A large West Antarctic ice sheet explains early Neogene sea-level amplitude

Marschalek, J.W. and Zurli, L. and Talarico, F. and van de Flierdt, T. and Vermeesch, P. and Carter, Andrew and Beny, F. and Bout-Roumazeilles, V. and Sangiorgi, F. and Hemming, S.R. and Pérez, L.F. and Colleoni, F. and Prebble, J.G. and van Peer, T.E. and Perotti, M. and Shevenell, A.E. and Browne, I. and Kulhanek, D.K. and Levy, R. and Harwood, D. and Sullivan, N.B. and Meyers, S.R. and Griffith, E.M. and Hillenbrand, C.-D. and Gasson, E. and Siegert, M. J. and Keisling, B. and Licht, K. J. and Kuhn, G. and Dodd, J. P. and Boshuis, C. and De Santis, L. and McKay, R. M. and Ash, J. and Beny, F. and Browne, I.M. and Cortese, G. and De Santis, L. and Dodd, J.P. and Esper, O.M. and Gales, J.A. and Harwood, D.M. and Ishino, S. and Keisling, B.A. and Kim, S. and Kim, S. and Kulhanek, D.K. and Laberg, J.S. and Leckie, R.M. and McKay, R.M. and Müller, J. and Patterson, M.O. and Romans, B.W. and Romero, O.E. and Sangiorgi, F. and Seki, O. and Shevenell, A.E. and Singh, S.M. and Cordeiro de Sousa, I.M. and Sugisaki, S.T. and van de Flierdt, T. and van Peer, T.E. and Xiao, W. and Xiong, Z. (2021) A large West Antarctic ice sheet explains early Neogene sea-level amplitude. Nature 600 (7889), pp. 450-455. ISSN 0028-0836.

Abstract

Early to Middle Miocene sea-level oscillations of approximately 40–60 m estimated from far-field records1–3 are interpreted to reflect the loss of virtually all East Antarctic ice during peak warmth2. This contrasts with ice-sheet model experiments suggesting most terrestrial ice in East Antarctica was retained even during the warmest intervals of the Middle Miocene4,5. Data and model outputs can be reconciled if a large West Antarctic Ice Sheet (WAIS) existed and expanded across most of the outer continental shelf during the Early Miocene, accounting for maximum ice-sheet volumes. Here we provide the earliest geological evidence proving large WAIS expansions occurred during the Early Miocene (~17.72–17.40 Ma). Geochemical and petrographic data show glacimarine sediments recovered at International Ocean Discovery Program (IODP) Site U1521 in the central Ross Sea derive from West Antarctica, requiring the presence of a WAIS covering most of the Ross Sea continental shelf. Seismic, lithological and palynological data reveal the intermittent proximity of grounded ice to Site U1521. The erosion rate calculated from this sediment package greatly exceeds the long-term mean, implying rapid erosion of West Antarctica. This interval therefore captures a key step in the genesis of a marine-based WAIS and a tipping point in Antarctic ice-sheet evolution.

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