24 Aug 2022
24 Aug 2022

Deglacial and Holocene sea ice and climate dynamics at the Western Antarctic Peninsula

Maria-Elena Vorrath1, Juliane Müller2,3,4, Paola Cárdenas5, Sebastian Mieruch2, Oliver Esper2, Thomas Opel2, Lester Lembke-Jene2, Johan Etourneau6,7, Andrea Vieth-Hillebrand8, Niko Lahajnar1, Carina B. Lange5,9,10,11, Amy Leventer12, Dimitris Evangelinos7,13, Carlota Escutia14, and Gesine Mollenhauer2,3 Maria-Elena Vorrath et al.
  • 1University Hamburg, Institute for Geology, Hamburg, Germany
  • 2Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 3MARUM – Center for Marine Environmental Sciences, University of Bremen, Germany
  • 4Department of Geosciences, University of Bremen, Germany
  • 5Centro de Investigación Dinámica de Ecosistemas Marinos de Altas Latitudes (IDEAL), Universidad Austral de Chile, Valdivia, Chile
  • 6EPHE/PSL Research University, France
  • 7UMR 5805 EPOC, CNRS, Université de Bordeaux, France
  • 8Helmholtz Centre Potsdam GFZ German Research Centre for Geosciences, Potsdam, Germany
  • 9Centro Oceanográfico COPAS Sur-Austral/COPAS-Coastal, Universidad de Concepción, Chile
  • 10Departamento de Oceanografía, Universidad de Concepción, Chile
  • 11Scripps Institution of Oceanography, La Jolla, CA 92037, USA
  • 12Department of Geology, Colgate University, New York, USA
  • 13Departament de Dinàmica de la Terra i de l'Oceà, Universitat de Barcelona, Spain
  • 14Instituto Andaluz de Ciencia de la tierra, CSIC-Univ. de Granada, Spain

Abstract. The reconstruction of past sea ice distribution in the Southern Ocean is crucial for an improved understanding of ice-ocean-atmosphere feedbacks and the evaluation of Earth system and Antarctic ice sheet models. The Western Antarctic Peninsula (WAP) is experiencing rapid warming and the associated decrease in sea ice cover contrasts the trend of growing sea ice extent in eastern Antarctica. To reveal the long-term sea ice history at the WAP under changing climate conditions we examined a marine sediment core from the eastern basin of the Bransfield Strait covering the last Deglacial and the Holocene. For sea ice reconstructions, we focused on the specific sea ice biomarker lipid IPSO25, a highly branched isoprenoid (HBI), and sea ice diatoms, whereas a phytoplankton-derived HBI triene (C25:3) and open ocean diatom assemblages reflect predominantly ice-free conditions. We further reconstruct ocean temperatures using glycerol dialkyl glycerol tetraether (GDGTs) and diatom assemblages, and compare our sea ice and temperature records with published marine sediment and ice core data. Our results document a retreat of the WAP ice shelf at 13.9 ka BP (before present). Maximum sea ice cover is observed during the Antarctic Cold Reversal, while a still extended but variable sea ice coverage characterized the core site during the early Holocene. An overall decreasing sea ice trend throughout the Middle Holocene is accompanied by a successive ocean warming and increasing phytoplankton productivity. The Late Holocene is characterized by unstable (winter) sea ice conditions and a further sea ice decline until 0.5 ka BP.

Maria-Elena Vorrath et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-804', Anonymous Referee #1, 25 Oct 2022
  • RC2: 'Comment on egusphere-2022-804', Anonymous Referee #2, 21 Nov 2022

Maria-Elena Vorrath et al.

Maria-Elena Vorrath et al.


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Short summary
Sea ice is important to stabilize the ice sheet in Antarctica. To understand how the global climate and sea ice were related in the past we looked on ancient molecules (IPSO25) from sea ice algae and other species whose dead cells accumulated on the ocean floor over time. With chemical analyses we could reconstruct the history of sea ice and ocean temperatures of the past 14 thousand years. We found out that sea ice became less and less as the ocean warmed and more phytoplankton was growing.