Millennial‐scale sea surface temperature variability in the western tropical North Atlantic from planktonic foraminiferal census counts

Abstract

Planktonic foraminiferal census counts are used to construct high‐resolution sea surface temperature (SST) and subsurface (thermocline) temperature records at a core site in the Tobago Basin, Lesser Antilles. The record is used to document climatic variability at this tropical site in comparison to middle‐ and high‐latitude sites and to test current concepts of cross‐equatorial heat transports as a major player in interhemispheric climate variability. Temperatures are estimated using transfer function and modern analog techniques. Glacial‐maximum cooling of 2.5°'3°C is indicated; maximum cooling by 4°C is inferred for isotope stage 3. The SST record displays millennial‐scale variability with temperature jumps of up to 3°C and closely tracks the structure of ice‐core Dansgaard/Oeschger cycles. SST variations in part of the record run opposite to the SST evolution at high northern latitude sites, pointing to thermohaline circulation and marine heat transport as an important factor driving SST in the tropical and high‐latitude Atlantic, both on orbital and suborbital timescales.