Norwegian sea‐surface palaeoenvironments of marine oxygen‐isotope stage 3: the paradoxical response of dinoflagellate cysts

Abstract

M. 2002. Norwegian sea-surface palaeoenvironments of marine oxygen-isotope stage 3: the paradoxical response of dinoflagellate cysts.ABSTRACT: High-resolution marine palynological data have been obtained from two very long sediment cores (MD952009 and MD952010) retrieved from the southern Norwegian Sea. The dinoflagellate cyst assemblages show pronounced fluctuations in composition, which correlate strongly with magnetic susceptibility records and also mimic the δ 18 O signal of the GISP2 Greenland ice-core. If focusing on the period from 48 to 30 cal. kyr BP, this correlation suggests a paradoxical response of the sea-surface environments to the atmospheric conditions over Greenland: when the Greenland δ 18 O signal reflects warm interstadial conditions, the Norwegian Sea depicts cold seasurface temperatures with quasi-perennial sea-ice cover (based on dinoflagellate cysts). In contrast, when the Greenland δ 18 O records cold stadial periods, the Norwegian Sea-surface temperatures are warm (based on dinoflagellate cysts), probably linked to inflow of the North Atlantic Drift. These results, similar in both cores, are contrary to those of previous studies and shed light on a possible decoupling of Norwegian sea surface-water conditions and atmospheric conditions over Greenland. This decoupling could be linked to an atmosphere-ocean system behaving similar to that which the Northern Hemisphere is experiencing at present, i.e. strongly variable owing to the North Atlantic Oscillation.

Regional seesaw between the North Atlantic and Nordic Seas during the last glacial abrupt climate events

“…S6 for further details). We provide here new sea-surface reconstructions for cores MD95-2009, MD95-2010and MD99-2281 based on previously published dinocyst counts (Eynaud et al, 2002;Eynaud, 2003a, b;Zumaque et al, 2011) and extend the previously published reconstructions for core MD99-2285 (Wary et al, 2016; see also Wary et al, 2017 for the complete raw dinocyst counts of core MD99-2285). Our statistical approach provides direct and quantitative reconstructions for mean summer and mean winter SST (with, in the present case, root mean square errors of prediction -RMSEP -of 1.5 and 1.05 • C, respectively), mean summer and mean winter sea-surface salinities (SSS; respective RMSEP of 2.4 and 2.3 psu), and mean annual sea-ice cover (SIC) duration (RM-SEP of 1.2 months year −1 ).…”

“…To complement our view of the system, we also compare our sea-surface hydrographical reconstructions with (i) the relative abundance of the mesopelagic polar planktonic foraminifera NPS obtained in the same cores (Eynaud et al, 2002;Zumaque et al, 2012;Wary, 2015) and considered as tracer of cold subsurface conditions (see Supplement Sects. S5 and S6 for further details; Carstens and Wefer, 1992;Bauch et al, 1997;Carstens et al, 1997;Hillaire-Marcel and Bilodeau, 2000;Volkmann and Mensch, 2001;Simstich et al, 2003;Hillaire-Marcel et al, 2004;Kretschmer et al, 2016), and (ii) Greenland ice core deuterium excess data as indicator of Greenland moisture origin (Masson-Delmotte et al, 2005).…”

“…In parallel, the few direct but qualitative sea-ice reconstructions based on lipid biomarker analyses (Müller and Stein, 2014;Hoff et al, 2016) yielded contrasting interpretations. Here, we provide direct and quantitative reconstructions of variations of seasurface conditions from a compilation of three Norwegian Sea cores and one northern Northeast Atlantic core strategically positioned across the Faeroe-Iceland Ridge to track rapid hydrographic changes (Dokken and Jansen, 1999;Eynaud et al, 2002;Rasmussen and Thomsen, 2004;Dokken et al, 2013) (Fig. 1a and Table S1 in the Supplement).…”

An ocean–ice coupled response during the last glacial: a view from a marine isotopic stage 3 record south of the Faeroe Shetland Gateway

“…Previous paleoceanographic studies have demonstrated the high sensitivity of the Faeroe area to millennial-scale climatic variability and its intimate relation to the MOC dynamics (Rasmussen et al, 1996a(Rasmussen et al, ,b, 2002a(Rasmussen et al, ,b, 2008Thomsen, 2004, 2008;Eynaud et al, 2002;Voelker, 2002). During the last glacial period, the southern part of the Faeroe Islands was under the direct influence of the proximal European ice sheets (Fennoscandian ice sheet: FIS and the British-Irish ice sheet: BIIS) (Fig.…”

“…1. Location of the studied core (MD99-2281: this work) and other cores discussed in the paper (MD95-2009;MD95-2010-Eynaud et al, 2002ENAM93-21 -Rasmussen and Thomsen, 2004;core SO82-5 -Van Kreveld et al, 2000;MD04-2822;MD95-2006-Knutz et al, 2001Hibbert et al, 2010;MD04-2829CQ -Hall et al, 2011. The yellow arrows depict the pathway of the main modern surface currents (Fogelqvist et al, 2003).…”