The dynamic mass loss of tidewater glaciers is strongly linked to glacier calving. We study calving mechanisms under a thinning regime, based on five years of field and remote sensing data of Bowdoin Glacier. Our data suggests that Bowdoin Glacier ungrounded recently, and its calving behaviour changed from calving due to surface crevasses to buoyancy-induced calving resulting from basal crevasses. This change may be a precursor of glacier retreat.
The dynamic mass loss of tidewater glaciers is strongly linked to glacier calving. We study...
Review status: a revised version of this preprint was accepted for the journal TC and is expected to appear here in due course.
Thinning leads to calving-style changes at Bowdoin Glacier, Greenland
Eef C. H. van Dongen1,Guillaume Jouvet2,3,Shin Sugiyama4,Evgeny A. Podolskiy4,Martin Funk1,Douglas I. Benn5,Fabian Lindner1,6,Andreas Bauder1,Julien Seguinot1,Silvan Leinss7,and Fabian Walter1Eef C. H. van Dongen et al.Eef C. H. van Dongen1,Guillaume Jouvet2,3,Shin Sugiyama4,Evgeny A. Podolskiy4,Martin Funk1,Douglas I. Benn5,Fabian Lindner1,6,Andreas Bauder1,Julien Seguinot1,Silvan Leinss7,and Fabian Walter1
Received: 01 Sep 2020 – Accepted for review: 05 Oct 2020 – Discussion started: 14 Oct 2020
Abstract. Ice mass loss from the Greenland Ice Sheet is the largest single contributor to sea-level rise in the 21st century. The mass loss rate has accelerated in recent decades mainly due to thinning and retreat of its outlet glaciers. The diverse calving mechanisms responsible for tidewater glacier retreat are not fully understood yet. Since a tidewater glacier’s sensitivity to external forcings depends on its calving style, a detailed insight into calving processes is necessary to improve projections of ice sheet mass loss by calving. As tidewater glaciers are mostly thinning, their calving styles are expected to change. Here, we study calving behaviour changes under a thinning regime at Bowdoin Glacier, Northwest Greenland, by combining field and remote sensing data from 2015 to 2019. Previous studies showed that major calving events in 2015 and 2017 were driven by hydro-fracturing and melt-undercutting. New observations from UAV imagery and a GPS network installed at the calving front in 2019 suggest ungrounding and buoyant calving have recently occurred, as they show (1) increasing tidal modulation of vertical motion compared to previous years, (2) absence of a surface crevasse prior to calving, and (3) uplift and horizontal surface compression prior to calving. Furthermore, an inventory of calving events from 2015 to 2019 based on satellite imagery provides additional support for a change towards buoyant calving since it shows an increasing occurrence of calving events outside of the melt season. The observed change of calving style could lead to a possible retreat of the terminus, which has been stable since 2013. We therefore highlight the need for high-resolution monitoring to detect changing calving styles and numerical models that cover the full spectrum of calving mechanisms to improve projections of ice sheet mass loss by calving.
The dynamic mass loss of tidewater glaciers is strongly linked to glacier calving. We study calving mechanisms under a thinning regime, based on five years of field and remote sensing data of Bowdoin Glacier. Our data suggests that Bowdoin Glacier ungrounded recently, and its calving behaviour changed from calving due to surface crevasses to buoyancy-induced calving resulting from basal crevasses. This change may be a precursor of glacier retreat.
The dynamic mass loss of tidewater glaciers is strongly linked to glacier calving. We study...