Antarctic ice-sheet sensitivity to obliquity forcing enhanced through ocean connections

Richard H. Levy, Stephen Meyers, Timothy R. Naish, Nicholas R. Golledge, Robert M. McKay, James S. Crampton, R DeConto, Laura De Santis, Fabio Florindo, Ed Gasson, David Harwood, B. P. Luyendyk, R Powell, C Clowes, Denise K. Kulhanek

Research output: Contribution to journalArticle (Academic Journal)peer-review

33 Citations (Scopus)
221 Downloads (Pure)

Abstract

Deep sea geological records indicate that Antarctic ice-sheet growth and decay is strongly influenced by the Earth’s astronomical variations (known as Milankovitch cycles), and that the frequency of the glacial–interglacial cycles changes through time. Here we examine the emergence of a strong obliquity (axial tilt) control on Antarctic ice-sheet evolution during the Miocene by correlating the Antarctic margin geological records from 34 to 5 million years ago with a measure of obliquity sensitivity that compares the variance in deep sea sediment core oxygen-isotope data at obliquity timescales with variance of the calculated obliquity forcing. Our analysis reveals distinct phases of ice-sheet evolution and suggests the sensitivity to obliquity forcing increases when ice-sheet margins extend into marine environments. We propose that this occurs because obliquity-driven changes in the meridional temperature gradient affect the position and strength of the circum-Antarctic easterly flow and enhance (or reduce) ocean heat transport across the Antarctic continental margin. The influence of obliquity-driven changes in ocean dynamics is amplified when marine ice sheets are extensive, and sea ice is limited. Our reconstruction of the Antarctic ice-sheet history suggests that if sea-ice cover decreases in the coming decades, ocean-driven melting at the ice-sheet margin will be amplified.
Original languageEnglish
Pages (from-to)132-137
Number of pages7
JournalNature Geoscience
Volume12
Issue number2
Early online date14 Jan 2019
DOIs
Publication statusPublished - 14 Jan 2019

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