CARIBEAN CLIMATE SINCE 1469: A CORAL PERSPECTIVE ON SEASONAL, MULTIDECADAL AND CENTENNIAL VARIABILITY

The tropical North Atlantic Ocean, including the Caribbean Sea, is an integral part of the primary modes of Atlantic climate variability, including the Atlantic Meridional Overturning Circulation (MOC) and multidecadal-scale hemispheric surface temperature anomalies (Atlantic Multidecadal Variability, AMV). However because modern climate and ocean circulation records are relatively short, it is unclear if AMV noted in the 20^th century is a persistent feature of the Atlantic climate system, if it is connected to MOC, and if the tropical Atlantic plays an active or passive role in the process. Isotopic and elemental ratio data from two continuous coral cores that grew offshore from Puerto Rico are used to reconstruct climate variability in the Caribbean region since the beginning of the Little Ice Age. New data include annually-resolved coral Sr/Ca and δ¹⁸O records spanning the years 1469 to1669. Spectral analysis of data from both cores indicate a persistent ~60 year period signal that appears to be primarily temperature-related in the earlier part of the record but is associated with a shift in the trade winds and the regional salinity gradient over the period of overlap with the instrumental record. We find that the northern Caribbean was relatively cool during most of the Little Ice Age, with a ~2˚warming trend since about 1750, broadly consistent with other temperature reconstructions of this region. Oxygen isotope data from core sections sampled at monthly resolution show no significant change in the seasonal cycle over the significant shift in mean temperature. These new data demonstrate that AMV is a persistent feature of the modern tropical Atlantic Ocean, at least over the last 540 years, paving the way for more process-oriented studies on its relationship to MOC and global climate processes.