Please use this identifier to cite or link to this item: http://hdl.handle.net/2122/12804
Authors: Levy, Richard H.* 
Meyers, S. R.* 
Naish, T. R.* 
Golledge, Nicholas* 
McKay, R. M.* 
Crampton, James S.* 
DeConto, R. M.* 
De Santis, L.* 
Florindo, Fabio* 
Gasson, Edward G. W.* 
Harwood, D. M.* 
Luyendyk, B. P.* 
Powell, R. D.* 
Clowes, C.* 
Kulhanek, Denise* 
Title: Antarctic ice-sheet sensitivity to obliquity forcing enhanced through ocean connections
Issue Date: Feb-2019
Series/Report no.: 2/12 (2019)
DOI: 10.1038/s41561-018-0284-4
URI: http://hdl.handle.net/2122/12804
Keywords: :MIDDLE MIOCENE CLIMATE; SEA-LEVEL; ROSS SEA; HEMISPHERE CLIMATE; CONTINENTAL-SHELF; ODP SITE-1165; PRYDZ BAY; SOUTHERN; INTENSIFICATION; HISTORY
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.
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