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Title: Dynamic influence of pinning points on marine ice-sheet stability: a numerical study in Dronning Maud Land, East Antarctica

Journal Article · · The Cryosphere (Online)

The East Antarctic ice sheet is likely more stable than its West Antarctic counterpart because its bed is largely lying above sea level. However, the ice sheet in Dronning Maud Land, East Antarctica, contains marine sectors that are in contact with the ocean through overdeepened marine basins interspersed by grounded ice promontories and ice rises, pinning and stabilising the ice shelves. In this paper, we use the ice-sheet model BISICLES to investigate the effect of sub-ice-shelf melting, using a series of scenarios compliant with current values, on the ice-dynamic stability of the outlet glaciers between the Lazarev and Roi Baudouin ice shelves over the next millennium. Overall, the sub-ice-shelf melting substantially impacts the sea-level contribution. Locally, we predict a short-term rapid grounding-line retreat of the overdeepened outlet glacier Hansenbreen, which further induces the transition of the bordering ice promontories into ice rises. Furthermore, our analysis demonstrated that the onset of the marine ice-sheet retreat and subsequent promontory transition into ice rise is controlled by small pinning points, mostly uncharted in pan-Antarctic datasets. Pinning points have a twofold impact on marine ice sheets. They decrease the ice discharge by buttressing effect, and they play a crucial role in initialising marine ice sheets through data assimilation, leading to errors in ice-shelf rheology when omitted. Our results show that unpinning increases the sea-level rise by 10%, while omitting the same pinning point in data assimilation decreases it by 10%, but the more striking effect is in the promontory transition time, advanced by two centuries for unpinning and delayed by almost half a millennium when the pinning point is missing in data assimilation. As a result, pinning points exert a subtle influence on ice dynamics at the kilometre scale, which calls for a better knowledge of the Antarctic margins.

Research Organization:
Office of Scientific and Technical Information, Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
OSTI ID:
1375915
Journal Information:
The Cryosphere (Online), Vol. 10, Issue 6; ISSN 1994-0424
Publisher:
European Geosciences UnionCopyright Statement
Country of Publication:
United States
Language:
English
Citation Metrics:
Cited by: 45 works
Citation information provided by
Web of Science

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Assessment of sub-shelf melting parameterisations using the ocean–ice-sheet coupled model NEMO(v3.6)–Elmer/Ice(v8.3) journal January 2019
Actively evolving subglacial conduits and eskers initiate ice shelf channels at an Antarctic grounding line journal May 2017
Recent rift formation and impact on the structural integrity of the Brunt Ice Shelf, East Antarctica journal January 2018
Mechanical analysis of pinning points in the Ross Ice Shelf, Antarctica journal December 2018
Sub-Annual Calving Front Migration, Area Change and Calving Rates from Swath Mode CryoSat-2 Altimetry, on Filchner-Ronne Ice Shelf, Antarctica journal November 2019
Kinematic response of ice-rise divides to changes in ocean and atmosphere forcing journal January 2019
Sea-level response to melting of Antarctic ice shelves on multi-centennial timescales with the fast Elementary Thermomechanical Ice Sheet model (f.ETISh v1.0) journal January 2017
The Holocene retreat dynamics and stability of Petermann Glacier in northwest Greenland journal May 2018
Developments in Simulating and Parameterizing Interactions Between the Southern Ocean and the Antarctic Ice Sheet journal October 2017
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