Ryder Glacier in northwest Greenland is shielded from warm Atlantic water by a bathymetric sill

Jakobsson, Martin; Mayer, Larry A.; Nilsson, Johan; Stranne, Christian; Calder, Brian R.; O’Regan, Matt; Farrell, John W; Cronin, Thomas M.; Brüchert, Volker; Chawarski, Julek; Eriksson, Birgitta; Fredriksson, Jonas; Gemery, Laura; Glueder, Anna; Holmes, Felicity; Jerram, Kevin; Kirchner, Nina; Mix, Alan C; Muchowski, Julia; Prakash, Abhay; Reilly, Brendan; Thornton, Brett F.; Ulfsbo, Adam; Weidner, Elizabeth; Åkesson, Henning; Handl, Tamara; Ståhl, Emelie; Boze, Lee-Gray; Reed, Sam; West, Gabriel; Padman, June

doi:10.1038/s43247-020-00043-0

Cited by 37 publications

(76 citation statements)

References 40 publications

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“…This is consistent with the age of the Warming Land Stade, bracketed between >9.5 cal ka BP and 8.0 cal ka BP by Kelly and Bennike (1992). The shallow inner sill, first identified through bathymetric mapping during the Ryder 2019 expedition (Jakobsson et al, 2020), is very close to the previously inferred grounding zone location for the Warming Land Stade and provides a natural pinning point for the marine-based glacier during this standstill (Fig. 2).…”

Section: Early Holocene Glacier and Ice Tongue Dynamicssupporting

confidence: 77%

“…2). Bathymetric mapping during the Ryder 2019 expedition revealed two prominent sills dissecting the fjord (Jakobsson et al, 2020) (Fig. 2).…”

Section: Geologic Oceanographic and Glaciologic Setting 85mentioning

confidence: 99%

“…2). These sills bound an over-deepened inner basin that has a maximum depth of 890 m. The outer sill has little sedimentary cover and appears to be a bedrock feature, while the inner sill is interpreted as a 90 sedimented former glacial grounding zone (Jakobsson et al, 2020), potentially developed on a pre-existing bedrock high. Kelly and Bennike (1992).…”

Section: Geologic Oceanographic and Glaciologic Setting 85mentioning

confidence: 99%

“…Despite these bathymetric barriers, waters of Atlantic origin that circulate through the Lincoln Sea are found between the two sills at depths greater than 350 m (Fig. 3; Jakobsson et al, 2020). These relatively warm (>0.3 o C) and saline (>34.7) waters are constrained by the inner sill with only a small amount of warmer water flowing across the inner sill through the <1 km wide and 390 m deep channel, to be strongly mixed with glacially derived meltwater.…”

Section: Geologic Oceanographic and Glaciologic Setting 85mentioning

confidence: 99%

“…Between August 13 and 25, unusually light sea-ice conditions allowed Oden to occupy nine coring stations and systematically map the fjord (Fig. 2; Jakobsson et al, 2020). Coring was conducted using a 12 m long piston core (PC) and small (1-2 m) trigger weight core (TWC), and a 6 m long gravity core (GC).…”

Section: Marine Sediment Coresmentioning

confidence: 99%

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The Holocene dynamics of Ryder Glacier and ice tongue in north Greenland

O’Regan¹,

Cronin²,

Reilly³

et al. 2021

Preprint

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Abstract. The northern sector of the Greenland ice sheet is considered to be particularly susceptible to ice mass loss arising from increased glacier discharge in the coming decades. However, the past extent and dynamics of outlet glaciers in this region, and hence their vulnerability to climate change, are poorly documented. In the summer of 2019, the Swedish icebreaker Oden entered the previously unchartered waters of Sherard Osborn Fjord, where Ryder Glacier drains approximately 2 % of Greenland's ice sheet into the Lincoln Sea. Here we reconstruct the Holocene dynamics of Ryder Glacier and its ice tongue by combining radiocarbon dating with sedimentary facies analyses along a 45 km transect of marine sediment cores collected between the modern ice tongue margin and the mouth of the fjord. The results illustrate that Ryder Glacier retreated from a grounded position at the fjord mouth during the Early Holocene (>10.7 ± 0.4 cal ka BP) and receded more than 120 km to the end of Sherard Osborn Fjord by the Middle Holocene (6.3 ± 0.3 cal ka BP), likely becoming completely land-based. A re-advance of Ryder Glacier occurred in the Late Holocene, becoming marine-based around 3.9 ± 0.4 cal ka BP. An ice tongue, similar in extent to its current position was established in the Late Holocene (between 3.6 ± 0.4 and 2.9 ± 0.4 cal ka BP) and extended to its maximum historical position near the fjord mouth around 0.9 ± 0.3 cal ka BP. Laminated, clast-poor sediments were deposited during the entire retreat and regrowth phases, suggesting the persistence of an ice tongue that only collapsed when the glacier retreated behind a prominent topographic high at the landward end of the fjord. Sherard Osborn Fjord narrows inland, is constrained by steep-sided cliffs, contains a number of bathymetric pinning points that also shield the modern ice tongue and grounding zone from warm Atlantic waters, and has a shallowing inland sub-ice topography. These features are conducive to glacier stability and can explain the persistence of Ryder’s ice tongue while the glacier remained marine-based. However, the physiography of the fjord did not halt the dramatic retreat of Ryder Glacier under the relatively mild changes in climate forcing during the Holocene. Presently, Ryder Glacier is grounded more than 40 km seaward of its inferred position during the Middle Holocene, highlighting the potential for substantial retreat in response to ongoing climate change.

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Section: Early Holocene Glacier and Ice Tongue Dynamicssupporting

confidence: 77%

“…2). Bathymetric mapping during the Ryder 2019 expedition revealed two prominent sills dissecting the fjord (Jakobsson et al, 2020) (Fig. 2).…”

Section: Geologic Oceanographic and Glaciologic Setting 85mentioning

confidence: 99%

Section: Geologic Oceanographic and Glaciologic Setting 85mentioning

confidence: 99%

Section: Geologic Oceanographic and Glaciologic Setting 85mentioning

confidence: 99%

Section: Marine Sediment Coresmentioning

confidence: 99%