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North Carolina's shoreline estuaries are transforming into "ghost forests," but why?

Hannah Breisinger
Rising seas — a result of climate change — are inundating North Carolina’s coast and killing off trees.

Along the coastal barrier islands of the Atlantic coast, maritime forests are home to mammals, reptiles, insects, plants, and migrating birds. They’re vital to coastal and storm resilience. And in areas undisturbed, some of these coastal trees date back to the 1st century.

In recent decades, commercial development has threatened these ecosystems. But research shows that another — perhaps even greater threat — is not only clearing forests, but burying them beneath the sea.

Ghostly forests of 'snags'

You can see them from a plane, and even from space. Marshes along North Carolina’s coast, peppered with dying or already-dead trees. When I first moved to Wilmington, I was puzzled by them — tall, lanky skeletons, pale limbs outstretched and barren. Void of life, and still standing.

Scientists call them “ghost forests,” the trees themselves, “snags.” They’re a coastal casualty to rising seas, storm surge, and extreme events like floods and droughts. As saltier water gets pushed further inland from neighboring oceans, once dry land becomes marsh. And what was marshland becomes sea.

When saltwater reaches native trees that have historically survived on freshwater, it poisons them. Eventually, those trees die, entombed in brackish marshes.

Ghost forests aren’t anything new. But now, they’re transforming the Eastern Seaboard at an unprecedented speed. A speed that points not to natural causes, but human-caused impacts on our natural world.

'Dead as far as the eye can see'

“The extent of ghost forests that we're seeing out on the coast is really, really shocking. It's not just a few trees here and there. It's trees that are dead as far as the eye can see. And that is something that's really not natural.”
Dr. Emily Ury

In 2016, Dr. Emily Ury began studying the impacts of salt on North Carolina wetlands. At the time, she was a Ph.D. student at Duke University.

And as she was heading out to the experimental sites, she started to notice — like I did — those weird, dead, puzzling trees. This time, they were lining the sides of the road at the Alligator River National Wildlife Refuge, located near the Outer Banks in the northeastern portion of the state.

“And this really led to the question of, ‘how much of this landscape is ghost forests? And how far inland beyond the edges of the roads do these dead trees extend?’”

But the forests were too dense and the channels were too deep to observe the site on the ground. So, to get a better view of the landscape, Ury tried a more unconventional tactic:

“I began spending a lot of time looking at aerial images and satellite images from space, and aerial images taken from airplanes on Google Earth.”

Ghost forests, located northeast of Wilmington, captured by a drone camera.
Nick Santillo
Ghost forests, located northeast of Wilmington, captured by a drone camera.

Her curious observation eventually led to a study that she co-authored, along with other scientists at Duke and the University of Virginia. Published this past April, the research finds that more than 10% of forested wetland within the refuge has been lost in the past 35 years.

The most significant annual loss of forest was in 2012. Ury notes that, interestingly, that was around a time of extreme drought, forest fires, and storm surge, following Hurricane Irene.

“And Hurricane Irene brought a storm surge of salty water over a large portion of the refuge into soils that were already stressed from prolonged drought.”

Scientists believe that maritime forest loss is accelerated in events of extreme weather. That’s a concern, as climate experts continue to point out that the strongest storms will grow even stronger as the climate continues to warm.

Another concern is the geographical position of the refuge, which makes it particularly vulnerable to rising seas — more so than most other areas along North Carolina’s coast.

Climate Central
The Alligator River National Wildlife Reserve at present day (left), and as simulated under a 2 ft. sea-level rise (right).

Climate Central, a nonprofit that analyzes climate science, projects that a water level rise of only about 2 feet would put much of the refuge below sea level. And that could mean a lot more disappearing trees.

“In these coastal endemic forested wetlands, which are really the last stronghold of their kind left, we've squeezed out a lot of the native forested wetland for logging and for agriculture. And so what remains is really just the remnants of this habitat type, and wildlife is really being pressed for where it would be able to go.”

Rising seas, dying trees

“So this is Eagles Island. The slightly lighter green trees generally are Cypress, and the darker ones are pines. Cypress are intolerant to saltwater.”

That’s Dr. Larry Cahoon, Professor of Biology and Marine Biology at UNC Wilmington. We’re on a boat, heading along the Northeast Cape Fear River — sandwiched between downtown Wilmington and an area of expansive swamp forest. Closer to the banks of the river are more snags, or dead trees.

Dr. Cahoon explains that the trees are generally pretty resilient. Cypress, especially, are hardy to water rot. And many cypress trees in North Carolina are among the oldest in the world, some dating back thousands of years. But, saltwater still damages their roots, especially trees at lower elevations.

“So if there's any saltwater coming in, they stop putting out leaves. They don't necessarily die unless it continues like that for a long time.”

Cahoon tells me that hundreds of years ago, in the 1700s, the Cape Fear River was used for rice production. Back then, the freshwater river conditions made that type of agriculture ideal.

Today, the river is brackish, but its salinity varies, depending on the weather. During a drought, saltier water is pushed miles upriver from the coast. Floods or excessive rain allow for more freshwater runoff.

But like the Alligator River National Wildlife Refuge, Eagles Island is highly vulnerable to rising seas. And the coming decades could bring a lot more water, a lot more salinity, and a lot fewer trees.

Snags along the Cape Fear River/Eagles Island.
Hannah Breisinger
Snags along the Cape Fear River/Eagles Island.

The implications of forest loss (and, tree farts)

Sea level rise is a global phenomenon. But, it’s also relative — different locations will see different impacts.

“Here in coastal North Carolina, our land is subsiding. So, therefore, the relative sea-level rise for us is actually greater than the global rate of sea-level rise.”

Dr. Christine Voss, a Research Associate at the UNC Chapel Hill Institute of Marine Sciences, explains to me that the loss of North Carolina’s forests isn’t a short-term issue. And, naturally, the problem can’t be fixed with a Band-Aid.

“We can put temporary measures, we can put up our bulkheads, and various structures and sea walls to try to hold those water levels back. But those are very temporary solutions. And in the big scheme of things, it's physics.”
Dr. Christine Voss

The implications of ghost forest expansion are multi-faceted. The irreplaceable loss of wildlife habitat is obviously a given. Less coastal protection from storms is another.

And recently, a study from North Carolina State University found that these snags act as conduits for soil-produced greenhouse gas emissions. This process, which scientists have amusingly dubbed as “tree farts,” could further increase the environmental toll of this gradual deforestation.

A dead cypress tree along the Cape Fear River.
Hannah Breisinger
A dead cypress tree along the Cape Fear River.

If a tree falls in a forest...

Talking about climate change often feels hypothetical — even now, when its ramifications are already staring you dead in the face. If a tree falls in a forest and no one is around to hear it, does it make a sound? What if the tree doesn’t fall at all, but instead undergoes a slow, quiet demise?

Driving along Martin Luther King Jr. Parkway — heading northeast of Wilmington — I cross the bridge over Smith’s Creek. To my right, I see the tall, gray, cadavers; still perfectly mummified, minus their leaves.

They’re the same cluster of trees I first observed two years ago. Somehow, it feels like there are much more of them now than back then. And I wonder if it’s possible that the trees haven’t changed at all, and I’m just more prone to noticing them.

I continue my drive, the trees expanding into the distance in seemingly endless rows outside my car window. A scene that once evoked a slight curiosity now feels like an eerie, daunting landscape of a rapidly changing planet. I stop and snap a picture, afraid that somehow, this moment will be lost in the transit of time.

Hannah is WHQR's All Things Considered host, and also reports on science, the environment, and climate change. She enjoys loud music, documentaries, and stargazing; and is the proud mother of three cats, a dog, and many, many houseplants. Contact her via email at hbreisinger@whqr.org, or on Twitter @hbreisinger.