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Measuring fossil corals
At Anse Source d'Argent on La Digue Island in the Seychelles, researchers examine fossil corals in a limestone outcrop (in shadow, far left). These fossil corals have been measured as the highest fossil corals observed from the last interglacial period in this area.
About 125,000 years ago, the average global temperature was only slightly warmer than today, but sea levels raised high enough to submerge the locations of many of the world's modern coastal cities. Understanding what caused seas to rise could shed light on how to protect those cities today.
By examining fossil corals found in the Seychelles, Dutton found evidence that the global mean sea level during that period peaked at 20 to 30 feet above current levels. Her 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.
The researchers concluded that while sea-level rise in the last interglacial period was driven by the same processes active today--thermal expansion of seawater, melting mountain glaciers and melting polar ice sheets in Greenland and Antarctica--most was driven by polar ice sheet melt. Their study also suggests the Antarctic Ice Sheet partially collapsed early in that period.
This research was supported in part by National Science Foundation grant DEB 11-55495.
To learn more, see the UF news story On a tropical island, fossils reveal the past--and possible future--of polar ice. (Date of Image: August 2009)
Credit: Dan Zwartz
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