Last Interglacial Sea Surface Temperature Variability in the Tropical Atlantic Warm Pool: A Comparison of Model and Coral-Based Reconstructions

The Last Interglacial (LIG), when sea level was ~6 m higher than today, serves as an analog for future climate scenarios yet only a few paleoclimatic reconstructions with seasonal to decadal resolution exist for this interval. Hispaniola, located in the northern Caribbean Sea, is a desirable site for producing sea surface temperature (SST) reconstructions as it is situated in the northern sector of the Atlantic Warm Pool (AWP), a primary moisture source region for precipitation in Central and North America, and this location has significant correlations with SST and precipitation anomalies for much of the AWP. Here we present an early LIG (128.6 ka) monthly-resolved coral SST reconstruction from a well-preserved Siderastrea siderea subfossil coral spanning 75 years from the northern coast of Hispaniola (19.913ºN, 70.925ºW). We compare our LIG SST reconstruction with three modern S. siderea microatolls, the longest spanning 84 years (1926–2010 CE) located near Port-au Prince, Haiti (18.479070°N, 72.668659°W), as well as the Community Climate System Model version 3 (CCSM3) 125 ka LIG model simulation spanning 300 years. We find similar SST seasonal cycles in the LIG coral (3.7ºC) and LIG simulation (3.8ºC) that are greater than those in the modern Haitian corals, observed SST (ERSSTv4.0 and HadISSTv1.1), and CCSM3 20th century simulations. This seasonal variability is consistent with the findings of other LIG coral reconstructions in the tropical Atlantic Ocean suggesting that orbital insolation changes are driving LIG SST seasonality in this region. Furthermore, our LIG reconstruction reveals larger multidecadal (2.8ºC, ~20–30 years/cycle) and interannual variability (3.0ºC, ~3–8 years/cycle) than the modern coral reconstructions and SST records in the AWP yet similar variability is present in the LIG model simulation but with a reduced magnitude. This interannual and decadal variability may reflect variations in the northern extent of the AWP on these time scales, which may covary with trade wind strength, westward moisture transport to the Americas, and precipitation in the Caribbean Sea region.