scholarly journals The link between climate warming and break-up of ice shelves in the Antarctic Peninsula

2000 ◽  
Vol 46 (154) ◽  
pp. 516-530 ◽  
Author(s):  
Ted A. Scambos ◽  
Christina Hulbe ◽  
Mark Fahnestock ◽  
Jennifer Bohlander
Keyword(s):  
Antarctic Peninsula ◽  
Remote Sensing Data ◽  
Element Model ◽  
Flow Speed ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Melt Ponds ◽  
Break Up ◽  
The Antarctic

AbstractA review of in situ and remote-sensing data covering the ice shelves of the Antarctic Peninsula provides a series of characteristics closely associated with rapid shelf retreat: deeply embayed ice fronts; calving of myriad small elongate bergs in punctuated events; increasing flow speed; and the presence of melt ponds on the ice-shelf surface in the vicinity of the break-ups. As climate has warmed in the Antarctic Peninsula region, melt-season duration and the extent of ponding have increased. Most break-up events have occurred during longer melt seasons, suggesting that meltwater itself, not just warming, is responsible. Regions that show melting without pond formation are relatively unchanged. Melt ponds thus appear to be a robust harbinger of ice-shelf retreat. We use these observations to guide a model of ice-shelf flow and the effects of meltwater. Crevasses present in a region of surface ponding will likely fill to the brim with water. We hypothesize (building on Weertman (1973), Hughes (1983) and Van der Veen (1998)) that crevasse propagation by meltwater is the main mechanism by which ice shelves weaken and retreat. A thermodynamic finite-element model is used to evaluate ice flow and the strain field, and simple extensions of this model are used to investigate crack propagation by meltwater. The model results support the hypothesis.

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

1993 ◽  
Vol 17 ◽  
pp. 211-218 ◽  
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.

scholarly journals Changes of Wilkins Ice Shelf over the past 15 years and inferences on its stability

2009 ◽  
Vol 3 (1) ◽  
pp. 41-56 ◽  
Author(s):  
M. Braun ◽  
A. Humbert ◽  
A. Moll
Keyword(s):  
Sar Interferometry ◽  
Tidal Effects ◽  
Ice Shelf ◽  
Structural Mapping ◽  
Ice Shelves ◽  
Ice Surface ◽  
Melt Ponds ◽  
Elevation Data ◽  
Break Up ◽  
The Antarctic

Abstract. The Wilkins Ice Shelf is situated on the Antarctic Peninsula, a region where seven ice shelves disintegrated or retreated between 1995 and 2002. This study combines various remote sensing datasets from Wilkins Ice Shelf, with the aim of detecting its present and recent dynamics as well as recent changes. The survey includes structural mapping, ERS-1/2 SAR interferometry and analysis of ICESat GLAS ice surface elevation data. Ice front retreat rates from 1986 to 2008 showed several distinct break-up events, including one in February 2008, when 40% of a part of the ice shelf that connected two islands broke off. Surface elevations have been used to study tidal effects, crack formation and to estimate the ice thickness over the floating area. The derived interferometric velocities cover the south-eastern part of the ice shelf as well as major tributaries and reveal maximum inflow speeds of up to 330 m a−1. We show that drainage of melt ponds into crevasses were of no relevance for the break-up at Wilkins Ice Shelf. Buoyancy forces caused rift formation before the break-up in February 2008. Additionally, the evolution of failure zones of the order of tenths of kilometres in length in pre-conditioned locations at ice rises is shown. Investigation of the current (February 2009) situation shows that about 3100 km2 at the Northern Wilkins Ice Shelf are endangered, however, there is no visible signature that the remaining 8000 km2 are at risk.

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

1993 ◽  
Vol 17 ◽  
pp. 211-218 ◽  
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.

Implications of the break-up of Wordie Ice Shelf, Antarctica for sea level

1993 ◽  
Vol 5 (4) ◽  
pp. 403-408 ◽  
Author(s):  
David G. Vaughan
Keyword(s):  
Sea Level ◽  
Antarctic Peninsula ◽  
Complete Removal ◽  
Ice Shelf ◽  
Ice Shelves ◽  
Mountain Glaciers ◽  
West Antarctic ◽  
Relative Contribution ◽  
Break Up ◽  
The Antarctic

Temperature records in the Antarctic Peninsula have shown a climatic warming of 1.5°C over the past 30 years and a number of ice shelves have retreated. The most dramatic retreat has been that of Wordie Ice Shelf which has undergone a catastrophic disintegration since the 1960s. Understanding the cause and mechanism of the break-up may provide important clues to the fate of ice shelves farther south which, it has been suggested, help to stabilize the West Antarctic Ice Sheet. The break-up of Wordie Ice Shelf has been analysed using Landsat and SPOT imagery. These observations show that the relative contribution of the various input glaciers to the grounding line flux has not altered during the break-up. This means that the effect of the rapid and almost complete removal of the ice shelf has not been transmitted upstream and is not causing a rapid increase in velocities on the input glaciers. The volume of grounded ice in the catchment of Wordie Ice Shelf will thus, be largely unaffected by the break-up and there will be no significant contribution to sea level change. Since other ice shelves around the Antarctic Peninsula are also fed by relatively steep mountain glaciers the effect of the loss of the ice shelves on sea level would be likely to be similarly small.

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

2010 ◽  
Vol 51 (55) ◽  
pp. 97-102 ◽  
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.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (3) ◽  
pp. 797-816 ◽  
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.

scholarly journals Speedup and fracturing of George VI Ice Shelf, Antarctic Peninsula

2013 ◽  
Vol 7 (1) ◽  
pp. 373-417 ◽  
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.

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

2018 ◽  
Vol 12 (4) ◽  
pp. 1347-1365 ◽  
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.

scholarly journals Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice shelf geometry

2019 ◽  
Vol 13 (10) ◽  
pp. 2771-2787 ◽  
Author(s):  
Jan De Rydt ◽  
Gudmundur Hilmar Gudmundsson ◽  
Thomas Nagler ◽  
Jan Wuite
Keyword(s):  
Large Scale ◽  
Ice Shelf ◽  
Ice Flow ◽  
Ice Shelves ◽  
Flow Models ◽  
Speed Up ◽  
The Antarctic ◽  
Detrimental Impact ◽  
Natural Laboratory

Abstract. Despite the potentially detrimental impact of large-scale calving events on the geometry and ice flow of the Antarctic Ice Sheet, little is known about the processes that drive rift formation prior to calving, or what controls the timing of these events. The Brunt Ice Shelf in East Antarctica presents a rare natural laboratory to study these processes, following the recent formation of two rifts, each now exceeding 50 km in length. Here we use 2 decades of in situ and remote sensing observations, together with numerical modelling, to reveal how slow changes in ice shelf geometry over time caused build-up of mechanical tension far upstream of the ice front, and culminated in rift formation and a significant speed-up of the ice shelf. These internal feedbacks, whereby ice shelves generate the very conditions that lead to their own (partial) disintegration, are currently missing from ice flow models, which severely limits their ability to accurately predict future sea level rise.

scholarly journals Electrical Resistivity of Ice from the Antarctic Peninsula, Antarctica

1984 ◽  
Vol 30 (106) ◽  
pp. 289-295 ◽  
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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