Abstract
In order to understand and predict climate in a world driven by anthropogenic influences, increased understanding of natural climate variability is vital. The doctoral dissertation presented here focuses on multi-decadal climate modes, and in particular, the Atlantic Multi-decadal Oscillation (AMO), and how it is expressed in the tropical to sub-tropical western Atlantic Ocean over the last ~700 years. Multi-decadal modes have been linked to weather around the Atlantic, and have also been correlated with the occurrence of anomalous climatic events (in both temperature and precipitation), although the relationship of these modes to anthropogenic impacts is still undefined. The study area for this project encompasses South Florida, the Bahamas, and the Caribbean; however, the dissertation begins with a review article covering the current published records and reconstructions of multi-decadal variability from the Atlantic sector. Beyond this, the research turns to the reconstruction of multi-decadal variability from biogenic carbonates, including corals and sclerosponges. Because Atlantic Multi-decadal Variability (AMV) is still poorly understood and current reconstructions diverge beyond the instrumental period, the use of long-lived coral and sclerosponge specimens allows for an examination of multi-decadal variability over the last several centuries. Two multi-century records of temperature and salinity are reconstructed from the geochemistry of a coral from coastal Florida and sclerosponge collected in the Bahamas. Additional analyses from corals collected throughout the Lesser Antilles are also examined to determine their sensitivity to Atlantic AMV for future work. The final chapter of this dissertation presents a study investigating the reproducibility and fidelity of some of the geochemical proxy techniques utilized in biogenic carbonates.