Title

Antarctic ice sheet sensitivity to atmospheric CO 2 variations in the early to mid-Miocene

Authors

Richard Levy, GNS Science
David Harwood, University of Nebraska–Lincoln
Fabio Florindo, Istituto Nazionale Di Geofisica E Vulcanologia, Rome
Francesca Sangiorgi, Utrecht University
Robert Tripati, University of California, Los Angeles
Hilmar von Eynatten, Universität Göttingen
Edward Gasson, University of Massachusetts Amherst
Gerhard Kuhn, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
Aradhna Tripati, University of California, Los Angeles
Robert Deconto, University of Massachusetts Amherst
Christopher Fielding, University of Nebraska–Lincoln
Brad Field, GNS Science
Nicholas Golledge, GNS Science
Robert McKay, Victoria University of Wellington
Timothy Naish, GNS Science
Matthew Olney, Hillsborough Community College
David Pollard, Pennsylvania State University
Stefan Schouten, Royal Netherlands Institute for Sea Research - NIOZ
Franco Talarico, Università degli Studi di Siena
Sophie Warny, Louisiana State University
Veronica Willmott, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
Gary Acton, Sam Houston State University
Kurt Panter, Bowling Green State University
Timothy Paulsen, University of Wisconsin Oshkosh
Marco Taviani, Istituto Di Scienze Marine Bologna
Rosemary Askin
Clifford Atkins, Victoria University of Wellington
Kari Bassett, University of Canterbury
Alan Beu, GNS Science
Brian Blackstone, University of Nebraska–Lincoln
Gregory Browne, GNS Science
Alessandro Ceregato, Consiglio Nazionale delle Ricerche
Rosemary Cody, Victoria University of Wellington

Document Type

Article

Publication Date

3-29-2016

Abstract

Geological records from the Antarctic margin offer direct evidence of environmental variability at high southern latitudes and provide insight regarding ice sheet sensitivity to past climate change. The early to mid-Miocene (23-14 Mya) is a compelling interval to study as global temperatures and atmospheric CO 2 concentrations were similar to those projected for coming centuries. Importantly, this time interval includes the Miocene Climatic Optimum, a period of global warmth during which average surface temperatures were 3-4 °C higher than today. Miocene sediments in the ANDRILL-2A drill core from the Western Ross Sea, Antarctica, indicate that the Antarctic ice sheet (AIS) was highly variable through this key time interval. A multiproxy dataset derived from the core identifies four distinct environmental motifs based on changes in sedimentary facies, fossil assemblages, geochemistry, and paleotemperature. Four major disconformities in the drill core coincide with regional seismic discontinuities and reflect transient expansion of grounded ice across the Ross Sea. They correlate with major positive shifts in benthic oxygen isotope records and generally coincide with intervals when atmospheric CO 2 concentrations were at or below preindustrial levels (∼280 ppm). Five intervals reflect ice sheet minima and air temperatures warm enough for substantial ice mass loss during episodes of high (∼500 ppm) atmospheric CO 2 . These new drill core data and associated ice sheet modeling experiments indicate that polar climate and the AIS were highly sensitive to relatively small changes in atmospheric CO 2 during the early to mid-Miocene.

Publication Source (Journal or Book title)

Proceedings of the National Academy of Sciences of the United States of America

First Page

3453

Last Page

3458

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