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North Carolina could lose up to 40% of its wetlands to sea level rise by 2070, new study shows

North Carolina

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Sea level rise poses a serious threat to salt marshes and other wetlands along the North Carolina coast, according to a newly published study.

North Carolina and Louisiana are the only two states that could lose coastal wetlands under almost any sea-level rise scenario. The study was published in the journal Environmental research Communication

“North Carolina can benefit a lot from various wetland protection measures, but it also needs to prepare for a world with fewer wetlands and think about what that will look like,” said Climate Central CEO and chief scientist Ben Strauss, who is one of the researchers. were researchers. authors.

The Climate Central team has created a mapping tool that can display estimates for various sea level rise and land use scenarios. For example, if the world meets the 2015 Paris Agreement goal of keeping global warming to 2 degrees Celsius (about 3.6 degrees Fahrenheit) and North Carolina fully develops its coast, Climate Central found that by 2070 could lose about 40% of its coastal wetlands and 62% by 2100. If North Carolina fully preserves its coastline under the same scenario, Climate Central estimates that wetlands could increase by 42% by 2070 and by 41% by 2100.

North Carolina’s 220,000 acres of salt marsh offers a wide variety of benefits, from providing habitat for juvenile fish to taking the power out of waves during hurricanes. Salt marshes naturally move inland, but many struggle to keep up with rapidly rising sea levels. And when a bulkhead or house is built along a swamp, that migration becomes impossible, causing the ecosystem to collapse.

A McClatchy report from last year found that since 1996 there has been a 22% increase in built-up land within half a mile of salt marshes in North Carolina, South Carolina and Georgia. Since 2009, regulators in North Carolina have approved about 3,300 bulkhead permits.

The Climate Central study indicates that while wetlands along the North Carolina coast would be endangered by sea level rise, the northeastern portion of the state is at greater risk.

“Our analysis boils down to the fact that you just don’t develop lowlands next to these wetlands,” Strauss said. “That’s all.”

Make salt marshes move

The findings come as no surprise to groups who have been working to conserve the wetlands on North Carolina’s coast. The Coastal Federation, for example, has long touted the benefits of living coastlines: marsh sills that allow sediment to accumulate along the coastline in an effort to help salt marshes keep up with rising seas.

Kerri Allen, a coastal attorney who heads the Federation’s Wrightsville Beach office, said wetlands play a critical role in North Carolina’s coastal economy.

“Without healthy wetlands, we don’t have healthy waterways, we don’t have clean water, we don’t have beaches where people want to come and swim,” Allen said.

All agrees that purchasing large parcels of undeveloped land or placing conservation easements on targeted parcels can play a key role in wetland conservation.

“That’s going to be a really important tool in that toolbox,” Allen said, “and really one that I don’t think is discussed as often as it should be when we talk about sea level rise and climate change and our vulnerability here on the coast.”

The Coastal Federation initiated such a project in 1999 with the North River Wetlands Preserve. The 6,000-acre Carteret County tract was once a working farm, but the wetlands over much of the land have been restored or preserved.

Pew Charitable Trusts has supported the South Atlantic Salt Marsh Initiative of the Southeast Regional Partnership for Planning and Sustainability. That effort, which kicked off in May 2021, aims to conserve a million acres of salt marsh from North Carolina to Florida by partnering with a wide variety of groups from the Department of Defense to the Gullah/Geechee Nation.

Leda Cunningham works on coastal issues for the Pew Charitable Trusts and is based in North Carolina. Cunningham said the state is an example of a place where it is important not only to consider and protect where the swamps are now, but also where they could be in the future.

The patchwork of interests owning land along and adjacent to the coast can make that difficult.

“Coastal communities really benefit from protecting their coasts, especially with green infrastructure,” Cunningham said. “This is about the survival of our own communities.”

Measuring salt marshes

Hannah Sirianni, a coastal geographer at East Carolina University, has begun measuring wetlands, particularly around the Swanquarter National Wildlife Refuge in Hyde County.

Sirianni expressed concern that Climate Central’s study and maps do not accurately reflect the elevation of the swamp to guide local planning. The laser from the LiDAR measurement system used, Sirianni said, cannot penetrate the thick grasses and vegetation of wetlands.

As part of her investigation, Sirianni trudged through the Swanquarter Refuge, a place where vegetation can be so thick it looked like she was walking on mats. By doing so, Sirianni and her team were able to put a rod on the ground and check how accurate the laser reading actually was.

Sirianni found that the laser measurements estimate the elevation of the North Carolina swamps to be 1.77 feet higher than they actually are in some places.

“We need to base the data on truth if we want to use it for local decision-making,” Sirianni said.

Strauss, the Climate Central scientist, agrees. The best use of the map tool, he said, is to switch between locations and scenarios to get an overall picture of the risk sea level rise poses to salt marshes.

If a place appears to have a serious threat, Strauss said, that could indicate it’s worth investing in a more site-specific study.

“It’s more of a screening tool, screening analysis,” Strauss said. “But with that in mind, it clearly says North Carolina has a lot to worry about.”

Wetlands will track sea level rise to offset climate change

More information:
Maya K Buchanan et al, Resilience of US coastal wetlands to accelerate sea level rise, Communication about environmental research (2022). DOI: 10.1088/2515-7620/ac6eef

©2022 The News & Observer. Distributed by Tribune Content Agency, LLC.

Quote: North Carolina could lose up to 40% of its wetlands to sea level rise by 2070, new study (June 2022, June 14) revealed June 14, 2022 from https://phys.org/news/2022-06-north-carolina -wetlands-sea.html

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