Glacier dynamics over the last quarter of a century at Helheim, Kangerdlugssuaq and 14 other major Greenland outlet glaciers

Bevan, Suzanne; Luckman, Adrian; Murray, Tavi

doi:10.5194/tc-6-923-2012

Cited by 107 publications

(140 citation statements)

References 89 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: 63%

“…In both regions atmospheric/ocean warming and the retreat of sea-ice have been hypothesised as the main triggers of recent 21 st century glacier retreat (e.g. Bevan et al, 2012;Cook et al, 2014a;Holland et al, 2008;McFadden et al, 2011;Moon and 15 Joughin, 2008). However, variability in the magnitude and rate of retreat between glaciers occurs due to local factors, such as the width and depth of fjords Enderlin et al, 2013;Howat et al, 2007;Porter et al, 2014).…”

mentioning

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: 63%

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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show abstract

“…In particular, Helheim underwent a major retreat between 2001 and 2005, before creating a floating tongue which advanced again between 2005(Howat et al, 2007. In the last decade, it has been intensively surveyed and studied (Luckman et al, 2006;Joughin et al, 2008b;Nick et al, 2009;Bevan et al, 2012;Cook, 2012;Bassis and Jacobs, 2013), and is therefore an interesting case study to calibrate a calving model.…”

Section: Data Sourcesmentioning

confidence: 99%

Combining damage and fracture mechanics to model calving

et al. 2014

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Abstract.Calving of icebergs is a major negative component of polar ice-sheet mass balance. Here we present a new calving model relying on both continuum damage mechanics and linear elastic fracture mechanics. This combination accounts for both the slow sub-critical surface crevassing and the rapid propagation of crevasses when calving occurs. First, damage to the ice occurs over long timescales and enhances the viscous flow of ice. Then brittle fractures propagate downward, at very short timescales, when the ice body is considered as an elastic medium. The model was calibrated on Helheim Glacier, Southeast Greenland, a well-monitored glacier with fast-flowing outlet. This made it possible to identify sets of model parameters to enable a consistent response of the model and to produce a dynamic equilibrium in agreement with the observed stable position of the Helheim ice front between 1930 and today.

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“…1a), which was selected due to its recent interesting behaviour. The mean annual terminus location of Helheim Glacier was stable throughout the late 1980s and early 1990s, although sub-annual variations of between 2 and 4 km are typical (Bevan et al, 2012). After a period of thinning in the 1990s (Abdalati et al, 2001), the front began to retreat in 2001.…”

Section: Introductionmentioning

confidence: 95%

Modelling environmental influences on calving at Helheim Glacier in eastern Greenland

et al. 2014

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Abstract.Calving is an important mass-loss process for many glaciers worldwide, and has been assumed to respond to a variety of environmental influences. We present a grounded, flowline tidewater glacier model using a physically-based calving mechanism, applied to Helheim Glacier, eastern Greenland. By qualitatively examining both modelled size and frequency of calving events, and the subsequent dynamic response, the model is found to realistically reproduce key aspects of observed calving behaviour. Experiments explore four environmental variables which have been suggested to affect calving rates: water depth in crevasses, basal water pressure, undercutting of the calving face by submarine melt and backstress from ice mélange. Of the four variables, only crevasse water depth and basal water pressure were found to have a significant effect on terminus behaviour when applied at a realistic magnitude. These results are in contrast to previous modelling studies, which have suggested that ocean temperatures could strongly influence the calving front. The results raise the possibility that Greenland outlet glaciers could respond to the recent trend of increased surface melt observed in Greenland more strongly than previously thought, as surface ablation can strongly affect water depth in crevasses and water pressure at the glacier bed.

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Glacier dynamics over the last quarter of a century at Helheim, Kangerdlugssuaq and 14 other major Greenland outlet glaciers

Cited by 107 publications

References 89 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

Combining damage and fracture mechanics to model calving

Modelling environmental influences on calving at Helheim Glacier in eastern Greenland

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