By Mike Toner
Part of a 19th century communal house constructed of driftwood in Kuukpak along the Mackenzie River—which flows through a vast, thinly populated region of forest and tundra within the Northwest Territories in Canada—has collapsed toward the beach.
Photo: Max Friesen / University of Toronto
For as long as humans have inhabited North America, sea level has fluctuated—sometimes up, sometimes down. But since the continent’s ice sheets began melting 18,000 years ago, the trend has been mostly up. And in the rapidly warming world of the 21st century, sea levels have been rising at a faster pace, washing away thousands of years of the archaeological record. Some sites are likely to disappear even before they are discovered.
While modern cities along America’s coast grapple with the threat of rising seas, archaeologists at Jamestown, Virginia, are working urgently to salvage the remains of the first permanent English colony in America. The waters of Chesapeake Bay are a foot and a half higher than they were just a century ago. In another 50 years, much of Jamestown Island and its archaeological resources will be underwater. Jamestown, of course, will still have its written history. But along the coasts of Florida, Georgia, and the Carolinas, scores of ancient shell rings and mounds—the unwritten record of the region’s earliest inhabitants—are under siege, too. Some are crumbling so rapidly that burials are tumbling out of eroded bluffs. Archaeologists sometimes work with waves lapping at their feet to salvage what can be learned from the earliest structures built in the Americas while they can.
In the Arctic, the combined effects of rising seas and melting permafrost are eroding early Inuit villages so swiftly that researchers are being forced to do archaeological triage—deciding which of hundreds of threatened sites they can save and which they must let go. At Red Bay in Labrador, Canada, waves are eating at the remains of a 16th Century Basque whaling station. In Belize, rising seas have inundated ancient salt works that date to the Terminal Classic period of Maya Civilization a thousand years ago. Throughout the Caribbean, high water, higher tides, and storm surges are eroding traces of ancient Indigenous cultures spanning thousands of years. The massive 400-year-old wall at Hawaii’s Pu‘uhonua o Hōnaunau National Historical Park—once a refuge for defeated warriors—is now routinely battered by storms and high tides.
Recent history is no safer. At Fort Jefferson in the Dry Tortugas, 60 miles off the coast of Key West, the sea has collapsed portions of a surrounding moat and covered the ruins of a forgotten cemetery and quarantine station built less than two centuries ago, when the “impregnable” brick fort was known as the Gibraltar of the Caribbean. The National Park Service has spent $25 million to stabilize the fort but said long-term sustainability of the structure is uncertain.
South Carolina Department of Natural Resources Heritage Trust Archaeologist Karen Smith kneels in an excavation trench at Pockoy Island Shell Ring Complex.
Photo: Meg Gaillard / SCDNR
The annual increase in global sea level, currently a little over 3 millimeters—one tenth of an inch—does not sound like much. But year after year, the numbers add up. Worldwide, mean sea level (the average height of the ocean’s surface over time) is 3.3 inches higher than it was in 1993. But as the melting of glaciers and polar ice caps accelerates and the oceans themselves expand from warmer temperatures, the water is now rising twice as fast as it did 50 years ago. The National Oceanic and Atmospheric Administration predicts that sea level along the U.S. coastline will rise an average of 10 to 12 inches in the next 30 years. Along the Gulf and Atlantic coasts, where the problem is compounded by subsiding land, the relative increase could total a foot and a half.
That outlook, however, is clouded by uncertainties. If the world fails to slow the pace of global warming, NOAA says the increase in sea level by the end of the century could range from 3 to 7 feet. The outlook is not encouraging. So far, 2024 was the hottest in recorded history and, for the first time, global temperatures surpassed a critical threshold the Paris Climate Agreement deemed necessary to stave off more destructive impacts in the future. For the people who now live in low-lying coastal areas today, rising sea levels might seem to be a new problem. But humans have lived along the coast of the Americas for millennia. As waters rose, they eventually retreated. Much of the record of their time is already underwater and more is disappearing all the time.
This is an excerpt of Going, Going, Nearly Gone , in American Archaeology, Spring 2024, Vol. 29, and No. 1. Subscribe to read the full text.
FURTHER READING
- Digital Index of North American Archaeology (DINAA), open-source aggregated archaeological site data from past century
- National Landmarks at Risk, Union of Concerned Scientists (May 21, 2014)
- Why Seas Are Surging: What one tide gauge reveals about America’s climate future, John Muyskens, Simon Ducroquet, Kevin Crowe, Shannon Osaka and Niko Kommenda, The Washington Post (Dec. 20, 2024)
