In the United States, there is famously little consensus on the topic of climate change. But among the community most concerned about it, certain convictions are widely shared: Fossil fuel emissions deserve nearly all the blame for warming our planet. Meat—especially from flatulent cattle—is an environmental scourge. The Koch brothers, with their campaigns against solar power and cap-and-trade legislation, are (to avoid a less printable word) jerks. And we are probably all doomed.
But over the past few years, a new strain of environmental thinking has begun to challenge nearly all of these tenets. This growing movement includes climate activists, scientists, and also farmers, who play a key role. Many of them would agree with mainstream environmentalists about the Koch brothers. But they argue that the way we’ve been thinking about climate has been, if not all wrong, at least woefully incomplete.
The core premise of their thinking is a belief in the overlooked importance of soil. Carbon, harmful at current levels in our air and water, is essential in the ground, where it makes soil rich and fertile. Our greenhouse-gas problem, they argue, began long before we realize, with agricultural mismanagement and other disruptions of land deep in human history, and solving it depends on restoring our soil to the point where it pulls immense amounts of carbon out of the atmosphere—possibly enough to reverse the effects of industrial emissions.
Throughout the country and abroad, farmers and rangers have begun experimenting with innovative ways of planting crops and grazing animals that are intended to revitalize the soil. The best known is a particular method of raising livestock devised by biologist Allan Savory, born in what is now Zimbabwe, who offers a vision of land management that would send cows grazing across the American plains, emulating the ancient herds of ruminants that once trampled and enriched grasslands.
The movement has spawned a number of advocacy organizations, including the Soil Carbon Coalition, an Oregon-based group whose motto is “Put the carbon back where it belongs.” Scientists have been studying the carbon storage capacity of soil to determine what is possible. And enthusiastically chronicling all of these developments is a small cottage industry of recent and forthcoming books: “The Soil Will Save Us,” by Kristin Ohlson; “Cows Save the Planet,” by Judith Schwartz; “Grass, Soil, Hope,” by Courtney White. All of them are characterized by an upbeat optimism at odds with the often bleak outlook of the traditional green movement.
“When we’re only talking about reducing fossil fuels, it’s depressing because as individuals we feel helpless,” said Schwartz. “When you start to look at the function of the soil and land, things look very different.”
This optimism can be tremendously seductive, and takes the form of some lavish claims—Savory has said that if his method were widely implemented, we could suck enough carbon out of the air to return atmospheric carbon dioxide to preindustrial levels within a matter of decades. When you see things from the perspective of this movement, the problem seems paradoxically both much bigger than we realized, and much easier to solve.
Though they share goals, and offer largely complementary solutions, these new activists don’t always sit easily alongside the more conventional climate movement. Some complain that the latter focuses too single-mindedly on emissions while paying no more than lip service to other remedies. And they’ve engendered critics who believe that soil doesn’t have close to the carbon-storing capacity that Savory and some advocates claim—and that if the movement gains steam, it could shift the focus dangerously away from the imperative to cut fossil fuel emissions.
Still, even these critics agree that carbon sequestration in soil should be part of the answer. How big a part remains to be seen, but the conversation about climate has begun to change—and the tensions that emerge offer a window into the full scope of how human activity affects the planet, for ill and, potentially, for good.
We may call it dirt, but soil is an enormously complex substance. When healthy, it’s moist, loamy, and black, teeming with living organisms. “The best way to describe it is just envision black cottage cheese,” says Gabe Brown, a North Dakota farmer who has gained renown in agricultural circles for his success in integrating crops and livestock. Much soil, though, bears more of a resemblance to a gray block of parmesan cheese. And the key ingredient that makes the difference—that allows all of that life to thrive—is carbon.
“If you scoop up some earth, you can see if it’s got carbon in it because it’s dark and it’s rich and it’s light, and it’s got many feet of fungal roots and roots of the plants holding it together,” said Adam Sacks, cofounder of Biodiversity for a Livable Climate, a Boston-area-based group that advocates for soil-based carbon storage. “It’s the most complicated ecosystem on earth. We know very little about how it works, but we know how it works when we use it, and when we abuse it.”
And for about 10,000 years, since humanity began practicing agriculture, we’ve been abusing it. Deforestation and plowing disrupt all of those exquisite networks, impoverishing the soil and releasing carbon into the air in the form of carbon dioxide. As far back as the 1950s, scientists were aware that loss of carbon from modern soil was possibly related to climate change.
According to one theory, there’s an additional contributor to the rich historical soil we are losing: animals. In the 1950s and 1960s, Allan Savory was a game ranger in his native Africa, where grasslands were rapidly turning to desert. His job involved closely observing the land and patterns of animal interactions with it, and he noticed that, contrary to conventional game ranger wisdom, clearing land of animals, to allow it to “rest,” did not help it recover; in fact, the land appeared to suffer.
The theory Savory developed, drawing on both agronomical thinkers and folk wisdom, held that wild herds of ruminants—bison, wildebeest, and so forth—displayed a cluster of behaviors that was essential to the health of the land. The animals bunched tightly in herds as a defense against predators. For a few hours or days they would graze on grasses and other plants, which stimulated plant growth; trample the ground underfoot, which left plant residue as cover; and deposit their dung and urine, which acted as fertilizer. Then they would all flee together to a different site, allowing the soil to absorb all those nutrients and the land to recover from the impact, and the process would repeat.
Humans have interrupted that process in various ways—by hunting the animals to extinction, by destroying their habitat, and by raising livestock with a completely different relationship to the land. Savory’s hypothesis was that rangers and farmers could reproduce it by managing livestock to mimic those ancient patterns. Working with pastoralists around the world, he began to implement this approach, which he calls Holistic Planned Grazing. (In a much-viewed TED talk last year, he brandished impressive before-and-after photos of land transformed from barren desert to lush and fertile terrain through these methods.)
His initial theory focused on improving the land, but eventually Savory came to see the soil as a powerful tool for capturing atmospheric carbon, and began to promote his idea as something much bigger: a way to fight climate change. In an e-mail interview, Savory lamented that biodiversity, desertification, and climate change are treated as separate problems. “But they are all one and the same issue—massive environmental disruption caused mainly by agriculture (the production of food and fibre from the world’s land and waters) and by fossil fuel use.” Holistic Planned Grazing, he believes, can help address all of them. (As for methane emissions from cattle, Savory and his supporters argue that they would be much more than offset by the carbon sequestration.)
Carbon sequestration isn’t a new idea—“carbon sinks” have long been considered one way to offset greenhouse gas emissions, whether in the form of new forests or exotic schemes to bury carbon in the ocean. But it has typically been seen as a sort of extra: By all means, plant some trees, but the most salient objective has been to stop burning fossil fuel and transition to clean energy. Savory, while agreeing with the need for that shift, switched the emphasis to capturing carbon—and saw far more promise in it than climate activists had.
Not everyone in the movement buys into Savory’s grazing theories; others focus more on planting patterns and cover crops. But like Savory, the advocates who have latched onto this idea see it as a corrective to the emissions-centric focus of the mainstream environmental movement, which they consider both too narrow and, so far, futile. “I see little hope of emissions reductions,” said Sacks of Biodiversity for a Livable Climate. “They’ve been a complete failure to date.” Seth Itzkan, president of the Somerville-based ecological consultancy Planet-TECH Associates, says: “I don’t want to berate the climate movement, but they also need to be doing something else. And the largest quickest way is ecological restoration and restoration of soils.”
The Savory Institute, founded in 2009, has established 10 Savory Hubs in various countries where people learn, teach, and locally adapt Holistic Planned Grazing. The past few years have seen a flourishing of related activity as well. Peter Donovan of the Soil Carbon Coalition has been traveling on an old school bus around the country trying to measure the carbon content of soil. Dozens of conferences and workshops have been held on the topic of improving soil health; the UN has designated next year the International Year of Soils. USDA scientists are working to understand better how soil works and how we can measure the carbon content.
“I do think that awareness of this dynamic is growing,” said Judith Schwartz, author of the 2013 book “Cows Save the Planet.” “There’s been incredible receptiveness.”
The movement has created some unexpected allies, attracting farmers and ranchers who are not typical environmentalists—indeed, who may not even believe in global warming. Healthy soil both absorbs much more water, meaning less runoff and flooding, and withstands drought better because of the water it retains. Even if soil played no role in sequestering carbon and mitigating climate change, it would help individuals to survive the extreme weather events that are projected to become more common. Soil quality also correlates with nutritional quality in crops and meat.
Gabe Brown, the North Dakota farmer, has implemented Holistic Planned Grazing as well as other techniques, such as cover crops, on his land. He has seen his soil go from dry and gray to black and crumbly, and says scientists who measured the carbon content in his soil found that in places it had tripled in the past 20 years. He says he speaks to other farmers at about 30 conferences and workshops each year. “They’re concerned about organic matter, but they do not think about it in terms of carbon sequestration and what it’s doing for climate change,” he said. “I’m going to catch a lot of flak for saying this: Carbon drives the system. It’s all about carbon.”
For all the optimism of the soil-as-savior movement, and all the promise of isolated local experiments such as Brown’s, it’s far from certain that global soils have anywhere near the carbon-storage capacity we’d need to compensate for emissions.
Rattan Lal, a soil scientist and director of Ohio State University’s Carbon Management and Sequestration Center, says that, based on extrapolation of his measurements, the earth’s soil could theoretically absorb about three gigatons of carbon per year. Currently, he says, the atmosphere retains about 4.3 gigatons of emissions during the same period. “The problem is that this three gigatons is the maximum potential,” he said. “And then it cannot go on forever.”
According to Lal, in about 50 years, the soil would be saturated. In effect, he sees this approach as a way to buy us some time to shift to alternative energy sources. (Lal believes Savory’s method is an effective way to increase the soil’s carbon content, but focuses on other methods himself, such as mulch farming, conservation tillage, agroforestry, diverse cropping systems, and cover crops.)
There is also debate about the effectiveness of Savory’s specific approach. David Briske, professor of ecosystem science and management at Texas A&M University, agrees that fighting global warming by capturing carbon in soil “is clearly a valid concept,” but calls Savory’s more ambitious claims “highly misleading,” and believes Savory is “using carbon sequestration as a way to garner support for his grazing method.”
Others cite other numbers that suggest the soil has a higher maximum capacity, and believe that we can continue adding carbon to the soil, and even build new soil, far more than science has recognized. Assessing carbon content at the global scale is tricky because, among other reasons, there are different kinds of carbon, organic and inorganic. Kristine Nichols, a USDA scientist who studies soil, says that over time, organic carbon, which is more prone to cycling in and out of the air, can be stored, with proper management, for longer persiods of time—and over the very long term, some of this will form new fossil fuels. “There’s a tremendous amount of potential for the soil to absorb carbon,” said Nichols. “The potential in that soil environment is greater than the amount of CO2 that’s in the atmosphere…there’s more carbon that can be in that soil environment than we ever thought possible.”
In part, the argument about soil has turned into a tug-of-war about data, which on a subject this large and complex is often inconclusive or missing. “There are things we know we’re doing, but the data is not there,” acknowledged Daniela Ibarra-Howell, CEO and cofounder of the Savory Institute, which has begun to systematically gather information about the carbon content at the Savory Hubs.
Beyond data, there are questions of competing priorities. The climate movement has limited resources, and it has its hands full with emissions control: reducing what we pump into the atmosphere, finding long-term solutions that don’t use fossil fuels, and persuading governments to invest more money in regulating and developing these technologies. In this framework, even a well-intentioned movement that offers a shiny but uncertain promise is potentially a risky distraction.
“I think it might detract from the major issues of reducing fossil fuel emissions,” said Pushker Kharecha, a research scientist at Columbia’s Earth Institute, referring to Savory’s approach. “A heavy over-emphasis on land use as a panacea does detract from the more fundamental issue of shifting our energy infrastructure to clean energy.”
It’s not hard to see the appeal of a movement that promises not only a carbon sponge, but more delicious food, hardier land, and profits for small farmers along the way. Better soil also enhances food security for developing countries. That doesn’t make soil improvement the miracle cure its staunchest advocates claim. But given the magnitude of the challenge, there’s sense in the message that we can make the most of the resources we already have underfoot—even if, as we might have guessed in the first place, the world will not be saved by cows alone.
Source: The Boston Globe