More than Skin Deep: Sea Surface Temperature as a Means of Inferring Atlantic Water Variability on the Southeast Greenland Continental Shelf Near Helheim Glacier

Snow, Tasha; Straneo, F.; Holte, James; Grigsby, S.; Abdalati, W.; Scambos, T. A.

doi:10.1029/2020jc016509

Cited by 9 publications

(23 citation statements)

References 87 publications

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“…This is the shallowest water column depth that warm water reached during the 2017–2020 site 144 CTD record (although CTD timings were inconsistent between years, ranging from August–October), suggesting AW intrusion was high proximal to Steenstrup in 2018. An anomalous 2018 AW intrusion was previously reported at Sermilik Fjord 59 , who inferred that AW extended along the entire trough year-round in 2018. Our conclusions are limited by the lack of observational thermal profiles from within the fjord that would provide in situ validation of AW intrusion, but modelling results and data presented are supportive of a hypothesis where, in 2018, AW could access even the shallowest sections of the coastal shelf in front of Steenstrup, overtopping the sill and inducing retreat.…”

Section: Discussionmentioning

confidence: 60%

Atlantic water intrusion triggers rapid retreat and regime change at previously stable Greenland glacier

Chudley¹,

Howat²,

King³

et al. 2023

Nat Commun

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Ice discharge from Greenland’s marine-terminating glaciers contributes to half of all mass loss from the ice sheet, with numerous mechanisms proposed to explain their retreat. Here, we examine K.I.V Steenstrups Nordre Bræ (‘Steenstrup’) in Southeast Greenland, which, between 2018 and 2021, retreated ~7 km, thinned ~20%, doubled in discharge, and accelerated ~300%. This rate of change is unprecedented amongst Greenland’s glaciers and now places Steenstrup in the top 10% of glaciers by contribution to ice-sheet-wide discharge. In contrast to expected behaviour from a shallow, grounded tidewater glacier, Steenstrup was insensitive to high surface temperatures that destabilised many regional glaciers in 2016, appearing instead to respond to a >2 °C anomaly in deeper Atlantic water (AW) in 2018. By 2021, a rigid proglacial mélange had developed alongside notable seasonal variability. Steenstrup’s behaviour highlights that even long-term stable glaciers with high sills are vulnerable to sudden and rapid retreat from warm AW intrusion.

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Section: Discussionmentioning

confidence: 60%

Atlantic water intrusion triggers rapid retreat and regime change at previously stable Greenland glacier

Chudley¹,

Howat²,

King³

et al. 2023

Nat Commun

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“…However, warm modes exist whereby AW can be present throughout the water column (Sutherland et al 2013) and driven onto the coastal shelf (Jackson et al 2014, Håvik andVåge, 2018). We suggest that 2018 is representative of a particularly extreme warm mode (also identified in observational data by Snow et al 2021) sufficient to incorporate an anomalous amount of AW high into the water column at Kangerlussuaq Fjord (Fig. S6), which was then carried south across the coastal shelf as part of the East Greenland Coastal Current (Sutherland and Pickart, 2008;Håvik and Våge, 2018).…”

Section: Forcing Mechanismsmentioning

confidence: 54%

Atlantic Water intrusion triggers rapid retreat and regime change at previously stable Greenland glacier

Chudley¹,

Howat²,

King³

et al. 2023

Preprint

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Discharge from Greenland’s marine-terminating glaciers contribute to half of all mass loss from the ice sheet, but the factors forcing their retreat are complex and contested. Here, we examine K.I.V Steenstrups Nordre Bræ (‘Steenstrup’), which, between 2018—2021, retreated ~7 km, thinned by ~20%, doubled in ice discharge, and quadrupled in flow speed. This rate of acceleration is unprecedented amongst Greenland’s glaciers, and now places Steenstrup in the top 10% of glaciers by contribution to Greenland’s discharge. In contrast to expected behaviour from a shallow, grounded tidewater glacier, Steenstrup was insensitive to high surface temperatures that destabilised many regional glaciers in 2016, responding instead to an extreme anomaly in deeper Atlantic Water (AW) in 2018. Steenstrup’s behaviour highlights that, as AW intrusions occur at increasingly shallow depths, even apparently long-term stable glaciers with high sills are vulnerable to sudden and rapid retreat.

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“…Freshwater from glaciers released into the fjords in the form of icebergs (Figure 2c; Mankoff et al, 2019), meltwater from submarine melting of the ice front (Slater et al, 2019), runoff of surface melt (Figure 2d; e.g., Noël et al, 2016), and basal meltwater (Karlsson et al, 2021) is transformed by processes within the glacial fjords before being exported into the upper layers of continental shelf waters (Beaird et al, 2015(Beaird et al, , 2018Moon et al, 2017). Deep troughs that cut across the continental shelf provide a pathway for warm, salty, denser shelf waters to flow into the fjords and drive melting of the glaciers at depth (Jakobsson et al, 2012;Straneo et al, 2012;Snow et al, 2021).…”

Section: Climate Ecosystems Fisheries and Humans At Greenland's Coast...mentioning

confidence: 99%

“…In many cases, hunting, fishing, and the collection of local food (e.g., seal, trout, salmon) in and around the fjord system is vital to social well-being and quality of life here (Steenholdt, 2021). Along the coast, warm, salty waters from the Irminger Sea mix with cold, fresh waters from the East Greenland Current and the Coastal Current (Sutherland et al, 2013;Snow et al, 2021) to support high productivity on the continental shelf. In addition, upwelling of nutrient-rich waters from the many tidewater glacial fjords in the region results in an upward nutrient flux that replenishes depleted macronutrients in the upper part of the water column (Cape et al, 2019).…”

Section: Historical and Projected Changes In Ammassalik And Qaanaaqmentioning

confidence: 99%

An Interdisciplinary Perspective on Greenland’s Changing Coastal Margins

Straneo¹,

Slater²,

Bouchard³

et al. 2022

Oceanog

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Greenland’s coastal margins are influenced by the confluence of Arctic and Atlantic waters, sea ice, icebergs, and meltwater from the ice sheet. Hundreds of spectacular glacial fjords cut through the coastline and support thriving marine ecosystems and, in some places, adjacent Greenlandic communities. Rising air and ocean temperatures, as well as glacier and sea-ice retreat, are impacting the conditions that support these systems. Projecting how these regions and their communities will evolve requires understanding both the large-scale climate variability and the regional-scale web of physical, biological, and social interactions. Here, we describe pan-Greenland physical, biological, and social settings and show how they are shaped by the ocean, the atmosphere, and the ice sheet. Next, we focus on two communities, Qaanaaq in Northwest Greenland, exposed to Arctic variability, and Ammassalik in Southeast Greenland, exposed to Atlantic variability. We show that while their climates today are similar to those of the warm 1930s–1940s, temperatures are projected to soon exceed those of the last 100 years at both locations. Existing biological records, including fisheries, provide some insight on ecosystem variability, but they are too short to discern robust patterns. To determine how these systems will evolve in the future requires an improved understanding of the linkages and external factors shaping the ecosystem and community response. This interdisciplinary study exemplifies a first step in a systems approach to investigating the evolution of Greenland’s coastal margins.

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More than Skin Deep: Sea Surface Temperature as a Means of Inferring Atlantic Water Variability on the Southeast Greenland Continental Shelf Near Helheim Glacier

Cited by 9 publications

References 87 publications

Atlantic water intrusion triggers rapid retreat and regime change at previously stable Greenland glacier

Atlantic water intrusion triggers rapid retreat and regime change at previously stable Greenland glacier

Atlantic Water intrusion triggers rapid retreat and regime change at previously stable Greenland glacier

An Interdisciplinary Perspective on Greenland’s Changing Coastal Margins

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