Rapid circulation of warm subtropical waters in a major glacial fjord in East Greenland

Straneo, Fiammetta; Hamilton, G. S.; Sutherland, David A.; Stearns, L. A.; Davidson, Fraser; Hammill, Mike O.; Stenson, Garry B.; Rosing‐Asvid, Aqqalu

doi:10.1038/ngeo764

Cited by 337 publications

(445 citation statements)

References 29 publications

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“…For example, in west Greenland the sustained attrition of Jakobshavn Isbrae, observed since 1998 (Joughin et al, 2012), has been attributed to warming of subsurface water in Disko Bay and adjacent coastal seas (Holland et al, 2008). Similarly, AW was identified circulating within Sermilik and Kangerdlugssuaq fjords in east Greenland and is implicated in the retreat of Helheim and Kangerdlugssuaq glaciers over the last decade (Straneo et al, 2010(Straneo et al, , 2011. In NW Greenland, two distinct phases of dynamic ice loss (1985-1990 and 2005-2010) across the Melville Coast have been attributed to oceanic rather than atmospheric forcing (Kjaer et al, 2012).…”

Section: N Chauché Et Al: Ice-ocean Interaction and Calving Front Mmentioning

confidence: 99%

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

et al. 2014

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Abstract. Warm, subtropical-originating Atlantic water (AW) has been identified as a primary driver of mass loss across the marine sectors of the Greenland Ice Sheet (GrIS), yet the specific processes by which this water mass interacts with and erodes the calving front of tidewater glaciers is frequently modelled and much speculated upon but remains largely unobserved. We present a suite of fjord salinity, temperature, turbidity versus depth casts along with glacial runoff estimation from Rink and Store glaciers, two major marine outlets draining the western sector of the GrIS during 2009 and 2010. We characterise the main water bodies present and interpret their interaction with their respective calving fronts. We identify two distinct processes of iceocean interaction which have distinct spatial and temporal footprints: (1) homogenous free convective melting which occurs across the calving front where AW is in direct contact with the ice mass, and (2) localised upwelling-driven melt by turbulent subglacial runoff mixing with fjord water which occurs at distinct injection points across the calving front. Throughout the study, AW at 2.8 ± 0.2 • C was consistently observed in contact with both glaciers below 450 m depth, yielding homogenous, free convective submarine melting up to ∼ 200 m depth. Above this bottom layer, multiple interactions are identified, primarily controlled by the rate of subglacial fresh-water discharge which results in localised and discrete upwelling plumes. In the record melt year of 2010, the Store Glacier calving face was dominated by these runoff-driven plumes which led to a highly crenulated frontal geometry characterised by large embayments at the subglacial portals separated by headlands which are dominated by calving. Rink Glacier, which is significantly deeper than Store has a larger proportion of its submerged calving face exposed to AW, which results in a uniform, relatively flat overall frontal geometry.

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Section: N Chauché Et Al: Ice-ocean Interaction and Calving Front Mmentioning

confidence: 99%

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

et al. 2014

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“…Considering the recent reports on beginning interactions of warm ocean waters and the Greenland Ice Sheet (e.g. Straneo et al, 2010), high-resolution palaeo-studies of such developments are important contributions to our understanding of possible future Arctic changes.…”

Section: Arctic Ocean Sea Icementioning

confidence: 99%

New insights on Arctic Quaternary climate variability from palaeo-records and numerical modelling

Jakobsson

Long

Inǵólfsson

et al. 2010

Quaternary Science Reviews

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a b s t r a c tTerrestrial and marine geological archives in the Arctic contain information on environmental change through Quaternary interglacialeglacial cycles. The Arctic Palaeoclimate and its Extremes (APEX) scientific network aims to better understand the magnitude and frequency of past Arctic climate variability, with focus on the "extreme" versus the "normal" conditions of the climate system. One important motivation for studying the amplitude of past natural environmental changes in the Arctic is to better understand the role of this region in a global perspective and provide base-line conditions against which to explore potential future changes in Arctic climate under scenarios of global warming. In this review we identify several areas that are distinct to the present programme and highlight some recent advances presented in this special issue concerning Arctic palaeo-records and natural variability, including spatial and temporal variability of the Greenland Ice Sheet, Arctic Ocean sediment stratigraphy, past ice shelves and marginal marine ice sheets, and the Cenozoic history of Arctic Ocean sea ice in general and Holocene oscillations in sea ice concentrations in particular. The combined sea ice data suggest that the seasonal Arctic sea ice cover was strongly reduced during most of the early Holocene and there appear to have been periods of ice free summers in the central Arctic Ocean. This has important consequences for our understanding of the recent trend of declining sea ice, and calls for further research on causal links between Arctic climate and sea ice.

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“…Submarine melting is thought to be promoted by the emergence of subglacial discharge at the grounding line, forming plumes which rise buoyantly up the calving front others, 2003, 2013;Jenkins, 2011;Straneo and Cenedese, 2015). These plumes both increase the transfer of heat from the ocean to the ice and help to draw warm water towards the calving front by setting up an exchange flow in the proglacial fjord (Straneo and others, 2010;Cowton and others, 2015). Progress has recently been made in modelling submarine melting, with the magnitude of subglacial discharge, fjord water properties, grounding line depth and near-terminus subglacial hydrology identified as key controls on the rate and distribution of submarine melting (Jenkins, 2011;Sciascia and others, 2013;Xu and others, 2013;Kimura and others, 2014;Slater others, 2015Slater others, , 2016Carroll and others, 2016).…”

Section: Introductionmentioning

confidence: 99%

Spatially distributed runoff at the grounding line of a large Greenlandic tidewater glacier inferred from plume modelling

et al. 2017

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ABSTRACT. Understanding the drivers of recent change at Greenlandic tidewater glaciers is of great importance if we are to predict how these glaciers will respond to climatic warming. A poorly constrained component of tidewater glacier processes is the near-terminus subglacial hydrology. Here we present a novel method for constraining near-terminus subglacial hydrology with application to marine-terminating Kangiata Nunata Sermia in South-west Greenland. By simulating proglacial plume dynamics using buoyant plume theory and a general circulation model, we assess the critical subglacial discharge, if delivered through a single compact channel, required to generate a plume that reaches the fjord surface. We then compare catchment runoff to a time series of plume visibility acquired from a time-lapse camera. We identify extended periods throughout the 2009 melt season where catchment runoff significantly exceeds the discharge required for a plume to reach the fjord surface, yet we observe no plume. We attribute these observations to spatial spreading of runoff across the grounding line. Persistent distributed drainage near the terminus would lead to more spatially homogeneous submarine melting and may promote more rapid basal sliding during warmer summers, potentially providing a mechanism independent of ocean forcing for increases in atmospheric temperature to drive tidewater glacier acceleration.

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Rapid circulation of warm subtropical waters in a major glacial fjord in East Greenland

Cited by 337 publications

References 29 publications

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

Ice–ocean interaction and calving front morphology at two west Greenland tidewater outlet glaciers

New insights on Arctic Quaternary climate variability from palaeo-records and numerical modelling

Spatially distributed runoff at the grounding line of a large Greenlandic tidewater glacier inferred from plume modelling

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