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

• Published in: Nature Geoscience
• Main 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
• Other Authors: #PLACEHOLDER_PARENT_METADATA_VALUE#, Istituto Nazionale di Geofisica e Vulcanologia (INGV), Sezione AC, Roma, Italia
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2019
• Subjects: :MIDDLE MIOCENE CLIMATE; SEA-LEVEL; ROSS SEA; HEMISPHERE CLIMATE; CONTINENTAL-SHELF; ODP SITE-1165; PRYDZ BAY; SOUTHERN; INTENSIFICATION; HISTORY; Antarctic; Prydz Bay; Ross Sea; The Antarctic; Antarc*; Ice Sheet; Sea ice
• Online Access: http://hdl.handle.net/2122/12804; https://doi.org/10.1038/s41561-018-0284-4

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. Published 132-137 1A. Geomagnetismo e Paleomagnetismo 4A. Oceanografia e clima 5A. Ricerche polari e paleoclima JCR Journal