By Sid PerkinsOct. 16, 2018 , 11:00 AM iStock.com/Givaga Sea-level rise could drown dozens of Mediterranean heritage sites Homes, businesses, and coastal infrastructure aren’t the only things endangered by sea-level rise: A new study suggests nearly 80% of World Heritage sites along the Mediterranean coast are at risk, too. These include the medieval city of Rhodes in Greece, the Kasbah of Algiers in Algeria, and Venice, Italy’s saltwater lagoon (above). An analysis of 49 such low-elevation sites reveals that by the year 2100, all or part of up to 40 will be endangered by storm surges that exceed the level of a 100-year flood, and as many as 46 of them will be threatened by coastal erosion.But nations seeking to protect these sites shouldn’t wait another 80 years to address the problems, researchers warn today in Nature Communications. That’s because 37 of the flood-prone sites and 42 of the erosion-prone sites are already vulnerable, although to a much smaller degree than they will be in the future.To save at-risk sites, some monuments could be moved to higher ground. But that will be impossible for large archaeological sites or urban areas, which will need to be protected through other measures, the researchers write. Some solutions could be as simple as sea walls. But others are more extreme: For example, Venice is now building—at an overall cost approaching €6 billion—a series of gates that can temporarily isolate the city’s lagoon from the Adriatic Sea during exceptionally high tides.