Antarctic Ice Sheet variability across the Eocene-Oligocene
Details of Research
TitleAntarctic Ice Sheet variability across the Eocene-Oligocene boundary climate transitionAbstractAbout 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 greater than 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.AcknowledgementsThis research is an outcome of a 2-year project (PNRA 2004/4.09) partly funded by Programma Nazionale di Ricerche in Antartide (Italy). Also supported by NSF grants ANT-0424589, 1043018, and OCE-1202632 and by New Zealand Ministry of Business Innovation and Employment contract C05X1001(TN). Data are available from www.pangaea.de/.Funding Details1043018, NSF, National Science Foundation; ANT-0424589, NSF, National Science Foundation; OCE-1202632, NSF, National Science Foundation
