25 Oct 2021

25 Oct 2021

Review status: this preprint is currently under review for the journal TC.

Antarctic Peninsula ice shelf collapse triggered by föhn wind-induced melt

Matthew K. Laffin1, Charles S. Zender1,2, Melchior van Wessem3, and Sebastián Marinsek4 Matthew K. Laffin et al.
  • 1Department of Earth System Science, University of California, Irvine
  • 2Department of Computer Science, University of California, Irvine
  • 3Institute for Marine and Atmospheric Research Utrecht (IMAU), Utrecht University
  • 4Instituto Antártico Argentino, Buenos Aires, Argentina

Abstract. Ice shelf collapse reduces buttressing and enables glaciers to contribute more rapidly to sea-level rise in a warming climate. The abrupt collapses of the Larsen A and B ice shelves on the Antarctic Peninsula (AP) have been attributed to increased surface melt. However, no studies examine the timing, magnitude, and location of surface melt processes immediately preceding these disintegrations. Here we use a regional climate model and Machine Learning analyses to evaluate the influence of föhn wind events on the surface liquid water budget for collapsed and extant ice shelves. We find föhn winds caused 25 % of the total annual melt in just 9 days on Larsen A which helped melt lakes surpass a critical stability depth that, we suggest, ultimately triggered collapse. By contrast, föhns appear to pre-condition, not trigger, Larsen B's collapse. AP extant ice shelves will remain less vulnerable to surface-melt-driven instability due to weaker föhn-driven melt so long as surface temperatures and föhn occurrence remain within historical bounds.

Matthew K. Laffin et al.

Status: open (until 20 Dec 2021)

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Matthew K. Laffin et al.

Matthew K. Laffin et al.


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Short summary
The rapid collapse of the Larsen A and B ice shelves on the Antarctic Peninsula was triggered in part by surface melt and melt lake formation. Numerous studies identify how much melt occurred during the years of collapse but no research explores the day-to-day melt timing or melt mechanisms during these collapse events. We find that downslope winds called föhn winds and associated surface melt triggered the Larsen A collapse and contributed to the Larsen B collapse through firn densification.