>Global Warning / Prairie Potholes

Pots of Gold

For years farmers in the Upper Midwest have been plowing up prairie potholes, the tiny seasonal wetlands that dot their fields. But now that scientists have discovered that potholes can reduce greenhouse-gas emissions, farmers and businessmen are eyeing the wetlands as the region's newest cash crop.

By Keith Kloor

 

On Tom Wiley's 3,000-acre farm, as in much of North Dakota, an early afternoon wind whistles across a grassy checkerboard of wheat, corn, and soybean fields. It's the same steady gale that Wiley's grandfather and uncles endured a hundred years ago, when they homesteaded the family farm. Since then, four generations of Wileys have lived off the land, outlasting locusts, dust storms, frigid winters, and floods.

But it's getting harder. Yesterday's pioneers helped feed a growing nation; today their descendants—the small independents like Wiley—are warding off obsolescence, their margins for survival squeezed ever tighter by global competition and by corporate agricultural firms with deep pockets. Still, the savviest, most adaptable farmers continue to defy the harsh elements and economics. What still bedevils many of them is geology—or, to be precise, the millions of slight depressions etched into the Great Plains that are known as prairie potholes.

Wiley's fields contain thousands of potholes—glacial remnants, ranging from a tenth of an acre to several acres—which fill up with water during spring rains and usually dry out by late summer or the season's first frost. Last spring was particularly wet in the Midwest. When I visit in June, Wiley's farm, in Millarton, North Dakota, about an hour and a half southwest of Fargo, is awash with the wetlands, turning large swaths of the region's rich soil into what farmers in these parts have long dismissed as "mud puddles."

The wildlife, on the other hand, is thriving. "I've got ducks living everywhere!" Wiley yells over the wind, as we wade through knee-high grass, past a recently planted soybean field. His lips are chapped, and his pale face—befitting his Scottish-Irish heritage—is framed by aviator glasses and a frayed brown cap that reads "Dakota Growers." A mallard flaps by overhead, before darting into the grass for cover. Wiley has nothing against the waterfowl. "My wife likes all the birds," he says. They arrive en masse every spring—northern pintails, mallards, American coots, pied-billed grebes, to name a few—4 million to 6 million strong, to mate in the small, mostly seasonal wetlands that pockmark portions of Canada, North and South Dakota, Montana, Iowa, and Minnesota. Still, the 52-year-old Wiley has had to put such sentiments aside: Like most farmers eking out a living on the plains, he has spent many an hour draining, burning, and plowing potholes.

Yet this bane of farmers' existence may soon prove to be their salvation, thanks to an emerging market based on a plan that would preserve the potholes as a way of offsetting greenhouse-gas emissions. The idea is rooted in recent, groundbreaking research by biologists with the United States Geological Survey (USGS) who have found the prairie pothole region to be a potentially vast "carbon sink"—a kind of natural sponge that absorbs carbon dioxide (CO2) from cars, factories, and power plants. Of all the pollutants heating up the atmosphere, CO2 is the most common; fortunately, it is also captured naturally in trees, soil, and plants. Scientists call this carbon sequestration: the storing of carbon dioxide.

Take Wiley's potholes, which USGS biologist Ned "Chip" Euliss Jr. has found to store an average of two and a half tons of carbon per acre, per year when not farmed. All told, Euliss and his USGS colleagues, based in Jamestown, North Dakota, estimate that if the remaining 40 million acres in the entire prairie pothole region in the United States and Canada stopped being farmed, they would hold about 400 million tons of carbon over 10 years—the equivalent of taking almost 4 million cars off the road.

About a decade ago scientists began eyeing trees and croplands as the most promising sources of carbon sequestration. Economists then devised a system to leverage the stored carbon as a commodity (valued in tons) that is expressed in shares or permits and then traded on the open market. Now a bold plan is being developed to turn prairie potholes into a kind of "greenhouse-gas crop" by actually paying farmers for the carbon stored in their unfarmed potholes. This is no pie-in-the-sky idea; a consortium of 24 state, federal, and university researchers recently joined together on a half-dozen projects to explore the plan's viability. Wiley and many other farmers have embraced it, betting that the additional revenues will help them stay afloat.

Environmentalists, for their part, are equally enthusiastic, because of the dividends the ingenious scheme will pay out for habitat protection and biodiversity. "This is a win-win for everybody," says Genevieve Thompson, executive director of Audubon Dakota, who has worked closely with North Dakota farmers, USGS scientists, and members of Congress to get the pothole plan off the ground. "Farmers are entrepreneurs, and here's a moneymaking opportunity they didn't have before. It will benefit them, as well as all the ducks and wildlife that rely on the potholes."

When the most recent ice age ended some 12,000 years ago, the retreating glaciers had created about 25 million depressions of all sizes and shapes across a 300,000-square-mile landscape—roughly the size of Texas and New York combined—or about 83 potholes per square mile. The wetlands were soon engulfed in a sea of fluttering shortgrass, mixed grass, and tallgrass. In the past century much of this landscape, including the native grasses and the potholes, has been transformed to cropland or hayed grasslands. Wheat, barley, soybeans, corn, sunflowers, cattle, and sheep occupy the land that was once prairie. As a result, several dozen grassland bird species, such as the grasshopper sparrow and the greater prairie chicken, have been steadily disappearing.

What remains of the glaciated wetlands, however, still supports more than 300 bird species, including impressive numbers of migrating shorebirds and waterfowl. Prairie pothole country is also world renowned as a "duck factory," because it produces half of North America's 35 million to 40 million ducks. Of these, roughly 8 million come from potholes in the Dakotas, according to the U.S. Fish and Wildlife Service (FWS).

In the Dakotas and northeastern Montana, the National Wetlands Inventory, part of the FWS, has mapped nearly 2.7 million wetlands, classifying most as small potholes that are seasonally flooded and smaller than an acre. FWS biologists estimate that if all remaining farmland potholes were eventually drained, the productivity of the duck factory would be cut by half.

"The highest densities of ducks are found on smaller wetlands," says Neal Niemuth, an FWS migratory bird specialist based in Bismarck, North Dakota. "They like the small potholes so they can have a little privacy when they form pairs." Territoriality is another big factor. "A pair of ducks will set up on a pond and chase off other ducks that will be in sight," Niemuth adds. "So if you have 10 one-acre wetlands, you'll have more ducks using them as pair ponds than if you had one 10-acre wetlands."

Several years ago, after mapping the remaining potholes in the Dakotas and Montana, Ron Reynolds, an FWS biologist also based in Bismarck and head of the office's Habitat and Population Evaluation Team, began crunching decades of breeding-waterfowl data to pinpoint where the highest concentrations of particular duck populations were located. From this he and his team developed a map for five primary species—northern pintails, mallards, northern shovelers, gadwalls, and blue-winged teals—so specific wetland areas could be targeted for conservation.

This work builds on the North American Waterfowl Management Plan, an international partnership between the United States, Canada, and Mexico, that includes numerous federal and state agencies, as well as conservation groups (such as Audubon and Ducks Unlimited). During the past 17 years the partnership has spent $2.3 billion to conserve 9.9 million acres of grasslands and wetland habitat.

When the Midwest swung from an extreme drought in the late 1980s to an extended wet period in the mid-1990s, previously bone-dry wetlands filled up all over the northern plains, flooding farmland. In low-lying parts of the Dakotas, wetlands didn't just reclaim their original basins, they overtook them. Many farmers were exasperated: They were used to plowing through the wetlands, but that was now virtually impossible. Facing the challenge of planting row crops on a landscape suddenly covered with millions of tiny, engorged wetlands, their only option was to farm around them.

The budding plan to pay farmers for the carbon stored in their wetlands couldn't be better timed. Concerns over climate change are rising along with temperatures, and scientists have been exploring a variety of carbon-sequestration methods to help capture the trapped greenhouse gases. Most current initiatives revolve around tree-planting and forest-preservation programs. Lately these have been coupled with what is called the cap-and-trade system, an economic vehicle that enables companies to buy and sell pollution credits on open markets. The credits are a kind of greenhouse-gas currency, and represent the right to emit a certain amount of CO2 or other gases that contribute to global warming.

A successful model for such a market already exists with sulfur dioxide; it was developed after the 1990 Clean Air Act set a cap on sulfur dioxide emissions in an effort to help reduce acid rain. Once the cap was established, the federal government issued emission "allowances" to companies, and trading began in earnest. Companies that operated more efficiently and emitted less sulfur dioxide sold their leftover allowances to companies that ran less efficiently or had higher costs for pollution controls.

The same principle applies to the fledgling carbon market. In this case, the emission credits are drawn from agreed-on sources of carbon sequestration, such as trees or croplands. To build momentum, last year the World Bank set aside $100 million for its new BioCarbon Fund, which will allow companies in the developing world to offset their emissions by investing in tree planting and other initiatives. Similar projects are under way in the United States. For example, Reliant Energy, a Texas-based utility, recently agreed to plant more than 160,000 trees on 600 acres of pastureland in the state. The trees are expected to capture 215,000 tons of carbon dioxide during the next 70 years.

International agreements that voluntarily reduce greenhouse gases are also gaining currency through the cap-and-trade system. Fifteen European countries have already agreed to participate in various carbon trading programs. Great Britain established the world's first organized carbon trading system two years ago, and the European Union has plans to kick off an emissions market in 2005 (it will include trading in all greenhouse gases).

In the United States, 13 companies, including DuPont and Ford, recently joined the newly formed Chicago Climate Exchange, in which members voluntarily reduce their CO2 emissions through the trading of greenhouse-gas credits.

Of course, absent any laws mandating a limit on CO2 emissions, there's little incentive to participate in greenhouse-gas trading programs. "Clearly, only under a regulatory environment will there be more broad-based participation and demand for this," admits Michael Intrator, managing director for Natsource, an energy brokerage firm based in New York City. Nonetheless, many industry executives and financial analysts are increasingly eager to take part in carbon trading ventures, convinced that a universal cap on greenhouse gases is all but inevitable.

When that day comes, some of those carbon credits are likely to be derived from prairie potholes. "If this [stored carbon] is treated as a measurable commodity, then that would be setting an important precedent," says Audubon's Genevieve Thompson. "It would be a commodity based on industry's demand for carbon." The distinction is important to farmers, she says, because many feel they aren't producing anything when land is set aside for conservation. "I look at it and say, 'Yes, you're producing lots of things,' " Thompson insists. " 'You've got bobolinks, you've got nesting habitat, flood control, etc." But some growers don't see it that way. With this, though, it'll be a commodity, it'll have measurable value."

Still, not everyone is ready to jump on the bandwagon. Last year, at a conference hosted by the USGS, several panels debated some of the unanswered questions about the whole carbon-storage and trading enterprise: for instance, how the different gases would be scientifically verified and quantified in the prairie potholes, and what criteria would be used to determine how much farmers are paid for their stored carbon.

Euliss is banking on many of these issues being resolved in a pilot program (see illustration, below) planned for North Dakota's Devils Lake Basin, a pothole area 90 miles west of Grand Forks. Besides quantifying the amount of gas stored in wetlands, the project would create a system in which participating farmers are awarded a pool of carbon credits to be traded on markets such as the Chicago Climate Exchange.

Others, though, like the FWS's Ron Reynolds, harbor reservations about potholes being preserved mainly through carbon trading. "We don't want to lose the environmental regulations that currently exist for wetlands," he cautions. Already the Supreme Court, in a ruling three years ago, weakened protections for seasonal wetlands, Reynolds points out. "I wouldn't want for this thing [carbon storage and trading] to become a substitute for real regulatory protection," he adds.

All the same, "carbon sequestration is going to happen," Euliss insists. "And the conservation and natural resource community can play an active role." What concerns him most is whether pure economics or ecological considerations will drive it. "If we let the economics drive it, then it becomes solely a business decision, based on maximum profits. If that happens, then people might ask, 'What's wrong with planting trees on the prairie? Let's get rid of the native grass and plant canary grass or something else.' I think the real challenge here is not only to find things that store carbon and have benefits for the greenhouse effect but to do it in an ecologically sensitive and sustainable manner."

None of this happens, of course, without the prairie potholes becoming another all-important greenhouse-gas sponge. Out on Tom Wiley's farm, where I am joined by Euliss and two of his USGS colleagues, I learn that turning potholes into a carbon crop will help combat global warming in other important ways, too.

"This is a wetland that has been plowed through," Euliss says, stopping at a small, muddy field where cattails, bulrushes, and other water vegetation have grown back. The one-acre wetland is one of 16 study potholes that Euliss is examining, to compare how much carbon and other greenhouse gases are stored in both tilled and nontilled wetlands. Edging closer without actually stepping in open water, we are serenaded by the strumming of chorus frogs. In the spring the potholes double as lovers' lanes for mating frogs as well as birds.

"This wetland has received lots of nutrients [through fertilizers] and is probably not storing very much carbon," Euliss speculates. "Right now Tom can't get in there [with his tractor], but later this summer or early next year, he'll be able to get through it and boil the carbon out [with the plow]." That, unfortunately, would release a stew of greenhouse gases into the air.

Alas, when it comes to the gases heating up the planet, all are not equal. "One thing that has given wetlands a bad name is methane," admits Euliss, who is the driving force behind carbon-storage research on prairie potholes, and also a beekeeper and dog breeder in his spare time. "Methane, of course, is a very potent greenhouse gas, but we're starting to see data that says, 'Yes, they do emit methane, but they emit more greenhouse gases when they are farmed because of the fertilizer mixed in,' " he says, referring to the nitrogen that farmers use to help their crops grow.

"If you restore a wetlands, though, you put grass back around it, and you're putting carbon back in the soil," continues Euliss. And just as important, "you're no longer putting fertilizers in it." Those agricultural fertilizers, it turns out, ramp up nitrous oxide emissions. And nitrous oxide, he adds, "is 310 times more potent a greenhouse gas than carbon dioxide." The U.S. Environmental Protection Agency estimates that 70 percent of nitrogen emissions result from agricultural practices. "So when you stop farming these wetlands, you're turning the flame down," says Euliss. "Basically it would be like trading your gas guzzler in for a car that gets 50 miles per gallon."

Wiley's farm is on the edge of North Dakota's lush Coteau Hills, a rolling green upland sculpted by the most recent glacial advance. Later in the week I spend a few hours driving through the area, about 40 miles south of Bismarck. Here, Niemuth, the FWS biologist, told me, I would be able to "envision what the prairie was like a couple hundred years ago."

The meadows and open sky are hypnotic. Vast stretches of pothole country in the northern plains look like a stark, cratered moonscape when viewed from above. But the Coteau Hills offer something more. Alongside the small wetlands dotting the deep grass are huge shimmering lakes cut in between the hills, courtesy of those ancient glacial deposits.

I pull over at Horsehead Lake, where a veritable duck and shorebird convention looks to be taking place. Dozens of birds seem to be coming and going in all directions, darting in and out of the grass cover. A cacophony of calls and shrieks echo across the lake. Overhead, a flock of about 20 marbled godwits noisily chase off a few blackbirds.

Back on the road, I seem to pass more abandoned farmsteads and grain elevators than cars. In the past decade, as North Dakota's small-farm economy has gradually given way to agribusiness, its rural communities have emptied out, leaving old windmills and peeling white barns to waste away in the windblown grass. Every so often I notice big rocks piled up neatly in the grass, where farmers must have moved them from nearby fields. Euliss had told me that they now mark wetlands, so farmers can avoid getting their tractors and other heavy machinery stuck in the mud during plowing and planting season.

To me the rocks also act like visual signposts, reminders that I'm still in pothole country. They also remind me of something Wiley said when we were discussing the merits of compensating farmers like him for the carbon stored in their wetlands.

"If farmers got paid for these areas, we'd quit going out there and burning them and trying to dig them up," he said as we stood next to one of his plowed-over potholes. "It'd be good for the pheasants, the ducks; it'd be good for all of us."