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.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Medicine (all); Multidisciplinary; Antarctic; Ross Sea; Antarc*; Antarctica; Ice Sheet
• Online Access: http://hdl.handle.net/11365/1007376; https://doi.org/10.1126/science.aab0669; http://science.sciencemag.org/content/sci/352/6281/76.full.pdf

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.