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Predicting the rate and magnitude of future sea level rise is paramount to the management of coastal fresh-water resources. Because we do not have historical records for time periods warmer than present to provide potential analogues for future sea level change, another approach is needed to resolve the sensitivity of ice sheets and sea level to sustained warming. The response of sea level during the Last Interglacial (LIG) period (129,000 – 116,000 years ago), when the poles were a few degrees warmer than present, offers an opportunity to improve our understanding of how sea level will respond to current global temperature changes. During recent field work in the Seychelles, we observed two exposure horizons within fossil coral layers preserved from the LIG period. Each exposure horizon represents an ephemeral emergence that implies a brief drop in sea level. The observation that sea level oscillated at least twice on a meter scale during the LIG period implies significant dynamic changes in ice sheet volume resulting from small changes in temperature. If these rapid sea level oscillations did arise from only a few degrees of temperature change, then similar rapid changes may be possible in the future. As sea level rises, salt water intrudes into coastal potable aquifers: knowing the rate and oscillatory phase of such intrusion is crucial to the management of the remaining fresh water. |