Antarctic ice sheet sensitivity to atmospheric CO2variations in the early to mid-Miocene

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 atm...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences
Main Authors: Levy, Richard, Harwood, David, Florindo, Fabio, Sangiorgi, Francesca, Tripati, Robert, Von Eynatten, Hilmar, Gasson, Edward, Kuhn, Gerhard, Tripati, Aradhna, DeConto, Robert, Fielding, Christopher, Field, Brad, Golledge, Nicholas, McKay, Robert, Naish, Timothy, Olney, Matthew, Pollard, David, Schouten, Stefan, Talarico, Franco, Warny, Sophie, Willmott, Veronica, Acton, Gary, Panter, Kurt, Paulsen, Timothy, Taviani, Marco, Rocchi, Sergio, SMS Science Team
Other Authors: Deconto, Robert, Golledge, Nichola, Mckay, Robert, SMS Science, Team
Format: Article in Journal/Newspaper
Language:English
Published: 2016
Subjects:
Online Access:http://hdl.handle.net/11568/896750
https://doi.org/10.1073/pnas.1516030113
http://www.pnas.org/content/113/13/3453.full.pdf
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Summary: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 CO2concentrations 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 CO2concentrations 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 CO2. 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 CO2during the early to mid-Miocene.