OBSERVATIONS OF CONTINUOUS INSTABILITY FOR SCAR INLET ICE SHELF, ANTARCTIC PENINSULA

Abstract. Observation of the evolving instability of ice shelves plays a very important role in global change research. Following the suddenly large-scale collapse of the Larsen B Ice Shelf in the Antarctic Peninsula in 2002, the evolving instability for its remnant, the Scar Inlet Ice Shelf, began to be increasingly studied to provide a deeper understanding of the disintegration of the Larsen B Ice Shelf in 2002 and also provide a chance for studying the response of ice shelves to the large-scale collapse events. In this study, based on sequential Landsat images spanning 2005–2020, we produced detailed maps of the ice velocity fields for the Scar Inlet Ice Shelf. The results indicate that the ice velocities for the Scar Inlet Ice Shelf region have substantially increased since 2005, the maximum ice velocity reached more than 900 m/y in the ice shelf front. Surface rifts have also substantially increased in both length and width and are moving seawards. The ice front position of the Scar Inlet Ice Shelf is relatively stable in 2008–2010 and then steadily advancing after 2010. The acceleration of ice velocities, the dynamic change of the ice front, the increase of major surface rifts and the newly added rifts in the central part of the ice shelf, and the heavily enhanced surface crevasses are all revealing the evolving instability of the Scar Inlet Ice Shelf.

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Evolving Instability of the Scar Inlet Ice Shelf based on Sequential Landsat Images Spanning 2005–2018

Remote Sensing ◽

10.3390/rs12010036 ◽

2019 ◽

Vol 12 (1) ◽

pp. 36

Author(s):

Gang Qiao ◽

Yanjun Li ◽

Song Guo ◽

Wenkai Ye

Keyword(s):

Large Scale ◽

Ice Shelf ◽

Landsat Images ◽

Ice Flow ◽

Surface Features ◽

Ice Flows ◽

Fast Ice ◽

Summer Temperatures ◽

Major Surface ◽

Flow Velocities

Following the large-scale disintegration of the Larsen B Ice Shelf (LBIS) in 2002, ice flow velocities for its remnants and tributary glaciers began to increase. In this study, we used sequential Landsat images spanning 2005–2018 to produce detailed maps of the ice flow velocities and surface features for the Scar Inlet Ice Shelf (SIIS). Our results indicate that the ice flow velocities for the SIIS and its tributary glaciers (Flask and Leppard Glaciers) have substantially increased since 2005. Surface features, such as rifts and crevasses, have also substantially increased in both scope and scale and are particularly evident in the region between the Leppard Glacier and the Jason Peninsula. Several indicators—including the acceleration of ice flows, the rapid growth of major surface rifts, the heavily enhanced surface crevasses, and the dynamic position of the ice front—point to the evolving instability of the SIIS. These same indicators describe the conditions for the LBIS leading up to its 2002 collapse. To date, however, the SIIS remains intact. The formation of fast ice supporting the ice shelf front, combined with moderate mean summer temperatures, may be preventing or delaying its collapse.

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Firn air depletion as a precursor of Antarctic ice-shelf collapse

Journal of Glaciology ◽

10.3189/2014jog13j183 ◽

2014 ◽

Vol 60 (220) ◽

pp. 205-214 ◽

Cited By ~ 65

Author(s):

Peter Kuipers Munneke ◽

Stefan R.M. Ligtenberg ◽

Michiel R. Van Den Broeke ◽

David G. Vaughan

Keyword(s):

Porous Medium ◽

Hydrostatic Pressure ◽

Antarctic Peninsula ◽

Large Scale ◽

Pore Space ◽

Climate Scenario ◽

Low Density ◽

Ice Shelf ◽

Ice Shelves ◽

The Antarctic

AbstractSince the 1970s, the sudden, rapid collapse of 20% of ice shelves on the Antarctic Peninsula has led to large-scale thinning and acceleration of its tributary glaciers. The leading hypothesis for the collapse of most of these ice shelves is the process of hydrofracturing, whereby a water-filled crevasse is opened by the hydrostatic pressure acting at the crevasse tip. This process has been linked to observed atmospheric warming through the increased supply of meltwater. Importantly, the low-density firn layer near the ice-shelf surface, providing a porous medium in which meltwater can percolate and refreeze, has to be filled in with refrozen meltwater first, before hydrofracturing can occur at all. Here we build upon this notion of firn air depletion as a precursor of ice-shelf collapse, by using a firn model to show that pore space was depleted in the firn layer on former ice shelves, which enabled their collapse due to hydrofracturing. Two climate scenario runs with the same model indicate that during the 21st century most Antarctic Peninsula ice shelves, and some minor ice shelves elsewhere, are more likely to become susceptible to collapse following firn air depletion. If warming continues into the 22nd century, similar depletion will become widespread on ice shelves around East Antarctica. Our model further suggests that a projected increase in snowfall will protect the Ross and Filchner–Ronne Ice Shelves from hydrofracturing in the coming two centuries.

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Ice loss processes in the Seal Nunataks ice shelf region from satellite altimetry and imagery

Annals of Glaciology ◽

10.1017/aog.2016.29 ◽

2016 ◽

Vol 57 (73) ◽

pp. 94-104 ◽

Cited By ~ 2

Author(s):

Christopher Shuman ◽

Ted Scambos ◽

Etienne Berthier

Keyword(s):

Detailed Analysis ◽

Antarctic Peninsula ◽

Satellite Altimetry ◽

Ice Shelf ◽

Ice Shelves ◽

Landsat 7 ◽

Fast Ice ◽

Shelf Region

ABSTRACTThe Seal Nunataks ice shelf (SNIS, ~743 km2 in 2013) is an unofficial name for a remnant area between the former Larsen A and Larsen B ice shelves off the northeastern Antarctic Peninsula. Analyses using Landsat 7 ETM+ and Terra ASTER images from 2001 to 13 and ICESat altimetry from 2003 to 09 show it has retreated and thinned following the Larsen A (1995) and Larsen B (2002) disintegrations. Despite some regional cooling and more fast ice since 2008, SNIS continues to lose ice along its margins and may be losing contact with some nunataks. Detailed analysis of data from four ICESat tracks indicates that ice shelf thinning rates range between 1.9 and 2.7 m a−1, and generally increase from west to east. An ICESat repeat track crossing the adjacent Robertson Island shows a mean elevation loss of 1.8 m a−1. Two tracks crossing the SNIS's remaining tributary, Rogosh Glacier, show sub-meter elevation losses. Comparing shelf remnant and grounded ice thinning rates implies that basal ocean melting augments SNIS thinning by ~1 m a−1, a rate that is consistent with other estimates of ocean-driven shelf thinning in the region.

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Climatically induced retreat and collapse of northern Larsen Ice Shelf, Antarctic Peninsula

Annals of Glaciology ◽

10.3189/s0260305500017262 ◽

1998 ◽

Vol 27 ◽

pp. 86-92 ◽

Cited By ~ 80

Author(s):

Helmut Rott ◽

Wolfgang Rack ◽

Thomas Nagler ◽

Pedro Skvarca

Keyword(s):

Mass Balance ◽

Antarctic Peninsula ◽

High Sensitivity ◽

Ice Shelf ◽

Landsat Images ◽

Surface Mass ◽

Ice Shelves ◽

Radar Images ◽

Near Future ◽

Larsen Ice Shelf

The areal changes of the northern Larsen Ite Shelf (LIS), Antarctic Peninsula, between March 1986 and March 1997 have been analyzed, based on synthetic aperture radar images of the European remote-sensing satellites ERS-1 and ERS-2 and on Landsat images. This analysis is complemented by data on ice motion and surface mass balance which have been obtained during several field campaigns since the early 1980s. After a period of retreat, coinciding with atmospheric warming and with decreasing net accumulation at the surface due to melt losses, the two northernmost sections of LIS disintegrated almost completely within a few days in January 1995. Recent observations of the ice-shelf section north of Jason Peninsula, which is presently the northernmost section of LIS, show increased summer melt and intensification of the rifting processes, probably causing accelerated retreat of this section in the near future. The retreat and the disintegration event of LIS indicate high sensitivity of ice shelves to prolonged perturbations of the mass balance.

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Seasonal evolution of Antarctic supraglacial lakes in 2015–2021 and links to environmental controls

The Cryosphere ◽

10.5194/tc-15-5205-2021 ◽

2021 ◽

Vol 15 (11) ◽

pp. 5205-5226

Author(s):

Mariel C. Dirscherl ◽

Andreas J. Dietz ◽

Claudia Kuenzer

Keyword(s):

Antarctic Peninsula ◽

Large Scale ◽

Environmental Drivers ◽

Ice Shelf ◽

Ice Shelves ◽

Shelf Stability ◽

Air Content ◽

Supraglacial Lakes ◽

Environmental Controls ◽

Lake Formation

Abstract. Supraglacial meltwater accumulation on ice shelves may have important implications for future sea level rise. Despite recent progress in the understanding of Antarctic surface hydrology, potential influences on ice shelf stability as well as links to environmental drivers remain poorly constrained. In this study, we employ state-of-the-art machine learning on Sentinel-1 synthetic aperture radar (SAR) and optical Sentinel-2 satellite imagery to provide new insight into the inter-annual and intra-annual evolution of surface hydrological features across six major Antarctic Peninsula and East Antarctic ice shelves. For the first time, we produce a high-resolution record of supraglacial lake extent dynamics for the period 2015–2021 at unprecedented 10 m spatial resolution and bi-weekly temporal scale. Through synergetic use of optical and SAR data, we obtain a more complete mapping record also enabling the delineation of buried lakes. Our results for Antarctic Peninsula ice shelves reveal below-average meltwater ponding during most of melting seasons 2015–2018 and above-average meltwater ponding throughout summer 2019–2020 and early 2020–2021 considering years 2015–2021 as a reference period. Meltwater ponding on investigated East Antarctic ice shelves was far more variable, with above-average lake extents during most 2016–2019 melting seasons and below-average lake extents during 2020–2021, considering the reference interval 2016–2021. This study is the first to investigate relationships with climate drivers both spatially and temporally including time lag analysis. The results indicate that supraglacial lake formation in 2015–2021 is coupled to the complex interplay of local, regional and large-scale environmental drivers with similar driving factors over both ice sheet regions. In particular, varying air temperature, solar radiation and wind conditions influenced supraglacial lake formation over all six ice shelves despite strong local to regional discrepancies, as revealed through pixel-based correlation analysis. Furthermore, regional climatic conditions were shown to be influenced by Southern Hemisphere atmospheric modes showing large-scale impacts on the spatio-temporal evolution of supraglacial lakes as well as on above- or below-average meltwater ponding with respect to the period 2015–2021. Finally, the local glaciological setting, including melt–albedo feedbacks and the firn air content, was revealed to strongly influence supraglacial lake distribution. Recent increases in Antarctic Peninsula surface ponding point towards a further reduction in the firn air content, implying an increased risk for ponding and hydrofracture. In addition, lateral meltwater transport was observed over both Antarctic regions with similar implications for future ice shelf stability.

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Climatic conditions, mass balance and dynamics of Larsen B ice shelf, Antarctic Peninsula, prior to collapse

Annals of Glaciology ◽

10.3189/172756404781814573 ◽

2004 ◽

Vol 39 ◽

pp. 557-562 ◽

Cited By ~ 17

Author(s):

Pedro Skvarca ◽

Hernán De Angelis ◽

Andrés F. Zakrajsek

Keyword(s):

Mass Balance ◽

Antarctic Peninsula ◽

Satellite Image ◽

Climatic Conditions ◽

Strain Rates ◽

Ice Shelf ◽

Ice Flow ◽

Ice Shelves ◽

Additional Information ◽

Significant Acceleration

AbstractFollowing the collapse of Larsen A in 1995, about 3200 km2 of Larsen B ice shelf disintegrated in early 2002 during the warmest summer recorded on the northeastern Antarctic Peninsula. Immediately prior to disintegration the last field campaign was carried out on Larsen B. Measurements included surface net mass balance, velocity and strain rate on a longitudinal transect along Crane Glacier flowline and over a remnant section confined within Seal Nunataks that survived the collapse. In addition, an automatic weather station located nearby allowed derivation of melt days relevant to the formation and extent of surface meltwater. Repeated surveys allowed us to detect a significant acceleration in ice-flow velocity and associated increasing strain rates along the longitudinal transect. It may be possible to use this acceleration as a predictor of imminent ice-shelf collapse, applicable to ice shelves subject to similar climatic conditions. Additional information on recent ongoing changes was provided by a visible satellite image acquired in early 2003.

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2001–2009 elevation and mass losses in the Larsen A and B embayments, Antarctic Peninsula

Journal of Glaciology ◽

10.3189/002214311797409811 ◽

2011 ◽

Vol 57 (204) ◽

pp. 737-754 ◽

Cited By ~ 46

Author(s):

Christopher A. Shuman ◽

Etienne Berthier ◽

Ted A. Scambos

Keyword(s):

Antarctic Peninsula ◽

Loss Rate ◽

Ice Shelf ◽

Laser Altimetry ◽

Ice Shelves ◽

Ice Volume ◽

Mass Losses ◽

Digital Elevation ◽

Modis Imagery ◽

Elevation Changes

AbstractWe investigate the elevation and mass-balance response of tributary glaciers following the loss of the Larsen A and B ice shelves, Antarctic Peninsula (in 1995 and 2002 respectively). Our study uses MODIS imagery to track ice extent, and ASTER and SPOT5 digital elevation models (DEMs) plus ATM and ICESat laser altimetry to track elevation changes, spanning the period 2001–09. The measured Larsen B tributary glaciers (Hektoria, Green, Evans, Punchbowl, Jorum and Crane) lost up to 160 m in elevation during 2001–06, and thinning continued into 2009. Elevation changes were small for the more southerly Flask and Leppard Glaciers, which are still constrained by a Larsen B ice shelf remnant. In the northern embayment, continued thinning of >3 m a−1 on Drygalski Glacier, 14 years after the Larsen A ice shelf disintegrated, suggests that mass losses for the exposed Larsen B tributaries will continue for years into the future. Grounded ice volume losses exceed 13 km3 for Crane Glacier and 30 km3 for the Hektoria–Green–Evans glaciers. The combined mean loss rate for 2001–06 is at least 11.2 Gt a−1. Our values differ significantly from published mass-budget-based estimates for these embayments, but are a reasonable fraction of GRACE-derived rates for the region (∼40 Gt a−1).

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Recent ice-surface-elevation changes of Fleming Glacier in response to the removal of the Wordie Ice Shelf, Antarctic Peninsula

Annals of Glaciology ◽

10.3189/172756410791392727 ◽

2010 ◽

Vol 51 (55) ◽

pp. 97-102 ◽

Cited By ~ 15

Author(s):

J. Wendt ◽

A. Rivera ◽

A. Wendt ◽

F. Bown ◽

R. Zamora ◽

...

Keyword(s):

Antarctic Peninsula ◽

Regional Climate ◽

Airborne Lidar ◽

Similar Data ◽

Ice Shelf ◽

International Polar Year ◽

Ice Flow ◽

Ice Shelves ◽

Elevation Changes ◽

The Antarctic

AbstractRegional climate warming has caused several ice shelves on the Antarctic Peninsula to retreat and ultimately collapse during recent decades. Glaciers flowing into these retreating ice shelves have responded with accelerating ice flow and thinning. The Wordie Ice Shelf on the west coast of the Antarctic Peninsula was reported to have undergone a major areal reduction before 1989. Since then, this ice shelf has continued to retreat and now very little floating ice remains. Little information is currently available regarding the dynamic response of the glaciers feeding the Wordie Ice Shelf, but we describe a Chilean International Polar Year project, initiated in 2007, targeted at studying the glacier dynamics in this area and their relationship to local meteorological conditions. Various data were collected during field campaigns to Fleming Glacier in the austral summers of 2007/08 and 2008/09. In situ measurements of ice-flow velocity first made in 1974 were repeated and these confirm satellite-based assessments that velocity on the glacier has increased by 40–50% since 1974. Airborne lidar data collected in December 2008 can be compared with similar data collected in 2004 in collaboration with NASA and the Chilean Navy. This comparison indicates continued thinning of the glacier, with increasing rates of thinning downstream, with a mean of 4.1 ± 0.2 m a−1 at the grounding line of the glacier. These comparisons give little indication that the glacier is achieving a new equilibrium.

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Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

The Cryosphere ◽

10.5194/tc-7-797-2013 ◽

2013 ◽

Vol 7 (3) ◽

pp. 797-816 ◽

Cited By ~ 20

Author(s):

T. O. Holt ◽

N. F. Glasser ◽

D. J. Quincey ◽

M. R. Siegfried

Keyword(s):

Antarctic Peninsula ◽

Structural Changes ◽

Surface Elevation ◽

Ice Shelf ◽

Ice Shelves ◽

The North ◽

Surface Elevation Change ◽

Elevation Changes ◽

Negative Surface ◽

The Antarctic

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.

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Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

The Cryosphere Discussions ◽

10.5194/tcd-7-373-2013 ◽

2013 ◽

Vol 7 (1) ◽

pp. 373-417 ◽

Cited By ~ 3

Author(s):

T. O. Holt ◽

N. F. Glasser ◽

D. J. Quincey ◽

M. R. Siegfried

Keyword(s):

Antarctic Peninsula ◽

Structural Changes ◽

Surface Elevation ◽

Ice Shelf ◽

Ice Shelves ◽

The North ◽

Surface Elevation Change ◽

Elevation Changes ◽

Negative Surface ◽

The Antarctic

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 on-going atmospheric and oceanic warming and is more susceptible to breakup along its southern margin in ice preconditioned for further retreat.

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