Extensive retreat of Greenland tidewater glaciers, 2000–2010

Murray, Tavi; Scharrer, K.; Selmes, N.; Booth, Adam; James, T. D.; Bevan, Suzanne; Bradley, J.; Cook, Sue; Llana, L. Cordero; Drocourt, Y.; Dyke, Laurence M.; Goldsack, A.; Hughes, Anna L.C.; Luckman, Adrian; McGovern, Joseph Henry

doi:10.1657/aaar0014-049

Cited by 74 publications

(125 citation statements)

References 43 publications

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“…Similar to other studies (e.g. Bevan et al, 2012;Howat and Eddy, 2012;Murray et al, 2015), an additional source of 15 error occurs in selecting the correct terminus position at several glaciers, due to the presence of year-round sea ice and the fractured nature of the glacier terminus. This was particularly the case at Steensby and C. H. Ostenfeld and glaciers draining the Northeast Greenland Ice Stream (Figure 1).…”

Section: Front Position Mappingsupporting

confidence: 65%

“…In the northern Greenland, several glaciers have thinned (Rignot et al, 1997), accelerated (Joughin et al, 2010a), and retreated, and have lost large sections of their floating ice tongues between 1990 to 2010 (Box and Decker, 2011;Carr et al, 2017b;20 Jensen et al, 2016;Moon and Joughin, 2008;Murray et al, 2015). This region is also characterised by large fjord-terminating outlet glaciers, many of which terminate in kilometres-long floating ice tongues, while several others are potentially surgetype (Hill et al, 2017;Joughin et al, 1996;Reeh et al, 2003;Rignot et al, 2001).…”

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confidence: 99%

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Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Hill¹,

Carr²,

Stokes³

et al. 2018

Preprint

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The Greenland Ice Sheet (GrIS) is losing mass in response to recent climatic and oceanic warming. Since the mid-1990s, marine-terminating outlet glaciers across the GrIS have retreated, accelerated and thinned, but recent changes in northern 10Greenland have been comparatively understudied. Consequently, the dynamic response (i.e. changes in surface elevation and velocity) of these outlet glaciers to changes at their termini, particularly calving from floating ice tongues, remains unknown.Here we use satellite imagery and historical maps to produce an unprecedented 68-year record of terminus change across 18 major outlet glaciers and combine this with previously published surface elevation and velocity datasets. Overall, recent (1995Overall, recent ( -2015 retreat rates were higher than at any time in the previous 47 years, but change-point analysis reveals three categories of 15 frontal position change: (i) minimal change followed by steady and continuous retreat, (ii) minimal change followed by a switch to a period of short-lived rapid retreat, (iii) glaciers that underwent cycles of advance and retreat. Furthermore, these categories appear to be linked to the terminus type, with those in category (i) having grounded termini and those in category (ii) characterised by floating ice tongues. We interpret glaciers in category (iii) as surge-type. Glacier geometry (e.g. fjord width and basal topography) is also an important influence on the dynamic re-adjustment of glaciers to changes at their termini. 20Taken together, the loss of several ice tongues and the recent acceleration in the retreat of numerous marine-terminating glaciers suggests northern Greenland is undergoing rapid change and could soon impact on some large catchments that have capacity to contribute an important component to sea level rise.

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Section: Front Position Mappingsupporting

confidence: 65%

mentioning

confidence: 99%

Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Hill¹,

Carr²,

Stokes³

et al. 2018

Preprint

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“…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%

“…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%

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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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Controls on the early Holocene collapse of the Bothnian Sea Ice Stream

et al. 2016

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New high‐resolution multibeam data in the Gulf of Bothnia reveal for the first time the subglacial environment of a Bothnian Sea Ice Stream. The geomorphological record suggests that increased meltwater production may have been important in driving rapid retreat of Bothnian Sea Ice during deglaciation. Here we apply a well‐established, one‐dimensional flow line model to simulate ice flow through the Gulf of Bothnia and investigate controls on retreat of the ice stream during the post‐Younger Dryas deglaciation of the Fennoscandian Ice Sheet. The relative influence of atmospheric and marine forcings are investigated, with the modeled ice stream exhibiting much greater sensitivity to surface melting, implemented through surface mass balance and hydrofracture‐induced calving, than to submarine melting or relative sea level change. Such sensitivity is supported by the presence of extensive meltwater features in the geomorphological record. The modeled ice stream does not demonstrate significant sensitivity to changes in prescribed ice stream width or overall bed slope, but local variations in basal topography and ice stream width result in nonlinear retreat of the grounding line, notably demonstrating points of short‐lived retreat slowdown on reverse bed slopes. Retreat of the ice stream was most likely governed by increased ice surface meltwater production, with the modeled retreat rate less sensitive to marine forcings despite the marine setting.

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Extensive retreat of Greenland tidewater glaciers, 2000–2010

Cited by 74 publications

References 43 publications

Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Dynamic changes in outlet glaciers in northern Greenland from 1948 to 2015

Glacier Calving in Greenland

Controls on the early Holocene collapse of the Bothnian Sea Ice Stream

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