Preprints
https://doi.org/10.5194/egusphere-2023-2737
https://doi.org/10.5194/egusphere-2023-2737
21 Nov 2023
 | 21 Nov 2023

Oceanic gateways in Antarctica – Impact of relative sea-level change on sub-shelf melt

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

Abstract. Relative sea level (local water depth) on the Antarctic continental shelf is changing by the complex interplay of processes associated with Glacial Isostatic Adjustment (GIA). This involves near-field visco-elastic bedrock displacement and self-gravitational effects in response to changes in Antarctic ice load, but also far-field interhemispheric effects on the sea-level pattern. On glacial time scales, these changes can be in the order of several hundred meters, modulating the access of ocean water masses at different depths to Antarctic grounding lines. Our study shows, that due to strong vertical gradients in ocean temperature and salinity at the continental shelf margin, basal melt rates of ice shelves can change significantly just by variations in relative sea level alone. Based on coupled ice sheet – GIA model experiments and the analysis of topographic features such as troughs and sills that regulate the access of open ocean water masses onto the continental shelf (oceanic gateways), we derive maximum estimates of Antarctic basal melt rate changes, solely driven by relative sea-level variations. Under Last Glacial Maximum sea-level conditions, this effect would lead to a substantial decrease of present-day sub-shelf melt rates in East Antarctica, while the strong subsidence of bedrock in West Antarctica can lead up to a doubling of basal melt rates. For a hypothetical globally ice-free sea-level scenario, which would lead to a global mean (barystatic) sea-level rise of around +70 m, sub-shelf melt rates for a present-day ice sheet geometry can more than double in East Antarctica, but can also decrease substantially, where bedrock uplift dominates. Also for projected sea-level changes at the year 2300 we find maximum possible changes of ±20 % in sub-shelf melt rates, as a consequence of relative sea-level changes only.

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Moritz Kreuzer, Torsten Albrecht, Lena Nicola, Ronja Reese, 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-2023-2737', Anonymous Referee #1, 02 Jan 2024
  • RC2: 'Comment on egusphere-2023-2737', Johannes Sutter, 16 Feb 2024
  • RC3: 'Comment on egusphere-2023-2737', Caroline van Calcar, 21 Feb 2024
Moritz Kreuzer, Torsten Albrecht, Lena Nicola, Ronja Reese, and Ricarda Winkelmann
Moritz Kreuzer, Torsten Albrecht, Lena Nicola, Ronja Reese, and Ricarda Winkelmann

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Short summary
The study investigates how changing sea levels around Antarctica can potentially affect the floating ice shelves. It utilizes numerical models for both the Antarctic Ice Sheet and the solid Earth, investigating features like troughs and sills that control the flow of ocean water onto the continental shelf. The research finds that variations in sea level alone can significantly impact the melting rates of ice shelves.