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Abstract. Direct observations of the size of the Greenland Ice Sheet during Quaternary interglaciations are sparse yet valuable for testing numerical models of ice-sheet history and sea level contribution. Recent measurements of cosmogenicnuclides in bedrock from beneath the Greenland Ice Sheet collected duringpast deep-drilling campaigns reveal that the ice sheet was significantlysmaller, and perhaps largely absent, sometime during the past 1.1 millionyears. These discoveries from decades-old basal samples motivate new,targeted sampling for cosmogenic-nuclide analysis beneath the ice sheet.Current drills available for retrieving bed material from the US IceDrilling Program require < 700 m ice thickness and a frozen bed,while quartz-bearing bedrock lithologies are required for measuring a largesuite of cosmogenic nuclides. We find that these and other requirementsyield only ∼ 3.4 % of the Greenland Ice Sheet bed as asuitable drilling target using presently available technology. Additionalfactors related to scientific questions of interest are the following: which areas of thepresent ice sheet are the most sensitive to warming, where would a retreating icesheet expose bare ground rather than leave a remnant ice cap, andwhich areas are most likely to remain frozen bedded throughout glacialcycles and thus best preserve cosmogenic nuclides? Here we identifylocations beneath the Greenland Ice Sheet that are best suited for potentialfuture drilling and analysis. These include sites bordering Inglefield Landin northwestern Greenland, near Victoria Fjord and Mylius-Erichsen Land innorthern Greenland, and inland from the alpine topography along the icemargin in eastern and northeastern Greenland. Results from cosmogenic-nuclide analysis in new sub-ice bedrock cores from these areas would help to constrain dimensions of the Greenland Ice Sheet in the past.
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This content will become publicly available on August 8, 2025
An ice-sheet modelling framework for leveraging sub-ice drilling to assess sea level potential applied to Greenland
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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- PAR ID:
- 10554512
- Publisher / Repository:
- EGU Copernicus Publications
- Date Published:
- Format(s):
- Medium: X
- Institution:
- EGU
- Sponsoring Org:
- National Science Foundation
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