Scientists Excavate Ancient Submerged Cities for Clues to Our Fate

Prehistoric humans moved their communities away from disappearing coasts, but it won’t be so easy for us.

(Photo: J. Henderson)

Oct 20, 2014· 1 MIN READ
Editor, reporter, and radio producer Zachary Slobig has covered coastal issues for Outside, NPR, Los Angeles Times, and many others.

With new research showing sea levels at their highest in 6,000 years, archaeologists are investigating the submerged ruins of early human settlements for hints to their destiny—and our own.

The emerging field of continental shelf prehistoric research, spurred by developments in remote sensing and ocean exploration technology, combines archaeology, geosciences, and oceanography to discover and analyze those communities now underwater. Much of the activity is centered in Europe, where some 2,500 sites have been located, most of them remaining unmapped or excavated, according to a new paper by the European Marine Board.

Europe was 40 percent larger 20,000 years ago and was the site of early human settlements. Clues to their social structure, technology, and, perhaps most important, response to sea level change, now all lie beneath the waves.

“If you go back 100,000 years, sea level change was about one meter in 100 years,” said Nicholas Flemming, a marine archaeologist at the University of Southampton and lead author of the report. “You would have noticed it. You would remember your grandfather telling you where the coast was when he was a boy.”

Around 5,000 years ago, human settlements began to get larger and more complex—and the footprint of those villages can be traced away from shorelines. “You can see as the sea level comes up how villages were abandoned and people built a mile farther from the shore,” said Flemming. “In the southern Baltic, you see that clearly, and also on the coast of Israel.”

Our own coastal cities are not as portable though. Some cities have begun to implement managed retreat practices that place infrastructure away from rising seas, but most low-lying coastlines remain at risk.

“We’re infinitely more sensitive to changes of sea level than the early Mesolithic or Paleolithic people,” said Flemming. “They lost a bit of hunting ground or fishing banks, but if we see a meter rise of the sea, we lose houses of Parliament and half of Tokyo. A meter to us means an awful lot.”

Marcy Rockman, the climate change adaptation coordinator for cultural resources with the National Park Service in the United States, points out that submerged sites on the U.S. coast, though far fewer than those in Europe, can also tell us how the earliest Americans reacted to changes in sea level.

Several promising sites on the southernmost tip of Florida await analysis, and she suspects the Gulf of Mexico may also be rich in submerged archaeological settlements.

“So often when I hear about ‘resilience’ in climate change, the thought is ‘Well, we’ll get through it—we’ll bounce back,’ ” said Rockman. “But when you add in the evidence of physical anthropology, it’s clear that it was not without a cost. We must recognize the physical trauma, and what stress are we willing to bear needs to be part of the question.”

Flemming says it’s no great mystery how humans who lived with rising seas reacted—they retreated.

“We have to calculate the repercussions of the present situation in terms of how much real estate, capital, and population is located within a few meters of sea level,” he said. “We must ask what are we prepared to do to modify the rate of change in climate and rate of change in sea level?”