The West Antarctic Ice Sheet and Sea-Level Change

2013 ◽  
pp. 1-11 ◽  
Author(s):  
R. B. Alley ◽  
R. A. Bindschadler
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Sea Level Change ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Level Change ◽  
West Antarctic ◽  
And Sea Level

Antarctic ice sheet balance and sea-level change

2012 ◽  
Author(s):  
T James ◽  
K Simon ◽  
A Darlington
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Sea Level Change ◽  
Antarctic Ice Sheet ◽  
Level Change ◽  
And Sea Level

scholarly journals Precipitation Ansatz dependent Future Sea Level Contribution by Antarctica based on CMIP5 Model Forcing

2020 ◽  
Author(s):  
Christian B. Rodehacke ◽  
Madlene Pfeiffer ◽  
Tido Semmler ◽  
Özgür Gurses ◽  
Thomas Kleiner
Keyword(s):  
Boundary Condition ◽  
Sea Level ◽  
Ice Sheet ◽  
Cmip5 Models ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Precipitation Boundary ◽  
Climate Forcings

Abstract. Various observational estimates indicate growing mass loss at Antarctica's margins but also heavier precipitation across the continent. In the future, heavier precipitation fallen on Antarctica will counteract any stronger iceberg discharge and increased basal melting of floating ice shelves driven by a warming ocean. Here, we use from nine CMIP5 models future projections, ranging from strong mitigation efforts to business-as-usual, to run an ensemble of ice-sheet simulations. We test, how the precipitation boundary condition determines Antarctica's sea-level contribution. The spatial and temporal varying climate forcings drive ice-sheet simulations. Hence, our ensemble inherits all spatial and temporal climate patterns, which is in contrast to a spatial mean forcing. Regardless of the applied boundary condition and forcing, some areas will lose ice in the future, such as the glaciers from the West Antarctic Ice Sheet draining into the Amundsen Sea. In general the simulated ice-sheet thickness grows in a broad marginal strip, where incoming storms deliver topographically controlled precipitation. This strip shows the largest ice thickness differences between the applied precipitation boundary conditions too. On average Antarctica's ice mass shrinks for all future scenarios if the precipitation is scaled by the spatial temperature anomalies coming from the CMIP5 models. In this approach, we use the relative precipitation increment per degree warming as invariant scaling constant. In contrast, Antarctica gains mass in our simulations if we apply the simulated precipitation anomalies of the CMIP5 models directly. Here, the scaling factors show a distinct spatial pattern across Antarctica. Furthermore, the diagnosed mean scaling across all considered climate forcings is larger than the values deduced from ice cores. In general, the scaling is higher across the East Antarctic Ice Sheet, lower across the West Antarctic Ice Sheet, and lowest around the Siple Coast. The latter is located on the east side of the Ross Ice Shelf.

A Model for Holocene Retreat of the West Antarctic Ice Sheet

1978 ◽  
Vol 10 (2) ◽  
pp. 150-170 ◽  
Author(s):  
Robert H. Thomas ◽  
Charles R. Bentley
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Ice Shelf ◽  
Ice Streams ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Ice Shelves ◽  
Ross Ice Shelf ◽  
West Antarctic

Marine ice sheets are grounded on land which was below sea level before it became depressed under the ice-sheet load. They are inherently unstable and, because of bedrock topography after depression, the collapse of a marine ice sheet may be very rapid. In this paper equations are derived that can be used to make a quantitative estimate of the maximum size of a marine ice sheet and of when and how rapidly retreat would take place under prescribed conditions. Ice-sheet growth is favored by falling sea level and uplift of the seabed. In most cases the buttressing effect of a partially grounded ice shelf is a prerequisite for maximum growth out to the edge of the continental shelf. Collapse is triggered most easily by eustatic rise in sea level, but it is possible that the ice sheet may self-destruct by depressing the edge of the continental shelf so that sea depth is increased at the equilibrium grounding line.Application of the equations to a hypothetical “Ross Ice Sheet” that 18,000 yr ago may have covered the present-day Ross Ice Shelf indicates that, if the ice sheet existed, it probably extended to a line of sills parallel to the edge of the Ross Sea continental shelf. By allowing world sea level to rise from its late-Wisconsin minimum it was possible to calculate retreat rates for individual ice streams that drained the “Ross Ice Sheet.” For all the models tested, retreat began soon after sea level began to rise (∼15,000 yr B.P.). The first 100 km of retreat took between 1500 and 2500 yr but then retreat rates rapidly accelerated to between 0.5 and 25 km yr−1, depending on whether an ice shelf was present or not, with corresponding ice velocities across the grounding line of 4 to 70 km yr−1. All models indicate that most of the present-day Ross Ice Shelf was free of grounded ice by about 7000 yr B.P. As the ice streams retreated floating ice shelves may have formed between promontories of slowly collapsing stagnant ice left behind by the rapidly retreating ice streams. If ice shelves did not form during retreat then the analysis indicates that most of the West Antarctic Ice Sheet would have collapsed by 9000 yr B.P. Thus, the present-day Ross Ice Shelf (and probably the Ronne Ice Shelf) serves to stabilize the West Antarctic Ice Sheet, which would collapse very rapidly if the ice shelves were removed. This provides support for the suggestion that the 6-m sea-level high during the Sangamon Interglacial was caused by collapse of the West Antarctic Ice Sheet after climatic warming had sufficiently weakened the ice shelves. Since the West Antarctic Ice Sheet still exists it seems likely that ice shelves did form during Holocene retreat. Their effect was to slow and, finally, to halt retreat. The models that best fit available data require a rather low shear stress between the ice shelf and its sides, and this implies that rapid shear in this region encouraged the formation of a band of ice with a preferred crystal fabric, as appears to be happening today in the floating portions of fast bounded glaciers.Rebound of the seabed after the ice sheet had retreated to an equilibrium position would allow the ice sheet to advance once more. This may be taking place today since analysis of data from the Ross Ice Shelf indicates that the southeast corner is probably growing thicker with time, and if this persists then large areas of ice shelf must become grounded. This would restrict drainage from West Antarctic ice streams which would tend to thicken and advance their grounding lines into the ice shelf.

scholarly journals Sea-level projections representing the deeply uncertain contribution of the West Antarctic ice sheet

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Alexander M. R. Bakker ◽  
Tony E. Wong ◽  
Kelsey L. Ruckert ◽  
Klaus Keller
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic

scholarly journals A new bed elevation model for the Weddell Sea sector of the West Antarctic Ice Sheet

2018 ◽  
Vol 10 (2) ◽  
pp. 711-725 ◽  
Author(s):  
Hafeez Jeofry ◽  
Neil Ross ◽  
Hugh F. J. Corr ◽  
Jilu Li ◽  
Mathieu Morlighem ◽  
...  
Keyword(s):  
Sea Level ◽  
Ice Sheet ◽  
Weddell Sea ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic ◽  
Bed Elevation ◽  
Grounding Line ◽  
Elevation Model

Abstract. We present a new digital elevation model (DEM) of the bed, with a 1 km gridding, of the Weddell Sea (WS) sector of the West Antarctic Ice Sheet (WAIS). The DEM has a total area of ∼ 125 000 km2 covering the Institute, Möller and Foundation ice streams, as well as the Bungenstock ice rise. In comparison with the Bedmap2 product, our DEM includes new aerogeophysical datasets acquired by the Center for Remote Sensing of Ice Sheets (CReSIS) through the NASA Operation IceBridge (OIB) program in 2012, 2014 and 2016. We also improve bed elevation information from the single largest existing dataset in the region, collected by the British Antarctic Survey (BAS) Polarimetric radar Airborne Science Instrument (PASIN) in 2010–2011, from the relatively crude measurements determined in the field for quality control purposes used in Bedmap2. While the gross form of the new DEM is similar to Bedmap2, there are some notable differences. For example, the position and size of a deep subglacial trough (∼ 2 km below sea level) between the ice-sheet interior and the grounding line of the Foundation Ice Stream have been redefined. From the revised DEM, we are able to better derive the expected routing of basal water and, by comparison with that calculated using Bedmap2, we are able to assess regions where hydraulic flow is sensitive to change. Given the potential vulnerability of this sector to ocean-induced melting at the grounding line, especially in light of the improved definition of the Foundation Ice Stream trough, our revised DEM will be of value to ice-sheet modelling in efforts to quantify future glaciological changes in the region and, from this, the potential impact on global sea level. The new 1 km bed elevation product of the WS sector can be found at https://doi.org/10.5281/zenodo.1035488.

scholarly journals The Antarctic Ice Sheet During the Last Glacial-Interglacial Cycle: A Three-Dimensional Experiment

1990 ◽  
Vol 14 ◽  
pp. 115-119 ◽  
Author(s):  
Philippe Huybrechts
Keyword(s):  
Sea Level ◽  
Three Dimensional ◽  
Ice Sheet ◽  
Weddell Sea ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Last Glacial ◽  
West Antarctic ◽  
The Last Glacial

A complete three-dimensional thermo-mechanical ice-shect model for the entire Antarctic ice sheet, including an ice shelf, grounding line-dynamics and isostatic bed adjustment, is employed to simulate the response of the ice sheet during the last glacial-interglacial cycle with respect to changing environmental conditions. To do this, the Vostok temperature signal is used to force changes in surface temperature and accumulation rate and sea level prescribed by a piecewise linear sawtooth function. Model calculations started at 160 ka B.P. In line with glacial geological evidence, the most pronounced fluctuations are found in the West Antarctic ice sheet and appear to be essentially controlled by changes in eustatic sea level. Grounding occurs more readily in the Weddell Sea than in the Ross Sea and, due to the long time scales involved, the ice sheet does not reach its full glacial extent until 16 ka B.p. The concomitant disintegration of the West Antarctic ice sheet is triggered by a rise in sea level and takes around 6000 years to complete. The ice sheet then halts close to the present state and no collapse takes place. This Holocene deglaciation appears to have added 6–8 million km3 of ice to the world oceans, corresponding with an Antarctic contribution to world-wide sea level of 12–15 m.

scholarly journals Environmental Constraints on West Antarctic Ice-Sheet Formation

1987 ◽  
Vol 33 (115) ◽  
pp. 346-356 ◽  
Author(s):  
D.R. Lindstrom ◽  
D.R. MacAyeal
Keyword(s):  
Sea Level ◽  
Environmental Influence ◽  
Accumulation Rate ◽  
Ice Sheet ◽  
Interglacial Period ◽  
Last Interglacial ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
West Antarctic

AbstractSmall perturbations in Antarctic environ-mental conditions can culminate in the demise of the Antarctic ice sheet’s western sector. This may have happened during the last interglacial period, and could recur within the next millennium due to atmospheric warming from trace gas and CO2increases. In this study, we investigate the importance of sea-level, accumulation rate, and ice influx from the East Antarctic ice sheet in the re-establishment of the West Antarctic ice sheet from a thin cover using a time-dependent numerical ice-shelf model. Our results show that a precursor to the West Antarctic ice sheet can form within 3000 years. Sea-level lowering caused by ice-sheet development in the Northern Hemisphere has the greatest environmental influence. Under favorable conditions, ice grounding occurs over all parts of the West Antarctic ice sheet except up-stream of Thwaites Glacier and in the Ross Sea region.

scholarly journals Stabilizing the West Antarctic Ice Sheet by surface mass deposition

2019 ◽  
Vol 5 (7) ◽  
pp. eaaw4132 ◽  
Author(s):  
Johannes Feldmann ◽  
Anders Levermann ◽  
Matthias Mengel
Keyword(s):  
New York ◽  
Sea Level ◽  
Ice Sheet ◽  
The West ◽  
Antarctic Ice Sheet ◽  
West Antarctic Ice Sheet ◽  
Surface Mass ◽  
West Antarctic ◽  
Short Period ◽  
Equivalent Mass

There is evidence that a self-sustaining ice discharge from the West Antarctic Ice Sheet (WAIS) has started, potentially leading to its disintegration. The associated sea level rise of more than 3m would pose a serious challenge to highly populated areas including metropolises such as Calcutta, Shanghai, New York City, and Tokyo. Here, we show that the WAIS may be stabilized through mass deposition in coastal regions around Pine Island and Thwaites glaciers. In our numerical simulations, a minimum of 7400 Gt of additional snowfall stabilizes the flow if applied over a short period of 10 years onto the region (−2 mm year−1 sea level equivalent). Mass deposition at a lower rate increases the intervention time and the required total amount of snow. We find that the precise conditions of such an operation are crucial, and potential benefits need to be weighed against environmental hazards, future risks, and enormous technical challenges.

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