessarily suffering from less rain, he says. The problem is that the water leaves too quickly, through runoff or evaporation from bare soil. Water needs to infiltrate and remain in the soil, entering the stream and river system, and leave only through plant growth or by entering aquifers. "All of this we're doing with the livestock," says Savory. "We keep operating on sound scientific principle, enhancing the organic matter and porosity of the soil, and keeping water in the system."

The key to improving water conditions lies in the carbon cycle. In Savory's words, "The fate of carbon and water tend to follow each other." Carbon in the soil acts as a giant sponge, keeping rain water in the ground rather than allowing it to stream off. "Every one-percent increase in soil carbon holds an additional 60,000 gallons of water per acre," says Steven Apfelbaum, founder of Applied Ecological Services, Inc., a landscape-restoration company based in Brodhead, Wisconsin. "This means reduced erosion and sedimentation and downstream flooding."

Desertification—and associated problems such as flooding, wildfires, and water shortages—can be seen as a symptom of the carbon cycle gone awry, says Savory. In the same way that plants need animals, as seen in the relationship between ruminants and grasses, soil needs plants. "For soil to form, it needs to be living, and to be living, soil needs to be covered," says Australian scientist Christine Jones. Without a cover of plants in various stages of growth and decomposition, much of the carbon oxidizes and enters the atmosphere as CO2.

So soil carbon has huge implications for climate change. Rattan Lal, Distinguished Professor of soil science in the School of Environment and Natural Resources at Ohio State University, estimates that soil-carbon restoration can potentially store about one billion tons of atmospheric carbon per year. This means that the soil could effectively offset around one-third of human-generated emissions annually absorbed in the atmosphere. Building soil carbon would also enhance food production; and, because carbon-rich soil holds significantly more water than its dried-out counterpart, it would help to secure watersheds and protect against flooding and drought.

"I teach my students that the goal [in agriculture] is to produce a positive carbon budget: the amount of carbon returned to the land should be more than the amount that is leaving the land," says Lal, noting that soil-carbon levels worldwide are dropping wherever extractive farming is practiced. He says much of Africa, Asia, and parts of Central Asia have soils which contain as little as 0.1 percent carbon, whereas the minimum for functionality is 1.5 percent to two percent. Savory's model, he says, offers valuable insight on how to increase soil-carbon levels and therefore increase fertility.

Despite his evident successes, Savory still occupies an equivocal position in the ranching and agricultural world. His methods have stirred surprising passions not only among farmers and ranchers who have used them with success but also among skeptics and detractors, who have called them "hocus-pocus" and "more religious belief than science." Savory himself has been likened to "the Wizard of Oz"—big on fanfare, empty of real ideas.

This may be as much about delivery as about science. Part of the resistance stems from the far-reaching nature of Savory's claims. Some skeptics who might be receptive to his ideas in the realm of animal husbandry balk at proclamations of a total "paradigm shift" with the ambition to rethink agriculture from the ground up. Others associate the language of his programs—"holistic management," "holistic decision-making"—with a New Age sensibility that seems unscientific. Then there's the inevitable resistance to new ideas, especially ones that bypass established business and technological systems. Apfelbaum says that most practitioners who balk at holistic management "simply are skeptical of change from their status quo and 'the way ranching has always been done.'"

Another factor is that Savory's system is less a recipe than a way of understanding the land. This means that even when his methods work, it can be hard to know exactly what prompts success. George Wuerthner, a photographer and author who has written extensively about western landscapes, says, "One thing Savory's methodology does is make ranchers pay more attention to what they're doing on the land. That may help in and of itself, regardless of the ecological assertions, which I don't buy."

Some ecologists are also concerned by the impression that Savory promotes "bring in the cows" as a one-size-fits-all panacea. These critics often conflate planned holistic grazing, which involves continual monitoring and adjustment, with more formulaic grazing strategies such as "short intensive grazing" (scheduled on-off grazing cycles) and, the latest craze, "mob grazing" (very large herds moved several times a day). "Grasslands are tremendously diverse," says Jason Neff, associate professor of geological sciences at the University of Colorado at Boulder. "Some have been grazed for thousands of years, and some not at all. You need to look at the cultural and ecological history of a place. I work in semi-arid lands that are sensitive to grazing. For example, the Colorado plateau—increase grazing out there, and the land will suffer."

Savory himself does not claim that his methods are equally applicable everywhere. They must take the specific local ecology into account and are best suited to what he calls "brittle environments," parts of the world that are dry most of the year, with seasonal rainfall. These areas are less forgiving of land management problems than are more temperate regions: "If, say, England had the climate of Israel, it would have desertified," he says. "The dry periods show up the faults [in how the land is managed]." But given that the grassland, rangeland, and savanna—where holistic management is most successful—cover two-thirds of the world's landmass, the potential of his ideas is still vast.

The strength of Savory's ideas may derive from the fact that he brings an outsider's eye—even a poet's eye—to environmental cycles. (Nature writer Gretel Ehrlich, who has spent time with Savory in the African bush, calls him "the best observer of wildlife I've ever met.") Seen from a holistic perspective, the secret of Dimbangombe is no secret. It simply required looking back to the land's prehistory—and learning a management principle from no management at all.