SEMINAR: GEOTOPICS 1/14: Andrea Dutton, Future Sea Level Rise from Seychelles fossil reefs

[Kelly Jackson <kjackson@rsmas.miami.edu>]

Dr. Andrea Dutton

Department of Geological Sciences

University of Florida

What can fossil coral reefs in the Seychelles tell us about future sea level rise?

Monday, January 14, 2013
3:15, SLAB Seminar Room, S/A 103
Refreshments at 3:00 PM

Abstract: In the search for a eustatic signal of sea level change on glacial-interglacial timescales, the Seychelles ranks as one of the best places on the planet to study.  Owing to its location with respect to the former margins of ice sheets that wax and wane on orbital cycles, the local, or relative, sea level history is predicted to lie within a few meters of the globally averaged eustatic signal during deglacial and interglacial periods.  We have surveyed and dated fossil coral reefs from the last interglacial period to ascertain peak sea level and hence infer maximum retreat of polar ice sheets attained during this time interval.  Our results confirm a pattern of gradually rising sea level between ~129 and 125 thousand years ago (ka), with peak eustatic sea level attained at 125 ka or later at 9.0 ± 1.5 meters higher than present.  After accounting for thermal expansion and mountain glaciers, this sea-level budget would require 8 meters of polar ice sheet contribution, relative to today’s volume, whereby only ~2 meters or so are thought to have come from the Greenland ice sheet.  This result clearly identifies the Antarctic ice sheet as a significant source of melt water (as much as 6 meters of ice-equivalent sea level), and implicates the East Antarctic ice sheet as well as the more unstable, marine-based West Antarctic ice sheet.