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  • 1
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    Dynamics of the LGM Antarctic ice-sheet [Earth, Atmospheric, and Planetary Sciences] (2012)
    National Academy of Sciences
    Details
    Publication Date: 2012-10-03
    Description: Retreat of the Last Glacial Maximum (LGM) Antarctic ice sheet is thought to have been initiated by changes in ocean heat and eustatic sea level propagated from the Northern Hemisphere (NH) as northern ice sheets melted under rising atmospheric temperatures. The extent to which spatial variability in ice dynamics may...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
    Published by National Academy of Sciences
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  • 2
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    Antarctic marine ice-sheet retreat in the Ross Sea during the early Holocene (2015)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2015-12-24
    Description: Geological constraints on the timing of retreat of the Last Glacial Maximum (LGM) Antarctic Ice Sheets provide critical insights into the processes controlling marine-based ice-sheet retreat. The overdeepened, landward-sloping bathymetry of Antarctica’s continental shelves is an ideal configuration for marine ice-sheet instability, with the potential for past and future ice-sheet collapse and accelerated sea-level rise. However, the chronology of retreat of the LGM ice sheet in the Ross Sea is largely constrained by imprecise radiocarbon chronology of bulk marine sediments or by coastal records that offer more reliable dating techniques but which may be influenced by local piedmont glaciers derived from East Antarctic outlet glaciers. Consequently, these coastal records may be ambiguous in the broader context of retreat in the central regions of the Ross Sea. Here, we present a sedimentary facies succession and foraminifera-based radiocarbon chronology from within the Ross Sea embayment that indicates glacial retreat and open-marine conditions to the east of Ross Island before 8.6 cal. (calibrated) kyr B.P., at least 1 k.y. earlier than indicated by terrestrial records in McMurdo Sound. Comparing these data to new modeling experiments, we hypothesize that marine-based ice-sheet retreat was triggered by oceanic forcings along most of the Pacific Ocean coastline of Antarctica, but continued Holocene retreat into the inner shelf region of the Ross Sea occurred primarily as a consequence of bathymetric controls on marine ice-sheet instability.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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  • 3
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    Widespread persistence of expanded East Antarctic glaciers in the southwest Ross Sea during the last deglaciation (2017)
    Geological Society of America (GSA)
    In: Geology
    Details
    Publication Date: 2017-04-12
    Description: It has been suggested that the grounding line of the Last Glacial Maximum (LGM) ice sheet in the Ross Sea, Antarctica, receded in an approximately north-to-south pattern during the Holocene. An implication of this hypothesis is that geological evidence from the southwestern Ross Sea has been used widely to interpret retreat histories of the West Antarctic Ice Sheet (WAIS) across the wider Ross Sea embayment. Accurately constraining the timing and pattern of marine-based ice sheet retreat in this embayment is critical to understanding the drivers that may have triggered this event, and its contribution to rapid sea-level rise events. Here, we present new multibeam swath bathymetry data that identifies well-preserved glacial features indicating that thick (〉700 m) marine-based ice derived from the East Antarctic Ice Sheet coastal outlet glaciers dominated the ice sheet input into the southwestern Ross Sea during the last phases of glaciation. Subglacial geomorphic features indicate that ice derived from present outlet glacier valleys in South Victoria Land flowed southeastward. This is more consistent with flowlines from model-based interpretations of an earlier retreat of the WAIS in the central Ross Sea than with previous land-based geological reconstructions. This implies that coastal records of deglaciation along the Transantarctic Mountains front record only the final phases of glacial retreat in the Ross Sea. Therefore, chronological data from the central embayment are required to accurately constrain the timing of large-scale glacial retreat in the Ross Sea and to identify the mechanisms that drove it.
    Print ISSN: 0091-7613
    Electronic ISSN: 1943-2682
    Topics: Geosciences
    Published by Geological Society of America (GSA)
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  • 4
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    The future sea-level contribution of the Greenland ice sheet: a multi-model ensemble study of ISMIP6 (2020)
    In:  EPIC3The Cryosphere, 14(9), pp. 3071-3096
    Details
    Publication Date: 2020-09-22
    Description: The Greenland ice sheet is one of the largest contributors to global mean sea-level rise today and is expected to continue to lose mass as the Arctic continues to warm. The two predominant mass loss mechanisms are increased surface meltwater run-off and mass loss associated with the retreat of marine-terminating outlet glaciers. In this paper we use a large ensemble of Greenland ice sheet models forced by output from a representative subset of the Coupled Model Intercomparison Project (CMIP5) global climate models to project ice sheet changes and sea-level rise contributions over the 21st century. The simulations are part of the Ice Sheet Model Intercomparison Project for CMIP6 (ISMIP6). We estimate the sea-level contribution together with uncertainties due to future climate forcing, ice sheet model formulations and ocean forcing for the two greenhouse gas concentration scenarios RCP8.5 and RCP2.6. The results indicate that the Greenland ice sheet will continue to lose mass in both scenarios until 2100, with contributions of 90±50 and 32±17 mm to sea-level rise for RCP8.5 and RCP2.6, respectively. The largest mass loss is expected from the south-west of Greenland, which is governed by surface mass balance changes, continuing what is already observed today. Because the contributions are calculated against an unforced control experiment, these numbers do not include any committed mass loss, i.e. mass loss that would occur over the coming century if the climate forcing remained constant. Under RCP8.5 forcing, ice sheet model uncertainty explains an ensemble spread of 40 mm, while climate model uncertainty and ocean forcing uncertainty account for a spread of 36 and 19 mm, respectively. Apart from those formally derived uncertainty ranges, the largest gap in our knowledge is about the physical understanding and implementation of the calving process, i.e. the interaction of the ice sheet with the ocean.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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  • 5
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    Simulating the Antarctic ice sheet in the late-Pliocene warm period: PLISMIP-ANT, an ice-sheet model intercomparison project (2015)
    In:  EPIC3The Cryosphere, 9(3), pp. 881-903, ISSN: 1994-0424
    Details
    Publication Date: 2016-12-09
    Description: In the context of future climate change, understanding the nature and behaviour of ice sheets during warm intervals in Earth history is of fundamental importance. The late Pliocene warm period (also known as the PRISM interval: 3.264 to 3.025 million years before present) can serve as a potential analogue for projected future climates. Although Pliocene ice locations and extents are still poorly constrained, a significant contribution to sea-level rise should be expected from both the Greenland ice sheet and the West and East Antarctic ice sheets based on palaeo sea-level reconstructions. Here, we present results from simulations of the Antarctic ice sheet by means of an international Pliocene Ice Sheet Modeling Intercomparison Project (PLISMIP-ANT). For the experiments, ice-sheet models including the shallow ice and shelf approximations have been used to simulate the complete Antarctic domain (including grounded and floating ice). We compare the performance of six existing numerical ice-sheet models in simulating modern control and Pliocene ice sheets by a suite of five sensitivity experiments. We include an overview of the different ice-sheet models used and how specific model configurations influence the resulting Pliocene Antarctic ice sheet. The six ice-sheet models simulate a comparable present-day ice sheet, considering the models are set up with their own parameter settings. For the Pliocene, the results demonstrate the difficulty of all six models used here to simulate a significant retreat or re-advance of the East Antarctic ice grounding line, which is thought to have happened during the Pliocene for the Wilkes and Aurora basins. The specific sea-level contribution of the Antarctic ice sheet at this point cannot be conclusively determined, whereas improved grounding line physics could be essential for a correct representation of the migration of the grounding-line of the Antarctic ice sheet during the Pliocene.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
    Format: application/pdf
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