Multi-decadal retreat of Greenland’s marine-terminating glaciers

Howat, I. M.; Eddy, Alex

doi:10.3189/002214311796905631

Cited by 159 publications

(175 citation statements)

References 28 publications

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“…Until mid-1996, cumulative D rep-resents a straight line, because its annual value is assumed constant at the 1996 value of 411 Gt yr −1 . The average value of SMB Greenland over the period 1958-1995 is within 2 % of this value (418 Gt yr −1 ), resulting in an estimated pre-1996 cumulative MB (red line) that remains close to 0, in line with previous results of Howat and Eddy (2011). The fact that the estimated 1995 value of D and the 1958-1995 average value of SMB are similar suggests that ice flow in the mid-1990s was well adjusted to the average annual mass input of the previous decades, reminiscent of an ice sheet in approximate balance ).…”

Section: Comparing Mbm and Gracesupporting

confidence: 77%

On the recent contribution of the Greenland ice sheet to sea level change

et al. 2016

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Abstract. We assess the recent contribution of the Greenland ice sheet (GrIS) to sea level change. We use the mass budget method, which quantifies ice sheet mass balance (MB) as the difference between surface mass balance (SMB) and solid ice discharge across the grounding line (D). A comparison with independent gravity change observations from GRACE shows good agreement for the overlapping period 2002-2015, giving confidence in the partitioning of recent GrIS mass changes. The estimated 1995 value of D and the 1958-1995 average value of SMB are similar at 411 and 418 Gt yr −1 , respectively, suggesting that ice flow in the mid1990s was well adjusted to the average annual mass input, reminiscent of an ice sheet in approximate balance. Starting in the early to mid-1990s, SMB decreased while D increased, leading to quasi-persistent negative MB. About 60 % of the associated mass loss since 1991 is caused by changes in SMB and the remainder by D. The decrease in SMB is fully driven by an increase in surface melt and subsequent meltwater runoff, which is slightly compensated by a small (< 3 %) increase in snowfall. The excess runoff originates from lowlying (< 2000 m a.s.l.) parts of the ice sheet; higher up, increased refreezing prevents runoff of meltwater from occurring, at the expense of increased firn temperatures and depleted pore space. With a 1991-2015 average annual mass loss of ∼ 0.47 ± 0.23 mm sea level equivalent (SLE) and a peak contribution of 1.2 mm SLE in 2012, the GrIS has recently become a major source of global mean sea level rise.

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Section: Comparing Mbm and Gracesupporting

confidence: 77%

On the recent contribution of the Greenland ice sheet to sea level change

et al. 2016

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“…Ice-ocean interactions are a major control on the evolution of Greenland glaciers 23 and the enhanced intrusion of warm water of sub-tropical origin (Atlantic water) in the glacial fjords is considered to be a leading explanation for the recent acceleration 24 . It has however been suggested that the current acceleration and retreat of these marine-terminating glaciers will decrease in the near future, as the ice sheet will lose contact with the ocean waters because the bed elevation of these glaciers rises above sea level within tens of kilometres of the coast 2,25,26 . Our results show that the submarine bed channels are more widespread, deeper and extend significantly farther inland than previously thought.…”

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confidence: 99%

“…16), the 107 marine-terminating glaciers are underlaid by fjords that extend on average 67 km below sea level inland, which is 50% longer than for B2013 (Supplementary Table 1) and 300% than for B2001. If these 107 glaciers were to retreat at an average rate of 110 m yr −1 in the coming century, as they have between 2000 and 2012 26 , only 30 of them would disconnect from the ocean by the end of the century. We report 123 marine-terminating glaciers versus 12 in B2001 and 102 in B2013.…”

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confidence: 99%

Deeply incised submarine glacial valleys beneath the Greenland ice sheet

et al. 2014

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“…Variations in basal topography and fjord width have been previously identified as an important control on the dynamic response of glaciers in many regions of the GrIS Howat and Eddy, 2011;McFadden et al, 2011;Thomas et al, 2009;Carr et al, 2017). In this study, the differences between periods of retreat, acceleration, and thinning between floating and grounded-terminus glaciers suggests basal topography may control the time taken for glaciers to return to a point where retreat 5 slows and velocities return to pre-retreat levels.…”

Section: Influence Of Glacier Geometrymentioning

confidence: 70%

“…Enderlin et al, 2013;Howat and Eddy, 2011;Jamieson et al, 2012), and could also explain differences between groundedterminus and floating ice-tongue glaciers (McFadden et al, 2011), as well as individual glacier variability. At Hagen Brae, for example, the ice tongue is confined by, and strongly attached to, its fjord walls, and retreat away from an island pinning point may have reduced back stress on inland grounded ice, and contributed to its acceleration (Joughin et al, 2010).…”

Section: Influence Of Glacier Geometrymentioning

confidence: 99%

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

Hill¹,

Carr²,

Stokes³

et al. 2018

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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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Multi-decadal retreat of Greenland’s marine-terminating glaciers

Cited by 159 publications

References 28 publications

On the recent contribution of the Greenland ice sheet to sea level change

On the recent contribution of the Greenland ice sheet to sea level change

Deeply incised submarine glacial valleys beneath the Greenland ice sheet

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

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