By Diana Kruzman, Inside Climate News
The bogs, logged for centuries and recently burned, sequester far more carbon than forests. Now, thousands of acres are being “rewetted” as part of a restoration strategy.
Fred Wurster’s favorite time to walk through the Great Dismal Swamp is at dusk. Pushing through thick vegetation and swatting away mosquitoes, he gets to a section of this 113,000-acre national wildlife refuge that was repeatedly burned by fires.
Wurster, a hydrologist with the U.S. Fish and Wildlife Service, spent a decade building small dams to encourage parts of this coastal ecosystem in southern Virginia, which has grown drier and more vulnerable to wildfire over centuries of human interference, to hold onto water once again. Now, he listens for the croaking of frogs and the shrieking of bugs coming from the newly flooded burn scar, proof that life has returned to this part of the forest.
“There’s a lot of nuance and subtlety to the system,” Wurster told Inside Climate News in a phone call from the refuge headquarters in Suffolk, Virginia. “To get to know it, you have to go off road.”
One of the features that sets it apart from other wetland ecosystems is what lies beneath the surface of the floodwaters: a layer of peat, up to nine feet deep in some places. Peat is a spongy mass of organic material that forms when plants die but, in the absence of oxygen, don’t fully decay, instead building up over thousands of years in the waterlogged, acidic environment of the swamp. From the bogs of Ireland to the Siberian tundra, peatlands cover just 3 percent of the planet’s land surface but contain twice as much carbon as all forests worldwide—making preserving them a crucial step in the fight against climate change.
But in the Great Dismal Swamp National Wildlife Refuge, as in most places around the world, they’ve been greatly reduced and are at risk of disappearing entirely. Starting in the 1760s, George Washington led efforts to drain the swamp with the help of enslaved labor. Where he failed, logging companies succeeded over the next two-plus centuries, cutting down the water-loving cypress trees and digging ditches that exposed the peat to the air—causing it to decay and sparking fires, like the 2011 blaze that created the scar Wurster often walked past.
Together, these forces have turned what was once a vast carbon sink into a net emitter of carbon. According to recent research, the Great Dismal Swamp has released an estimated 183 teragrams of carbon dioxide equivalents since the late 1700s, the same as driving more than 42 million gas-powered cars for one year.
Seeking to reverse this trend, agencies like the Fish and Wildlife Service and nonprofit groups like The Nature Conservancy have started to restore the peatland ecosystem, rewetting 60,000 acres of the Great Dismal Swamp since 2012. Covering the peat with water slows the process of decay and allows new deposits to build up, reducing the amount of carbon that’s emitted into the air, said Eric Soderholm, coastal wetlands restoration lead at The Nature Conservancy.
Peatland restoration is “one of the most compelling and greatest opportunities in our region to achieve the emissions reductions we need to avoid some of the more dramatic climate change scenarios,” Soderholm said. “It plays a tremendous role—there’s no doubt about that.”
In the coming years, thanks to more than $200 million in funding from the Inflation Reduction Act, The Nature Conservancy is planning to restore 33,000 acres and protect 10,500 acres of peatlands in Virginia and nearby North Carolina. The project will result in an estimated annual greenhouse gas reduction equivalent to taking between 57,120 and 1.4 million cars off the road, the organization announced last year.
It’s also developed a tool that private landowners, who own around 260,000 acres of drained peatlands in North Carolina alone, can use to calculate the carbon sequestered by rewetting their own peatlands, which they could potentially sell as carbon credits in the future, Soderholm said. It uses a methodology called “carbon dioxide flux measurement,” based on peer-reviewed scientific models to estimate the amount of carbon dioxide that’s sequestered based on a proxy variable—in this case, groundwater levels.
The tool takes into account the makeup of southeastern U.S. peatlands, which are more resistant to decay than others around the world, and therefore less likely to release methane when they’re flooded with water, which in other types of peat can stimulate microbes that produce the gas. Entering the voluntary carbon market, Soderholm added, can cover the startup and maintenance costs of peatland restoration for landowners.
These new strategies build upon a history of peatland rewetting at the Great Dismal Swamp, which began in earnest around the time Wurster started working at the refuge in 2010. Its original mission, Wurster said, was not to keep carbon in the ground, but to restore the forested wetland ecosystem that had existed in this area before timber companies built a network of roads and ditches, which kept the soil dry and had caused the ecosystem to transition from water-loving trees like Atlantic white cedar to more drought-tolerant species like red maple.
The forest had been owned by several different timber companies until 1974, when the land was purchased by The Nature Conservancy and donated to the federal government. Officials began planting more white cedar trees and attempting to undo some of the disturbance created by the logging companies. Wurster’s job was also to reduce wildfire risk, spurred by the fallout from a 2008 wildfire that burned through 4,884 acres of the swamp from June to October—the largest blaze in the refuge’s history up until that point.
But understanding the forest’s carbon sequestration potential provided an additional justification for prioritizing some species of trees over others, said Chris Lowie, director of the Great Dismal Swamp National Wildlife Refuge. “If we’re going to get rid of white maple to increase Atlantic white cedar,” as he told ICN the thinking went at the time, “it would be nice to know which forest community has the potential to sequester more carbon.” A 2016 study led by researchers from USFWS, USGS and Clemson University found that Atlantic white cedar forests, which grow in peat-based soils, contain more carbon than drier maple gum forests, bolstering the idea that restoring the restoric ecosystem has carbon benefits.
Wurster started out by collecting data on the swamp’s hydrology, then planned out where to plug ditches and build “water control structures” to prevent the 50 inches of annual rainfall that the ecosystem receives from draining to the ocean. Because areas where peatlands were exposed to the air sank over time, those parts of the swamp also benefited the most from rewetting, which raised the groundwater level. Over time, he began to see plants adapted to wetter conditions, such as orchids and swamp magnolias, begin to appear in these “hollows.”
The work, which was mostly completed by 2022, has been limited to about half the refuge’s area, but the site shows great potential. A 2018 study conducted by the U.S. Geological Survey calculated that increased management of the swamp, which would rewet 95 percent of the refuge and restore the original Atlantic white cedar forests, could avoid up to 16.5 million tons of carbon dioxide emissions between 2013 and 2062.
But restoring peatlands isn’t as easy as simply flooding them. Researchers have also found that degraded peatlands don’t hold onto water as easily as pristine ones, making them more likely to dry out despite efforts to rewet them. And although it’s possible that some new peat has begun to accumulate, it’s not yet enough to outweigh the carbon that was lost through fires in 2008 and 2011, which burned up to a meter of peat, said Miriam Jones, a geologist with the USGS who conducts research in the Great Dismal Swamp. Not enough data has been collected to establish how much new peat has built up, if any, or if the land is continuing to dry out and sink overall.
“Peatland restoration is not straightforward,” Jones told Inside Climate News. “It’s hard to just undo [the damage that’s been done]. You have to think strategically about how to get the system to absorb more water.”
Jones and Wurster both believe more aggressive measures are needed to turn ecosystems like the Great Dismal Swamp from a carbon source back into a carbon sink. But these can be a tough sell, as officials have to balance the needs of forestry, agriculture and recreation with ecological restoration. Roads, which contribute to drying out the peatlands, are also necessary to fight fires, making them impossible to remove fully.
“We’re making it wetter—we’re definitely wetter than we were [before],” Wurster said. “But in parts of the swamp, we can only get it so wet because we didn’t get rid of roads and ditches entirely.”
Restoring wetter peat-loving forests also comes at a cost, stressing out the maple and gum trees that make up a large portion of the current ecosystem. “It’s a tradeoff—you have to lose something to gain something,” Lowie said. But the goal, he added, is not to entirely revert the swamp back to what it was before it was drained and logged, but to increase the forest diversity and make it more resilient to storms, fires and other forms of extreme weather made worse by climate change. Restoring wetlands also provides wildlife habitat, stores stormwater and reduces flood risk.
“When you add up all of those factors, it is a no-regrets strategy,” Soderholm said.
With the Trump administration poised to deprioritize climate change, the onus of peatland restoration will fall more heavily onto nonprofits like The Nature Conservancy to work with private landowners. Although it can be difficult to convince people at first that peatlands—which local communities have long worked to make “productive” through logging or farming—should be flooded, Soderholm believes that everyone stands to benefit.
“It’s not fun to breathe in peat smoke,” Soderholm said. “We need to be open to dialogue in both directions.”