Repeated large-scale retreat and advance of Totten Glacier i

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TitleRepeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosionAbstractClimate variations cause ice sheets to retreat and advance, raising or lowering sea level by metres to decametres. The basic relationship is unambiguous, but the timing, magnitude and sources of sea-level change remain unclear; in particular, the contribution of the East Antarctic Ice Sheet (EAIS) is ill defined, restricting our appreciation of potential future change. Several lines of evidence suggest possible collapse of the Totten Glacier into interior basins during past warm periods, most notably the Pliocene epoch1,2,3,4, causing several metres of sea-level rise. However, the structure and long-term evolution of the ice sheet in this region have been understood insufficiently to constrain past ice-sheet extents. Here we show that deep ice-sheet erosion—enough to expose basement rocks—has occurred in two regions: the head of the Totten Glacier, within 150 kilometres of today’s grounding line; and deep within the Sabrina Subglacial Basin, 350–550 kilometres from this grounding line. Our results, based on ICECAP aerogeophysical data, demarcate the marginal zones of two distinct quasi-stable EAIS configurations, corresponding to the ‘modern-scale’ ice sheet (with a marginal zone near the present ice-sheet margin) and the retreated ice sheet (with the marginal zone located far inland). The transitional region of 200–250 kilometres in width is less eroded, suggesting shorter-lived exposure to eroding conditions during repeated retreat–advance events, which are probably driven by ocean-forced instabilities. Representative ice-sheet models indicate that the global sea-level increase resulting from retreat in this sector can be up to 0.9 metres in the modern-scale configuration, and exceeds 2 metres in the retreated configuration. Copyright 2016 Macmillan Publishers Limited. All rights reserved.AcknowledgementsCollection of ICECAP data was supported by: National Science Foundation grant PLR-0733025; National Aeronautics and Space Administration grants NNX09AR52G, NNG10HPO6C and NNX11AD33G (Operation Ice Bridge and the American Recovery and Reinvestment Act); Australian Antarctic Division projects 3013 and 4077; National Environment and Research Council grant NE/D003733/1; the Jackson School of Geosciences; the G. Unger Vetlesen Foundation; and the Australian GovernmentÅ› Cooperative Research Centres Programme through the Antarctic Climate and Ecosystems Cooperative Research Centre (ACE CRC). Ice-sheet modelling was funded under contract VUW1203 of the Royal Society of New ZealandÅ› Marsden Fund. We thank S. Jamieson for comments and for supplying model images for comparison. This is the University of Texas Institute of Geophysics contribution 2950.

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1st AuthorAitken, A.AuthorAitken, A.Roberts, J.Van Ommen, T.Young, D.Golledge, N.Greenbaum, J.Blankenship, D.Siegert, M.Year2016JournalNatureVolume533Pages385-389DOI10.1038/nature17447URLhttps://www.scopus.com/inward/recor.....cded6e39c7eb98bc4a65f2539Keywordsclimate variationglacial erosionglacier advanceice retreatice sheetinland seamarginal ice zonePliocenesea level changesubglacial environment, AntarcticaArticleenvironmental erosionglacierglobal climateice sheetinland bed erosionpriority journalsea level riseanalysisclimatefreezinggravitygreenhouse effectice coverremote sensingsedimentstatistics and numerical datatheoretical modeltime factor, Antarctic Ice SheetAntarcticaEast Antarctic Ice SheetEast Antarctica, sea water, Antarctic RegionsClimateFreezingGeologic SedimentsGlobal WarmingGravitationIce CoverModels, TheoreticalRemote Sensing TechnologySeawaterTime Factors, rank3ProgrammeK001

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TypeArticleCitationAitken, A., Roberts, J., Van Ommen, T., Young, D., Golledge, N., Greenbaum, J., Blankenship, D. and Siegert, M. (2016). Repeated large-scale retreat and advance of Totten Glacier indicated by inland bed erosion. Nature, 533: 385-389 IdentifierAitken2016Relevancerank3

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