Dynamic Antarctic ice sheet during the early to mid-Miocene

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TitleDynamic Antarctic ice sheet during the early to mid-MioceneAbstractGeological data indicate that there were major variations in Antarctic ice sheet volume and extent during the early to mid-Miocene. Simulating such large-scale changes is problematic because of a strong hysteresis effect, which results in stability once the ice sheets have reached continental size. A relatively narrow range of atmospheric CO2 concentrations indicated by proxy records exacerbates this problem. Here, we are able to simulate large-scale variability of the early to mid-Miocene Antarctic ice sheet because of three developments in our modeling approach. (i) We use a climate-ice sheet coupling method utilizing a high-resolution atmospheric component to account for ice sheet-climate feedbacks. (ii) The ice sheet model includes recently proposed mechanisms for retreat into deep subglacial basins caused by ice-cliff failure and ice-shelf hydrofracture. (iii)We account for changes in the oxygen isotopic composition of the ice sheet by using isotope-enabled climate and ice sheet models. We compare our modeling results with ice-proximal records emerging from a sedimentological drill core from the Ross Sea (Andrill-2A) that is presented in a companion article. The variability in Antarctic ice volume that we simulate is equivalent to a seawater oxygen isotope signal of 0.52-0.66% or a sea level equivalent change of 30-36 m, for a range of atmospheric CO2 between 280 and 500 ppm and a changing astronomical configuration. This result represents a substantial advance in resolving the long-standing model data conflict of Miocene Antarctic ice sheet and sea level variability.AcknowledgementsE. Gasson, D. Kowalewski, C. Fogwill,and Z. Thomas are gratefully acknowledged for contributions to anearlier project from which this work subsequently evolved. C. Khroulev and PISM developers are thanked forvaluable assistance with the ice sheet model. We are grateful to J. Sutterand and an anonymous referee for comments that improved the clarity of the manuscript. This work was funded by contracts RDF-VUW1501 and VUW1203 of the Royal Society of New Zealand, with support from the Antarctic Research Centre (Victoria University of Wellington), New Zealand Ministry for Business, Innovation and Employment contract CO5X1001,and GNS Science. Development of PISM is supported by NASA grants NNX13AM16G and NNX13AK27G. Data presented in this paper are availablefrom the author on request. The authors thank the editor and three anonymous reviewers for their valuable comments. This study was supported US National Science Foundation Awards OCE-1202632 and AGS-1203910.

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1st AuthorGasson, E.AuthorGasson, E.DeConto, R.Pollard, D.Levy, R.Year2016JournalProceedings of the National Academy of Sciences of the United States of AmericaVolume113Number13Pages3459-3464DOI10.1073/pnas.1516130113URLhttps://www.scopus.com/inward/recor.....2d2a47343fd5d365901b60ff8Keywordscarbon dioxideoxygensea water, AntarcticaArticleastronomyclimatecontinental shelfglaciationice sheetice shelfLower MioceneMiddle Miocenepriority journalsea levelvegetation, rank3Author KeywordsAntarctic ice sheetMioceneOxygen isotopesSea level

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TypeArticleCitationGasson, E., DeConto, R., Pollard, D. and Levy, R. (2016). Dynamic Antarctic ice sheet during the early to mid-Miocene. Proceedings of the National Academy of Sciences of the United States of America, 113(13): 3459-3464 IdentifierGasson2016Relevancerank3