Even if the Norfolk base got all the money it needed, and hoisted everything out of the floodplain, it would be worthless if the surrounding cities weren’t protected too. Just to the south, on the far side of the Lafayette River, a tiny corner of Norfolk’s Larchmont-Edgewater neighborhood shows how difficult that will be. The area is home to many military families and is bisected by Hampton Boulevard, the main route between downtown and the naval station.

Beginning in 2010, the city gave in to the relentless creep of the water by converting a tiny park at the end of a finger-shaped inlet into a wetland. The project also raised a stretch of road that runs along the park. All told, the work cost $1.25 million. It worked, and on a drizzly May morning with a full-moon high tide, the new road was clear.

But the elevated section is only five houses long. Where the road curves along the sides of the inlet, the river had spilled over its banks, reaching past the street and up to the front lawn of a small brick house. Dark green wetland plants sprouted in the lawn. Just to the right, a nearly identical home sat jacked up on cinderblocks, the main floor at eye level, raised three feet above the base flood elevation, a requirement for any new construction.

Along its 144 miles of shoreline, Norfolk has to raise homes and roads, revamp drainage systems, build seawalls and replace concrete bulkheads with living shorelines and earthen berms. And these are not projects for later in the century.

“It’s a now problem,” said Skip Stiles, who runs a nonprofit called Wetlands Watch and is a leading advocate of adaptation in the region.

Norfolk is trying to embrace its extreme vulnerability as an opportunity, to become “the Silicon Valley of sea level rise,” said George Homewood, its planning director, whose business card is stamped with the city’s mermaid mascot. Norfolk received $120 million in federal funding last year to reshape another vulnerable neighborhood by elevating roads and erecting berms and floodwalls.

The city’s plans are laid out in “Vision 2100,” a document that describes how Norfolk can adapt over the next century. It divides the city into four zones, with a “red zone” of high risk and high value—including all of downtown and the naval base—where expensive fixes like seawalls are needed. (Part of downtown is already protected by a barrier erected after a storm flooded the area in 1962.) Much of the city’s shoreline, including Larchmont-Edgewater, falls in a “yellow zone,” where Norfolk cannot afford such expensive projects and will instead hope for a mix of innovation, private funding and, ultimately, planned abandonment.

The city says a rise of 2.6 feet would flood about 5 percent of its land on a daily basis and place nearly half of Norfolk in a high-risk flood zone. Most projections say such a rise will come some time in the second half of this century. And it won’t stop there. “The numbers we’re playing with are 3 meters in 100 years,” Homewood said.

No one has ventured realistic estimates for costs, but everyone seems to agree there won’t be enough money to protect everything. “How much money as a country are we going to put into Norfolk, Virginia? Is it $1 billion? Is it $10 billion? Is it $50 billion?” asked Titley, the retired admiral. “Over the next century or so, we’re talking at least in the tens of billions and probably in the hundreds of billions to protect parts of Hampton Roads.”

The 2013 state-sponsored study, which projected 1.5 feet of sea level rise within 20 to 50 years, said it takes two to three decades to plan and implement adaptation strategies. “We’re rapidly approaching the go/no-go point,” Stiles said. He pointed to a bridge in Virginia Beach that was first proposed in 2005 and is slated for completion next year. “That’s 13 years for a four-lane bridge. So if we don’t start pretty soon thinking about adding additional margins of safety, the ribbon cutting on the decisions we’re making today will be done in 15 or 20 years and the water will be X feet higher.”

At high tide, Stiles drove to the Hague, a crescent-shaped inlet where the Elizabeth River enters one of Norfolk’s historic neighborhoods. The Army Corps of Engineers is considering installing a tide gate on the inlet, at a cost of $70 to $90 million. Stiles stopped in the parking lot of an apartment building at the edge of the water and got out to look towards the Chrysler Museum, a grand limestone construction at one end of the inlet.

The Hague was spilling over its banks, covering the entire road ahead. “They’ll build this up,” he said, musing about what the area might look like in a few decades. “They’ll build a wall, they’ll put pumps in, they’ll protect it. But 80 years? That’s the head-scratcher. Because if in 80 years we get three feet of water …” Three feet would have put Stiles thigh-deep. “It’s hard to imagine a lot of this stuff still being here.”