Ice sheet–free West Antarctica during peak early Oligocene glaciation
Johann Philipp Klages, Claus‐Dieter Hillenbrand, Steven M. Bohaty, Ulrich Salzmann, Torsten Bickert, Gerrit Lohmann, Hanna Knahl, Paul Gierz, Lu Niu, Jürgen Titschack, Gerhard Kühn, Thomas Frederichs, Juliane Müller, Thorsten Bauersachs, Robert D Larter, Katharina Hochmuth, Werner Ehrmann, Gernot Nehrke, Francisco J. Rodríguez‐Tovar, Gerhard Schmiedl, Silvia Spezzaferri, Andreas Läufer, Frank Lisker, Tina van de Flierdt, Anton Eisenhauer, Gabriele Uenzelmann‐Neben, Oliver Esper, James A Smith, Heiko Pälike, Cornelia Spiegel, Ricarda Dziadek, Thomas A. Ronge, Tim Freudenthal, Karsten Gohl
Abstract
One of Earth's most fundamental climate shifts, the greenhouse-icehouse transition 34 million years ago, initiated Antarctic ice sheet buildup, influencing global climate until today. However, the extent of the ice sheet during the Early Oligocene Glacial Maximum (~33.7 to 33.2 million years ago) that immediately followed this transition-a critical knowledge gap for assessing feedbacks between permanently glaciated areas and early Cenozoic global climate reorganization-is uncertain. In this work, we present shallow-marine drilling data constraining earliest Oligocene environmental conditions on West Antarctica's Pacific margin-a key region for understanding Antarctic ice sheet evolution. These data indicate a cool-temperate environment with mild ocean and air temperatures that prevented West Antarctic Ice Sheet formation. Climate-ice sheet modeling corroborates a highly asymmetric Antarctic ice sheet, thereby revealing its differential regional response to past and future climatic change.