The balmy islands of Seychelles couldn't feel farther from Antarctica, but their fossil corals could reveal much about the fate of polar ice sheets.

 

About 125,000 years ago, the average global temperature was only slightly warmer, but sea levels rose high enough to submerge the locations of many of today's coastal cities. Understanding what caused seas to rise then could shed light on how to protect those cities today.

 

By examining fossil corals found on the Indian Ocean islands, University of Florida geochemist Andrea Dutton found evidence that global mean sea level during that period peaked at 20 to 30 feet above current levels. Dutton's team of international researchers concluded that rapid retreat of an unstable part of the Antarctic ice sheet was a major contributor to that sea-level rise.

 

"This occurred during a time when the average global temperature was only slightly warmer than at present," Dutton said.

 

Dutton evaluated fossil corals in Seychelles because sea level in that region closely matches that of global mean sea level. Local patterns of sea-level change can differ from global trends because of variations in Earth's surface and gravity fields that occur when ice sheets grow and shrink.