Caribbean Climate Reconstructions Using Coral Skeletal Geochemistry: Initial Results From Puerto Rico

The Northern Caribbean Sea influences many Atlantic climate processes, including: the North Atlantic Oscillation, Tropical Atlantic Variability, Meridional Overturning Circulation, the varying influence of the Pacific El Nino-Southern Oscillation, and air-sea interactions in the Western Hemisphere Warm Pool. Understanding of decadal- to multidecadal-scale Atlantic climate variability has been inhibited by the temporal limits of the instrumental record. Climate-sensitive geochemical variations in corals have the potential to extend our knowledge of climate variability back in time, although currently very few continuous records of Atlantic climate variability from corals have been published. Coral cores from La Parguera, Puerto Rico were collected during August 2004 to reconstruct ocean conditions in the northern Caribbean over the past 200-300 years. The goals of this project are three-fold: 1) describe the thermal and hydrologic variations in the surface waters of the northern Caribbean, 2) investigate the nature of the relationships between climatic conditions in the Caribbean and other regions including the tropical Pacific and North America, 3) explore the possible changes in the proportion of North Atlantic versus South Atlantic waters entering the Caribbean and determine the effects (if any) on the density characteristics of the waters leaving the Caribbean, which contribute a substantial proportion of the water in the Gulf Stream. Acquisition of geochemical data representing surface temperature (Sr/Ca, (δ ¹⁸O), hydrologic variations (δ ¹⁸O), and ocean mixing (¹³C) is in progress. Newly collected elemental ratio data are compared with instrumental records of local to regional sea surface conditions and are used to reconstruct sea surface temperature.