Abstract
ABSTRACTWe use ice flow modelling to simulate the englacial stratigraphy of Blåskimen Island, an ice rise in Dronning Maud Land and elucidate the evolution of this data-sparse region. We apply a thermo-mechanically coupled Elmer/Ice model to a profile along flowlines and through the ice-rise summit, where surface mass balance (SMB), flow velocity and ice stratigraphy were recently measured. We conclude that: (i) the ice rise is presently thickening at a rate of 0.5~0.6 m ice equivalent per year (mieq a−1), which is twice an earlier estimate using the field data and the input–output method; (ii) present thickening started 20–40 years in the past, before which the ice rise was in a steady state; (iii) SMB contrast between the upwind and downwind slopes was stronger than the present value by ~23% (or 0.15 mieq a−1) prior to ~1100 years ago. Since then, this contrast has been decreasing overall. We surmise that these SMB changes are likely a result of synoptic-scale atmospheric changes, rather than local atmospheric changes controlled by local ice topography. Our technique effectively assimilates geophysical data, avoiding the complexity of ice flow beneath the ice divide. Thus, it could be applied to other ice rises to elucidate the recent glacial retreat.
Highlights
During the Last Glacial Maximum (∼26.5 to 19 ka B.P., Clark and others, 2009) the Antarctic Ice Sheet in most regions extended all the way to the continental shelf (Anderson and others, 2002; Bentley and others, 2014), but details of the deglaciation history are poorly known
Using a thermo-mechanically coupled Elmer/Ice flow model, we examined the evolution of Blåskimen Island, western Dronning Maud Land (DML), in East Antarctica
We found that this ice rise is presently thickening at a rate of 0.4–0.6 mieq a−1
Summary
During the Last Glacial Maximum (∼26.5 to 19 ka B.P., Clark and others, 2009) the Antarctic Ice Sheet in most regions extended all the way to the continental shelf (Anderson and others, 2002; Bentley and others, 2014), but details of the deglaciation history are poorly known. Knowledge of the glacio-geological history of Dronning Maud Land (DML), East Antarctica, is very sparse even during the Holocene period (Mackintosh and others, 2014) For this period, such knowledge is required to better constrain icesheet models, models used to make reliable predictions on ice-sheet behaviour under possible warming scenarios (e.g., DeConto and Pollard, 2016). Ice rises can provide local, highresolution information of the Holocene history near ice shelves (Hindmarsh, 1996; Conway and others, 1999; Nereson and Waddington, 2002; Martín and others, 2006, 2009a; Drews and others, 2013, 2015; Kingslake and others, 2016) Ice rises exhibit their own local flow that differs from the surrounding ice-shelf flow. We test several hypotheses to elucidate the onset of recent thickening and past changes in surface mass balance (SMB)
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