Preprints
https://doi.org/10.5194/egusphere-2023-2583
https://doi.org/10.5194/egusphere-2023-2583
27 Nov 2023
 | 27 Nov 2023

Oceanic gateways to Antarctic grounding lines – Impact of critical access depths on sub-shelf melt

Lena Nicola, Ronja Reese, Moritz Kreuzer, Torsten Albrecht, and Ricarda Winkelmann

Abstract. Melting underneath the floating ice shelves surrounding the Antarctic continent is a key process for the stability of the Antarctic Ice Sheet and therefore its current and future mass loss. Troughs and sills on the continental shelf play a crucial role in modulating sub-shelf melt rates, as they can allow or block the access of relatively warm, modified Circumpolar Deep Water to ice-shelf cavities. Here we identify potential oceanic gateways that could allow the access of warm water masses to Antarctic grounding lines based on critical access depths inferred from high-resolution bathymetry data. We analyse the properties of water masses that are currently present in front of the ice shelf and that might intrude into the respective ice-shelf cavities in the future. We use the ice-shelf cavity model PICO to estimate an upper limit of melt rate changes in case all warm water masses up to a certain depth level gain access to the cavities. We find that melt rates could increase in all regions at least by a factor of 2. Depending on the presence or absence of an oceanic gateway and the current ice-shelf melt conditions we find up to 200-fold larger melt rates. The identification of oceanic gateways is thus valuable for assessing the potential of ice-shelf cavities to switch from a 'cold' to a 'warm' state, which could result in widespread ice loss from Antarctica.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
Lena Nicola, Ronja Reese, Moritz Kreuzer, Torsten Albrecht, and Ricarda Winkelmann

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2023-2583', Anonymous Referee #1, 07 Jan 2024
    • AC1: 'Initial reply to RC1', Lena Nicola, 02 Feb 2024
    • AC2: 'Reply on RC1', Lena Nicola, 27 May 2024
  • RC2: 'Comment on egusphere-2023-2583', Erwin Lambert, 26 Feb 2024
    • AC3: 'Reply on RC2', Lena Nicola, 27 May 2024
  • RC3: 'Comment on egusphere-2023-2583', Anonymous Referee #3, 29 Feb 2024
    • AC4: 'Reply on RC3', Lena Nicola, 27 May 2024
Lena Nicola, Ronja Reese, Moritz Kreuzer, Torsten Albrecht, and Ricarda Winkelmann
Lena Nicola, Ronja Reese, Moritz Kreuzer, Torsten Albrecht, and Ricarda Winkelmann

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Short summary
We identify potential oceanic gateways to Antarctic grounding lines based on high-resolution bathymetry data and examine the effect of critical access depths on basal melt rates. These gateways manifest the deepest topographic features that connect the deeper open ocean and the ice-shelf cavity. We detect 'prominent' oceanic gateways in some Antarctic regions and estimate an upper limit of melt rate changes in case all warm water masses gain access to the cavities.