Preprints
https://doi.org/10.5194/tc-2021-105
https://doi.org/10.5194/tc-2021-105

  16 Apr 2021

16 Apr 2021

Review status: a revised version of this preprint is currently under review for the journal TC.

The impact of recent and future calving events on the Larsen C ice shelf

Tom Mitcham1, G. Hilmar Gudmundsson2, and Jonathan L. Bamber1 Tom Mitcham et al.
  • 1Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, UK
  • 2Department of Geography and Environmental Sciences, Northumbria University, Newcastle, UK

Abstract. The Antarctic Peninsula has seen rapid and widespread changes in the extent of its ice shelves in recent decades, including the collapse of the Larsen A and B ice shelves in 1995 and 2002, respectively. In 2017 the Larsen C ice shelf (LCIS) lost around 10 % of its area by calving one of the largest icebergs ever recorded (A68). This has raised questions about the structural integrity of the shelf and the impact of any changes in its extent on the flow of its tributary glaciers. In this work, we used an ice flow model to study the instantaneous impact of changes in the thickness and extent of the LCIS on ice dynamics, and in particular on changes in the grounding line flux (GLF). We initialised the model to a pre-A68 calving state, and first replicated the calving of the A68 iceberg. We found that there was a limited impact on upstream flow – with speeds increasing by less than 10 % across almost all of the shelf – and a 0.5 % increase in GLF. This result is supported by observations of ice velocity made before and after the calving event. We then perturbed the ice-shelf geometry through idealised calving and thinning experiments of increasing magnitude. We found that significant changes to the geometry of the ice shelf, through both calving and thinning, resulted in limited changes in GLF. For example, to produce a doubling of GLF from calving, the new calving front needed to be moved to 5 km from the grounding line, removing almost the entire ice shelf. For thinning, over 200 m of the ice-shelf thickness had to be removed across the whole shelf to produce a doubling of GLF. Calculating the increase in GLF (607 %) after removing the entire ice shelf allowed us to quantify the total amount of buttressing provided by the LCIS. From this, we identified that the region of the ice shelf in the first 5 km downstream of the grounding line provided over 80 % of the buttressing capacity of the shelf. This is due to the large resistive stresses generated in the narrow, local embayments downstream of the largest tributary glaciers.

Tom Mitcham et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-105', Anonymous Referee #1, 25 May 2021
    • AC1: 'Reply on RC1', Tom Mitcham, 14 Jul 2021
  • RC2: 'Comment on tc-2021-105', Anonymous Referee #2, 03 Jun 2021
    • AC2: 'Reply on RC2', Tom Mitcham, 14 Jul 2021

Tom Mitcham et al.

Tom Mitcham et al.

Viewed

Total article views: 578 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
413 150 15 578 5 4
  • HTML: 413
  • PDF: 150
  • XML: 15
  • Total: 578
  • BibTeX: 5
  • EndNote: 4
Views and downloads (calculated since 16 Apr 2021)
Cumulative views and downloads (calculated since 16 Apr 2021)

Viewed (geographical distribution)

Total article views: 567 (including HTML, PDF, and XML) Thereof 567 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Latest update: 29 Jul 2021
Download
Short summary
We modelled the response of the Larsen C ice shelf (LCIS) and its tributary glaciers to the calving of the A68 iceberg and validated our results with observations. We found that the impact was limited, confirming that mostly passive ice was calved. Through further calving experiments we quantified the total buttressing provided by the LCIS and found that over 80 % of the buttressing capacity is generated in the first 5 km of the ice shelf downstream of the grounding line.