title: Antarctic Ice Sheet variability across the Eocene-Oligocene boundary climate transition.
abstract: 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.
authors.affiliation: Dipartimento di Scienze Pure e Applicate, Università degli Studi di Urbino "Carlo Bo," 61029 Urbino, Italy. simone.galeotti@uniurb.it.
authors.forename: Simone
authors.initials: S
authors.lastname: Galeotti
authors.affiliation: Department of Geosciences, University of Massachusetts, Amherst, MA, USA.
authors.forename: Robert
authors.initials: R
authors.lastname: DeConto
authors.affiliation: Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand. GNS Science, P.O. Box 30368, Lower Hutt, New Zealand.
authors.forename: Timothy
authors.initials: T
authors.lastname: Naish
authors.affiliation: NIOZ Royal Netherlands Institute for Sea Research, Department of Coastal Systems, and Utrecht University, 1790 AB Den Burg, Texel, Netherlands.
authors.forename: Paolo
authors.initials: P
authors.lastname: Stocchi
authors.affiliation: Istituto Nazionale di Geofisica e Vulcanologia, 00143 Rome, Italy.
authors.forename: Fabio
authors.initials: F
authors.lastname: Florindo
authors.affiliation: Department of Geology and Geophysics, Yale University, New Haven, CT, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Pagani
authors.affiliation: Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand.
authors.forename: Peter
authors.initials: P
authors.lastname: Barrett
authors.affiliation: Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton SO14 3ZH, UK.
authors.forename: Steven M
authors.initials: SM
authors.lastname: Bohaty
authors.affiliation: Dipartimento di Scienze Pure e Applicate, Università degli Studi di Urbino "Carlo Bo," 61029 Urbino, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Lanci
authors.affiliation: Earth System Science Center, Pennsylvania State University, State College, PA, USA.
authors.forename: David
authors.initials: D
authors.lastname: Pollard
authors.affiliation: Museo Nazionale dell'Antartide, Università degli Studi di Siena, 53100 Siena, Italy.
authors.forename: Sonia
authors.initials: S
authors.lastname: Sandroni
authors.affiliation: Museo Nazionale dell'Antartide, Università degli Studi di Siena, 53100 Siena, Italy. Dipartimento di Scienze Fisiche, della Terra e dell'Ambiente, Università degli Studi di Siena, 53100 Siena, Italy.
authors.forename: Franco M
authors.initials: FM
authors.lastname: Talarico
authors.affiliation: Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA.
authors.forename: James C
authors.initials: JC
authors.lastname: Zachos