Preprints
https://doi.org/10.5194/egusphere-2024-2427
https://doi.org/10.5194/egusphere-2024-2427
08 Aug 2024
 | 08 Aug 2024

An ice-sheet modelling framework for leveraging sub-ice drilling to assess sea level potential applied to Greenland

Benjamin A. Keisling, Joerg M. Schaefer, Robert M. DeConto, Jason P. Briner, Nicolás E. Young, Caleb K. Walcott, Gisela Winckler, Allie Balter-Kennedy, and Sridhar Anandakrishnan

Abstract. The contribution of the Greenland Ice Sheet (GIS) to sea level rise (SLR) is accelerating and there is an urgent need to improve predictions of when and from what parts of the ice sheet Greenland will contribute its first meter. Estimating the volume of Greenland ice that was lost during past warm periods offers a way to constrain the ice sheet’s response to future warming. Sub-ice sediment and bedrock, retrieved from deep ice core campaigns or targeted drilling efforts, yield critical and direct information about past ice-free conditions. However, it is challenging to scale the few available sub-ice point measurements to the geometry of the entire ice sheet. Here, we provide a framework for assessing sea-level potential, which we define as the amount the GIS has contributed to sea level when a particular location in Greenland is ice-free, from an ensemble of ice-sheet model simulations representing a wide range of plausible deglaciation scenarios. An assessment of dominant sources of uncertainty in our paleo ice sheet modelling, including climate forcing, ice-sheet initialization, and solid-Earth properties, reveals spatial patterns in the sensitivity of the ice sheet to these processes and related feedbacks. We find that the sea-level potential of central Greenland is most sensitive to lithospheric feedbacks and ice-sheet initialization, whereas the ice-sheet margins are most sensitive to climate forcing parameters. Our framework allows us to quantify the local and regional uncertainty in sea-level potential, which we use to evaluate the GIS bedrock according to the usefulness of information sub-ice sediments and bedrock provide about past ice-sheet geometry. Through our ensemble approach, we can assign a plausible range of GIS contributions to global sea level for deglaciated conditions at any site. Our results identify primarily areas in southwest Greenland, and secondarily north Greenland, as best-suited for subglacial access drilling that seeks to constrain the response of the ice sheet to past and future warming.

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Benjamin A. Keisling, Joerg M. Schaefer, Robert M. DeConto, Jason P. Briner, Nicolás E. Young, Caleb K. Walcott, Gisela Winckler, Allie Balter-Kennedy, and Sridhar Anandakrishnan

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Review of Keisling et al', Anonymous Referee #1, 17 Sep 2024
  • RC2: 'Comment on egusphere-2024-2427', Anonymous Referee #2, 04 Oct 2024
Benjamin A. Keisling, Joerg M. Schaefer, Robert M. DeConto, Jason P. Briner, Nicolás E. Young, Caleb K. Walcott, Gisela Winckler, Allie Balter-Kennedy, and Sridhar Anandakrishnan
Benjamin A. Keisling, Joerg M. Schaefer, Robert M. DeConto, Jason P. Briner, Nicolás E. Young, Caleb K. Walcott, Gisela Winckler, Allie Balter-Kennedy, and Sridhar Anandakrishnan

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Short summary
Understanding how much the Greenland ice sheet melted in response to past warmth helps better predicting future sea-level change. Here we present a framework for using numerical ice-sheet model simulations to provide constraints on how much mass the ice sheet loses before different areas become ice-free. As observations from subglacial archives become more abundant, this framework can guide subglacial sampling efforts to gain the most robust information about past ice-sheet geometries.