Articles | Volume 9, issue 6
Clim. Past, 9, 2489–2505, 2013

Special issue: Oldest Ice: finding and interpreting climate proxies in ice...

Special issue: International Partnerships in Ice Core Sciences (IPICS): 2012...

Clim. Past, 9, 2489–2505, 2013

Research article 05 Nov 2013

Research article | 05 Nov 2013

Where to find 1.5 million yr old ice for the IPICS "Oldest-Ice" ice core

H. Fischer1, J. Severinghaus2, E. Brook3, E. Wolff4,*, M. Albert5, O. Alemany6, R. Arthern4, C. Bentley7, D. Blankenship8, J. Chappellaz6, T. Creyts9, D. Dahl-Jensen10, M. Dinn4, M. Frezzotti11, S. Fujita12, H. Gallee6, R. Hindmarsh4, D. Hudspeth13, G. Jugie14, K. Kawamura12, V. Lipenkov15, H. Miller16, R. Mulvaney4, F. Parrenin6, F. Pattyn17, C. Ritz6, J. Schwander1, D. Steinhage16, T. van Ommen13, and F. Wilhelms16 H. Fischer et al.
  • 1Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, 3012 Bern & Oeschger Centre for Climate Change Research, University of Bern, Switzerland
  • 2Scripps Institution of Oceanography, University of California, San Diego, California, USA
  • 3Department of Geosciences, Oregon State University, Corvallis, Oregon, USA
  • 4British Antarctic Survey, High Cross, Cambridge, UK
  • 5Thayer School of Engineering, Dartmouth University, Hanover, New Hampshire, USA
  • 6Laboratoire de Glaciologie et Géophysique de l'Environnement, UJF-Grenoble, CNRS, St Martin d'Hères, France
  • 7University of Wisconsin Madison, Madison, Wisconsin, USA
  • 8Institute for Geophysics, University of Texas at Austin, Austin, Texas, USA
  • 9Lamont Doherty Earth Observatory, Columbia University, Palisades, New York, USA
  • 10Centre for Ice and Climate, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
  • 11ENEA-CRE, Casaccia, Rome, Italy
  • 12National Institute of Polar Research, Tokyo, Japan
  • 13Australian Antarctic Division, Hobart, Tasmania, Australia
  • 14Institut Polaire Français Paul-Emile Victor, Plouzané, France
  • 15Arctic and Antarctic Research Institute, St. Petersburg, Russia
  • 16Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
  • 17Laboratoire de Glaciologie, Université Libre de Bruxelles, Brussels, Belgium
  • *now at: Department of Earth Sciences, University of Cambridge, Cambridge, UK

Abstract. The recovery of a 1.5 million yr long ice core from Antarctica represents a keystone of our understanding of Quaternary climate, the progression of glaciation over this time period and the role of greenhouse gas cycles in this progression. Here we tackle the question of where such ice may still be found in the Antarctic ice sheet. We can show that such old ice is most likely to exist in the plateau area of the East Antarctic ice sheet (EAIS) without stratigraphic disturbance and should be able to be recovered after careful pre-site selection studies. Based on a simple ice and heat flow model and glaciological observations, we conclude that positions in the vicinity of major domes and saddle position on the East Antarctic Plateau will most likely have such old ice in store and represent the best study areas for dedicated reconnaissance studies in the near future. In contrast to previous ice core drill site selections, however, we strongly suggest significantly reduced ice thickness to avoid bottom melting. For example for the geothermal heat flux and accumulation conditions at Dome C, an ice thickness lower than but close to about 2500 m would be required to find 1.5 Myr old ice (i.e., more than 700 m less than at the current EPICA Dome C drill site). Within this constraint, the resolution of an Oldest-Ice record and the distance of such old ice to the bedrock should be maximized to avoid ice flow disturbances, for example, by finding locations with minimum geothermal heat flux. As the geothermal heat flux is largely unknown for the EAIS, this parameter has to be carefully determined beforehand. In addition, detailed bedrock topography and ice flow history has to be reconstructed for candidates of an Oldest-Ice ice coring site. Finally, we argue strongly for rapid access drilling before any full, deep ice coring activity commences to bring datable samples to the surface and to allow an age check of the oldest ice.