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

• Published in: Science
• Main Authors: Galeotti, S., DeConto, R., Naish, T., Stocchi, P., Florindo, F., Pagani, M., Barrett, P., Bohaty, S.M., Lanci, L., Pollard, D., Sandroni, S., Talarico, F. M., Zachos, J. C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2016
• Subjects: Antarctic; Ross Sea; Antarc*; Antarctica; Ice Sheet
• Online Access: https://eprints.soton.ac.uk/393827/; https://eprints.soton.ac.uk/393827/1/Galeotti_et_al_2016_accepted_version_comb.pdf

About 34 million years ago (Ma) Earth’s climate cooled and an ice sheet formed on Antarctica as atmospheric CO2 fell below ~750 ppm. Sedimentary cycles from a drill core in western Ross Sea provide the first direct evidence of orbitally-controlled glacial cycles between 34–31 Ma. Initially, under atmospheric CO2 levels ? 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 Ma coincident with the first time atmospheric CO2 levels fell below ~600 ppm. Our results provide new insights into the potential of the AIS for threshold behavior, and its sensitivity to atmospheric CO2 concentrations above present day levels.