Publication Date:
2016-04-02
Description:
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.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉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 -- New York, N.Y. -- Science. 2016 Apr 1;352(6281):76-80. doi: 10.1126/science.aab0669. Epub 2016 Mar 10.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Dipartimento di Scienze Pure e Applicate, Universita degli Studi di Urbino "Carlo Bo," 61029 Urbino, Italy. simone.galeotti@uniurb.it. ; Department of Geosciences, University of Massachusetts, Amherst, MA, USA. ; Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand. GNS Science, P.O. Box 30368, Lower Hutt, New Zealand. ; NIOZ Royal Netherlands Institute for Sea Research, Department of Coastal Systems, and Utrecht University, 1790 AB Den Burg, Texel, Netherlands. ; Istituto Nazionale di Geofisica e Vulcanologia, 00143 Rome, Italy. ; Department of Geology and Geophysics, Yale University, New Haven, CT, USA. ; Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand. ; Ocean and Earth Science, University of Southampton, National Oceanography Centre, Southampton SO14 3ZH, UK. ; Dipartimento di Scienze Pure e Applicate, Universita degli Studi di Urbino "Carlo Bo," 61029 Urbino, Italy. ; Earth System Science Center, Pennsylvania State University, State College, PA, USA. ; Museo Nazionale dell'Antartide, Universita degli Studi di Siena, 53100 Siena, Italy. ; Museo Nazionale dell'Antartide, Universita degli Studi di Siena, 53100 Siena, Italy. Dipartimento di Scienze Fisiche, della Terra e dell'Ambiente, Universita degli Studi di Siena, 53100 Siena, Italy. ; Earth Sciences Department, University of California, Santa Cruz, CA 95064, USA.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/27034370" target="_blank"〉PubMed〈/a〉
Print ISSN:
0036-8075
Electronic ISSN:
1095-9203
Topics:
Biology
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Chemistry and Pharmacology
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Computer Science
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Medicine
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Natural Sciences in General
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Physics
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