EGU2020-13504
https://doi.org/10.5194/egusphere-egu2020-13504
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Limited Retreat of the Wilkes Basin Ice Sheet during the Last Interglacial.

Johannes Sutter1, Olaf Eisen2, Martin Werner2, Klaus Grosfeld2, Thomas Kleiner2, and Hubertus Fischer1
Johannes Sutter et al.
  • 1University of Bern, Climate and Environmental Physics (CEP), Switzerland (johannes.sutter@awi.de)
  • 2Alfred Wegener Institute Helmholtz-Centre for Polar and Marine Research, Bremerhaven, Germany

The response of the marine sectors of the East Antarctic Ice Sheet to future global warming represents a major source of uncertainty in sea level projections. If greenhouse gas emissions continue unbridled, ice loss in these areas may contribute up to several meters to long-term global sea level rise. In East Antarctica, thinning of the ice cover of the George V and Sabrina Coast is currently taking place, and its destabilization in past warm climate periods has been implied. The extent of such past interglacial retreat episodes cannot yet be quantitatively derived from paleo proxy records alone. Ice sheet modelling constrained by paleo observations is therefore critical to assess the stability of the East Antarctic Ice Sheet during warmer climates. We propose that a runaway retreat during the Last Interglacial of the George V Coast grounding line into the Wilkes Subglacial Basin would either leave a clear imprint on the water isotope composition in the neighbouring Talos Dome ice-core record or prohibit the preservation of an ice core record from the Last Interglacial alltogether. We test this hypothesis using a dynamic ice sheet model and infer that the marine Wilkes Basin ice sheet remained stable throughout the Last Interglacial (130,000-120,000 years ago). Our analysis provides the first constraint on Last Interglacial East Antarctic grounding line stability by benchmarking ice sheet model simulations with ice core records. Our findings also imply that ambitious mitigation efforts keeping global temperature rise in check could safeguard this region from irreversible ice loss in the long term.

How to cite: Sutter, J., Eisen, O., Werner, M., Grosfeld, K., Kleiner, T., and Fischer, H.: Limited Retreat of the Wilkes Basin Ice Sheet during the Last Interglacial., EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-13504, https://doi.org/10.5194/egusphere-egu2020-13504, 2020

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Display material version 1 – uploaded on 04 May 2020
  • CC1: Comment on EGU2020-13504, User deleted account, 05 May 2020

    Hi Johannes,

    How are you doing? Nice work. Just wondering what your initial ice sheet(s) are for the experiments, include glacial spin-up? Nice resolution by the way. Did you do a full 4km on whole Antarctica or nesting possible with PISM?

    Best

    • AC1: Reply to CC1, Johannes Sutter, 05 May 2020

      Hi Bas, thank you! Yes we did 4 km for the whole AIS, it took a while ...

      the initial conditions are from a transient spinup of the AIS from 2M a BP to 140 ka BP/130 ka BP (Sutter et al. 2019 TC). Therefore at 130 ka BP we still have a slightly advanced grounding line around the George V Coast.

      • AC2: Reply to AC1, Johannes Sutter, 05 May 2020

        p.s.: as far as I know, nesting is not yet possible with PISM.

      • CC2: Reply to AC1, User deleted account, 05 May 2020

        OK nice to do it like that. You've then downscaled from the lower resolution to 4km?

        • AC3: Reply to CC2, Johannes Sutter, 05 May 2020

          Yes, exactly. We ran simulations on 16 km, 8km and 4 km. Regridding always from 16 km either at 140 ka or 130 ka, differences between the two cases (140 v 130) are relatively small but can be strong locally (e.g. Mertz Glacier). We hope this study will be out on GRL soonish. 

  • CC3: Comment on EGU2020-13504, Lennert Stap, 05 May 2020

    Hi Johannes,

    Nice Work! Just wondering if your climate forcing is coming from COSMOS output?

    Cheers, Lennert

    • AC4: Reply to CC3, Johannes Sutter, 05 May 2020

      Hi Lennert,

      yes it does.