Large obliquity-paced Antarctic ice-volume fluctuations suggest melting by atmospheric and ocean warming during late Oligocene

• Main Authors: Swaantje Brzelinski, André Bornemann, Diederik Liebrand, Tim E van Peer, Paul A Wilson, Oliver Friedrich
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: 2023
• Subjects: Uncategorized; Uncategorised value; Antarc*; Antarctic; Ice Sheet
• Online Access: https://figshare.com/articles/journal_contribution/Large_obliquity-paced_Antarctic_ice-volume_fluctuations_suggest_melting_by_atmospheric_and_ocean_warming_during_late_Oligocene/23629815

The late Oligocene (~27.8–23 My ago) offers an opportunity to study past climate variability under high-CO2, warmer-than-present and the unipolar (Antarctic) glaciated state. Here, we present new high-resolution geochemical records from exquisitely well-preserved benthic foraminifera for the late Oligocene, an interval for which Antarctic ice-sheet size and stability are debated. Our records indicate four obliquity-paced glacial-interglacial cycles with ice-volume changes of up to ~70% of the modern Antarctic ice-sheet. The amplitude of ice-volume change during these late Oligocene glacial-interglacial cycles is comparable to that of the late Pliocene and early Pleistocene. Ice-volume estimates for interglacials are small enough to be accommodated by a land-based Antarctic ice-sheet but, for three of the four glacials studied, our calculations imply that ice sheets likely advanced beyond the Antarctic coastline onto the shelves. Our findings suggest an Antarctic ice-sheet vulnerable to melting driven by both bottom-up (ocean) and top-down (atmospheric) warming under late Oligocene warmer-than-present climate conditions.