Sea Level Rise Threatens UNESCO World Heritage Sites

As sea levels rise and if current global warming trends hold true, dozens of UNESCO World Heritage list will be impacted by rising water, according to new research.

Writing in the journal Environmental Research Letters (open access), a team led by professor Ben Marzeion from the University of Innsbruck reports that a number of iconic cultural sites and historic city centers will be affected by sea level rise.

Among the sites that will be affected are the Tower of London, the Sydney Opera House, the Statue of Liberty and Independence Hall, the researchers report.

There are 720 cultural sites listed on the UNESCO World Heritage list. Marzeion and his colleagues found that if the current global temperature was sustained for the next two millennia, about 6 percent of the UNESCO sites (about 40) will be affected. Additionally, 0.7 percent of global land area will be below the mean sea level.

If temperatures rise by 3 degrees Celsius in the next 2,000 years - a scenario the researchers say is likely - then the number of UNESCO World Heritage sites affected rises to 136 (19 percent) and 1.1 percent of global land area will be below mean sea level. At this level of warming, the researchers contend that as many as 12 countries - including the Bahamas, the Maldives and the Cayman Islands - will lose more than half of their current land surface.

"Our results show that if there is a 3 degree Celsius temperature increase over the next 2,000 years, which seems likely to be reached and is generally considered not to be an extreme scenario, the impacts on global heritage would be severe," Marzeion said. "We've assumed that a heritage site is impacted when at least part of it is below local mean sea-level; however, tides and storm surges may dictate whether or not the site should be protected before sea-levels reach this point."

Marzeion said as continental ice melts due to increasing temperatures, sea levels will naturally rise. Because of the processes involved, this sea level rise will continue even after warming of the atmosphere has stopped, he said.

"After 2,000 years, the oceans would have reached a new equilibrium state and we can compute the ice loss from Greenland and Antarctica from physical models," said study co-author Anders Levermann, from the Potsdam Institute for Climate Impact Research. "At the same time, we consider 2,000 years a short enough time to be of relevance for the cultural heritage we cherish."