Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

T O Holt,D J Quincey,M R Siegfried,N F Glasser

doi:10.5194/tc-7-797-2013

T O Holt, D J Quincey + Show 2 more

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https://doi.org/10.5194/tc-7-797-2013

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Abstract

Abstract. George VI Ice Shelf (GVIIS) is located on the Antarctic Peninsula, a region where several ice shelves have undergone rapid breakup in response to atmospheric and oceanic warming. We use a combination of optical (Landsat), radar (ERS 1/2 SAR) and laser altimetry (GLAS) datasets to examine the response of GVIIS to environmental change and to offer an assessment on its future stability. The spatial and structural changes of GVIIS (ca. 1973 to ca. 2010) are mapped and surface velocities are calculated at different time periods (InSAR and optical feature tracking from 1989 to 2009) to document changes in the ice shelf's flow regime. Surface elevation changes are recorded between 2003 and 2008 using repeat track ICESat acquisitions. We note an increase in fracture extent and distribution at the south ice front, ice-shelf acceleration towards both the north and south ice fronts and spatially varied negative surface elevation change throughout, with greater variations observed towards the central and southern regions of the ice shelf. We propose that whilst GVIIS is in no imminent danger of collapse, it is vulnerable to ongoing atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

Highlights

At the south ice front, approximately 925 km2 of ice was lost, with 182 km2 of ice advancing into the Ronne Entrance (Fig. 2c, d and Fig. 3); a net loss of 743 km2 was recorded between January 1973 and January 2010
During 1973, 390 km2 of shelf ice was captured calving off the south ice front towards Monteverdi Peninsula but not included in loss calculations as it was deemed to have already detached from the ice shelf
Retreat was concentrated in the central portions of the south ice front, with only limited retreat observed at the ice-front pinning points along Monteverdi Peninsula, De Atley Island and Spatz Island

Summary

Introduction

1.1 BackgroundIn recent years, several Antarctic Peninsula (AP) ice shelves have undergone dramatic and rapid retreat (Cook and Vaughan, 2010): for example, Prince Gustav Channel ice shelf (Rott et al, 1996; Cooper, 1997; Glasser et al, 2011), Larsen Inlet (Skvarca, 1993), Larsen A (Rott et al, 1998; Doake et al, 1998), Larsen B (Rott et al, 2002; Glasser and Scambos, 2008), Jones (Fox and Vaughan, 2005), Wordie (Reynolds, 1988; Vaughan, 1993) and Muller (Ward, 1995). During 1998, 2008 and 2009, the Wilkins Ice Shelf experienced major breakup phases (Braun et al, 2009; Scambos et al, 2009; Padman et al, 2012) that highlighted the ongoing cryospheric response to atmospheric (Vaughan et al, 2003) and oceanic (Martinson et al, 2008) warming. Ice-shelf stability on the AP has been linked to the southward migration of a critical atmospheric thermal boundary by a number of previous studies, linked to a rapid warming in the 1980s and 1990s. Morris and Vaughan (2003) remarked that the timing of ice-shelf collapse events was closely linked to the arrival of the −9 °C mean-annual isotherm. Attributing specific ice-shelf changes to a single mechanism is still challenging, due to the complexity of ocean– ice–atmosphere interactions

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