Rise in sea level threatens Atlantic coastline

Sea-level rise could imperil low-lying areas along the length of the Atlantic Coast, but people are still building beach houses and condominiums there, which could lead to hard decisions about what to save, according to a scientific study released Tuesday.

The study, published in the journal Environmental Research Letters, mapped coastal development from Florida to Massachusetts and found that about 60 percent of the lowest land along the shoreline is built up or probably will be. Thirty-three percent is rural land that might be developed in the future.

That could become a problem, said Will Nuckols, who wrote the report with state and federal scientists. Over the next century, many scientists expect sea levels to rise between 7 and 24 inches as climate change melts polar ice and causes the world's oceans to warm and expand in volume.

Nuckols, a scientist and consultant, said there might not be enough money to build the bulkheads, seawalls and levees that would be necessary to hold back the water across such a wide area.

"If the water's going to come up, and we're going to have to protect big chunks of the coast, somebody's going to have to figure out how to do that," Nuckols said. For now, he said, there isn't much of a plan behind coastal development: "We're just sort of stumbling along in this direction, not with a lot of thought."

In Maryland, the study found that the fate of the Atlantic Coast is obvious: condo-studded Ocean City would probably be protected from rising waters, even at high cost. The rest of the state's ocean coast is a federal wilderness, Assateague Island National Seashore, where the coastline would probably recede naturally.

Less clear, the study found, is what will happen along the state's Chesapeake Bay shorelines. The Eastern Shore's Dorchester County, for instance, has vast areas that might flood.

In Virginia, the Atlantic Coast is almost all protected wilderness, the study found. But along the Chesapeake, it found that development was spreading into low-lying regions along bays and rivers.

In the District, the study found, the shoreline of the Potomac and Anacostia rivers is built up and will probably remain so. The only place where sea-level rise might be a threat, the study found, is on the wooded shores of Theodore Roosevelt Island.