Accelerated Ice Discharge from the Antarctic Peninsula following the Collapse of Larsen B Ice Shelf

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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Downslope föhn winds over the Antarctic Peninsula and their effect on the Larsen ice shelves

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-9481-2014 ◽

2014 ◽

Vol 14 (18) ◽

pp. 9481-9509 ◽

Cited By ~ 19

Author(s):

D. P. Grosvenor ◽

J. C. King ◽

T. W. Choularton ◽

T. Lachlan-Cope

Keyword(s):

Heat Flux ◽

Wind Speed ◽

Surface Energy ◽

Antarctic Peninsula ◽

Energy Budget ◽

Surface Flux ◽

Surface Energy Budget ◽

Ice Shelf ◽

Aircraft Observations ◽

The Antarctic

Abstract. Mesoscale model simulations are presented of a westerly föhn event over the Antarctic Peninsula mountain ridge and onto the Larsen C ice shelf, just south of the recently collapsed Larsen B ice shelf. Aircraft observations showed the presence of föhn jets descending near the ice shelf surface with maximum wind speeds at 250–350 m in height. Surface flux measurements suggested that melting was occurring. Simulated profiles of wind speed, temperature and wind direction were very similar to the observations. However, the good match only occurred at a model time corresponding to ~9 h before the aircraft observations were made since the model föhn jets died down after this. This was despite the fact that the model was nudged towards analysis for heights greater than ~1.15 km above the surface. Timing issues aside, the otherwise good comparison between the model and observations gave confidence that the model flow structure was similar to that in reality. Details of the model jet structure are explored and discussed and are found to have ramifications for the placement of automatic weather station (AWS) stations on the ice shelf in order to detect föhn flow. Cross sections of the flow are also examined and were found to compare well to the aircraft measurements. Gravity wave breaking above the mountain crest likely created a~situation similar to hydraulic flow and allowed föhn flow and ice shelf surface warming to occur despite strong upwind blocking, which in previous studies of this region has generally not been considered. Our results therefore suggest that reduced upwind blocking, due to wind speed increases or stability decreases, might not result in an increased likelihood of föhn events over the Antarctic Peninsula, as previously suggested. The surface energy budget of the model during the melting periods showed that the net downwelling short-wave surface flux was the largest contributor to the melting energy, indicating that the cloud clearing effect of föhn events is likely to be the most important factor for increased melting relative to non-föhn days. The results also indicate that the warmth of the föhn jets through sensible heat flux ("SH") may not be critical in causing melting beyond boundary layer stabilisation effects (which may help to prevent cloud cover and suppress loss of heat by convection) and are actually cancelled by latent heat flux ("LH") effects (snow ablation). It was found that ground heat flux ("GRD") was likely to be an important factor when considering the changing surface energy budget for the southern regions of the ice shelf as the climate warms.

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Climate-Induced Ice Shelf Disintegration in the Antarctic Peninsula

Antarctic Peninsula Climate Variability: Historical and Paleoenvironmental Perspectives - Antarctic Research Series ◽

10.1029/ar079p0079 ◽

2013 ◽

pp. 79-92 ◽

Cited By ~ 128

Author(s):

Ted Scambos ◽

Christina Hulbe ◽

Mark Fahnestock

Keyword(s):

Antarctic Peninsula ◽

Ice Shelf ◽

The Antarctic

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A synthesis of remote sensing data on Wilkins Ice Shelf, Antarctica

Annals of Glaciology ◽

10.3189/s0260305500012866 ◽

1993 ◽

Vol 17 ◽

pp. 211-218 ◽

Cited By ~ 14

Author(s):

D.G. Vaughan ◽

D.R. Mantripp ◽

J. Sievers ◽

C.S.M. Doake

Keyword(s):

Mass Balance ◽

Antarctic Peninsula ◽

Accumulation Rate ◽

Remote Sensing Data ◽

Dynamic Effect ◽

Remotely Sensed Data ◽

Ice Shelf ◽

Ice Shelves ◽

Limit Of Viability ◽

The Antarctic

Wilkins Ice Shelf has an area of 16000 km2 and lies off the west coast of the Antarctic Peninsula bounded by Alexander, Latady, Charcot and Rothschild islands. Several ice shelves, including Wilkins, exist close to a climatic limit of viability. The recent disintegration of the neighbouring Wordie Ice Shelf has been linked to atmopsheric warming observed on the Antarctic Peninsula. The limit of ice-shelf viability thus appears to have migrated south. Should this continue, the question arises; how long will Wilkins Ice Shelf survive?Compared with the other ice shelves on the Antarctic Peninsula, few surface glaciological data have been collected on Wilkins Ice Shelf. We compare, contrast and combine a variety of remotely sensed data: the recently declassified GEOSAT Geodetic Mission altimetry, Landsat MSS and TM imagery, and radio-echo sounding data (RES), to study its structure and mass balance regime.We find that this shelf has an unusual mass balance regime and relies heavily for sustenance on in situ accumulation. Its response to a continued atmospheric warming may be significantly different from that of Wordie Ice Shelf. Wordie Ice Shelf was fed by several dynamic outlet glaciers which accelerated the disintegration process when the ice shelf fractured. Wilkins Ice Shelf by contrast is almost stagnant and is expected to respond by normal calving at the ice front. Changes in the accumulation rate or basal melt-rate may, however, dominate any dynamic effect. Over the last two decades the ice front positions have remained stable.

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Recent dynamic changes on Fleming Glacier after the disintegration of Wordie Ice Shelf, Antarctic Peninsula

The Cryosphere ◽

10.5194/tc-12-1347-2018 ◽

2018 ◽

Vol 12 (4) ◽

pp. 1347-1365 ◽

Cited By ~ 11

Author(s):

Peter Friedl ◽

Thorsten C. Seehaus ◽

Anja Wendt ◽

Matthias H. Braun ◽

Kathrin Höppner

Keyword(s):

Antarctic Peninsula ◽

Remote Sensing Data ◽

Data Sets ◽

Ice Shelf ◽

Glacier Tongue ◽

Marguerite Bay ◽

Grounding Line ◽

Continuous Dynamic ◽

The 1960S ◽

The Antarctic

Abstract. The Antarctic Peninsula is one of the world's regions most affected by climate change. Several ice shelves have retreated, thinned or completely disintegrated during recent decades, leading to acceleration and increased calving of their tributary glaciers. Wordie Ice Shelf, located in Marguerite Bay at the south-western side of the Antarctic Peninsula, completely disintegrated in a series of events between the 1960s and the late 1990s. We investigate the long-term dynamics (1994–2016) of Fleming Glacier after the disintegration of Wordie Ice Shelf by analysing various multi-sensor remote sensing data sets. We present a dense time series of synthetic aperture radar (SAR) surface velocities that reveals a rapid acceleration of Fleming Glacier in 2008 and a phase of further gradual acceleration and upstream propagation of high velocities in 2010–2011.The timing in acceleration correlates with strong upwelling events of warm circumpolar deep water (CDW) into Wordie Bay, most likely leading to increased submarine melt. This, together with continuous dynamic thinning and a deep subglacial trough with a retrograde bed slope close to the terminus probably, has induced unpinning of the glacier tongue in 2008 and gradual grounding line retreat between 2010 and 2011. Our data suggest that the glacier's grounding line had retreated by ∼ 6–9 km between 1996 and 2011, which caused ∼ 56 km2 of the glacier tongue to go afloat. The resulting reduction in buttressing explains a median speedup of ∼ 1.3 m d−1 (∼ 27 %) between 2008 and 2011, which we observed along a centre line extending between the grounding line in 1996 and ∼ 16 km upstream. Current median ice thinning rates (2011–2014) along profiles in areas below 1000 m altitude range between ∼ 2.6 to 3.2 m a−1 and are ∼ 70 % higher than between 2004 and 2008. Our study shows that Fleming Glacier is far away from approaching a new equilibrium and that the glacier dynamics are not primarily controlled by the loss of the former ice shelf anymore. Currently, the tongue of Fleming Glacier is grounded in a zone of bedrock elevation between ∼ −400 and −500 m. However, about 3–4 km upstream modelled bedrock topography indicates a retrograde bed which transitions into a deep trough of up to ∼ −1100 m at ∼ 10 km upstream. Hence, this endangers upstream ice masses, which can significantly increase the contribution of Fleming Glacier to sea level rise in the future.

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State of Balance of the Ice Sheet in the Antarctic Peninsula

Annals of Glaciology ◽

10.1017/s0260305500002561 ◽

1982 ◽

Vol 3 ◽

pp. 77-82 ◽

Cited By ~ 25

Author(s):

Christopher S. M. Doake

Keyword(s):

Antarctic Peninsula ◽

East Coast ◽

Accumulation Rate ◽

Level Line ◽

Ice Shelf ◽

High Accumulation ◽

Glacier Recession ◽

Valley Glacier ◽

The Antarctic ◽

Small Valley

Data from ice rises on the east coast of the Antarctic Peninsula can be interpreted as showing that the ice is thinning at rates of up 0.5 m a−1. However, a level line between two nunataks in Palmer Land showed no change in surface elevation over a period of 5 a. Melt rates on George VI Ice Shelf vary with position and may indicate that parts of the ice shelf are thickening at the rate of several m a−1, presumably in response to a higher accumulation rate over the peninsula a few hundred years ago. A small valley glacier, Spartan Glacier, is wasting away at about 0.27 m a−1. Ice fronts on both east and west coasts of the peninsula have been retreating for the last 30 a. It seems that there is general glacier recession in response to a wanner climate and decreased snowfall for at least the last 30 a, while parts of the peninsula are still thickening in response to a high accumulation rate several hundred years ago.

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State of Balance of the Ice Sheet in the Antarctic Peninsula

Annals of Glaciology ◽

10.3189/s0260305500002561 ◽

1982 ◽

Vol 3 ◽

pp. 77-82 ◽

Cited By ~ 6

Author(s):

Christopher S. M. Doake

Keyword(s):

Antarctic Peninsula ◽

East Coast ◽

Accumulation Rate ◽

Level Line ◽

Ice Shelf ◽

High Accumulation ◽

Glacier Recession ◽

Valley Glacier ◽

The Antarctic ◽

Small Valley

Data from ice rises on the east coast of the Antarctic Peninsula can be interpreted as showing that the ice is thinning at rates of up 0.5 m a−1. However, a level line between two nunataks in Palmer Land showed no change in surface elevation over a period of 5 a. Melt rates on George VI Ice Shelf vary with position and may indicate that parts of the ice shelf are thickening at the rate of several m a−1, presumably in response to a higher accumulation rate over the peninsula a few hundred years ago. A small valley glacier, Spartan Glacier, is wasting away at about 0.27 m a−1. Ice fronts on both east and west coasts of the peninsula have been retreating for the last 30 a. It seems that there is general glacier recession in response to a wanner climate and decreased snowfall for at least the last 30 a, while parts of the peninsula are still thickening in response to a high accumulation rate several hundred years ago.

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Electrical Resistivity of Ice from the Antarctic Peninsula, Antarctica

Journal of Glaciology ◽

10.1017/s0022143000006110 ◽

1984 ◽

Vol 30 (106) ◽

pp. 289-295 ◽

Cited By ~ 10

Author(s):

John M. Reynolds ◽

J. G. Paren

Keyword(s):

Antarctic Peninsula ◽

Flow Line ◽

Polar Regions ◽

List Type ◽

Electrical Measurements ◽

Ice Shelf ◽

Ice Shelves ◽

History Of ◽

Surface Ice ◽

The Antarctic

AbstractGeoresistivity soundings have been carried out at four sites in the Antarctic Peninsula. The objective of the work was to investigate the electrical behaviour of ice from an area where substantial melting occurs in summer and from contrasting thermal regimes. Electrical measurements made at three sites along a flow line within George VI Ice Shelf reveal that:(a)the resistivity of deep ice is similar to that of other Antarctic ice shelves,(b)the resistivity of the ice-shelf surface, which is affected by the percolation and refreezing of melt water, is similar to that of deep ice and hence the ice is polar in character.A compilation of published resistivities of deep ice from polar regions shows that the range of resistivities is very narrow (0.4 –2.0) x 105Ω m between –2 and – 29°C, irrespective of the physical setting and history of the ice. Typically, resistivity is within a factor of two of 80 kΩ m at –20° C with an activation energy of 0.22 eV. In contrast, the resistivity of surface ice at Wormald Ice Piedmont, where the ice is at 0°C throughout, is two orders of magnitude higher and falls at the lower end of the range of resistivities for temperate ice.

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