Golledge et al. (2026) State dependent ice-sheet resonance under Cenozoic and future climates

Identification

• Journal: Communications Earth & Environment
• Year: 2026
• Date: 2026-01-12
• Authors: N. R. Golledge, Richard H. Levy, Peter M. Sadler, N. Wermes, Peter U. Clark, Julianne E. Burns, Hana Ishii, Hanna Knahl, Daniel P. Lowry, Robert M. McKay, Tim R. Naish, Georgia Grant
• DOI: 10.1038/s43247-025-03135-x

Research Groups

• Antarctic Research Centre, Victoria University of Wellington, Wellington 6140, New Zealand
• Earth Sciences New Zealand, Avalon, Lower Hutt 5010, New Zealand
• Department of Geoscience, University of Wisconsin-Madison, Madison, WI, USA
• University of Bonn, Steinmann-Institute, Bonn, Germany
• College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, OR, USA
• Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung, Bremerhaven, Germany
• University of South Florida, St. Petersburgh, FL, USA

Short Summary

This study uses 500-kiloyear (kyr) ice-sheet simulations to demonstrate that the phasing of ice sheet response to climate forcing is state-dependent, implying that future ice sheet behavior under warming may differ significantly from past responses.

Objective

• To systematically explore how the phasing of climate-ice sheet relationships changes under different background climate states and orbital forcing periodicities, using an ensemble of simplified ice sheet simulations.

Study Configuration

• Spatial Scale: Radially symmetric domain measuring 3200 kilometers by 3200 kilometers.
• Temporal Scale: Main ensemble simulations run for 500 kiloyears each; gradual secular cooling simulations span 1 megayear; total modeled time is 102 megayears.

Methodology and Data

• Models used: Parallel Ice Sheet Model (PISM), a thermodynamic coupled ice-sheet – ice-shelf model; elastic lithosphere, relaxing asthenosphere solid Earth model; Astrochron R package for paleoclimate data analysis.
• Data sources: Ensemble of 198 simplified ice sheet simulations; paleoenvironmental proxies (e.g., benthic foraminifera δ18O, iceberg-rafted debris); global δ18O megasplice record (Ref. 57); clast abundance data (Ref. 56); IMBIE ice sheet drainage divides.

Main Results

• The directionality of ice sheet change is dependent on the background climate state.
• Under cold atmospheric conditions with high-amplitude glacial–interglacial sub-shelf melt, ice sheets advance during cold phases and retreat during warming (anti-phase).
• Under warmer air temperatures with reduced glacial–interglacial ice-shelf melt variability, ice sheets advance during warm phases and retreat during colder periods (in-phase).
• When forced with a linearly changing climate, the ice sheet switches between these modes, exhibiting a resonant response at half the forcing frequency (e.g., 50 kyr response to 100 kyr forcing).
• The amplitude of oceanic variability, rather than its absolute magnitude, is critical for this switching behavior, particularly at longer forcing frequencies (41 kyr and 100 kyr).
• Asymmetric ice volume oscillations, characteristic of the Late Pleistocene, primarily occur under 100 kyr forcing and are attributed to a specific combination of oceanic forcing and solid Earth feedbacks (mantle viscosity).
• Iceberg calving fluxes exhibit leptokurtic variability (short, sharp spikes) that respond sensitively to peak melt-rate acceleration, rather than solely to melt rate magnitude or rate-of-change.

Contributions

• Systematically demonstrates that climate-ice sheet phasing is not constant but state-dependent, challenging the assumption of an unchanging ice-sheet response to climate.
• Identifies a novel half-wavelength harmonic resonance mechanism in ice sheets during transitional climate states, linking it to a delicate balance between surface accumulation and basal melt.
• Provides a mechanistic explanation for the emergence of asymmetric ice volume cycles (e.g., Late Pleistocene 100 kyr cycles) through the interplay of oceanic forcing and solid Earth feedbacks (mantle viscosity).
• Offers critical insights into how future warming could fundamentally alter ice sheet periodicity, phasing, and asymmetry, suggesting that past proxy interpretations need to account for state-dependency.

Funding

• Royal Society Te Apārangi (contracts RDF-VUW1501 and MFP-VUW2207)
• New Zealand Ministry for Business, Innovation and Employment (contracts RTVU2206 & ANTA1801)
• Guggenheim Fellowship (SRM)
• Heising-Simons Foundation Award #2021-2797 (SRM)
• Deutsche Forschungsgemeinschaft (DFG–Priority Programme 527, Grant We2039/17-1) (MEW)
• Helmholtz Association “Changing Earth – Sustaining our future” program (HK)
• NSF grant OAC-2118285 (PISM development)

Citation

@article{Golledge2026State,
  author = {Golledge, N. R. and Levy, Richard H. and Sadler, Peter M. and Wermes, N. and Clark, Peter U. and Burns, Julianne E. and Ishii, Hana and Knahl, Hanna and Lowry, Daniel P. and McKay, Robert M. and Naish, Tim R. and Grant, Georgia},
  title = {State dependent ice-sheet resonance under Cenozoic and future climates},
  journal = {Communications Earth & Environment},
  year = {2026},
  doi = {10.1038/s43247-025-03135-x},
  url = {https://doi.org/10.1038/s43247-025-03135-x}
}