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1. Sediment discharge from Greenland’s marine-terminating glaciers is linked with surface melt

   https://doi.org/10.1038/s41467-024-45694-1  

   Andresen, Camilla S; Karlsson, Nanna B; Straneo, Fiammetta; Schmidt, Sabine; Andersen, Thorbjørn J; Eidam, Emily F; Bjørk, Anders A; Dartiguemalle, Nicolas; Dyke, Laurence M; Vermassen, Flor; et al (December 2024, Nature Communications)

   Abstract Sediment discharged from the Greenland Ice Sheet delivers nutrients to marine ecosystems around Greenland and shapes seafloor habitats. Current estimates of the total sediment flux are constrained by observations from land-terminating glaciers only. Addressing this gap, our study presents a budget derived from observations at 30 marine-margin locations. Analyzing sediment cores from nine glaciated fjords, we assess spatial deposition since 1950. A significant correlation is established between mass accumulation rates, normalized by surface runoff, and distance down-fjord. This enables calculating annual sediment flux at any fjord point based on nearby marine-terminating outlet glacier melt data. Findings reveal a total annual sediment flux of 1.324 + /− 0.79 Gt yr-1 over the period 2010-2020 from all marine-terminating glaciers to the fjords. These estimates are valuable for studies aiming to understand the basal ice sheet conditions and for studies predicting ecosystem changes in Greenland’s fjords and offshore areas as the ice sheet melts and sediment discharge increase. 

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2. New coasts emerging from the retreat of Northern Hemisphere marine-terminating glaciers in the twenty-first century

   https://doi.org/10.1038/s41558-025-02282-5  

   Kavan, Jan; Szczypińska, Małgorzata; Kochtitzky, William; Farquharson, Louise; Bendixen, Mette; Strzelecki, Mateusz C (March 2025, Nature Climate Change)

   Abstract Accelerated climate warming has caused the majority of marine-terminating glaciers in the Northern Hemisphere to retreat substantially during the twenty-first century. While glacier retreat and changes in mass balance are widely studied on a global scale, the impacts of deglaciation on adjacent coastal geomorphology are often overlooked and therefore poorly understood. Here we examine changes in proglacial zones of marine-terminating glaciers across the Northern Hemisphere to quantify the length of new coastline that has been exposed by glacial retreat between 2000 and 2020. We identified a total of 2,466 ± 0.8 km (123 km a⁻¹) of new coastline with most (66%) of the total length occurring in Greenland. These young paraglacial coastlines are highly dynamic, exhibiting high sediment fluxes and rapidly evolving landforms. Retreating glaciers and associated newly exposed coastline can have important impacts on local ecosystems and Arctic communities. 

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3. Strong Year‐Round Variation in Circulation and Heat Transport in a Proglacial Southwest Greenland Fjord

   https://doi.org/10.1029/2025JC022753  

   Vries, Anneke L; Mortensen, John; Schulz, Kirstin; van_de_Berg, Willem Jan; van_den_Broeke, Michiel R; Meire, Lorenz (December 2025, Journal of Geophysical Research: Oceans)

   Greenland's glacial fjords serve as pathways for the transport of heat and freshwater between the continental shelf and the outlet glaciers of the Greenland Ice Sheet. Despite increasing attention from the research community, seasonal studies in Greenland fjords remain scarce. This is especially true for near‐surface measurements. Here, we present year‐round, near‐full water column velocity observations and water mass data in Nuup Kangerlua, a glacial fjord in southwest Greenland. In July, a strong exchange flow is present in the upper 200 m, coinciding with the presence of subglacial discharge waters in the upper 10–50 m. Fjord circulation remains active throughout the year. Net heat transport toward the glaciers is most pronounced in the glacial melt domain (upper 150 m) in summer, while the heat transport occurs mostly in deeper layers in the winter months. Episodic dense coastal inflows renew the deep water in the fjord and can profoundly increase or decrease fjord water temperatures depending on the timing and depth of the inflow. We estimate vertical diffusivity in deeper layers to be around during stagnant periods (i.e., when no inflows occur). This study underlines the importance of seasonal variations and episodic events in fjord current dynamics and associated heat transport as a potentially important control for the submarine melting of marine‐terminating glaciers. 

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4. Impact of icebergs on the seasonal submarine melt of Sermeq Kujalleq

   https://doi.org/10.5194/tc-17-371-2023  

   Kajanto, Karita; Straneo, Fiammetta; Nisancioglu, Kerim (January 2023, The Cryosphere)

   Abstract. The role of icebergs in narrow fjords hosting marine-terminating glaciers in Greenland is poorly understood, even though iceberg melt results in asubstantial freshwater flux that can exceed the subglacial discharge. Furthermore, the melting of deep-keeled icebergs modifies the verticalstratification of the fjord and, as such, can impact ice–ocean exchanges at the glacier front. We model an idealised representation of thehigh-silled Ilulissat Icefjord in West Greenland with the MITgcm ocean circulation model, using the IceBerg package to study the effect of submarineiceberg melt on fjord water properties over a runoff season, and compare our results with available observations from 2014. We find the subglacialdischarge plume to be the primary driver of the seasonality of circulation, glacier melt and iceberg melt. Furthermore, we find that melting oficebergs modifies the fjord in three main ways: first, icebergs cool and freshen the water column over their vertical extent; second, iceberg-melt-induced changes to fjord stratification cause the neutral buoyancy depth of the plume and the export of glacially modified waters to be deeper;third, icebergs modify the deep basin, below their vertical extent, by driving mixing of the glacially modified waters with the deep-basin watersand by modifying the incoming ambient waters. Through the combination of cooling and causing the subglacial-discharge-driven plume to equilibratedeeper, icebergs suppress glacier melting in the upper layer, resulting in undercutting of the glacier front. Finally, we postulate that the impactof submarine iceberg melt on the neutral buoyancy depth of the plume is a key mechanism linking the presence of an iceberg mélange with theglacier front, without needing to invoke mechanical effects. 

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5. The dynamics of a subglacial salt wedge

   https://doi.org/10.1017/jfm.2020.308  

   Wilson, Earle A.; Wells, Andrew J.; Hewitt, Ian J.; Cenedese, Claudia (July 2020, Journal of Fluid Mechanics)

   Marine-terminating glaciers, such as those along the coastline of Greenland, often release meltwater into the ocean in the form of subglacial discharge plumes. Though these plumes can dramatically alter the mass loss along the front of a glacier, the conditions surrounding their genesis remain poorly constrained. In particular, little is known about the geometry of subglacial outlets and the extent to which seawater may intrude into them. Here, the latter is addressed by exploring the dynamics of an arrested salt wedge – a steady-state, two-layer flow system where salty water partially intrudes a channel carrying fresh water. Building on existing theory, we formulate a model that predicts the length of a non-entraining salt wedge as a function of the Froude number, the slope of the channel and coefficients for interfacial and wall drag. In conjunction, a series of laboratory experiments were conducted to observe a salt wedge within a rectangular channel. For experiments conducted with laminar flow (Reynolds number $Re<800$ ), good agreement with theoretical predictions are obtained when the drag coefficients are modelled as being inversely proportional to $Re$ . However, for fully turbulent flows on geophysical scales, these drag coefficients are expected to asymptote toward finite values. Adopting reasonable drag coefficient estimates for this flow regime, our theoretical model suggests that typical subglacial channels may permit seawater intrusions of the order of several kilometres. While crude, these results indicate that the ocean has a strong tendency to penetrate subglacial channels and potentially undercut the face of marine-terminating glaciers. 

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