Browsing by Author "Stutz, J"

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A data-model comparison on the glacial thinning history of Byrd Glacier, Antarctica
    (Australian Institute of Nuclear Science and Engineering, 2021-11-17) Stutz, J; Eaves, S; Moore, C; Wilcken, KM; Norton, K; Lowry, D
    Response of marine based sectors of the Antarctic Ice Sheet (AIS) to projected warming remains a significant uncertainty in sea level rise projections. The aim of this project is to provide understanding of past mechanisms and feedbacks of ice sheet change, and to reduce uncertainty in projections of future change. We extend the satellite record of ice sheet change by targeting strategic locations around the margins of the Ross Ice Shelf, which is responsible for buttressing large sectors of the marine-based West AIS. At these locations, glacial sediments deposited on nunataks adjacent to dynamic ice margins record the transient evolution of ice thickness throughout the Holocene period. Here, we focus on the Byrd Glacier, which drains 10% of the East AIS by area and contributes ~20% of the total mass of the Ross Ice Shelf. At Lonewolf Nunataks along the upper Byrd Glacier, our cosmogenic surface exposure ages constrain (i) past rates of ice thinning; (ii) total magnitudes of ice elevation change; and (iii) the absolute timing of ice discharge and thinning events in these sensitive regions. In this presentation, we will review the existing knowledge of Transantarctic Mountain outlet glaciers and present new data from our 2019-20 season along the upper Byrd Glaciers. Comparing our data to recent regional-scale ice sheet model simulations of the last deglaciation, we observe a distinct time lag between modelled thinning and our data-constrained thinning history. Our new data-model comparison will inform high-resolution, sector-scale numerical glacier model experiments, in which we seek to determine drivers of ice sheet thinning and retreat. © The Authors
  • Thumbnail Image
    Item
    Using in situ 14C to unravel complex exposure histories along the David Glacier, Antarctica
    (Australian Nuclear Science and Technology Organisation, 2021-11-17) Stutz, J; Fülöp, RH; Norton, KP; Mackintosh, AN; Whitemore, R; Yang, B; Smith, AM
    Understanding the past Antarctic Ice Sheet (AIS) is critical to forecast the impacts of future of the AIS and its contribution to sea level rise. Ice sheet models constrained by geological data provide improved confidence in future projections. Both marine and terrestrial geologic data are required for a robust reconstruction of both the extent and thickness of the AIS. On land, cosmogenic nuclides have transformed the ability to constrain reconstructions of the past AIS through time. Highresolution, low-inheritance chronologies focused on large outlet glaciers provide enhanced understanding on the timing, rate and potential mechanisms driving past ice sheet change. Using the ‘glacial dip stick’ approach at each site, we sample glacial debris and bedrock from the local peak down to the modern ice surface. While field sampling strategies and analytical capability continues to improve, ‘complex’ exposure histories remain a common occurrence in practice. Inheritance, or a signal of cumulative exposure, can arise due to burial by cold-based, non-crosive nature of the AIS. At Mt. Kring along the upper David Glacier, previous studies show a distinct mid-Holocene signal of glacier thinning as well as at least two populations of apparent older glacial thinning events. Here, we use 14C measurements on samples suspected of having an inherited signal. We show that samples with >30 ka 10Be exposure ages indeed carry a mid-Holocene 14C exposure age and improve the existing thinning history. This multi-nuclide comparison approach provides a preliminary data set to bolster previous and emerging studies where complex exposure histories occur around Antarctica. © The Authors