A 100-year long record of alkenone-derived SST changes by Southeast Greenland

Abstract

Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Continental Shelf Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Continental Shelf Research, 71, 1 December 2013, https://doi.org/10.1016/j.csr.2013.10.003Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. Highlights Alkenone analysis on sediment core from Sermilik Fjord, SE Greenland. Reconstruction of ocean surface temperature changes of the past 100 years. Alkenones advected and represent temperature changes on nearby shelf. Warm ocean c. 1940 concurs with increased calving from Helheim Glacier  Similar to observation from Disko Bay and Jakobshavn Isbrae in West Greenland. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 2 of warm subsurface waters ~ 1940 concurrent with markedly increased calving and retreat of Helheim Glacier. Our results therefore suggest that alkenone-derived SST time series from highsedimentation rate glacial fjords may provide a new approach for reconstruction of past changes of shelf water properties and variability around Greenland.

Exceptional 20th century glaciological regime of a major SE Greenland outlet glacier

“…Alkenone biomarkers, mainly produced by the coccolitophorid Emiliana huxleyi , have successfully been used for SST reconstructions in this region 17 , 18 . This method was previously applied to core ER07 for reconstructing the SST variability of the last 100 years 17 . Our new 1700-year long record shows SSTs ranging from 6 to 12.6 °C (Fig.…”

Surface and sub-surface multi-proxy reconstruction of middle to late Holocene palaeoceanographic changes in Disko Bugt, West Greenland

“…Many tidewater glaciers in southeast and west Greenland show significant changes in velocity and consequent ice flux to the ocean since 2000 (e.g. Andresen et al, 2013;Holland et al, 2008;Howat et al, 2007Howat et al, , 2008Howat et al, , 2011Moon and Joughin, 2008;Rignot and Kanagaratnam, 2006;Straneo et al, 2010;Walsh et al, 2012;Zwalley et al, 2002). The forcing mechanism for the enhanced ice velocity is unclear although there is strong support for the importance of the influence of changing ocean temperatures driving glacier dynamics (e.g.…”

Sea Surface Temperature Variability on the SE‐Greenland Shelf (1796–2013 CE) and Its Influence on Thrym Glacier in Nørre Skjoldungesund

“…This makes it unlikely that the reconstructed temperature range between 5°C and 12°C represents SSTs within the fjord. Previous studies from Sermilik Fjord located 350 km north of Skjoldungen (Figure a) have already shown that alkenones deposited in the fjord originate mostly from inner shelf waters advected into the fjord and thus reflect values and variability of coastal waters outside the Sermilik Fjord (Andresen et al, ).…”

“…Alkenone‐based temperature reconstructions in the Nordic seas are sparse and often challenged by temperatures below a correlation limit of −5°C (Bendle et al, ; Conte et al, ; Filippova et al, ; Sicre et al, ). Previous studies have shown that the local signal in SE‐Greenland fjords can be biased by nearby highly alkenone productive waters such as south of Iceland or local upwelling, calling for cautious interpretation of the alkSST reconstruction (Andresen et al, , ). The bias that can be introduced by surface current advection in regions with a weak local production has also been demonstrated (Conte et al, ; Rühlemann & Butzin, ).…”

“…The proxy ocean data are compared with the available instrumental oceanographic temperature observations and other proxy temperature records from offshore SE-Greenland. Sediment cores have additionally been used to investigate the link between ocean warming and glacier dynamics of some of the largest marine-terminating glaciers in Greenland, such as Jakobshavn Isbrae (Holland et al, 2008;Lloyd, 2006Lloyd, , 2011Andresen et al, 2011, Wangner et al, 2018, Helheim Glacier (Andresen et al, , 2013, and Kangerlussuaq glacier (Vermassen, Bjørk, et al, 2019). While the glacier geometry of these glaciers are characterized by deep subglacial troughs connected directly to the fjords, smaller glaciers terminating in shallower fjords such as Thrym Glacier, which terminates into Skjoldungen Fjord, usually have a limited ice-ocean interface.…”