Preprints
https://doi.org/10.5194/tc-2022-199
https://doi.org/10.5194/tc-2022-199
 
01 Nov 2022
01 Nov 2022
Status: this preprint is currently under review for the journal TC.

High mid-Holocene accumulation rates over West Antarctica inferred from a pervasive ice-penetrating radar reflector

Julien A. Bodart1, Robert G. Bingham1, Duncan A. Young2, Joseph A. MacGregor3, David W. Ashmore4, Enrica Quartini2,5, Andrew S. Hein1, David G. Vaughan6, and Donald D. Blankenship2 Julien A. Bodart et al.
  • 1School of GeoSciences, University of Edinburgh, Edinburgh, UK
  • 2Institute for Geophysics, University of Texas at Austin, Austin, Texas, USA
  • 3Cryospheric Sciences Laboratory, NASA Goddard Space Flight Center, Greenbelt, Maryland, USA
  • 4School of Environmental Sciences, University of Liverpool, Liverpool, UK
  • 5Department of Astronomy, Cornell University, Ithaca, New York, USA
  • 6British Antarctic Survey, Cambridge, UK

Abstract. Modelling the past and future evolution of the West Antarctic Ice Sheet (WAIS) to atmospheric and ocean forcing is challenged by the availability and quality of observed palaeo-boundary conditions. Key potential data for reconstructing past ice-sheet processes on large spatial scales are Internal Reflecting Horizons (IRHs) detected by Radio-Echo Sounding (RES) techniques. When isochronal and dated at ice cores, IRHs can be used to determine palaeo-accumulation rates and patterns. Using a spatially extensive IRH over Pine Island Glacier, Thwaites Glacier, Institute and Möller Ice Streams, and a local layer approximation model, we infer mid-Holocene accumulation rates over the slow-flowing parts of these catchments for the past ~5000 years. By comparing our results with modern climate reanalysis models and observational syntheses, we estimate that accumulation rates over the Amundsen-Weddell-Ross divide were on average 18 % higher than modern rates during the mid-Holocene. However, no significant spatial changes in the accumulation pattern were observed. These higher mid-Holocene accumulation-rate estimates match previous palaeo-accumulation estimates from ice-core and targeted IPR surveys over the ice divide, and also coincide with periods of grounding-line re-advance during the Holocene over the Weddell and Ross Sea sectors. Our results highlight the need for ice-sheet models to account for time-varying accumulation rates across the WAIS during the Holocene to provide better estimates of its contribution to past sea-level rise.

Julien A. Bodart et al.

Status: open (until 01 Jan 2023)

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Julien A. Bodart et al.

Julien A. Bodart et al.

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Short summary
Estimating how West Antarctica will change in response to future climatic changes depends on our understanding of past ice processes. Here, we use reflectors detected by airborne radio-echo sounding data across West Antarctica to estimate accumulation rates over the past ~5000 years. By comparing our estimates with current climate data, we find that accumulation rates were 18 % greater than modern rates. This has implications for our understanding of past ice-sheet processes in the region.