Coastal waters threaten Florida's historic resources

DAYTONA BEACH — The Castillo de San Marcos withstood two sieges in 330 years and changed hands five times, but its latest invader — the rising Atlantic Ocean — threatens to erode the historic St. Augustine fortress. The coquina shell walls of the oldest masonry fort in the United States once absorbed cannonballs but will be susceptible to the buffetings of the sea.

On the other side of the state, Egmont Key was named one of the state’s 11 most endangered places this year by the Florida Trust for Historic Preservation because rising seas threaten to submerge the island. Just outside Tampa Bay in the Gulf of Mexico, the island holds sacred significance for the Seminole Tribe of Florida, as well as the ruins of another Spanish-American era fort, but its elevation is just six feet.

“It’s the first project that we’ve placed on our annual endangered list because it’s endangered by sea level rise,” said Clay Henderson, president of the trust, when the key was added to the list earlier this year.

Like the St. Augustine fort and Egmont Key, thousands of Florida’s heritage sites are vulnerable to rising seas, said Henderson, executive director of Stetson University’s Institute for Water and Environmental Resilience. “Jupiter Lighthouse, Fort Zachary Taylor in Key West, Fort Jefferson and Fort Pickens in Pensacola — all of these places are threatened.”

“When you look at St. Augustine, the oldest city in existence in our country, and it’s flooded twice in the last year, these are real threats,” he said. “They’re no longer academic and off in the future. They’re in real time.”

Growing concerns

Similar concerns are growing across the state and country as experts begin to assess what could be damaged or lost and how soon that could happen. In some places, damage already is occurring.

Federal scientists say seas in parts of Florida have risen at a rate of about a third of an inch a year over the past decade. Mid-range forecasts from the National Oceanic and Atmospheric Administration indicate seas could rise anywhere from 13 to 39 inches in Florida by 2070 and as much as 72 inches by 2100.