Publikationsdatum:
2022-04-22
Beschreibung:
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.
Beschreibung:
Published
Beschreibung:
132-137
Beschreibung:
1A. Geomagnetismo e Paleomagnetismo
Beschreibung:
4A. Oceanografia e clima
Beschreibung:
5A. Ricerche polari e paleoclima
Beschreibung:
JCR Journal
Schlagwort(e):
:MIDDLE MIOCENE CLIMATE; SEA-LEVEL; ROSS SEA; HEMISPHERE CLIMATE; CONTINENTAL-SHELF; ODP SITE-1165; PRYDZ BAY; SOUTHERN; INTENSIFICATION; HISTORY
Repository-Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Materialart:
article
Permalink
