![\"\"](\"https:\/\/worldcampaign.net\/wp-content\/uploads\/2018\/04\/P6EM_fFootage-4.pct_-300x237.jpg\")
<\/p>\nWhen John Wick and his wife, Peggy Rathmann, bought their ranch in Marin County, Calif., in 1998, it was mostly because they needed more space. Rathmann is an acclaimed children\u2019s book author \u2014 \u201cOfficer Buckle and Gloria\u201d won a Caldecott Medal in 1996 \u2014 and their apartment in San Francisco had become cluttered with her illustrations. They picked out the 540-acre ranch in Nicasio mostly for its large barn, which they planned to remake into a spacious studio. Wick, a former construction foreman \u2014 they met when he oversaw a renovation of her bathroom \u2014 was eager to tackle the project. He knew the area well, having grown up one town away, in Woodacre, where he had what he describes as a \u201cfree-range\u201d childhood: little supervision and lots of biking, rope-swinging and playing in the area\u2019s fields and glens.<\/p>\n
The couple quickly settled into their bucolic new surroundings. Wick began fixing leaks in the barn. Rathmann loved watching the many animals, including ravens, deer and the occasional gopher, from the large porch. She even trained the resident towhees, small brown birds, to eat seed from her hand. So smitten were they with the wildlife, in fact, that they decided to return their ranch to a wilder state. For nearly a century, this had been dairy country, and the rounded, coastal hills were terraced from decades of grazing. Wick and Rathmann would often come home and find, to their annoyance, cows standing on their porch. The first step they took toward what they imagined would be a more pristine state was to revoke the access enjoyed by the rancher whose cows wandered their property.<\/p>\n
Within months of the herd\u2019s departure, the landscape began to change. Brush encroached on meadow. Dried-out, uneaten grass hindered new growth. A mysterious disease struck their oak trees. The land seemed to be losing its vitality. \u201cOur vision of wilderness was failing,\u201d Wick told me recently. \u201cOur na\u00efve idea was not working out so well.\u201d<\/p>\n
Wick was especially bothered by the advance of a prickly, yellow-flowered invasive weed called the woolly distaff thistle. He pulled it, mowed it, doused it with herbicides. But the distaff kept moving into what had been pasture. He thought about renting goats to eat the weeds and brush, but they were too expensive. He even considered introducing wild elk, but the bureaucratic hurdles seemed too onerous.<\/p>\n
Then Wick and Rathmann met a rangeland ecologist named Jeff Creque. Instead of fighting against what you dislike, Creque suggested, focus on cultivating what you want. Squeeze out weeds by fostering conditions that favor grasses. Creque, who spent 25 years as an organic-pear-and-apple farmer in Northern California before earning a Ph.D. in rangeland ecology, also recommended that they bring back the cows. Grasslands and grazing animals, he pointed out, had evolved together. Unlike trees, grasses don\u2019t shed their leaves at the end of the growing season; they depend on animals for defoliation and the recycling of nutrients. The manure and urine from grazing animals fuels healthy growth. If done right, Creque said, grazing could be restorative.<\/p>\n
This view ran counter to a lot of conservationist thought, as well as a great deal of evidence. Grazing has been blamed for turning vast swaths of the world into deserts. But from Creque\u2019s perspective, how you graze makes all the difference. If the ruminants move like wild buffalo, in dense herds, never staying in one place for too long, the land benefits from the momentary disturbance. If you simply let them loose and then round them up a few months later \u2014 often called the \u201cColumbus method\u201d \u2014 your land is more likely to end up hard-packed and barren.<\/p>\n
Wick was persuaded. He began preparing for the cows\u2019 return. He dug wells for water, pounded in steel posts and strung nonbarbed wire. He even bought a molasses lick to supplement the animals\u2019 diet of dry thatch. He didn\u2019t want medicated livestock excreting drugs that might harm the worms and insects living in his soil \u2014 most cows are routinely dewormed \u2014 so he tracked down a herd of untreated cows and borrowed them for the summer of 2005.<\/p>\n<\/div>\n<\/div>\n
The cows beat back the encroaching brush. Within weeks of their arrival, new and different kinds of grass began sprouting. Shallow-rooted annuals, which die once they\u2019re chewed on, gave way to deep-rooted perennials, which can recover after moderate grazing. By summer\u2019s end, the cows, which had arrived shaggy and wild-eyed after a winter spent near the sea, were fat with shiny coats. When Wick returned the herd to its owner that fall, collectively it had gained about 50,000 pounds. Wick needed to take an extra trip with his trailer to cart the cows away. That struck him as remarkable. The land seemed richer than before, the grass lusher. Meadowlarks and other animals were more abundant. Where had that additional truckload of animal flesh come from?<\/p>\n
Creque had an answer for him. The carbohydrates that fattened the cows had come from the atmosphere, by way of the grass they ate. Grasses, he liked to say, were like straws sipping carbon from the air, bringing it back to earth. Creque\u2019s quiet observation stuck with Wick and Rathmann. It clearly illustrated a concept that Creque had repeatedly tried to explain to them: Carbon, the building block of life, was constantly flowing from atmosphere to plants into animals and then back into the atmosphere. And it hinted at something that Wick and Rathmann had yet to consider: Plants could be deliberately used to pull carbon out of the sky.<\/p>\n
Climate change often <\/strong>evokes images of smokestacks, and for good reason: The single largest source of carbon emissions related to human activity is heat and power generation, which accounts for about one-quarter of the carbon we put into the atmosphere. Often overlooked, though, is how we use land, which contributes almost as much. The erosion and degradation of soil caused by plowing, intense grazing and clear-cutting has played a significant role in the atmospheric accumulation of heat-trapping gases. The process is an ancient one. Ice cores from Greenland, which contain air samples trapped thousands of years ago, reveal increases in greenhouse gases that correspond with the rise of farming in Mesopotamia.<\/p>\n Since the start of the Industrial Revolution, agricultural practices and animal husbandry have released an estimated 135 gigatons \u2014 135 billion metric tons \u2014 of carbon into the atmosphere, according to Rattan Lal, a soil scientist at Ohio State University. Even at current rates, that\u2019s more than a decade\u2019s worth of carbon dioxide emissions from all human sources. The world is warming not only because fossil fuels are being burned, but also because soils, forests and wetlands are being ravaged.<\/p>\n In recent years, some scientists have begun to ask whether we can put some of that carbon back into the soil and into living ecosystems, like grasslands and forests. This notion, known as carbon farming, has gained traction as it becomes clear that simply reducing emissions will not sufficiently limit global warming. According to the 2014 report by the Intergovernmental Panel on Climate Change, an authority on climate science that operates under the auspices of the United Nations, humankind also needs to remove some of the carbon already in the atmosphere to avoid, say, the collapse of polar glaciers and the inundation of coastal cities worldwide. \u201cWe can\u2019t just reduce emissions,\u201d Keith Paustian, a soil scientist at Colorado State University and an author of an earlier I.P.C.C. report, told me. \u201cIt\u2019s all hands on deck. Things like soil and land use \u2014 everything is important.\u201d<\/p>\n Some of the proposed methods to begin this drawdown include scrubbing the air with great air-conditioner-like machines; fertilizing the oceans with iron dust to prompt algal blooms that, when they die, carry captured carbon to the bottom of the sea; capturing and storing the carbon dioxide that results when energy is produced by burning trees and other plants that removed carbon from the atmosphere during their growth; and crushing and spreading certain types of rock, like basalt, that naturally absorb atmospheric carbon. None of these approaches are yet proved or affordable at the scale needed to make a difference. The most obvious hurdle is the additional energy some of them require, which, unless it comes from a free, renewable source, adds more costs.<\/p>\n Plants, however, remove carbon from the atmosphere already, require no additional power and grow essentially free. During photosynthesis they harness the sun\u2019s energy to make sugars by combining hydrogen atoms (acquired from water molecules) with carbon atoms (from carbon dioxide), while emitting oxygen as a byproduct. (Lest we forget, the fossil fuels that now power civilization contain carbon removed from the air during photosynthesis millions of years ago.) Every spring, as the Northern Hemisphere greens, the concentration of carbon dioxide in the atmosphere dips, before rising again the following fall and winter as foliage dies. Some scientists describe this fluctuation as the earth breathing.<\/p>\n Nearly all the carbon that enters the biosphere is captured during photosynthesis, and as it moves through life\u2019s web, every organism takes a cut for its own energy needs, releasing carbon dioxide as exhaust. This circular voyage is the short-term carbon cycle. Carbon farming seeks to interfere with this cycle, slowing the release of carbon back into the atmosphere. The practice is often conceptualized and discussed in terms of storing carbon, but really the idea is to change the flow of carbon so that, for a time at least, the carbon leaving a given ecosystem is less than the carbon entering it.<\/p>\n Dozens of land-management practices are thought to achieve this feat. Planting or restoring forests, for one: Trees lock up carbon in woody material. Another is adding biochar, a charcoal made from heated organic material, directly to soil. Or restoring certain wetlands that have an immense capacity to hold carbon. (Coal beds are the fossilized remains of ancient marshes and peatlands.)<\/p>\n More than one-third of earth\u2019s ice-free surface is devoted to agriculture, meaning that much of it is already managed intensively. Carbon farming\u2019s fundamental conceit is that if we change how we treat this land, we could turn huge areas of the earth\u2019s surface into a carbon sponge. Instead of relying solely on technology to remove greenhouse gases from the air, we could harness an ancient and natural process, photosynthesis, to pump carbon into what\u2019s called the pedosphere, the thin skin of living soil at the earth\u2019s surface. If adopted widely enough, such practices could, in theory, begin to remove billions of tons of carbon dioxide from the atmosphere, nudging us toward a less perilous climate trajectory than our current one.<\/p>\n In a 2016 paper, Pete Smith, a soil scientist at the University of Aberdeen in Scotland, and the influential climate scientist James Hansen argued that land-management practices are one of the few affordable options available today for drawing down carbon. \u201cWhat\u2019s surprising to me is that we\u2019ve not done it sooner,\u201d says Smith, who is also a lead author on a recent U.N. report that explores carbon-dioxide-removal technologies. \u201cThis has the potential to make a huge difference.\u201d Otherwise, Hansen told me, we\u2019re leaving the problem to our grandchildren. \u201cThat assumption that somehow young people, and people later this century, are going to figure out how to suck it out of the air \u2014 that\u2019s a pretty big burden to place on them,\u201d he said.<\/p>\n The I.P.C.C. is preparing a special report on climate change and land use, to be finalized in 2019, that will consider in greater detail the potential of sequestering carbon in soil. But for now the biggest international effort to promote carbon farming is a French-led initiative called \u201cfour per 1,000.\u201d The proposal aims to increase the amount of carbon in the soil of crop- and rangelands by 0.4 percent per year through a variety of agricultural and forestry practices. These include agroforestry (growing trees and crops together increases carbon retention), no-till agriculture (plowing causes erosion and carbon loss) and keeping farmland covered (bare dirt bleeds carbon). Doing so, the French argue, could completely halt the buildup of atmospheric carbon dioxide.<\/p>\n Few experts I spoke to think the impact would be quite that grand; Pete Smith, for example, estimates that soil could, at the most, store just 13 percent of annual carbon-dioxide emissions at current levels. \u201cI appreciate that everyone wants to save the planet,\u201d he told me, \u201cbut we shouldn\u2019t fool ourselves that this is all we need to do.\u201d Even so, the four-per-1,000 goal highlights how a relatively small annual increase in soil carbon could, on a large-enough scale, have a substantial impact. Increasing soil carbon could yield other benefits, too: Improvements in soil fertility, water retention and greater crop resilience would help agriculture adapt to a warming world. More soil carbon would also reduce the amount of fertilizer needed, decreasing emissions of the powerful greenhouse gas nitrous oxide, a byproduct of excess nitrogen fertilization. It would be profoundly appropriate if agriculture, whose modern practices have themselves contributed to climate change, could become part of its solution. Farming, responsible for the birth of civilization, could now help save it.<\/p>\n In 2007, at<\/strong> Jeff Creque\u2019s behest, John Wick got in touch with Whendee Silver, an ecologist at the University of California, Berkeley. Letting cows graze on his property had certainly made the land look healthier, he told Silver. But he and Creque wanted to know: Had it put carbon in the ground? And if so, was it possible to measure how much?<\/p>\n<\/div>\n<\/div>\n Silver was skeptical that she could measure what was likely to amount to very small changes in his land\u2019s soil carbon. The endeavor seemed akin to looking for cups of water added to a swimming pool. But she did sketch out a way to arrive at a definitive answer. When Wick offered to underwrite such a study, she warned him that he might not like the results. She wasn\u2019t just going to tell him what he wanted to hear. \u201cThat\u2019s when I knew I had to work with her,\u201d Wick recalls.<\/p>\n Silver agreed to the project, which she began that year. Seeking baseline values for the carbon concentrations in the soil, she and her students collected samples from different rangelands in Marin and Sonoma Counties. The samples with the most carbon, it turned out, came from current and former dairy farms. What distinguished these operations, she learned, was that they often sprayed manure onto their pastures; this was done both to fertilize the land and dispose of waste. Apparently, how soil was treated could very much affect its carbon content \u2014 a surprise. The larger implication was that people could potentially \u201cgrow\u201d soil carbon deliberately.<\/p>\n But how quickly could they do so? Silver found an answer, in part, by looking for nuclear fallout. In the mid-20th century, radioactive carbon isotopes were spewed into the atmosphere as a result of aboveground nuclear tests. Plants around the world absorbed those isotopes during photosynthesis, effectively turning them into a time stamp. Wherever that carbon shows up, it must have arrived there relatively recently. On dairy farms, Silver found the isotopes a full three feet below the surface. This was another surprise. Conventional wisdom holds that it takes perhaps hundreds of years for carbon-rich topsoil to accumulate. On these dairy farms, however, atmospheric carbon had pushed deep into the earth in a matter of decades.<\/p>\n Wick wanted to know if he could deliberately replicate this process on his ranch \u2014 but without manure, which, as it decomposes, can release potent greenhouse gases like methane and nitrous oxide. The former traps about 30 times as much heat as carbon dioxide, the latter 300 times as much. As a carbon-farming tool, manure might be self-defeating.<\/p>\n Jeff Creque, a onetime organic farmer, had a suggestion: Why not use compost? Compost can contain manure, but whereas manure alone can release nitrogen as nitrous oxide, the nitrogen in compost becomes locked up in complex molecules. At least in theory, that limits the escape of a powerful greenhouse gas. In 2008, Wick, Silver and Creque spread several semi trucks full of the stuff, purchased from a composting plant near Sacramento, onto Wick\u2019s ranch and on another ranch in the foothills of the Sierra Nevada. In total, it amounted to about half an inch spread over three acres.<\/p>\n After three years, Wick was disappointed to discover that grazing on its own wasn\u2019t leading to carbon sequestration. In fact, the soil lost carbon in untreated control plots. No one knows precisely why, but grasslands throughout California are bleeding carbon. European settlers introduced shallow-rooted annual grasses to the state, which partly displaced deeper-rooted perennial grasses. So carbon put into the ground long ago by deep-rooted grasses may now be seeping out. That\u2019s what made the treated plots so remarkable. They had the same history and were exposed to the same conditions, but instead of losing carbon, they absorbed it \u2014 at a rate equivalent to nearly 1.5 tons of carbon dioxide per acre per year. That\u2019s roughly equal to your car\u2019s emissions if you drove from Miami to Seattle.<\/p>\n Silver had thought that the compost would simply break down, releasing its carbon back into the atmosphere or, worse, produce nitrous oxide. But those emissions never occurred; moreover, judging by its chemical signature, most of the carbon moving into the soil came from the air, not the compost. The compost appeared to help the plants draw more carbon from the atmosphere than they otherwise would have.<\/p>\n When it comes to mitigating climate change, soil scientists are most interested in what Silver calls occluded carbon \u2014 organic material, often in the form of dead microbes, trapped in clods of dirt. This type of carbon can potentially stay locked away for centuries. (Another carbon type, called labile carbon, continuously cycles among the atmosphere, plants and organisms in the soil.) It was precisely this more durable carbon, Silver discovered, that increased in the treated plots.<\/p>\n Her findings corresponded with a shift in recent decades in scientists\u2019 understanding of how soil carbon forms. Previously they emphasized how dead organic material had to physically work its way into the soil. But the newer model stressed the importance of living plants. Their rootlets are constantly dying, depositing carbon underground, where it\u2019s less likely to go airborne. And perhaps more important, as plants pull carbon from the air, their roots inject some of it into the soil, feeding microorganisms and fungi called mycorrhiza. An estimated 12,000 miles of hyphae, or fungal filaments, are found beneath every square meter of healthy soil. Some researchers refer to this tangled, living matrix as the \u201cworld wood web.\u201d Living plants increase soil carbon by directly nourishing soil ecosystems.<\/p>\n In the years that followed, Silver\u2019s analyses of soil cores indicated that the treated land kept taking in carbon. Computer simulations suggest that it will continue to do so for decades. It also retained more moisture and grew about 50 percent more grass. One dose of compost ignited what Silver calls a state change: The plants and the soil \u2014 and everything that inhabited it \u2014 moved toward a new equilibrium in which the soil ecosystem pulled in and retained greater amounts of carbon.<\/p>\n Silver began publishing her findings in scientific journals in 2010. Her second paper, written with her postdoc Marcia DeLonge and the graduate student Rebecca Ryals, offered a remarkable bit of extrapolation. California has about 56 million acres of rangeland, the single largest type of land use in the state. If compost made with manure was applied to just 5 percent of that area, they calculated, it would offset emissions from about 80 percent of the state\u2019s agricultural sector \u2014 all the cows raised, crops grown, fertilizer applied and tractors driven in California. Much of that offset came from diverting manure from festering lagoons \u2014 where it releases methane and nitrous oxide into the atmosphere \u2014 into compost, a one-time benefit. But the ongoing drawdown of carbon dioxide from enhanced grass growth could be important, too. If you treated 41 percent of the state\u2019s rangeland, Silver told me, carbon pumped into the earth by photosynthesis might render the entire agricultural sector of the world\u2019s sixth-largest economy carbon-neutral for years to come.<\/p>\n The soil-improving<\/strong> practices that Wick, Silver and Creque stumbled into have much in common with another movement known as regenerative agriculture. Its guiding principle is not just to farm sustainably \u2014 that implies mere maintenance of what might, after all, be a degraded status quo \u2014 but to farm in such a way as to improve<\/em> the land. The movement emphasizes soil health and, specifically, the buildup of soil carbon. This happy coincidence is one reason that carbon-farming advocates repeatedly describe their project as a \u201cwin-win.\u201d Society could theoretically remove carbon from the atmosphere and store it in the earth, and at the same time enhance the fortunes of farmers and the overall stability of the nation\u2019s food supply.<\/p>\n Farmers\u2019 obsession with soil health isn\u2019t new, of course. It has been a preoccupation for ages. But modern, conventional agriculture has largely relied on synthetic fertilizer to compensate for losses in natural fertility. And while fertilizers help plants grow, some evidence suggests that they can, in excess, accelerate the loss of carbon from the soil. An influx of nutrients may feed precisely those microbes that release carbon back into the atmosphere. Plants may also excrete less carbon into the earth when bathed in synthetic fertilizers, causing the ancient relationship among plant roots, soil fungi and microbes \u2014 the symbiosis that increases soil carbon \u2014 to fray.<\/p>\n In recent years, the United States Department of Agriculture\u2019s Natural Resources Conservation Service, which was founded in response to the Dust Bowl crisis of the 1930s, has promoted the fostering of soil carbon as an important farming practice. But one of the more remarkable aspects of the regenerative-agriculture movement is that it has been driven largely by farmers themselves. Its proponents fret over soil carbon not necessarily because the N.R.C.S. tells them to, or because they worry about the planet\u2019s fate. They have discovered that doing so can help their bottom line.<\/p>\n Darin Williams is one such farmer. He lives near Waverly, Kan., with his wife, Nancy, in a tidy, gray-painted house with a stone chimney. A life-size plastic deer sits on his front lawn, run through with arrows; he uses it for target practice to sharpen his hunting skills. He\u2019s a big man with a baby face and a mischievous squint. When he drove me around his farm last October in his red \u201cone-tonner\u201d pickup truck, he talked incessantly about soil.<\/p>\n For nearly 20 years, Williams worked as a contractor, building houses in Kansas City. But work dried up after the financial crisis hit in 2007. Williams decided to return to the family farm near Waverly, an area of gently rolling plains, and give farming a try. His family had farmed some when he was a teenager before leasing the land to tenants for years, and he knew it was difficult to make ends meet. But he was inspired by an article about a North Dakota rancher and farmer named Gabe Brown, who claimed to have developed, through trial and error, a more efficient and cost-effective way to farm.<\/p>\n<\/div>\n<\/div>\n The gist of Brown\u2019s argument was that if you focus on the health of the soil and not on yield, eventually you come out ahead, not necessarily because you grow more corn or wheat per acre but because the reduction in spending on fertilizer and other inputs lets you produce each bushel of grain more cheaply. Williams decided to follow Brown\u2019s prescription. \u201cIf after three years, I\u2019m bankrupt, I\u2019ll admit it was a bad joke,\u201d Williams remembers thinking.<\/p>\n Seven years later, his gamble seems to have paid off. He started with 60 acres, now farms about 2,000 and, when I visited last fall, had just purchased an additional 200. In one of his fields, we walked down a lane he had mowed through his warm-weather cover crops \u2014 plants grown not to be harvested, but to enrich the soil \u2014 which towered over us, reaching perhaps eight feet. They included sorghum, a canelike grass with red-tinted tassels spilling from the tops, mung beans and green-topped daikon radishes low to the ground. Each plant was meant to benefit the earth in a different way. The long radishes broke it up and drew nutrients toward the surface; tall grasses like sorghum produced numerous fine rootlets, adding organic material to the land; legumes harbored bacteria that put nitrogen into the soil. His 120-strong herd of British white cattle \u2014 he introduced livestock in 2013 \u2014 would eventually eat through the field, turning the plants into cow patties and enriching the soil further. Then he would plant his cash crops. \u201cHad I not found this way to farm,\u201d he told me, \u201cwe would not be farming.\u201d<\/p>\n A mat of dead vegetation \u2014 from cover crops, cash-crop residue and dung \u2014 covered Williams\u2019s fields. The mulch, along with his cover crops, inhibited weeds from becoming established, a major concern for conventional farmers, because so many weeds have evolved resistance to herbicides. \u201cI don\u2019t lie awake at night wondering how I\u2019m going to kill weeds,\u201d Williams said.<\/p>\n Williams doesn\u2019t till his fields. By minimizing soil disturbance, no-till farming prevents erosion, helps retain moisture and leaves the soil ecosystem \u2014 worms, fungi, roots and more \u2014 mostly intact. At one of his soybean fields, Williams showed me how this translated to soil with \u201cstructure.\u201d \u201cSee how that crumbles into a cottage-cheese look?\u201d he said, massaging a fistful of earth. Small clods fell through his fingers. \u201cThat\u2019s what you want.\u201d Worm holes riddled the dirt, giving it a spongelike quality that was critical, he said, for absorbing rain and preventing runoff. Weather patterns seemed to be changing, he noted. Rain used to arrive in numerous light storms. Now fewer storms came, but they were more intense. \u201cWe have to be able to capture rain and store it,\u201d he said.<\/p>\n By focusing on soil health, Williams says he has reduced his use of herbicides by 75 percent and fertilizers by 45 percent. He doesn\u2019t use pesticides \u2014 he relies instead on beneficial insects for pest control \u2014 and he saves money by not buying expensive genetically modified, herbicide-resistant seed. He estimates that he produces a bushel of soybeans for about 20 percent less than his conventionally farming neighbors. Last fall, he claims, his yields ranked among the highest in the county. While doing all this, he has so far raised the amount of soil organic matter, a rough predictor of soil carbon concentrations, from around 2 percent to 3.5 percent in some fields. Gabe Brown, for his part, says he has more than tripled his soil carbon since the 1990s. And an official with the U.S.D.A.\u2019s Agricultural Research Service confirmed to me that the amount of carbon in Brown\u2019s soil \u2014 what his farming has pulled from the atmosphere \u2014 was between two and three times as high as it was in his neighbors\u2019 land.<\/p>\n The successes of Brown and Williams suggest that farmers can increase carbon in the soil while actually reducing their overall expenses. This could be vital, because in order for carbon farming to have an impact on the climate, as much land as possible, including both crop- and rangeland, will have to be included in the effort.<\/p>\n Critics of regenerative agriculture say that it can\u2019t be adopted broadly and intensively enough to matter \u2014 or that if it can, the prices of commodities might be affected unfavorably. Mark Bradford, a professor of soils and ecosystem ecology at Yale, questions what he sees as a quasi-religious belief in the benefits of soil carbon. The recommendation makes sense intuitively, he told me. But the extent to which carbon increases crop yield hasn\u2019t been quantified, making it somewhat \u201cfaith-based.\u201d<\/p>\n William Schlesinger, an emeritus soil scientist at Duke, points out that \u201cregenerative\u201d practices might inadvertently cause emissions to rise elsewhere. If you stop tilling to increase soil carbon, for example, but use more herbicides because you have more weeds, then you probably haven\u2019t changed your overall emissions profile, he says. He thinks the climate-mitigation potential of carbon farming has been greatly oversold.<\/p>\n Williams has reduced his herbicide use, not increased it, but Schlesinger\u2019s broader point \u2014 about the need for a careful overall accounting of greenhouse gases \u2014 is important. Williams, Brown and others like them aren\u2019t focused on climate change; no one really knows if the carbon they put in the ground more than offsets the methane produced by their cows, for example. What they do demonstrate is that augmenting soil carbon while farming is not only possible, but also beneficial, even in a business sense. And that makes the prospect of rolling out these practices on a larger scale much easier to imagine.<\/p>\n The carbon-farming <\/strong>idea is gathering momentum at a time when national climate policy is backsliding. The Trump administration has reversed various Obama-era regulations meant to combat or adapt to climate change, including the Clean Power Plan, which required power plants to reduce their carbon emissions, and a rule instructing the federal government to consider sea-level rise and other effects of a changing climate when building new roads, bridges and other infrastructure.<\/p>\n In the absence of federal leadership on climate \u2014 and as emissions continue to rise globally, shrinking the time available to forestall worst-case outcomes \u2014 state and local governments (as well as nonprofits) have begun to look into carbon farming. Last year, Hawaii passed legislation meant to keep it aligned with the Paris agreement, which President Trump has said he will abandon; the state has also created a task force to research carbon farming. The New York state assemblywoman Didi Barrett introduced legislation that would make tax credits available to farmers who increase soil carbon, presumably through methods like those employed by Darin Williams and Gabe Brown. A bill to educate farmers about soil has been proposed in Massachusetts. And in Maryland, legislation focused on soil health passed in 2017. Other carbon-farming projects are in the works in Colorado, Arizona and Montana.<\/p>\n But it is California, already in the vanguard on climate-mitigation efforts, that has led the way on carbon farming. By 2050, the state aims to reduce greenhouse-gas emissions to 20 percent of what they were in 1990. Nearly half its 58 counties have farmers and ranchers at various stages of developing and implementing carbon-farming plans. San Francisco, which already has the largest urban composting program in the country, hopes to become a model carbon-farming metropolis. Cities don\u2019t have much room to plant trees or undertake other practices that remove carbon from the atmosphere, says Deborah Raphael, the director of San Francisco\u2019s Department of the Environment. But they can certainly produce plenty of compost. \u201cIf we can show other cities how doable it is to get green waste out of landfills, we can prove the concept,\u201d Raphael told me. \u201cWe like to say that San Francisco rehearses the future.\u201d<\/p>\n Many of California\u2019s carbon-farming efforts owe a debt to Wick, Creque and Silver. In 2008, they founded the Marin Carbon Project, a consortium of ranchers, scientists and land managers. The goal is to develop science-based carbon-farming practices and to help establish the incentives needed to encourage California farmers to adopt them. Silver continues to publish her findings in respected journals. Creque also started a nonprofit, the Carbon Cycle Institute, that assists farmers and ranchers in making carbon-farming plans.<\/p>\n Wick has thrown himself into the policy realm, hiring a lobbyist in Sacramento to push a carbon-farming agenda. (In 2014, he even testified before Congress, outlining the project\u2019s discoveries and explaining how compost could increase soil carbon on public lands. He deliberately mentioned \u201cclimate\u201d only once.) Educating policymakers matters because, as Torri Estrada, executive director of the Carbon Cycle Institute, points out, carbon-mitigation efforts that focus on agriculture can be much cheaper per ton of carbon avoided than the flashier energy-efficiency and renewable-energy projects that usually get most of the attention. The major obstacle to their implementation, he says, is that government officials don\u2019t understand or know about them.<\/p>\n California\u2019s Healthy Soils Initiative, which Wick helped shape, explicitly enlists agriculture in the fight against climate change. In principle, that means this carbon farmers can receive money from the state\u2019s climate-mitigation funds not just for compost but also for 34 other soil-improving practices already approved by the Natural Resources Conservation Service. That\u2019s important because the compost needed to cover just a few acres can cost thousands of dollars. Wick has also tried to tap federal funding. Once N.R.C.S. scientists vet Silver\u2019s work, a compost amendment could become the service\u2019s 35th recommendation. As a result, farm bill money, which farmers receive to subsidize food production, could help finance carbon farming done according to Wick\u2019s protocol \u2014 not to fight climate change explicitly (which is now seen as politicized), but to bolster the health of soil (which isn\u2019t).<\/p>\n As a carbon-farming tool, compost bears some notable advantages \u2014 namely, it works both preventively and correctively. Composting prevents emissions from the starter material \u2014 manure, food scraps \u2014 that, if allowed to decompose, might emit potent greenhouse gases. (About one-fifth of United States methane emissions comes from food and other organic material decomposing in dumps.) By enhancing plant growth, it also aids in removing carbon from the atmosphere, a corrective process. And because the carbon in nearly all organic material was originally pulled from the atmosphere during photosynthesis, compost that enters the soil represents the storage of carbon removed from the air earlier \u2014 the grass eaten by cows that became manure, or the trees that became wood chips \u2014 and at a different location. That, too, is corrective.<\/p>\n Calla Rose Ostrander, Wick\u2019s right-hand person at the Marin Carbon Project, told me that the project\u2019s greater goal is to completely reframe how we think about waste, to see it as more than a nuisance \u2014 to recognize it as a resource, a tool that can help us garden our way out of the climate problem. Before the modern era, farmers had no choice but to return human and animal waste to the fields. (Wick is looking into the possibility of composting human waste as well; the end product is called humanure.) In a sense, Wick and Ostrander seek to resurrect these ancient practices and, with the aid of modern science, to close the loop among livestock, plants, air and soil \u2014 and between cities and the agricultural land that feeds them.<\/p>\n What seems to<\/strong> most impress experts about the Marin Carbon Project is the quality of Silver\u2019s research. Eric Toensmeier, the author of \u201cThe Carbon Farming Solution\u201d and a lecturer at Yale, says that the project figured out a new way to increase carbon storage on the semiarid grasslands that cover so much of the world. Jason Weller, the former head of the Natural Resources Conservation Service, told me that \u201cthe level of science investment is out of the ordinary, or extraordinary, for a group that is really self-started.\u201d Weller added that the agency\u2019s scientists still needed to vet the research, which they are in the midst of doing. In late 2016 the agency oversaw the application of compost to different California regions \u2014 inland, Southern, Northern \u2014 to see if land in various conditions would, like Wick\u2019s ranch, suck up atmospheric carbon.<\/p>\n But the group also has critics. \u201cI\u2019m very skeptical of their results and their claims,\u201d William Horwath, a soil scientist at the University of California, Davis, told me. He wants to see Silver\u2019s experiments replicated. This is the project\u2019s major weakness: Its big idea is based almost entirely on extrapolation from a few acres in California. At this point, it\u2019s impossible to say whether compost can cause land to become a carbon sponge in all climates and conditions, and for how long treated grassland will continue to take in and retain its carbon.<\/p>\n Cows, a flash point in any discussion about climate change, may also present problems. Ruminants burp methane, and while carbon farming does not require their presence, some argue that merely accepting them on the land undermines the goal of reaching a carbon-neutral or -negative future. Livestock emissions account for almost half the heat-trapping gases associated with agriculture, so an obvious way to reduce emissions is to decrease the number of cows on the planet. Instead of dumping compost on rangeland, says Ian Monroe, a lecturer on energy and climate at Stanford University, why not allow forests cleared for pasture to regrow, and change people\u2019s eating habits so they include less meat?<\/p>\n Criticism is directed at compost too. The stuff requires energy to produce; huge machines are required to shred the material and keep it aerated. And it\u2019s unclear if compost, like synthetic fertilizer, can cause nitrogen pollution when put on the land, or how much greenhouse gas composting itself generates. (As long as compost mounds are regularly aerated to prevent low-oxygen conditions, composting is thought to produce few emissions.)<\/p>\n Organic material from municipal sources can contain bits of plastic and glass, which no one wants on their fields. Manure might carry seeds of invasive plants. (Silver has seen no evidence of this.) Spreading compost on public rangeland could disrupt plant communities, squeezing out species adapted to conditions of scarcity. And in any carbon-farming scheme, who will monitor and verify that far-flung stretches of land are really absorbing and storing the carbon as they\u2019re supposed to?<\/p>\n Horwath considers the amount of compost used in Silver\u2019s research \u2014 about 10 times the usual application, he estimates \u2014 to be unrealistically high for practical use. \u201cIt seems an inordinately large amount to apply to any system,\u201d he told me. And given what he sees as the many unknowns in Silver\u2019s research, that compost would be put to better use on cropland where, he says, scientists know with greater certainty that it could improve water retention and the efficiency of fertilizer.<\/p>\n Then there\u2019s the problem of supply. Demand for San Francisco\u2019s compost, which mostly goes to vineyards in California\u2019s wine country, already outstrips what\u2019s available. But Wick thinks more starter material shouldn\u2019t be hard to find: Americans throw out between 30 and 40 percent of all the food they buy, sending it to landfills where it rots and generates greenhouse gases. Silver has calculated that there\u2019s enough organic waste material in California to treat one-quarter of its rangeland every few decades.<\/p>\n Still, given the energy requirements, the logistical headaches and the cost, skeptics question whether spreading compost across extensive portions of the world\u2019s surface \u2014 including conflict zones in the Sahel or Central Asia \u2014 is really feasible. Even if it is, soils probably can\u2019t soak up carbon indefinitely. If they have a saturation point, increases in carbon will eventually stop when that moment is reached. And because soil degradation can cause the release of whatever carbon it holds, treated lands would have to be well cared for in perpetuity.<\/p>\n On a cool<\/strong> autumn day at Wick and Rathmann\u2019s ranch house, Wick fielded phone calls while I wandered around the cluttered, semicircular room that served as his office and meeting space. A whiteboard displayed scribbles from a presentation on the carbon cycle. Coils of warmly hued yarn hung from the doorways. They came via a local nonprofit dedicated to climate-friendly ranching practices called Fibershed. And draped over a chair was a T-shirt bearing what might as well have been Wick\u2019s battle cry: \u201cseq-C,\u201d it read, punny shorthand for \u201csequester carbon.\u201d Under that it read, \u201cDoing it in the dirt.\u201d<\/p>\n Down the road, he showed me a composting facility that Creque dreamed up initially. He and Wick hoped it would serve as a self-sustaining prototype. \u201cAnything that has ever been alive can be composted,\u201d he told me, surveying the 10-foot-tall piles of chicken droppings and feathers, horse bedding (manure and straw) and shredded trees. A tractor mixed woody refuse with animal waste \u2014 to get the composting process started requires the right mix of carbon- and nitrogen-rich materials. (That\u2019s why some backyard composters recommend urinating on the pile to kick things off: Urine is rich in nitrogen.)<\/p>\n Across the lot, a hulking machine straddled rows of steaming black compost, turning them with a metal spinner. Compost has to be regularly \u201cfluffed,\u201d or aerated, Wick explained, to prevent anaerobic microbes from producing methane and nitrous oxide. The manure piles were acrid, but the compost itself had a rich and pleasant odor, like cigars.<\/p>\n<\/div>\n<\/div>\n Wick hopes that facilities like this will someday dot the American agricultural landscape. The idea is to manufacture compost close to both its source material and the place where it will be used, obviating the emissions from carting heavy materials over long distances. The plant also embodied Wick\u2019s contention that composting can help farm carbon and manage waste at the same time. The challenge of affordably creating millions of tons of compost and applying it to great expanses of land is formidable. But there is a pleasing symmetry to the idea that we could use waste to bring the excess carbon in the atmosphere back to Earth, all while making the world lusher and more bountiful.<\/p>\n When I first got in touch with Wick, in late 2016, he greeted me with a question: \u201cDo you know how the earth\u2019s atmosphere was oxygenated?\u201d He was referring to a period 2.3 billion years ago when oxygen, produced by photosynthetic organisms, began building up in the atmosphere, prompting a mass extinction and clearing the way for multicellular life (and, eventually, humans).<\/p>\n \u201cCyanobacteria?\u201d I guessed.<\/p>\n \u201cVery good,\u201d he said. \u201cThis might work.\u201d Evidently I had passed some sort of scientific literacy test. But his bigger point was that living things \u2014 and particularly photosynthetic life \u2014 had always been the great engineers of the planet\u2019s climate. Now, he believed, we could use that fact to our advantage.<\/p>\n That sort of cosmic thinking about the planet and its history is ultimately what makes Wick\u2019s vision so compelling and potentially powerful. The essential insight is one often overlooked when we talk about climate change: The element that threatens to smother civilization is also, in different forms, the fundamental building block of life. To prevent carbon from causing misery and destruction, perhaps we just need to change its location. Perhaps we can find a way to pull it from the air and restore it to the earth.<\/i><\/p>\n