Obliquity Disruption and Antarctic Ice Sheet Dynamics Over a 2.4-Myr Astronomical Grand Cycle

Authors

• Nicholas B. Sullivan, University of Wisconsin–Madison and Pennsylvania State UniversityFollow
• Stephen R. Meyers, University of Wisconsin–Madison
• Richard H. Levy, Victoria University of Wellington and GNS Science, New Zealand
• Robert M. McKay, Victoria University of Wellington
• Tina Van De Flierdt, Imperial College London
• James Marschalek, Imperial College London
• Matteo Perotti, University of Siena
• Luca Zurli, University of Siena
• Franco Talarico, University of Siena
• David Harwood, University of Nebraska–Lincoln
• Laura De Santis, National Institute of Oceanography and Applied Geophysics, Italy
• Fabio Florindo, Istituto Nazionale di Geofisica e Vulcanologia, Italy
• Tim R. Naish, Victoria University of Wellington
• Georgia R. Grant, GNS Science, New Zealand
• Molly O. Patterson, Binghamton University--SUNY

ORCID IDs

Sullivan https://orcid.org/0000-0003-2009-8992

Meyers https://orcid.org/0000-0003-4422-720X

Levy https://orcid.org/0000-0002-8783-0167

McKay https://orcid.org/0000-0002-5602-6985

Flierdt https://orcid.org/0000-0001-7176-9755

Marschalek https://orcid.org/0000-0003-2057-4012

Zurli https://orcid.org/0000-0002-7669-7305

Harwood https://orcid.org/0000-0002-9449-2127

Santis https://orcid.org/0000-0002-7752-7754

Florinda https://orcid.org/0000-0002-6058-9748

Grant https://orcid.org/0000-0002-2615-9322

Document Type

Article

Date of this Version

2025

Citation

Science Advances (2025) 11: eadl1996

doi: 10.1126/sciadv.adl1996

Comments

Open access

License: CC BY-NC 4.0

Abstract

Marine δ¹⁸O data reveal astronomical forcing of the climate and cryosphere during the Miocene, when atmospheric Pco₂ was on par with emissions scenarios over the next century. This inspired hypotheses for how Milankovitch cycles, ice-ocean interactions, and greenhouse gases influence ice volume. Mass balance controls for marine and terrestrial ice sheets differ, and proxy data collected far from Antarctica provide valuable but limited insight into regional processes. We evaluate clast abundance data from Antarctic marine sedimentary records, observing a strong signal of eccentricity and precession coincident with a terrestrial ice sheet and a clear obliquity signal at the margins of a marine ice sheet. These analyses are integrated with a synthesis of proxy data, and we argue that high variance in obliquity forcing (mediated and enhanced by the ocean and atmosphere) can inhibit ice sheet growth, even when insolation forcing is conducive to glaciation. This “obliquity disruption” explains cryosphere variability before the existence of large northern hemisphere ice sheets.