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The Cryosphere An interactive open-access journal of the European Geosciences Union
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Discussion papers
https://doi.org/10.5194/tc-2019-83
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/tc-2019-83
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Research article 10 May 2019

Research article | 10 May 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal The Cryosphere (TC).

Nonlinear response of the Antarctic ice sheet to Quaternary sea level and climate forcing

Michelle Tigchelaar1, Axel Timmermann2,3, Tobias Friedrich4, Malte Heinemann5, and David Pollard6 Michelle Tigchelaar et al.
  • 1Center for Ocean Solutions, Stanford University, Palo Alto, CA, USA
  • 2Center for Climate Physics, Institute for Basic Science, Busan, South Korea
  • 3Pusan National University, Busan, South Korea
  • 4Department of Oceanography, University of Hawai'i at Mānoa, Honolulu, HI, USA
  • 5Institute of Geosciences, Kiel University, Kiel, Germany
  • 6Earth and Environmental Systems Institute, Pennsylvania State University, University Park, PA, USA

Abstract. Antarctic ice volume has varied substantially during the Quaternary, with reconstructions suggesting a glacial ice sheet extending to the continental shelf break, and interglacial sea level highstands of several meters. Throughout this period, changes in the Antarctic ice sheet were driven by changes in atmospheric and oceanic conditions and global sea level, yet so far, modeling studies have not addressed which of these environmental forcings dominate, and how they interact in the dynamical ice sheet response. Here we force an Antarctic ice sheet model with global sea level reconstructions and transient, spatially explicit boundary conditions from a 408 ka climate model simulation, not only in concert with each other but, for the first time, also separately. We find that together, these forcings drive glacial-interglacial ice volume changes of 12–14 m SLE, in line with reconstructions and previous modeling studies. None of the individual drivers – atmospheric temperature and precipitation, ocean temperatures, sea level – single-handedly explains the full ice sheet response. In fact, the sum of the individual ice volume changes amounts to less than half of the full ice volume response, indicating the existence of strong nonlinearities and forcing synergy. Both sea level and atmospheric forcing are necessary to create full glacial ice sheet growth, whereas the contribution of ocean melt changes is found to be more a function of ice sheet geometry than climatic change. Our results highlight the importance of accurately representing the relative timing of forcings of past ice sheet simulations, and underscore the need for developing coupled climate-ice sheet modeling frameworks that properly capture key feedbacks.

Michelle Tigchelaar et al.
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Michelle Tigchelaar et al.
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Short summary
The Antarctic ice sheet has expanded and retracted often in the past, but so far studies have not identified which environmental driver is most important: air temperature, snowfall, ocean conditions, or global sea level. In a modeling study of 400,000 years of Antarctic ice sheet variability we isolated different drivers and found that no single one dominates. Air temperature and sea level are most important, and combine in a synergistic way, with important implications for future change.
The Antarctic ice sheet has expanded and retracted often in the past, but so far studies have...
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