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

• Main Authors: Brzelinski, Swaantje, Bornemann, André, Liebrand, Diederik, van Peer, Tim E., Wilson, Paul, Friedrich, Oliver
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2023
• Subjects: Antarctic; The Antarctic; Antarc*; Ice Sheet
• Online Access: https://eprints.soton.ac.uk/479443/; https://eprints.soton.ac.uk/479443/1/s43247_023_00864_9.pdf

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.