T14 Rapid Sea-Level Rise and Its Impacts: Past, Present, and Future I

Sunday, 4 November 2012
8:00 AM - 12:00 PM
219AB

SENSITIVITY AND STABILITY OF POLAR ICE SHEETS DURING PREVIOUS WARM CLIMATES: LESSONS FROM THE LAST INTERGLACIAL

Paper number: T14-11
Program: Technical Sessions
Time: 10:30 AM – 10:45 AM

Authors

Abstract

We are interested in the timing, stability, and magnitude of sea level changes during the last interglacial period, ~125,000 years ago, to ascertain the behavior of polar ice sheets during a previous warm climate. While the last interglacial period is not a perfect analogue for future sea level behavior, it can inform us with respect to the potential for rapid changes in sea level under amplified polar temperatures as well as the potential long-term commitment of sea level rise and associated polar ice melt back. Our approach to study this problem is multi-faceted, and includes: (1) compilation of age-elevation data of fossil corals that record former sea level position; (2) consideration of glacio-hydro-isostatic effects that must be combined with the observational data to extract meaningful interpretations of eustatic sea level change; and (3) field work in far-field localities to better constrain the eustatic sea level signal.

Using a combination of published observational data and glacio-hydro-isostatic modeling, we infer that the last interglacial sea level highstand peaked between 5.5 and 9 meters above present sea level, implying a strong sensitivity of polar ice sheets to a relatively modest increase in polar temperatures. Moreover, the sedimentary evidence in combination with the observational data suggest at least one rapid (<1000 years) sea level oscillation during the highstand, although the magnitude of the oscillation and the ice sheet(s) involved are not yet clear. Finally, recent field work that we conducted in the Seychelles implies that the sea level peak was at the upper end of our inferred range (9 m), which we attribute to loss of part of the Greenland Ice Sheet, the entire marine-based portion of the West Antarctic Ice Sheet, as well as adjacent sectors of both the West and East Antarctic Ice Sheet. The distribution of this budget of increased sea level from the various ice sheets remains speculative at this stage and requires additional evidence.