Global Cooling During the Eocene-Oligocene Climate Transition

Zhonghui Liu, Yale University
Mark Pagani, Yale University
David Zinniker, Yale University
Robert M. Deconto, University of Massachusetts - Amherst
Matthew Huber, Purdue University
Henk Brinkhuis, Utrecht University
Sunita R. Shah, Harvard University
Ann Pearson, Harvard University

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DOI: 10.1126/science.1166368

Abstract

About 34 million years ago, Earth's climate shifted from a relatively ice-free world to one with glacial conditions on Antarctica characterized by substantial ice sheets. How Earth's temperature changed during this climate transition remains poorly understood, and evidence for Northern Hemisphere polar ice is controversial. Here, we report proxy records of sea surface temperatures from multiple ocean localities and show that the high-latitude temperature decrease was substantial and heterogeneous. High-latitude (45 degrees to 70 degrees in both hemispheres) temperatures before the climate transition were ∼20°C and cooled an average of ∼5°C. Our results, combined with ocean and ice-sheet model simulations and benthic oxygen isotope records, indicate that Northern Hemisphere glaciation was not required to accommodate the magnitude of continental ice growth during this time.