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Rising Seas Threaten to Swallow These Ten Global Wonders

Climate change-induced increases in sea level are forcing archaeologists and communities to get creative and make tough calls

Reproduction of early English vessels at Jamestown, Virginia. (NOAA)

Not all of the world's treasures are kept in museums. Cultural heritage sites—historic cities, monuments and archaeological sites—inspire awe and show the best of humanity throughout time.

Yet cultural heritage sites around the world face a host of impending threats, and perhaps none seems more inevitable than rising seas fueled by melting ice caps. “It’s one of the most dramatic effects of climate change,” says May Cassar, a professor of sustainable heritage at University College London.

While the drama of submerged landmarks piques the artistic imagination, it’s a harsh reality that both scientists and local communities will soon have to cope with. Current projections suggest that by 2100, sea levels may rise by six feet on average. Earlier this summer, researchers reported that sea-level rise is speeding up, and according to estimates released this month, burning off Earth’s remaining fossil fuels would completely melt the Antarctic ice sheet and raise sea levels by 190 feet.

If things continue unchanged, many coastal sites of historical and cultural significance will be underwater. “We have to deal with that knowledge and make some prioritizations,” says Adam Markham of the Union of Concerned Scientists. International organizations like the United Nations Educational, Scientific and Cultural Organization (UNESCO) compile lists of important sites, but determining what’s at most risk and what’s worth saving is no easy task.

Last year, climate scientists Anders Levermann and Ben Marzeion modeled how sea-level rise might play out at 720 UNESCO World Heritage sites. If global temperatures rise only moderately—by three degrees Celsius—over the next 2,000 years, their models suggest that 136 of these sites could be underwater, including the Tower of London and the Sydney opera house. However, predicting this worst-case scenario in the short term is a bit of a crapshoot.

Further complicating matters, sea-level rise can have other unintended impacts. Flood levels and frequencies may increase, and storm surges might be higher. That’s a problem because "a single storm can completely destroy a site," explains Tom Dawson, an archaeologist at St. Andrews University in Scotland.

Still, storms can also have beneficial effects. "What’s more likely is that a storm will do some damage but actually expose something in the process,” Dawson says. On Scotland's coasts, storms have revealed ancient dwellings and even skeletons of past inhabitants.

Coastal erosion is a more chronic issue that rising seas could exacerbate. “It’s not new, but it has gotten a lot worse. We’re kind of powerless against it,” says Torben Rick, an archaeologist at the National Museum of Natural History. Most coastal archaeological sites aren’t famous or flashy but contain evidence of how people lived thousands of years ago. “With every bit that erodes away, we’re losing a piece of cultural heritage,” says Rick.

On the plus side, the impending demise of some sites has spurred new levels of creativity in efforts to preserve and record them—though photographs, excavations, ground-penetrating radar and land and aerial surveys. A startup called CyArk aims to create 3D digital blueprints of 500 heritage sites using lasers in the next five years.

Successful efforts will depend on local communities. “The focus is typically on the monument. But the focus also needs to be on the people that surround that monument,” says Cassar. Sea levels may displace a lot of coastal communities, but helping them survive and preserve heritage extends the life of those sites as well.

Ultimately, communities will have to make tough decisions about whether to try to preserve, move or abandon these areas. Here are ten sites that could face a watery fate:

Turtle Mound, Florida

It might not look like much, but Turtle Mound is a shell midden (basically an ancient trash heap of oysters, fish bones and clams) left behind by the Timucuan people who inhabited Florida’s shores around 1,200 years ago—long before Europeans arrived. At 35 to 50 feet tall, it’s one of the largest shell middens in North America.

By 2100, sea level is expected to rise 26.4 centimeters at Turtle Mound—combined with hurricanes and other storm surges, that will likely exacerbate coastal erosion at the site. To protect the mound, the National Park Service and the University of Central Florida constructed a living shoreline of oysters, grasses and mangrove trees to buffer the onslaught of waves.

Turtle Mound is one of a larger body of shell midden sites that line coasts around the globe—all at risk of being swallowed or eroded by rising seas. Many are thousands of years old and hold clues to how ancient cultures coped with life along the coast.

About Helen Thompson
Helen Thompson

Helen Thompson writes about science and culture for Smithsonian. She's previously written for NPR, National Geographic News, Nature and others.

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