The Chesapeake Bay is swallowing up hundreds of acres of coastline so quickly experts say low-lying areas like Blackwater National Wildlife Refuge will probably vanish within our lifetimes.
“When we look at historical maps of the loss, it’s just dramatic,” says Matt Whitbeck, a supervisory biologist with the U.S. Fish and Wildlife Service.
It’s happening because the land is sinking and the water is rising, according to Zoe Johnson with the National Oceanic Atmospheric Administration.
“The sinking is due to a process called glacial isostatic adjustment,” she explained. “The land is readjusting as the pressure from the glacial period about 18,000 years ago lifts.”
And the water, she said, is rising because of a combination of three different forces. “The ocean is warming and expanding its volume,” Johnson said. “There’s also changes in ocean currents that are being affected from glacial melting and then there’s the melting water itself coming off of the glaciers in Antarctica and Greenland.”
Johnson said, as a result, the Chesapeake coastline is one of the most vulnerable regions in the nation when it comes to sea level rise, along with Louisiana and Southern Florida.
The Chesapeake Bay has already risen about eight inches over the past 100 years, according to Johnson. She said conservative estimates predict at least another foot of rise within the next 50 years. “But on the high end, when you take into account increasing global emissions, you’re looking at two feet within the next 50 years and between four to six feet within the next one hundred years.”
“We’re concerned about the impacts we’re already starting to see today,” she said. “People may not associate the impacts with sea level rise, but there are changes happening. They’re seeing more nuisance flooding. High tides are able to reach further inland. They’re seeing increased flood levels and increased storm surge during hurricanes and nor’easters. And those impacts are expected to increase.”
To help communities understand their risk, NOAA created this Sea Level Rise Viewer to see what areas could become submerged at various water levels, Johnson said. It shows massive quantities of Dorchester County on Maryland’s Eastern Shore disappearing under just a foot of sea-level rise, including most of the Blackwater National Wildlife Refuge.
But as alarming as the map is, Whitbeck cautioned the models shouldn’t be used as crystal balls, but rather as a warning about what could happen if nothing changes.
Changing Chesapeake: Assateague Island
“The sea level rise models are extremely helpful,” Whitbeck said. “They’ve revolutionized the way we think about habitat protection on the Chesapeake.”
At Blackwater they’ve focused on eradicating nutria, a giant rodent species that looks like the native muskrat but grows to 20 pounds by “essentially devouring the root mass” of Blackwater marshland, Whitbeck said.
“It was introduced in the late ‘30s, early ‘40s, when a lot of people were making money on the furbearing trade,” Whitbeck explained. But then the “economy dropped out on the trapping and the nutria just went wild.”
Whitbeck said his agency launched a nutria eradication program that just hit its “one-year anniversary without detecting nutria on the entire Delmarva peninsula. We can’t call it eradicated yet, but we are darn close to succeeding in that.”
By eliminating the nutria and restoring the marsh’s general health, Whitbeck said they can now focus on general sea level rise. “We’re thinking we may not be able to maintain the marsh exactly where it was when the refuge was established, but we can maintain its ecological function if we can maintain the capacity of these landscapes to naturally migrate inland.”
Both Whitbeck and Johnson agree marshes provide a critical buffer between open water and inland communities because storms “roll over these marshes and don’t impact them much,” Whitbeck said. “They can take it.”
And if properly managed, Whitbeck said, the marshes will naturally rise with the water levels as storms and floods bring in sediments to help the marsh accrete.
“Some of these marshes will build elevation faster than predicted in the models and some marshes will build them slower,” Whitbeck explained. “So you have to know what is going on with your specific marsh. You can’t develop a uniform habitat management plan for all marshes in the Chesapeake Bay.”
So all this week, the News4 I-Team will be traveling along the Eastern Shore to show you how different communities are grappling with rising sea levels. We’re starting at Assateague National Seashore, before heading up the Bay to Smith Island and Poplar Island. Everyone is taking a different approach and they’ve discovered unexpected surprises along the way – so tune in to see what we find.