Buoyant flexure and basal crevassing in dynamic mass loss at Helheim Glacier

James, T. D.; Murray, Tavi; Selmes, N.; Scharrer, K.; O’Leary, Martin

doi:10.1038/ngeo2204

Cited by 88 publications

(161 citation statements)

References 31 publications

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“…3). This results in rotation and uplift of the glacier tongue around a 'flexion zone' located near the ungrounding point [59,61]. Geometric considerations show that block rotation is associated with the growth of basal crevasses, which eventually lead to calving and overturning of the terminal block, usually closely followed by block disintegration.…”

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

“…Geometric considerations show that block rotation is associated with the growth of basal crevasses, which eventually lead to calving and overturning of the terminal block, usually closely followed by block disintegration. Buoyancy-driven calving events can be very large, typically affecting the full thickness of the glacier for many hundreds of metres across-and along-flow [59,60,64]. Collisions between capsizing bergs and the glacier terminus are the likely source of seismic signals associated with large calving events [65][66][67].…”

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

“…Buoyancy-driven calving is an important process on large, fast-flowing outlet glaciers [59][60][61][62][63][64]. Rapid ice flow into deep water can create 'super-buoyant' conditions, in which ice fronts are out of hydrostatic equilibrium and subject to large upward-directed torque forces (Fig.…”

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

“…[30,59,61,68,81,85]). Exciting new opportunities have been created by the advent of remotely controlled or autonomous vehicles [86,87].…”

Section: Conclusion and Priorities For Future Researchmentioning

confidence: 99%

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Glacier Calving in Greenland

Benn

Cowton

Todd

et al. 2017

Curr Clim Change Rep

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In combination, the breakaway of icebergs (calving) and submarine melting at marine-terminating glaciers account for between one third and one half of the mass annually discharged from the Greenland Ice Sheet into the ocean. These ice losses are increasing due to glacier acceleration and retreat, largely in response to increased heat flux from the oceans. Behaviour of Greenland's marine-terminating ('tidewater') glaciers is strongly influenced by fjord bathymetry, particularly the presence of 'pinning points' (narrow or shallow parts of fjords that encourage stability) and overdeepened basins (that encourage rapid retreat). Despite the importance of calving and submarine melting and significant advances in monitoring and understanding key processes, it is not yet possible to predict the tidewater glacier response to climatic and oceanic forcing with any confidence. The simple calving laws required for ice-sheet models do not adequately represent the complexity of calving processes. New detailed process models, however, are increasing our understanding of the key processes and are guiding the design of improved calving laws. There is thus some prospect of reaching the elusive goal of accurately predicting future tidewater glacier behaviour and associated rates of sea-level rise.

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Section: Processes Of Frontal Ablationmentioning

confidence: 99%

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

Section: Processes Of Frontal Ablationmentioning

confidence: 99%

“…[30,59,61,68,81,85]). Exciting new opportunities have been created by the advent of remotely controlled or autonomous vehicles [86,87].…”

Section: Conclusion and Priorities For Future Researchmentioning

confidence: 99%

See 2 more Smart Citations

Glacier Calving in Greenland

Benn

Cowton

Todd

et al. 2017

Curr Clim Change Rep

View full text Add to dashboard Cite

show abstract

“…Furthermore, inverse modelling suggests that basal friction beneath the trunks of three of Greenland's fastest flowing tidewater glaciers supports very little of the driving stress [114], such that the impact on ice dynamics of variability in basal friction due to surface melt input may be limited. However, subglacial hydrology may yet provide the perturbation necessary to drive a glacier into retreat; it has been inferred that surface melt-induced acceleration is responsible for significant dynamic thinning at Helheim Glacier [115], which has the potential to drive long-term glacier retreat if combined with a calving process dependent on ice terminus thickness [116].…”

Section: The Influence Of Hydrology On Marine Terminating ('Tidewatermentioning

confidence: 99%

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Nienow

Sole

Slater

et al. 2017

Curr Clim Change Rep

100

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Purpose of the Review This review discusses the role that meltwater plays within the Greenland ice sheet system. The ice sheet's hydrology is important because it affects mass balance through its impact on meltwater runoff processes and ice dynamics. The review considers recent advances in our understanding of the storage and routing of water through the supraglacial, englacial, and subglacial components of the system and their implications for the ice sheet. Recent Findings There have been dramatic increases in surface meltwater generation and runoff since the early 1990s, both due to increased air temperatures and decreasing surface albedo. Processes in the subglacial drainage system have similarities to valley glaciers and in a warming climate, the efficiency of meltwater routing to the ice sheet margin is likely to increase. The behaviour of the subglacial drainage system appears to limit the impact of increased surface melt on annual rates of ice motion, in sections of the ice sheet that terminate on land, while the large volumes of meltwater routed subglacially deliver significant volumes of sediment and nutrients to downstream ecosystems. Summary Considerable advances have been made recently in our understanding of Greenland ice sheet hydrology and its wider influences. Nevertheless, critical gaps persist both in our understanding of hydrology-dynamics coupling, notably at tidewater glaciers, and in runoff processes which ensure that projecting Greenland's future mass balance remains challenging.

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Dynamic jamming of iceberg‐choked fjords

Peters

Amundson

Cassotto

et al. 2015

Geophysical Research Letters

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Key Points:• Ice melange experiences widespread jamming during calving events • The ice melange is closely packed during periods of terminus quiescence • The kinetic energy of the melange is about 1% of the total released energy Supporting Information:• Text S1• Movie S1• Movie S2 Abstract We investigate the dynamics of ice mélange by analyzing rapid motion recorded by a time-lapse camera and terrestrial radar during several calving events that occurred at Jakobshavn Isbrae, Greenland. During calving events (1) the kinetic energy of the ice mélange is 2 orders of magnitude smaller than the total energy released during the events, (2) a jamming front propagates through the ice mélange at a rate that is an order of magnitude faster than the motion of individual icebergs, (3) the ice mélange undergoes initial compaction followed by slow relaxation and extension, and (4) motion of the ice mélange gradually decays before coming to an abrupt halt. These observations indicate that the ice mélange experiences widespread jamming during calving events and is always close to being in a jammed state during periods of terminus quiescence. We therefore suspect that local jamming influences longer timescale ice mélange dynamics and stress transmission.

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Buoyant flexure and basal crevassing in dynamic mass loss at Helheim Glacier

Cited by 88 publications

References 31 publications

Glacier Calving in Greenland

Glacier Calving in Greenland

Recent Advances in Our Understanding of the Role of Meltwater in the Greenland Ice Sheet System

Dynamic jamming of iceberg‐choked fjords

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