This reporting project was made possible by a grant from the Fourth Estate Fund.
You can find more from the series here: Rising Waters: A series focusing on the changing climate's impact on North Carolina's coast
The Riverwalk along the Cape Fear waterfront is Wilmington's top tourist attraction. It's lined with hotels, restaurants, and other businesses. But this is a tidal river, and every once in a while when tides peak, during what's called a "spring tide" or "King Tide," Water Street lives up to its name.
"The folks who have businesses on Water Street may regret the name of the street because it's got high-tide flooding water in it all too often, and that's only going to continue to get worse," said Larry Cahoon, a UNC Wilmington professor who has been analyzing Wilmington's tide gauge data for nearly 25 years.
Cahoon said with sea-level rise, high tides are higher and that means those "every once in a while" floods are more frequent.
High-tide flooding also plagues the battleship USS North Carolina Memorial, across the river.
"It's been getting worse by the day," said Christopher Vargo, the site's assistant director. "When I started here 12 years ago, we would flood with high tide, full moon, wind out of the south, blowing water up the river, or a major rain event. But now we essentially flood every high tide. It's pretty dramatic."
Flooding at the riverfront tourist site has risen from 20 days a year in 2011 to 175 days in 2020, according to data on the battleship website.
Sea level rise speeds up
All along the East Coast, sea level rose by about one foot in the past century. And the trend is accelerating: Federal scientists predict it will rise another foot in just the next three decades. The National Oceanic and Atmospheric Administration, or NOAA, said in a new report out this month that the country saw a record number of high-tide flood days over the past year.
"Events like hurricanes get a lot of attention. But high tide flooding is one of the most tangible impacts of long-term sea-level rise, reminding us that while we brace for impact today, the United States must also plan for a wetter future," said Nicole LeBoeuf, who oversees NOAA's National Ocean Service.
By 2050, NOAA predicts coastal communities nationwide will average 45 to 85 high-tide flood days per year. That's 10 times the current rate. And some places could see even more.
"That means every four to eight days, Americans along our coast will face disruptive and damaging sea water inundation, regardless of the weather at the time," LeBoeuf said.
NOAA says 34 communities nationwide broke or tied records for high-tide flood days over the past year. They included Charleston, South Carolina (17 days); Duck at the Outer Banks (22); Atlantic City (26); and the Battery, at the tip of Manhattan (24). On average, coastal communities in the Southeast saw about 10 high-tide flood days between May 2023 and April 2024.
It's worth noting that NOAA counts only more serious flooding - about 2 feet above high tide. But flooding also can be a problem at lower levels. That means many coastal areas saw even more days of high tide flooding than NOAA's numbers.
Wilmington averaged one day a year of high-tide flooding in 2000. In recent years that has ranged from two to five. By 2050, it's expected to be 40 days annually, says NOAA oceanographer William Sweet. Other North Carolina communities could be worse off. Predictions are for up to 110 days a year of high-tide flooding in Dare County and up to 70 for Emerald Isle and Beaufort.
"Decades worth of sea level rise is catching up. In places in North Carolina, water is, quite frankly, nearing the brim," said Sweet.
Two main factors contribute to sea level rise, says UNC Wilmington's Larry Cahoon.
"One is the expansion of seawater as it warms up. Warm water is less dense than cold water, and as you warm the water up, it literally expands," Cahoon said. "You can demonstrate that for yourself real easily. You put a pot full of water on the burner and turn it up, and it'll overflow before it boils. The other factor is that we're melting ice at a very high rate compared to historic levels."
Melting ice sheets
NASA satellite data show billions of tons of continental ice are lost every year, even accounting for seasonal changes in the size of the ice sheet. That's a net loss of 150 billion tons a year in Antarctica about 270 billion tons in Greenland, says NASA.
That raises sea levels and translates into higher tides and more flooding in coastal communities, especially during the highest tides of the year. Those "King Tides" happen when the sun, earth, and moon align and the moon is at its closest point to earth. The next window for these extra-high tides is mid-September.
Another factor in flooding is that coastal land is subsiding in some areas of the East Coast, Cahoon said.
In North Carolina, high-tide floods happen from Duck, Oregon Inlet, and Rodanthe on the Outer Banks south to Beaufort and Wilmington and to Carolina Beach, where NOAA documented 60 days when water flooded roads at high tide over the past year — not including storm-driven flooding.
"If you go to Carolina Beach and drive down what they call Canal Drive, there will be a significant amount of water in that street during a King Tide event. Matter of fact, they have no-wake zones posted along the street there, because people insist on driving through the water and the wake from the cars causes trouble for the lawns and that sort of thing," Cahoon said.
Flooding at Carolina Beach was the subject of a Washington Post report in June. Reporter Brady Dennis and his colleagues set up time-lapse cameras at five locations during a King Tide. Videos show water rising over waterfronts and sea walls, and even coming up through storm drains. Dennis spent hours watching the water rise.
"As the high tide approaches, there is this kind of wild … tipping point might be a good way to explain it, where it just reaches a point where there's nowhere else for the water to go, and the drains, or the groundwater coming up, water spilling into low lying areas, and it all just takes over the road," Dennis said. "In I would say 20 to 30 minutes, the road just filled up with water and was like a foot or more deep."
Flooded streets are an inconvenience for drivers and homeowners. But high-tide flooding has other long-term consequences. It can lead to repeated and expensive insurance claims for property owners. Pollution from chemical runoff, sewer overflows, and trash can bring public health concerns. The disruption can hurt businesses financially. And saltwater intrusion can damage roads, corrode pipes and equipment and threaten agriculture.
Even a couple of inches of water can be destructive, said NOAA oceanographer Analise Keeney.
"The long and the short of it is that we have to plan for where this water is moving, knowing that sea levels are rising. Sea levels end up creating more, like, you know, saline and salt water that comes up to our coastlines and into our infrastructure, that has the potential to degrade things over time," Keeney said.
Solutions can be expensive. Many flood-prone communities require new buildings and homes to be elevated. The federal flood insurance program may require the same for existing homes being rebuilt after floods.
In Wilmington, the USS North Carolina is closing part of its parking area and raising the level of the rest of the lot by three feet. It's part of a $4 million project called "Living Waters" to be completed in January. And repeated flooding has forced the Army Corps of Engineers to consider abandoning its engineering yard on Eagles Island, near the Cape Fear bridge.
Experts say more public officials, businesses, and homeowners in coastal areas need to be thinking about how to adapt. Rob Moore with the Natural Resources Defense Council wants to see better planning that takes sea level rise into account.
"You need to be asking what is the future going to look like? And what changes do we need to make in building codes, zoning ordinances, [and] land use regulations? How do we make the right decisions today that are going to hold up in a very climate-altered future," Moore said.
Moore said that in the past, before climate change became so evident, we humans had the luxury of assuming the future would look a lot like the past, and we didn't need to change our ways.
That's no longer true, Moore said.
