29 Mar 2022
29 Mar 2022
Status: this preprint is currently under review for the journal TC.

Subglacial hydrology modulates basal sliding response of the Antarctic ice sheet to climate forcing

Elise Kazmierczak1, Sainan Sun1,2, Violaine Coulon1, and Frank Pattyn1 Elise Kazmierczak et al.
  • 1Laboratoire de Glaciologie, Université libre de Bruxelles (ULB), Brussels, Belgium
  • 2Department of Geography and Environmental Sciences, Northumbria University, Newcastle upon Tyne, UK

Abstract. Major uncertainties in the response of ice sheets to environmental forcing are due to subglacial processes. These processes pertain to the type of sliding or friction law as well as the spatial and temporal evolution of the effective pressure at the base of ice sheets. We evaluate the classical Weertman/Budd sliding law for different power exponents (viscous to near plastic) and for different representations of effective pressure at the base of the ice sheet, commonly used for hard and soft beds. The sensitivity of above slip laws is evaluated for the Antarctic ice sheet in two types of experiments, i.e., (i) the ABUMIP experiments in which ice shelves are instantaneously removed, leading to rapid grounding line retreat and ice sheet collapse, and (ii) the ISMIP6 experiments with realistic ocean and atmosphere forcings for different RCP scenarios. Results confirm earlier work that the power in the sliding law is the most determining factor in the sensitivity of the ice sheet, where a higher power in the sliding law leads to increased mass loss for a given forcing. Here we show that spatial and temporal changes in water pressure or water flux at the base modulates basal sliding for a given power. In particular, subglacial models depending on subglacial water pressure decrease effective pressure significantly near the grounding line, leading to an increased sensitivity for a given power in the sliding law.

Elise Kazmierczak et al.

Status: open (until 24 May 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2022-53', Samuel Cook, 31 Mar 2022 reply
    • AC1: 'Reply on RC1', Elise Kazmierczak, 19 Apr 2022 reply
  • RC2: 'Review of tc-2022-53', Anonymous Referee #2, 10 May 2022 reply

Elise Kazmierczak et al.

Elise Kazmierczak et al.


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Short summary
The water at the interface between the ice sheet and the underlying bedrock leads to lubrification between the ice and the bed. Due to the lack of direct observations, subglacial conditions beneath the Antarctic ice sheet are poorly understood. Here, we compare different approaches in which the suglacial water could influence sliding on the underlying bedrock and suggest that it modulates the Antarctic ice sheet response and increases the uncertainties especially in a context of global warming.