Linkages between ocean circulation and the Northeast Greenland Ice Stream in the Early Holocene

Davies, Joanna P.; Mathiasen, Anders Møller; Kristiansen, Kristiane; Hansen, Katrine Elnegaard; Wacker, Lukas; Alstrup, Aage Kristian Olsen; Munk, Ole Lajord; Pearce, Christof; Seidenkrantz, Marit‐Solveig

doi:10.1016/j.quascirev.2022.107530

Cited by 21 publications

(32 citation statements)

References 113 publications

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“…Multiproxy data from core PS100/270, 16 km from the calving front of the 79 • N ice shelf (Fig. 11), indicate the strong inflow of warm recirculating Atlantic Water between ∼ 10 and 7.5 ka cal BP (Syring et al, 2020), and this is consistent with foraminifera assemblage data from a core in the inner Norsk Trough that indicate a shift towards warmer conditions, an increase in nutrient supply, and higher productivity between 9.6 and 7.9 ka cal BP (Davies et al, 2022). The relative abundance of the Atlantic indicator C. neoteretis remains relatively high until approximately 6.5 ka cal BP in core PS100/270 but then decreases as the relatively coldwater indicator C. reniforme increases to over 40 % of the assemblage after ∼ 6.0 ka cal BP (Syring et al, 2020).…”

Section: Discussionsupporting

confidence: 75%

Holocene history of the 79° N ice shelf reconstructed from epishelf lake and uplifted glaciomarine sediments

et al. 2023

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Abstract. Nioghalvfjerdsbrae, or 79∘ N Glacier, is the largest marine-terminating glacier draining the Northeast Greenland Ice Stream (NEGIS). In recent years, its ∼ 70 km long fringing ice shelf (hereafter referred to as the 79∘ N ice shelf) has thinned, and a number of small calving events highlight its sensitivity to climate warming. With the continued retreat of the 79∘ N ice shelf and the potential for accelerated discharge from NEGIS, which drains 16 % of the Greenland Ice Sheet (GrIS), it has become increasingly important to understand the long-term history of the ice shelf in order to put the recent changes into perspective and to judge their long-term significance. Here, we reconstruct the Holocene dynamics of the 79∘ N ice shelf by combining radiocarbon dating of marine molluscs from isostatically uplifted glaciomarine sediments with a multi-proxy investigation of two sediment cores recovered from Blåsø, a large epishelf lake 2–13 km from the current grounding line of 79∘ N Glacier. Our reconstructions suggest that the ice shelf retreated between 8.5 and 4.4 ka cal BP, which is consistent with previous work charting grounding line and ice shelf retreat to the coast as well as open marine conditions in Nioghalvfjerdsbrae. Ice shelf retreat followed a period of enhanced atmospheric and ocean warming in the Early Holocene. Based on our detailed sedimentological, microfaunal, and biomarker evidence, the ice shelf reformed at Blåsø after 4.4 ka cal BP, reaching a thickness similar to present by 4.0 ka cal BP. Reformation of the ice shelf coincides with decreasing atmospheric temperatures, the increased dominance of Polar Water, a reduction in Atlantic Water, and (near-)perennial sea-ice cover on the adjacent continental shelf. Along with available climate archives, our data indicate that the 79∘ N ice shelf is susceptible to collapse at mean atmospheric and ocean temperatures ∼ 2 ∘C warmer than present, which could be achieved by the middle of this century under some emission scenarios. Finally, the presence of “marine” markers in the uppermost part of the Blåsø sediment cores could record modern ice shelf thinning, although the significance and precise timing of these changes requires further work.

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Section: Discussionsupporting

confidence: 75%

Holocene history of the 79° N ice shelf reconstructed from epishelf lake and uplifted glaciomarine sediments

et al. 2023

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“…Simple box models have shown a consistent link between sea-ice cover and the radiocarbon reservoir age (Bard et al, 1994), and high-resolution studies using tephrochronology coupled with radiocarbon dates have documented North Atlantic reservoir ages of > 2000 years during deep stadials of MIS3 (Olsen et al, 2014). Despite the advice against using Marine20 in polar regions, it has already been used extensively for this purpose since its publication (Pados-Dibattista et al, 2022;Glueder et al Hansen et al, 2022;El bani Altuna et al, 2021;Brouard et al, 2021;Stevenard et al, 2022;Davies et al, 2022;Jackson et al, 2022). Since publication of Marine20, a more recent paper by the same main authors has now been published and clarifies this issue.…”

Section: The Marine20 Curve In Polar Regionsmentioning

confidence: 99%

The marine reservoir age of Greenland coastal waters

Pearce

Özdemir²,

Forchhammer

et al. 2023

Preprint

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Abstract. Knowledge of the marine reservoir age is fundamental for creating reliable chronologies of marine sediment archives based on radiocarbon dating. This age difference between the 14C age of a marine sample and that of its contemporaneous atmosphere is dependent on several factors, among others ocean circulation, water mass distribution, terrestrial runoff, upwelling, sea-ice cover and is therefore spatially heterogenous. Anthropogenic influence on the global isotopic carbon system, mostly through atmospheric nuclear tests, has complicated the determination of the regional reservoir age correction ΔR, which therefore can only be measured on historic samples of known age. In this study we expand on the few existing measurements of ΔR for the coastal waters around Greenland, by adding 92 new radiocarbon dates on mollusks from museum collections. All studied mollusk samples were collected during historic expeditions of the late 19th and early 20th centuries and besides coastal sites around Greenland, the dataset also includes localities from the western Labrador Sea, Baffin Bay, and the Iceland Sea. Together with existing measurements, the new results are used to calculate average ΔR values for different regions around Greenland, all in relation to Marine20, the most recent radiocarbon calibration curve. To support further discussions and comparison with previous datasets, we introduce the term ΔR13 where the suffix 13 refers to the previous calibration curve Marine13. Our study explores the links between the marine reservoir age and oceanography, sea ice cover, water depth, mollusk feeding habits, and the presence of carbonate bedrock. Although we provide regional averages, we encourage people to consult the full catalogue of measurements and determine a suitable ΔR for each case individually, based on the exact location including water depth. Despite this significant expansion of the regional reservoir age database around Greenland, data from the northern coast, directly bordering the Arctic Ocean remains missing.

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“…Timing of the initial retreat across the NEGIS outer continental shelf remains uncertain, but occurred between 13.4–12.5 ka bp , driven by an influx of Atlantic Water (Davies et al, 2022). The ice shelf margin then remained close to the inner continental shelf until 11.2–10.8 ka bp , before retreating westwards (Arndt et al, 2017; Davies et al, 2022). Concomitant rates and patterns of ice thinning across the coastal mountains during early deglaciation are unconstrained, despite their importance for numerical model validation.…”

Section: Previous Workmentioning

confidence: 99%

“…Ice stream subglacial landforms such as megascale glacial lineations, lateral shear moraines, grounding zone wedges, and De Geer moraines show that the palaeo-ice stream reached the continental shelf break, most likely at the LGM although these landforms are undated (Arndt et al, 2015(Arndt et al, , 2017Batchelor & Dowdeswell, 2016;Evans et al, 2009;Winkelmann et al, 2010). Timing of the initial retreat across the NEGIS outer continental shelf remains uncertain, but occurred between 13.4-12.5 ka BP, driven by an influx of Atlantic Water (Davies et al, 2022). The ice shelf margin then remained close to the inner continental shelf until 11.2-10.8 ka BP, before retreating westwards (Arndt et al, 2017;Davies et al, 2022).…”

Section: Negis and Nioghalvfjerdsfjorden Glaciermentioning

confidence: 99%

The geomorphological record of an ice stream to ice shelf transition in Northeast Greenland

Lane

Darvill

Rea

et al. 2023

Earth Surf Processes Landf

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We thank Chris Orton for help with production of figures. Finally, we would like to thank our Field Ranger Isak (after which Isakdalen is informally named) and dog Ooni for keeping us safe in the field. We thank Rob Storrar and an anonymous reviewer for their comments which helped improve the manuscript. AUTHOR CONTRIBUTIONS TPL, CMD, and DHR conceptualised the idea of the manuscript. DHR, BRR, MJB, SSRJ, JAS, and COC acquired funding for the project. TPL, CMD, MJB, JAS, SSRJ and DHR completed fieldwork. TPL, CMD, BRR, and DHR completed initial data analysis and wrote the initial draft. All authors assisted with editing the manuscript.

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Linkages between ocean circulation and the Northeast Greenland Ice Stream in the Early Holocene

Cited by 21 publications

References 113 publications

Holocene history of the 79° N ice shelf reconstructed from epishelf lake and uplifted glaciomarine sediments

Holocene history of the 79° N ice shelf reconstructed from epishelf lake and uplifted glaciomarine sediments

The marine reservoir age of Greenland coastal waters

The geomorphological record of an ice stream to ice shelf transition in Northeast Greenland

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