Antarctic Ice Sheet variability across the Eocene-Oligocene boundary climate transition

• Published in: Science
• Main Authors: GALEOTTI, SIMONE, Deconto, Robert, Naish, Timothy, Stocchi, Paolo, Florindo, Fabio, Pagani, Mark, Barrett, Peter, Bohaty, Steven M, LANCI, LUCA, Pollard, David, Sandroni, Sonia, Talarico, Franco M, Zachos, James C.
• Other Authors: Galeotti, Simone, Lanci, Luca
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Antarc*; Antarctic; Antarctica; Ice Sheet; Ross Sea
• Online Access: http://hdl.handle.net/11576/2632475; https://doi.org/10.1126/science.aab0669

About 34 million years ago, Earth's climate cooled and an ice sheet formed on Antarctica as atmospheric carbon dioxide (CO2) fell below ~750 parts per million (ppm). Sedimentary cycles from a drill core in the western Ross Sea provide direct evidence of orbitally controlled glacial cycles between 34 million and 31 million years ago. Initially, under atmospheric CO2 levels of ≥600 ppm, a smaller Antarctic Ice Sheet (AIS), restricted to the terrestrial continent, was highly responsive to local insolation forcing. A more stable, continental-scale ice sheet calving at the coastline did not form until ~32.8 million years ago, coincident with the earliest time that atmospheric CO2 levels fell below ~600 ppm. Our results provide insight into the potential of the AIS for threshold behavior and have implications for its sensitivity to atmospheric CO2 concentrations above present-day levels.