Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-132
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
16 Oct 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Simulation of the Greenland Ice sheet over two glacial cycles: Investigating a sub-ice shelf melt parameterisation and relative sea level forcing in an ice sheet-ice shelf model
Sarah L. Bradley1,2, Thomas J. Reerink1, Roderik S. W. van de Wal1, and Michiel M. Helsen1 1Institute for Marine and Atmospheric research Utrecht, Utrecht University, Utrecht, the Netherlands
2Department of Geoscience & Remote Sensing, Delft University of Technology, the Netherlands
Abstract. Observational evidence, including offshore moraines and sediment cores confirm that at the Last Glacial maximum (LGM) the Greenland ice sheet (GrIS) grew to a significantly larger spatial extent than seen at present, grounding into Baffin Bay and to the continental shelf break. Given this larger spatial extent and it is close proximity to the neighboring Laurentide (LIS) and Innuitian Ice sheet (IIS), it is likely these ice sheets will have had a strong non-local influence on the spatial and temporal behaviour of the GrIS. Most previous paleo ice sheet modelling simulations recreated an ice sheet that either did not extend out onto the continental shelf; or utilized a simplified marine ice parametersiation and therefore did not fully include ice shelf dynamics, and or the sensitivity of the GrIS to this non-local signal from the surrounding ice sheets. In this paper, we investigated the evolution of the GrIS over the two most recent glacial-interglacial cycles (240 kyr BP to present day), using the ice sheet-ice shelf model, IMAU-ICE and investigated the influence of the LIS and IIS via an offline relative sea level (RSL) forcing generated by a GIA model. This RSL forcing controlled via changes in the water depth below the developing ice shelves, the spatial and temporal pattern of sub-ice shelf melting, which was parametrised in relation to changes in water depth. In the suite of simulations, the GrIS at the glacial maximums coalesced with the IIS to the north, expanded to the continental shelf break to the south west but remained too restricted to the north east. In terms of an ice-volume equivalent sea level contribution, at the Last Interglacial (LIG) and LGM the ice sheet added 1.46 m and −2.59 m to the budget respectively. The estimated lowering of the sea level by the Greenland contribution is considerably more (1.26 m) than most previous studies indicated whereas the contribution to the LIG high stand is lower (0.7 m). The spatial and temporal behaviour of the northern margin was highly variable in all simulations, controlled by the sub surface melt (SSM), which was dictated by the RSL forcing and the glacial history of the IIS and LIS. In contrast, the southwestern part of the ice sheet was insensitive to these forcing’s, with a uniform response in an all simulations controlled by the surface air temperature (SAT) forcing, derived from ice cores.

Citation: Bradley, S. L., Reerink, T. J., van de Wal, R. S. W., and Helsen, M. M.: Simulation of the Greenland Ice sheet over two glacial cycles: Investigating a sub-ice shelf melt parameterisation and relative sea level forcing in an ice sheet-ice shelf model, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-132, in review, 2017.
Sarah L. Bradley et al.
Sarah L. Bradley et al.
Sarah L. Bradley et al.

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