RALEIGH — Sea level on the North Carolina coast could rise by as little as 1.2 feet to as much as 4.6 feet this century, potentially reshaping the state's beaches and inshore coastline, a panel of scientists and engineers reported Friday.
The broad range reflects the measurable upward creep of the Atlantic and the uncertainty of how far and how fast it will go. Globally, sea-level rise has accelerated since the 1990s, and that trend is expected to continue.
Panel members, whose findings concluded a two-day science forum organized by the N.C. Division of Coastal Management, expect that the rise on the North Carolina coast will continue at a moderate clip - about 4 millimeters a year - for 25 years. But that pace could accelerate later in the century, scientists say, raising global seas 3feet or more by 2100.
At that point, researchers say, the protective Outer Banks would be shattered, leaving vast Pamlico Sound as virtually open ocean. Brackish wetlands that nurture much of the East Coast's young sea life could be drowned by saltwater. About 2,300 square miles of low-lying coastal land would be underwater or easily flooded.
Scientists say increasing storm activity and stronger waves predicted by climate change scenarios will magnify sea-level rise effects. North Carolina is among the states most vulnerable to rising seas, the National Oceanic and Atmospheric Administration says.
Coastal managers will use the estimates for planning purposes, which could widely affect the people who live and work in the 20coastal counties. Land management plans that include sea-rise projections, for example, could declare areas that are likely to flood off-limits to development.
Already, the N.C. Department of Transportation is beginning to consider rising water as it designs coastal bridges and highways.
"Having to be out there planning things that will last 50 years or so is perhaps the most challenging aspect" of the expected rise, said Margery Overton, a professor of civil engineering at N.C. State University, who led the panel.
The panel recommended that the state add more monitoring stations and revisit its estimates every five years.
But North Carolina is ahead of most states because of its retinue of coastal scientists and accurate data, useful in assessing risks, said Virginia Burkett, the U.S. Geological Survey's chief climate scientist.
On the Outer Banks, rising seas aren't the biggest threat occupying Nags Head officials. The town plans to spend $36 million to pump sand on its eroding beaches, where some houses have been undermined, and will continue an orderly retreat from the sea.
"It's an incremental change," Mayor Bob Oakes said. "We've been dealing with sea-level rise for the past 100 years."