Antarctic ice-sheet sensitivity to obliquity forcing enhanced through ocean connections
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...
Published in: | Nature Geoscience |
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Main Authors: | , , , , , , , , , , , , , , |
Other Authors: | , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
2019
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Subjects: | |
Online Access: | http://hdl.handle.net/2122/12804 https://doi.org/10.1038/s41561-018-0284-4 |
Summary: | 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 |
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