Interaction between warm Atlantic‐sourced waters and the East Greenland Current in northern Denmark Strait (68°N) during the last 10 600 cal a BP

Abstract

Changes in the Holocene interaction of the (i) cold/fresh East Greenland Current (EGC) and (ii) warm/saline Irminger Current (IC) in northern Denmark Strait have been reconstructed from benthic and planktic foraminifera assemblages, ice‐rafted debris, grain‐size analyses and quantitative X‐ray diffraction. During the time from c. 10 600 to 8000 cal a BP, palaeoceanographic reconstructions reveal waning deglacial influence from the receding Greenland Ice Sheet and presence of a strong EGC caused low surface water productivity. From c. 8000 cal a BP, a predominant influence of Atlantic‐sourced IC waters on subsurface water conditions became established in northern Denmark Strait, which accompanied low surface water productivity. Relatively warm surface and subsurface water conditions, i.e. reduced EGC and strong IC influence, are found from c. 6500 to 4500 cal a BP, representing Holocene optimum‐like conditions. A mid‐ to late Holocene EGC strengthening caused increased stratification and formation of a distinct halocline. However, we recognize millennial‐scale periods of reduced stratification by an enhanced influence of Atlantic‐sourced IC Water on surface water conditions: (i) at c. 2500–1400 cal a BP − the time of the Roman Warm Period and (ii) at c. 300 cal a BP − the later part of the Little Ice Age. These periods of oceanic warming probably relate to changes in the Subpolar Gyre dynamics that led to enhanced entrainment of Atlantic‐sourced IC Water into northern Denmark Strait.

Variability in the Northern North Atlantic and Arctic Oceans Across the Last Two Millennia: A Review

“…Farther south in the Denmark Strait, few paleoceanographic records exist. Records from northern Denmark Strait at Nansen Trough show a millennial reduction of subsurface warm Recirculating Atlantic waters (Perner et al, ; Figure l), consistent with lower resolution time series from the same site (Jennings & Weiner, ). Both pieces of evidence either indicate a weaker transport or cooler subsurface/bottom Atlantic waters of the IC.…”

“…Ice and oceanographic conditions along Eastern Greenland and North Iceland. Left panel shows sea/drift ice conditions (a) sea ice conditions in PS2641 BC/GC at Foster Bugt (Kolling et al, ); (b) drift ice recorded in the Denmark Strait JM96‐1206/2GC (Perner et al, ) North Iceland; (c) %Quartz from MD99‐2269 (Moros et al, ); sea ice biomarker (d) MD99‐2275 (Massé et al, ) and (e) MD99‐2269 (Cabedo‐Sanz et al, ); (f) April sea ice cover from diatom assemblages in the West Denmark Strait (MD99‐2322; Miettinen et al, );and (g) Haematite Stained Grains (HSG) transported from northwest Greenland to South Greenland (GS06‐144‐03; Alonso‐Garcia et al, ). Right panel shows oceanographic conditions (h) benthic foraminiferal assemblages at ~430 m, which are indicator of Atlantic Intermediate Waters (PS2641 BC/GC; (Perner et al, ), North Iceland upper water column conditions; (i) sea surface temperatures from alkenones (MD99–2275; Sicre et al, ; Sicre et al, ); (j) summer sea surface temperatures from diatom assemblages (Jiang et al, ; MD99–2275); (k) δ 18 O shell (black; Reynolds et al, ) and ∆ R (orange; Wanamaker et al, ) from Arctica islandica from the North Iceland shelf; (l) benthic assemblage from ~400‐m deep in the Northern Denmark Strait (JM96‐1206/2GC; Perner et al, ); (m) % planktonic foraminifera species N. pachyderma from the Eastern Labrador Sea (South Greenland; RAPiD‐35‐COM; Moffa‐Sánchez & Hall, ).…”

High‐resolution proglacial lake records of pre‐Little Ice Age glacier advance, northeast Greenland

“…G. Foraminiferal assemblage productivity group % (Perner et al . ). H. Glacier records from West Greenland: Kiagtut Sermia, southwest Greenland (red square: Winsor et al .…”

“…F, G; Perner et al . , ), and periods of enhanced sea ice in Prinz Josef Fjord, ~150 km southwest of Madsen Lake (Kolling et al . ) throughout the Neoglacial.…”

“…a BP (Fig. 6F, G; Perner et al 2015Perner et al , 2016, and periods of enhanced sea ice in Prinz Josef Fjord,~150 km southwest of Madsen Lake (Kolling et al 2017) throughout the Neoglacial. Van der Bilt et al (2018) propose a mechanism by which weakening of the Sub Polar Gyre caused a change in North Atlantic Oscillation phasing, leading to climatic conditions conducive for glacier growth in Greenland, but not in western Europe.…”