Northeast sector of the Greenland Ice Sheet to undergo the greatest inland expansion of supraglacial lakes during the 21st century

Ignéczi, Ádám; Sole, Andrew; Livingstone, Stephen J.; Leeson, Amber; Fettweis, Xavier; Selmes, N.; Gourmelen, Noël; Briggs, K.

doi:10.1002/2016gl070338

Cited by 45 publications

(62 citation statements)

References 67 publications

(104 reference statements)

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“…Nevertheless, an investigation of strain rates in a west Greenland catchment predicted that new hydrofractures at high elevations are unlikely [52•] such that most high elevation (> 1600 m) melt will be routed over the ice sheet surface and delivered to existing moulins at lower elevations; a finding supported by research suggesting that surface-to-bed connections via hydrofracture of lakes will continue to be limited at higher elevations [47]. It is important to note however that both these studies were undertaken in regions of the ice sheet with slow flow (~100 m year −1 ) and the stress regime at higher elevations, in faster flowing tidewater glacier catchments, could encourage higher and expanding surface-to-bed connections [54].…”

Section: Englacial Meltwater Processesmentioning

confidence: 82%

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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

105

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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Section: Englacial Meltwater Processesmentioning

confidence: 82%

“…The potential for ice bed connections to develop will depend on the bed to surface transfer of basal topography which controls the distribution and size of surface depressions and thus lakes [54] and on how surface melt and stress regimes, and thus crevasses, evolve [52•].…”

Section: Surface To Bed Connections At Higher Elevationsmentioning

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

105

100

View full text Add to dashboard Cite

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“…At several glaciers, the presence of supraglacial lakes has also been noted (Humboldt, Ryder, Nioghalvfjerdsfjorden;Joughin et al, 1996b;Thomsen et al, 1997;Carr et al, 2015), and they are likely to be present on other outlet glaciers across northern Greenland. These lakes may enhance rates of calving through hydrofracture (e.g., Sohn et al, 1998;van der Veen, 1998;Carr et al, 2015), and the role of supraglacial lakes in northern Greenland, particularly across the NEGIS, could become increasingly important in the future (Ignéczi et al, 2016).…”

Section: Subaerial Ice Meltmentioning

confidence: 99%

A Review of Recent Changes in Major Marine-Terminating Outlet Glaciers in Northern Greenland

2017

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Over the past two decades, mass loss from the Greenland Ice Sheet (GrIS) has accelerated and contributed to global sea level rise. This has been partly attributed to dynamic changes in marine terminating outlet glaciers. Outlet glaciers at the northern margin of the ice sheet drain 40% of its area but are comparatively less well-studied than elsewhere on the ice sheet (e.g., central-west or south-east). In order to improve our understanding of this region of the GrIS, this paper synthesizes previously-published research on 21 major marine terminating outlet glaciers. Over the last 130 years, there has been a clear pattern of glacier retreat, particularly over the last two decades. This was accompanied by velocity increases on the majority of glaciers for which records exist. Despite a distinct signal of retreat, however, there is clear variability within the region, which has complicated efforts to determine the precise drivers of recent changes, such as changes in ice tongue buttressing, atmospheric and/or oceanic warming, in addition to the possibility of glacier surging. Thus, there is an important need for further work to ascertain the precise drivers of glacier change, which is likely to require datasets on recent changes in the ocean-climate system (particularly sub-surface ocean temperatures) and numerical modeling of glacier sensitivity to these various forcings. Objective identification of surge-type glaciers is also required. Given that Northern Greenland is predicted to undergo greater warming due to Arctic Amplification during the twenty-first century, we conclude that the region has the potential to become an increasingly important source of mass loss.

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“…At this point, the conclusions drawn from modelling surface ice sheet hydrology changes of the upper ablation zone into the future [Leeson et al, 2015;Ignéczi et al, 2016] greatly outpaces our understanding of how lake drainage; moulin and crevasse formation; and subglacial hydrology and bed properties work in the upper ablation zone. For these reasons, observations of ice sheet motion and stress changes should also be measured for high elevation lakes.…”

Section: Future Directions Towards Synthesismentioning

confidence: 99%

Influence of meltwater on Greenland Ice Sheet dynamics

Stevens¹

2017

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Seasonal fluxes of meltwater control ice-flow processes across the Greenland Ice Sheet ablation zone and subglacial discharge at marine-terminating outlet glaciers. With the increase in annual ice sheet meltwater production observed over recent decades and predicted into future decades, understanding mechanisms driving the hourly to decadal impact of meltwater on ice flow is critical for predicting Greenland Ice Sheet dynamic mass loss. This thesis investigates a wide range of meltwater-driven processes using empirical and theoretical methods for a region of the western margin of the Greenland Ice Sheet. I begin with an examination of the seasonal and annual ice flow record for the region using in situ observations of ice flow from a network of Global Positioning System (GPS) stations. Annual velocities decrease over the seven-year time-series at a rate consistent with the negative trend in annual velocities observed in neighboring regions. Using observations from the same GPS network, I next determine the trigger mechanism for rapid drainage of a supraglacial lake. In three consecutive years, I find precursory basal slip and uplift in the lake basin generates tensile stresses that promote hydrofracture beneath the lake. As these precursors are likely associated with the introduction of meltwater to the bed through neighboring moulin systems, our results imply that lakes may be less able to drain in the less crevassed, interior regions of the ice sheet. Expanding spatial scales to the full ablation zone, I then use a numerical model of subglacial hydrology to test whether model-derived effective pressures exhibit the theorized inverse relationship with melt-season ice sheet surface velocities. Finally, I pair near-ice fjord hydrographic observations with modeled and observed subglacial discharge for the Saqqardliup sermia-Sarqardleq Fjord system. I find evidence of two types of glacially modified waters whose distinct properties and locations in the fjord align with subglacial discharge from two prominent subcatchments beneath Saqqardliup sermia. Continued observational and theoretical work reaching across discipline boundaries is required to further narrow our gap in understanding the forcing mechanisms and magnitude of Greenland Ice Sheet dynamic mass loss.

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Northeast sector of the Greenland Ice Sheet to undergo the greatest inland expansion of supraglacial lakes during the 21st century

Cited by 45 publications

References 67 publications

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

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

A Review of Recent Changes in Major Marine-Terminating Outlet Glaciers in Northern Greenland

Influence of meltwater on Greenland Ice Sheet dynamics

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