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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)
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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:

Skara Brae, Scotland

Perched on an eroding bluff on the Scottish island of Orkney, the Neolithic site called Skara Brae includes eight stone-walled houses built into the ground. Humans occupied the site from 3100 B.C. to 2500 B.C., and it's one of four sites flagged by UNESCO in the region as being of “outstanding universal value.”

A seawall protects Skara Brae from swells, but it’s taken a beating over the years, and rising tides may overcome the barrier. By the time global temperatures rise by more than 1.8 degrees Celsius, parts of those sites may be submerged. But the more immediate threat is coastal erosion. Archaeologists have worked to extensively excavate and document the site. Back in 2010, CyArk scanned Skara Brae along with other Neolithic sites in the region.

The larger issue is that Skara Brae is just one of thousands of archaeological sites along Scotland’s coast—and many more may await discovery. That’s why Tom Dawson, the St. Andrews archaeologist, and his colleagues started SCHARP, short for Scotland’s Coastal Heritage At Risk Project. The program enlists help from local communities in recording and documenting new sites revealed by changes in vegetation, storms and erosion through a smartphone app. They’ve recorded 11,000 sites so far. Recently, the citizen science project also helped scan and 4D model the Wemyss Caves, a series of seaside caves adorned with Pictish petroglyphs carved between 400 to 600 B.C.

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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