Ice Flow Direction Change in Interior West Antarctica

Siegert, Martín J.; Welch, Brian C.; Morse, D. L.; Vieli, Andreas; Blankenship, D. D.; Joughin, Ian; King, Edward C.; Vieli, Gwendolyn J.-M. C. Leysinger; Payne, Antony J.; Jacobel, R. W.

doi:10.1126/science.1101072

Cited by 62 publications

(50 citation statements)

References 18 publications

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“…can be achieved through the comparison of present-day fl ow from global positioning system (GPS) or satellite data with paleo-fl ow orientations derived from structure tracking of englacial layer features. Studies of this kind have shown that Holocene deglaciation (Conway et al, 1999) forced signifi cant fl ow regime change in the WAIS interior, with rapid and abrupt changes in the confi guration and rate of inland ice stream fl ow in the Ross Sea sector (e.g., Conway et al, 2002;Siegert et al, 2004).…”

Section: Introductionmentioning

confidence: 99%

Holocene stability of the Amundsen-Weddell ice divide, West Antarctica

Ross

Siegert

Woodward

et al. 2011

Geology

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We analyze Holocene ice fl ow using global positioning system and radio-echo sounding data acquired near the Amundsen-Weddell ice divide, between Pine Island Glacier and the Institute Ice Stream, West Antarctica. The data show that this part of the West Antarctic Ice Sheet (WAIS) has maintained a stable ice fl ow regime and ice divide position for ~7000 yr. Independent glacial geological data, in support of this assertion, suggest that the interior of the WAIS west of the Ellsworth Mountains has thinned by only a few hundred meters since the Last Glacial Maximum (LGM) and that the position of the ice divide may be recurrent over longer (more than 20 k.y., perhaps pre-Quaternary) time scales. We suggest that basal topography constrains ice fl ow in this sector of the WAIS, making the ice divide relatively insensitive to perturbations around the margins of the ice sheet compared with other ice divides. Large-scale forcing measured elsewhere in the WAIS as major reorganizations of the ice sheet surface and fl owline pattern may be manifested only in simple vertical changes of the Amundsen-Weddell interior.

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Section: Introductionmentioning

confidence: 99%

Holocene stability of the Amundsen-Weddell ice divide, West Antarctica

Ross

Siegert

Woodward

et al. 2011

Geology

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“…Primary evidence includes: englacial layer geometry indicative of ground-line migration and non-steady flow patterns (Siegert et al 2013;Kingslake et al 2016); small length-scale englacial folding thought to represent ice-stream convergent flow where there is presently slow flow (Bingham et al 2007(Bingham et al , 2015; and surface flow structure in a presently slow-flowing region (Glasser et al 2015). Additionally, buried crevasses in Kamb Ice Stream and Siple Dome suggest a stagnation of ice streams (Retzlaff & Bentley 1993;Jacobel et al 2000), flow stripe variability observed on the Ross Ice Shelf supports cyclical ice streaming activity with a frequency of between 100 and 1000 years (Fahnestock et al 2000), and variations in englacial radar reflector geometry are thought to show flow reorganization (Ng & Conway 2004;Siegert et al 2004). Most evidence for flow reorganization exists near ice-sheet margins but reorganization may be expected along the full length of the ice flow path.…”

Section: Q13mentioning

confidence: 99%

Ice-flow reorganization within the East Antarctic Ice Sheet deep interior

Beem

Cavitte

Blankenship

et al. 2017

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Near the South Pole, a large subglacial lake exists beneath the East Antarctic Ice Sheet less than 10 km from where the bed temperature is inferred to be −9°C. A thermodynamic model was used to investigate the apparent contradiction of basal water existing in the vicinity of a cold bed. Model results indicate that South Pole Lake is freezing and that neither present-day geothermal flux nor ice flow is capable of producing the necessary heat to sustain basal water at this location. We hypothesize that the lake comprises relict water formed during a different configuration of ice dynamics when significant frictional heating from ice sliding was available. Additional modelling of assumed basal sliding shows frictional heating was capable of producing the necessary heat to fill South Pole Lake. Independent evidence of englacial structures measured by airborne radar revel ice-sheet flow was more dynamic in the past. Ice sliding is estimated to have ceased between 16.8 and 10.7 ka based on an ice chronology from a nearby borehole. These findings reveal major post-Last Glacial Maximum ice-dynamic change within the interior of East Antarctica, demonstrating that the present interior ice flow is different than that under full glacial conditions

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“…Although thermoviscous fingering (Section 4.2) has been appealed to as an explanation for ice streams, some ice streams are known to flow almost entirely by basal sliding (Engelhardt & Kamb 1997), and this sliding motion can change direction and speed (Siegert et al 2004, Hulbe & Fahnestock 2007 or even cease altogether without the bed actually freezing (Retzlaff & Bentley 1993, Catania et al 2003, pointing to subglacial drainage as a crucial factor (Anandakrishnan & Alley 1997).…”

Section: Ice Streamsmentioning

confidence: 98%

Ice-Sheet Dynamics

Schoof

Hewitt

2013

Annu. Rev. Fluid Mech.

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We describe the development of mathematical models of ice sheets, focusing on underlying physics and the minimal components that successful models must contain. Our review describes the basic fluid dynamical ice-flow models currently in use; points out numerous poorly understood thermomechanical feedbacks in ice flow; and describes the current, often poorly constrained, state of models for ice-sheet sliding and subglacial drainage, as well as their role in ice-stream dynamics. We conclude with a survey of marine ice-sheet models, outlining recent developments of self-consistent free-boundary models and ongoing research into three-dimensional marine ice sheets.

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Ice Flow Direction Change in Interior West Antarctica

Cited by 62 publications

References 18 publications

Holocene stability of the Amundsen-Weddell ice divide, West Antarctica

Holocene stability of the Amundsen-Weddell ice divide, West Antarctica

Ice-flow reorganization within the East Antarctic Ice Sheet deep interior

Ice-Sheet Dynamics

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