Milankovitch-Band Evolution of Tropical Sea Surface Temperatures Over the Plio- Pleistocene

Benthic foraminiferal oxygen isotope records indicate a transition from relatively warm and weakly variable high latitude conditions during the early and middle Pliocene (3-5 Ma) to increasingly cold, more variable, and more intensely glaciated conditions throughout the late Pliocene and Pleistocene (0-3 Ma). Here, we complement this high latitude perspective on Plio-Pleistocene climate evolution through analysis of three long, continuous, and highly resolved records of sea surface temperature (SST) changes in the tropics. We find that the eastern equatorial Pacific, eastern equatorial Atlantic, and Arabian Sea all record very similar SST histories beginning 2.7 Ma, coincident with the intensification of northern hemisphere glaciation. Amplified ice albedo and carbon cycle feedbacks associated with northern hemisphere glaciations were likely responsible for coupling SST responses throughout the tropics from this time forward. Intensification of the 41 kyr band SST response in the eastern equatorial Pacific beginning ~3 Ma may have provided the trigger for northern hemisphere glaciation, through feedbacks involving poleward heat export. Detailed analysis of the tropical surface ocean response across the mid-Pleistocene transition suggests that tropical SSTs evolved largely in tandem with the benthic foraminiferal oxygen isotope record over this interval.