Twenty percent of the more than 700 places on UNESCO’s list of World Heritage Sites could be inundated by rising global sea levels if nothing is done to stem the tide of rising greenhouse gas emissions worldwide, according to a new study.

Released this week by the Potsdam Institute for Climate Impact Research and the University of Innsbruck, the study examines the outlook for rising sea levels during the next 2,000 years. Because so many World Heritage sites are located in population centers on or near the coast, they’re particularly vulnerable to climate change impacts.

“The physical processes behind the global rise of the oceans are gradual, but they will continue for a very long time,” Ben Marzeion, a climate scientist at the University of Innsbruck and a study co-author, said in a press release.

“One hundred thirty-six sites will be below sea level in the long run in that case if no protection measures are taken,” he added. “The fact that tides and storm surges could already affect these cultural sites much earlier has not even been taken into account.”

To determine which sites were at risk, the scientists computed how far sea levels would rise for each degree of future global warming — a range the Intergovernmental Panel on Climate Change has said could reach between 2.6 C and 4.8 C by 2100, if nothing is done to control GHG emissions.

After mapping out where sea levels reached, they applied their calculations to the locations of the World Heritage sites, places identified by the United Nations for their historical and cultural significance like New York’s Statue of Liberty, the Tower of London and Italy’s Leaning Tower of Pisa.

The study’s authors looked out 2,000 years largely because projections for global sea level rise during the next century vary widely (between roughly one and three feet in last September’s IPCC report, which some scientists say is too conservative), to smooth out any uncertainties in long-term forecasts.

Also, today’s UNESCO sites could still be here 2,000 years from now, as many of those on the list now are 2,000 years or older.“It’s relatively safe to say that we will see the first impacts at these sites in the 21st century,”Marzeion told The Guardian.

“Typically when people talk about climate change it’s about the economic or environmental consequences, how much it’s going to cost,”he added.“We wanted to take a look at the cultural implications.”

Read the full study here, or visit DrownYourTown for the Google Earth template to create the sea-level rise visualizations above.