Rising sea levels have killed entire forests off the North Carolina coast, releasing vast stores of carbon into the air.
Long before this year’s wildfires scorched forests on the west coast, rising seas have been slowly poisoning forests in North Carolina. The resulting “ghost forests” could have big implications for climate change.
A new study found that trees on the coastline of North Carolina’s Albemarle-Pamlico Peninsula have been dying off as the land turns to salty marsh, leaving nothing but old snags. Worse, while alive these forests held vast quantities of carbon, which is gradually escaping into the atmosphere.
The ghost forests are a sign that the effects of climate change are here and now, argued study lead author Lindsey Smart.
“Many people think about sea-level rise as being more of a long-term threat,” said Smart, a research associate at the North Carolina State University Center for Geospatial Analytics. “But we’re actually seeing significant changes over shorter time periods because of this interaction between gradual sea level rise and extreme weather events like hurricanes or droughts, which can bring salt water further inland.”
The study found that of the nearly 2,500 square miles of land tracked, 15% had become ghost forests between 2001 and 2014 — leaving their mortal coils behind, but not their carbon.
Around 130,000 metric tons of carbon were lost from the ghost forests during this time period, equivalent to a year’s emissions of more than 100,000 passenger vehicles, according to the U.S. Environmental Protection Agency’s Greenhouse Gas Equivalencies Calculator.
“Coastal forests are really unique in that they store carbon both in their foliage and in their really rich organic soil,” Smart said. “As saltwater intrusion increases, you’re going to see impacts both to the aboveground and the belowground carbon. While we measured aboveground carbon losses, the next step will be to look at the response of these carbon stores below ground to saltwater exposure.”
The study also found that poor maintenance of manmade structures such as canals can increase the likelihood of ghost forests in the region. “Drainage networks, if not maintained, can serve as conduits for saltwater intrusion,” Smart said.
Fires and droughts are believed to be an additional cause for the damage across the coastline. “We think there may be an interaction between salt water and fire that accelerates forest retreat, and facilitates marsh migration into areas that were once healthy coastal forest,” Smart added.
“Two severe droughts within the study period produced larger-than-typical wildfires and facilitated salinization of normally freshwater ecosystems,” said study co-author Paul Taillie, a postdoctoral researcher at the University of Florida and former graduate student at NC State University. “Thus, the combination of rising sea level and future drought would be expected to cause a large net loss in biomass.”
On a positive note, the study helped identify regions that are most at risk of becoming ghost forests, which can assist the ongoing effort to prevent carbon loss in North Carolina.