Antarctic role in Northern Hemisphere glaciation

• Published in: Science
• Main Authors: Woodard, Stella C., Rosenthal, Yair, Miller, Kenneth G., Wright, James D., Chiu, Beverly K., Lawrence, Kira T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science (AAAS) 2014
• Subjects: Antarctic; Pacific; Antarc*; Antarctica; North Atlantic Deep Water; North Atlantic
• Online Access: http://dx.doi.org/10.1126/science.1255586; https://www.science.org/doi/pdf/10.1126/science.1255586

Earth’s climate underwent a major transition from the warmth of the late Pliocene, when global surface temperatures were ~2° to 3°C higher than today, to extensive Northern Hemisphere glaciation (NHG) ~2.73 million years ago (Ma). We show that North Pacific deep waters were substantially colder (4°C) and probably fresher than the North Atlantic Deep Water before the intensification of NHG. At ~2.73 Ma, the Atlantic-Pacific temperature gradient was reduced to <1°C, suggesting the initiation of stronger heat transfer from the North Atlantic to the deep Pacific. We posit that increased glaciation of Antarctica, deduced from the 21 ± 10–meter sea-level fall from 3.15 to 2.75 Ma, and the development of a strong polar halocline fundamentally altered deep ocean circulation, which enhanced interhemispheric heat and salt transport, thereby contributing to NHG.