Large-scale changes in Greenland outlet glacier dynamics triggered at the terminus

Nick, F. M.; Vieli, Andreas; Howat, I. M.; Joughin, Ian

doi:10.1038/ngeo394

Cited by 470 publications

(568 citation statements)

References 26 publications

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“…processes of calving, grounding line retreat and submarine melting), it has a robust treatment of grounding line migration 28 and calving 29 , and reproduces the current observed dynamical behaviour of several narrow marine outlet glaciers well 13,14,21 .…”

Section: Methods Summarysupporting

confidence: 52%

“…S3 to S6), and confirms the sensitivities to different forcing mechanisms indicated by observations. We find that Helheim and Kangerdlugssuaq largely respond to a reduction in sea-ice and enhanced hydro-fracturing due to surface melt, with little response to submarine melt or basal and lateral lubrication 21 . The dynamics of Jakobshavn are more sensitive to forcing by submarine melt, due to the high submarine melt rate 22 and a more extensive ice-ocean interface when an ice tongue is present.…”

mentioning

confidence: 77%

“…S12), which take place as an episodic series of rapid retreats. These step changes are closely related to channel geometry and occur, in particular, after an ice front retreats from a basal high through an overdeepening 21 . In particular, our results indicate that for different parameter choices, episodes of rapid retreat occur at different times, but at the same locations (Fig.…”

mentioning

confidence: 99%

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Future sea-level rise from Greenland’s main outlet glaciers in a warming climate

Nick

Vieli

Andersen

et al. 2013

Nature

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Over the past decade, ice loss from the Greenland Ice Sheet increased as a result of both increased surface melting and ice discharge to the ocean 1,2 . The latter is controlled by acceleration of ice flow and subsequent thinning of fast-flowing marine-terminating outlet glaciers 3 . Quantifying the future dynamic contribution of such glaciers to sea-level rise (SLR) remains a major challenge since outlet-glacier dynamics are poorly understood 4 . Here we present a model that includes a fully dynamic treatment of marine termini. We use this model to

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Section: Methods Summarysupporting

confidence: 52%

mentioning

confidence: 77%

mentioning

confidence: 99%

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Future sea-level rise from Greenland’s main outlet glaciers in a warming climate

Nick

Vieli

Andersen

et al. 2013

Nature

Self Cite

276

296

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“…The resulting cyclonic circulation anomaly results in stronger onshore flow and increased precipitation in the north-eastern GrIS and a decrease in the north-western ice sheet, on the lee side of the main divide. In south Greenland, RACMO2.3 simulates decreased precipitation with respect to the previous model version; this is related to enhanced north-westerly advection of colder and drier air masses on the western side of the divide, more frequent offshore katabatic circulation and consequently weakened onshore flow to the east (Noël et al, 2014).…”

Section: Large-scale Precipitation Changesmentioning

confidence: 99%

“…Combined observational and model studies show that increased meltwater runoff, and solid ice discharge through the acceleration of marine-terminating outlet glaciers Nick et al, 2009;Fettweis et al, 2011;Rignot et al, 2011), account for ∼ 60 and ∼ 40 % respectively of the recent GrIS mass loss (Rignot et al, 2008;Van den Broeke et al, 2009;Enderlin and Howat, 2013).…”

Section: Introductionmentioning

confidence: 99%

Evaluation of the updated regional climate model RACMO2.3: summer snowfall impact on the Greenland Ice Sheet

et al. 2015

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Abstract. We discuss Greenland Ice Sheet (GrIS) surface mass balance (SMB) differences between the updated polar version of the RACMO climate model (RACMO2.3) and the previous version (RACMO2.1). Among other revisions, the updated model includes an adjusted rainfall-to-snowfall conversion that produces exclusively snowfall under freezing conditions; this especially favours snowfall in summer. Summer snowfall in the ablation zone of the GrIS has a pronounced effect on melt rates, affecting modelled GrIS SMB in two ways. By covering relatively dark ice with highly reflective fresh snow, these summer snowfalls have the potential to locally reduce melt rates in the ablation zone of the GrIS through the snow-albedo-melt feedback. At larger scales, SMB changes are driven by differences in orographic precipitation following a shift in large-scale circulation, in combination with enhanced moisture to precipitation conversion for warm to moderately cold conditions. A detailed comparison of model output with observations from automatic weather stations, ice cores and ablation stakes shows that the model update generally improves the simulated SMBelevation gradient as well as the representation of the surface energy balance, although significant biases remain.

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The effect of basal channels on oceanic ice‐shelf melting

et al. 2013

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[1] The presence of ice-shelf basal channels has been noted in a number of Antarctic and Greenland ice shelves, but their impact on basal melting is not fully understood. Here we use the Massachusetts Institute of Technology general circulation model to investigate the effect of ice-shelf basal channels on oceanic melt rate for an idealized ice shelf resembling the floating tongue of Petermann Glacier in Greenland. The introduction of basal channels prevents the formation of a single geostrophically balanced boundary current; instead the flow is diverted up the right-hand (Coriolis-favored) side of each channel, with a return flow in the opposite direction on the left-hand side. As the prescribed number of basal channels is increased the mean basal melt rate decreases, in agreement with previous studies. For a small number of relatively wide channels the subice flow is found to be a largely geostrophic horizontal circulation. The reduction in melt rate is then caused by an increase in the relative contribution of weakly melting channel crests and keels. For a larger number of relatively narrow channels, the subice flow changes to a vertical overturning circulation. This change in circulation results in a weaker sensitivity of melt rates to channel size. The transition between the two regimes is governed by the Rossby radius of deformation. Our results explain why basal channels play an important role in regulating basal melting, increasing the stability of ice shelves.Citation: Millgate, T., P. R. Holland, A. Jenkins, and H. L. Johnson (2013), The effect of basal channels on oceanic ice-shelf melting,

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Large-scale changes in Greenland outlet glacier dynamics triggered at the terminus

Cited by 470 publications

References 26 publications

Future sea-level rise from Greenland’s main outlet glaciers in a warming climate

Future sea-level rise from Greenland’s main outlet glaciers in a warming climate

Evaluation of the updated regional climate model RACMO2.3: summer snowfall impact on the Greenland Ice Sheet

The effect of basal channels on oceanic ice‐shelf melting

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