Abrupt Climate Change During the Last Interglacial: Testing a New Approach to U-Series Coral Dating and Sea-Level Reconstruction

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Abrupt Climate change during the Last Interglacial: Testing a new approach to U-series coral dating and sea level reconstruction.AbstractThe objectives of this project are twofold: First, we will test a promising new approach to U/Th coral dating and sea level reconstruction. Second, we will test an emerging hypothesis that sea level during the last interglacial was quite variable. The most pressing problem in U/Th dating of older fossil corals is a well-documented disturbance of the U-series isotopes that are used for dating, thereby creating a paucity of specimens for analysis. Recent advances in U/Th dating of corals suggest that it is possible to correct for these disturbances, thereby producing coherent and reproducible results. Sea level reconstructions using corrected ages suggest that last interglacial sea level was more variable that previously thought. If these implied sea-level oscillations are in fact real, it has serious implications regarding the stability of our present climate and requires a rethinking of proposed mechanisms for rapid climate change. In this proposal, we will conduct high-resolution sampling of outcrops of last interglacial fossil reefs at Barbados, the Bahamas, and Western Australia in order to analyze the age reproducibility of corals within and between samples. Agreement of ages within stratigraphic layers will provide strong support for their accuracy and differences will help define the limits and precision of the method. Discrepancies within and between individual records will guide future efforts in sea-level reconstruction. If this new approach proves robust, it will lead to significant improvements in sea level chronologies for the past 600,000 years and will provide a more complete database for future research on the mechanisms and ice sheet response to rapid climate change. This project will fund a new PI and will involve undergraduates from Smith College and Wooster College of Ohio in sampling and mapping fieldwork.