Tropical Atlantic Temperature Seasonality at the End of the Last Interglacial

Abstract:

The end of the last interglacial period, ~118 kyr ago, was characterized by substantial ocean circulation and climate perturbations resulting from instabilities of polar ice sheets, which are partially comparable to those projected for future climate change. The seasonal temperature changes of the tropical ocean, however, which play an important role in seasonal climate extremes such as hurricanes, floods and droughts at the present day, are not well known for this period that lead into the last glacial. Here we present a monthly resolved snapshot of reconstructed sea surface temperature variability in the tropical North Atlantic Ocean for 117.7 ± 0.8 kyr ago, using fossil coral (Diploria strigosa) Sr/Ca and δ¹⁸O records from Bonaire (Caribbean Netherlands). Our 20-year snapshot of reconstructed sea surface temperature variability for the end of the last interglacial is compared with Bonaire monthly coral Sr/Ca and δ¹⁸O records for snapshots since the mid-Holocene, comprising a total length of 295 years. We find that temperature seasonality in the southern Caribbean Sea at the end of the last interglacial was relatively stable and similar to today. Our coral records and simulations with a coupled atmosphere-ocean general circulation model (COSMOS) indicate an orbital control on temperature seasonality in the tropical North Atlantic at the end of the last interglacial, despite the large-scale perturbations of ocean circulation and climate during this period, and suggest that temperature seasonality of the tropical surface ocean was a relatively stable feature of the ocean-atmosphere system at the end of the last interglacial.