As sea levels rise, shorelines, homes, and cities will start flooding more frequently. But mitigation and adaptation strategies to deal with a changing climate that involves rising seas sometimes leave out plans for everything else in between.

A study published in PLOS One on Wednesday examined the impact rising sea levels will have on historical and archaeological sites, specifically those in the southeastern part of the United States.

The researchers involved found that the 1 meter of sea level rise will leave more than 13,000 archeological sites, that they classified as historic and prehistoric, under water. Not including an additional 1,000 or more sites that are eligible National Register of Historic Places sites that will also be, said the study.

Projections of when exactly sea level rise will reach a meter tend to vary. But by 2100, somewhere between 0.2 and 2 meters of sea-level rise is expected, according to NASA projections.

The reason for the wide range is that it’s difficult for researchers to predict emissions related to human activity, or the forcing that will happen to cause rise like sea ice melt. Climate models show that in a “business as usual” scenario, meaning emissions stay on track as-is, about a meter or so of sea level rise is expected by the end of the century, the authors of the study wrote.

Aside from those sites that will be submerged and lost due to flooding, the authors of the study also pointed out that historic locations will be altered by the relocation of those people who will be forced to flee their homes in low-lying areas and on the coast. To make their conclusions they examined the elevation and proximity to the coast along with projected rise of the historic sites in nine states along the southeast coast of the U.S. as well as along the Gulf of Mexico. There were more than 5,500 sites at or below sea level sites that would likely be the first to flood, with those lower-lying sites flooding soon thereafter.

The researchers suggest that creating and completing databases that could house information on when sites might flood and what was being done to protect them. The hope is that such databases will increase sample size and allow archaeologists and land managers to better prepare.

“Ultimately, what will be needed is a commitment, like that last seen in the Great Depression, to document that which will be lost if the effects of sea level rise are not mitigated,” the authors of the study wrote.

They even suggested buildings barriers around, or even moving, historic sites like the Lincoln and Jefferson Memorials in Washington, D.C. to save them from rising sea level.

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