scholarly journals Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate

2015 ◽  
Vol 9 (4) ◽  
pp. 1579-1600 ◽  
Author(s):  
S. L. Cornford ◽  
D. F. Martin ◽  
A. J. Payne ◽  
E. G. Ng ◽  
A. M. Le Brocq ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Ice Shelf ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Ice Accumulation ◽  
Grounding Line ◽  
Ocean Models

Abstract. We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet, deploying sub-kilometer resolution around the grounding line since coarser resolution results in substantial underestimation of the response. Each of the simulations begins with a geometry and velocity close to present-day observations, and evolves according to variation in meteoric ice accumulation rates and oceanic ice shelf melt rates. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rate anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions and ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Within the Amundsen Sea Embayment the largest single source of variability is the onset of sustained retreat in Thwaites Glacier, which can triple the rate of eustatic sea level rise.

scholarly journals Century-scale simulations of the response of the West Antarctic Ice Sheet to a warming climate

2015 ◽  
Vol 9 (2) ◽  
pp. 1887-1942 ◽  
Author(s):  
S. L. Cornford ◽  
D. F. Martin ◽  
A. J. Payne ◽  
E. G. Ng ◽  
A. M. Le Brocq ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
The West ◽  
Amundsen Sea ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Ice Accumulation ◽  
Grounding Line ◽  
Mesh Resolution

Abstract. We use the BISICLES adaptive mesh ice sheet model to carry out one, two, and three century simulations of the fast-flowing ice streams of the West Antarctic Ice Sheet. Each of the simulations begins with a geometry and velocity close to present day observations, and evolves according to variation in meteoric ice accumulation, ice shelf melting, and mesh resolution. Future changes in accumulation and melt rates range from no change, through anomalies computed by atmosphere and ocean models driven by the E1 and A1B emissions scenarios, to spatially uniform melt rates anomalies that remove most of the ice shelves over a few centuries. We find that variation in the resulting ice dynamics is dominated by the choice of initial conditions, ice shelf melt rate and mesh resolution, although ice accumulation affects the net change in volume above flotation to a similar degree. Given sufficient melt rates, we compute grounding line retreat over hundreds of kilometers in every major ice stream, but the ocean models do not predict such melt rates outside of the Amundsen Sea Embayment until after 2100. Sensitivity to mesh resolution is spurious, and we find that sub-kilometer resolution is needed along most regions of the grounding line to avoid systematic under-estimates of the retreat rate, although resolution requirements are more stringent in some regions – for example the Amundsen Sea Embayment – than others – such as the Möller and Institute ice streams.

scholarly journals Stabilizing effect of mélange buttressing on the Marine Ice Cliff Instability of the West Antarctic Ice Sheet

2021 ◽  
Author(s):  
Tanja Schlemm ◽  
Johannes Feldmann ◽  
Ricarda Winkelmann ◽  
Anders Levermann
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Ice Shelf ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Grounding Line ◽  
Calving Rate ◽  
The Antarctic

Abstract. Due to global warming and particularly high regional ocean warming, both Thwaites and Pine Island glaciers in the Amundsen region of the Antarctic Ice Sheet could lose their buttressing ice shelves over time. We analyze the possible consequences using the Parallel Ice Sheet Model (PISM), applying a simple cliff-calving parameterization and an ice-mélange-buttressing model. We find that the instantaneous loss of ice-shelf buttressing, due to enforced ice-shelf melting, initiates grounding line retreat and triggers the marine ice sheet instability (MISI). As a consequence, the grounding line progresses into the interior of the West Antarctic Ice Sheet and leads to a sea level contribution of 0.6 m within 100 a. By subjecting the exposed ice cliffs to cliff calving using our simplified parameterization, we also analyze the marine ice cliff instability (MICI). In our simulations it can double or even triple the sea level contribution depending on the only loosely constraint parameter which determines the maximum cliff-calving rate. The speed of MICI depends on this upper bound on the calving rate which is given by the ice mélange buttressing the glacier. However, stabilization of MICI may occur for geometric reasons. Since the embayment geometry changes as MICI advances into the interior of the ice sheet, the upper bound on calving rates is reduced and the progress of MICI is slowed down. Although we cannot claim that our simulations bear relevant quantitative estimates of the effect of ice-mélange buttressing on MICI, the mechanism has the potential to stop the instability. Further research is needed to evaluate its role for the past and future evolution of the Antarctic Ice Sheet.

scholarly journals Ocean access beneath the southwest tributary of Pine Island Glacier, West Antarctica

2017 ◽  
Vol 59 (76pt1) ◽  
pp. 10-15 ◽  
Author(s):  
Dustin M. Schroeder ◽  
Andrew M. Hilger ◽  
John D. Paden ◽  
Duncan A. Young ◽  
Hugh F. J. Corr
Keyword(s):  
Radar System ◽  
Ocean Water ◽  
West Antarctica ◽  
Ice Shelf ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Grounding Line

ABSTRACTThe catchments of Pine Island Glacier and Thwaites Glacier in the Amundsen Sea Embayment are two of the largest, most rapidly changing, and potentially unstable sectors of the West Antarctic Ice Sheet. They are also neighboring outlets, separated by the topographically unconfined eastern shear margin of Thwaites Glacier and the southwest tributary of Pine Island Glacier. This tributary begins just downstream of the eastern shear margin and flows into the Pine Island ice shelf. As a result, it is a potential locus of interaction between the two glaciers and could result in cross-catchment feedback during the retreat of either. Here, we analyze relative basal reflectivity profiles from three radar sounding survey lines collected using the UTIG HiCARS radar system in 2004 and CReSIS MCoRDS radar system in 2012 and 2014 to investigate the extent and character of ocean access beneath the southwest tributary. These profiles provide evidence of ocean access ~12 km inland of the 1992–2011 InSAR-derived grounding line by 2014, suggesting either retreat since 2011 or the intrusion of ocean water kilometers inland of the grounding line.

Grounding-line retreat of the West Antarctic Ice Sheet from inner Pine Island Bay

Geology ◽  
2012 ◽  
Vol 41 (1) ◽  
pp. 35-38 ◽  
Author(s):  
C.-D. Hillenbrand ◽  
G. Kuhn ◽  
J. A. Smith ◽  
K. Gohl ◽  
A. G. C. Graham ◽  
...  
Keyword(s):  
Ice Sheet ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Grounding Line

scholarly journals Dynamical processes involved in the retreat of marine ice sheets

2001 ◽  
Vol 47 (157) ◽  
pp. 271-282 ◽  
Author(s):  
Richard C.A. Hindmarsh ◽  
E. Le Meur
Keyword(s):  
Ice Sheets ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Grounding Line ◽  
Neutral Equilibrium ◽  
Generally True

AbstractMarine ice sheets with mechanics described by the shallow-ice approximation by definition do not couple mechanically with the shelf. Such ice sheets are known to have neutral equilibria. We consider the implications of this for their dynamics and in particular for mechanisms which promote marine ice-sheet retreat. The removal of ice-shelf buttressing leading to enhanced flow in grounded ice is discounted as a significant influence on mechanical grounds. Sea-level rise leading to reduced effective pressures under ice streams is shown to be a feasible mechanism for producing postglacial West Antarctic ice-sheet retreat but is inconsistent with borehole evidence. Warming thins the ice sheet by reducing the average viscosity but does not lead to grounding-line retreat. Internal oscillations either specified or generated via a MacAyeal–Payne thermal mechanism promote migration. This is a noise-induced drift phenomenon stemming from the neutral equilibrium property of marine ice sheets. This migration occurs at quite slow rates, but these are sufficiently large to have possibly played a role in the dynamics of the West Antarctic ice sheet after the glacial maximum. Numerical experiments suggest that it is generally true that while significant changes in thickness can be caused by spatially uniform changes, spatial variability coupled with dynamical variability is needed to cause margin movement.

scholarly journals Antarctic glacier-tongue velocities from Landsat images: first results

1993 ◽  
Vol 17 ◽  
pp. 356-366 ◽  
Author(s):  
B.K. Lucchitta ◽  
Κ.F. Mullins ◽  
A.L. Allison ◽  
J.G. Ferrigno
Keyword(s):  
Ice Sheet ◽  
Ice Shelf ◽  
Landsat Images ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Glacier Tongue ◽  
West Antarctic ◽  
First Results

We measured the velocities of six glacier tongues and a few tongues within ice shelves distributed around the Antarctic coastline by determining the displacement of crevasse patterns seen on sequential Landsat images. The velocities range from less than 0.2 km a−1 for East Antarctic ice-shelf tongues to more than 2.5 km a−1 for the Thwaites Glacier Tongue. All glacier tongues show increases in velocity toward their distal margins. In general, the tongues of glaciers draining the West Antarctic ice sheet have moved significantly faster than those in East Antarctica. This observation may be significant in light of the hypothesized possible disintegration of the West Antarctic ice sheet.

Active subglacial volcanism in West Antarctica as assessed by airborne geophysics: Distribution and context

2020 ◽  
Author(s):  
Donald Blankenship ◽  
Enrica Quatini ◽  
Duncan Young
Keyword(s):  
Ice Sheet ◽  
Ice Cores ◽  
Rift System ◽  
West Antarctica ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Subglacial Volcanism

<p>A combination of aerogeophysics, seismic observations and direct observation from ice cores and subglacial sampling has revealed at least 21 sites under the West Antarctic Ice sheet consistent with active volcanism (where active is defined as volcanism that has interacted with the current manifestation of the West Antarctic Ice Sheet). Coverage of these datasets is heterogenous, potentially biasing the apparent distribution of these features. Also, the products of volcanic activity under thinner ice characterized by relatively fast flow are more prone to erosion and removal by the ice sheet, and therefore potentially underrepresented. Unsurprisingly, the sites of active subglacial volcanism we have identified often overlap with areas of relatively thick ice and slow ice surface flow, both of which are critical conditions for the preservation of volcanic records. Overall, we find the majority of active subglacial volcanic sites in West Antarctica concentrate strongly along the crustal thickness gradients bounding the central West Antarctic Rift System, complemented by intra-rift sites associated with the Amundsen Sea to Siple Coast lithospheric transition.</p>

scholarly journals Preventing a Collapse of the West Antarctic Ice Sheet: Civil Engineering on a Continental Scale (Abstract only)

1983 ◽  
Vol 4 ◽  
pp. 302-302 ◽  
Author(s):  
D. R. MacAyeal
Keyword(s):  
Sea Water ◽  
Ice Sheet ◽  
Stable Condition ◽  
Ice Shelf ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Continental Scale ◽  
West Antarctic ◽  
Sea Bed

A collapse of the West Antarctic ice sheet due to warming by atmospheric carbon dioxide is a potential threat to mankind because low-lying land would be flooded by rising sea-level. Intervention would be possible by creating one or several artifical ice rises on the floating ice shelves surrounding the West Antarctic ice sheet. Ice rises are places where the ice shelf has run aground locally on the sea bed. Existing ice rises obstruct ice flow and are responsible for maintaining the ice sheet in its present stable condition. An artificial ice rise could be created by (1) drilling a hole through the ice shelf in a choice position such as over a sea-bed ridge, (2) pumping large volumes of sea-water from beneath the ice shelf so as to flood the surface, and (3) continuing to pump until the frozen sea-water has thickened the ice shelf by 100 m over an area of 100 km2. Approximately 1.6 × 106 kW of power would be required to accomplish the task in ten years. This would cost approximately 20 × 109 US dollars.

scholarly journals The Impact of the Amundsen Sea Freshwater Balance on Ocean Melting of the West Antarctic Ice Sheet

2020 ◽  
Vol 125 (9) ◽  
Author(s):  
David T. Bett ◽  
Paul R. Holland ◽  
Alberto C. Naveira Garabato ◽  
Adrian Jenkins ◽  
Pierre Dutrieux ◽  
...  
Keyword(s):  
Ice Sheet ◽  
The West ◽  
Amundsen Sea ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
The Impact ◽  
Freshwater Balance
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