Norwegian Sea warm pulses during Dansgaard-Oeschger stadials: Zooming in on these anomalies over the 35–41 ka cal BP interval and their impacts on proximal European ice-sheet dynamics. (1st November 2016)

• Record Type: Journal Article
• Authors: Wary, Mélanie; Eynaud, Frédérique; Rossignol, Linda; Lapuyade, Joanna; Gasparotto, Marie-Camille; Londeix, Laurent; Malaizé, Bruno; Castéra, Marie-Hélène; Charlier, Karine
• Is Part Of: Quaternary science reviews. Volume 151(2016)
• Page Start: 255
• Page End: 272
• Publication Date: 2016-11-01
• Subjects: Dansgaard-Oeschger events -- Heinrich events -- Trigger mechanism -- Sea ice -- Surface/subsurface hydrological conditions -- High resolution multiproxy approach; NPS Neogloboquadrina pachyderma sinistral coiling -- CSC Continental Slope Current; Geology, Stratigraphic -- Quaternary -- Periodicals; Stratigraphie -- Quaternaire -- Périodiques; 551.79
• DOI: 10.1016/j.quascirev.2016.09.011
• Languages: English
• ISSNs: 0277-3791

Abstract

Abstract: The last glacial millennial climatic events (i.e. Dansgaard-Oeschger and Heinrich events) constitute outstanding case studies of coupled atmosphere-ocean-cryosphere interactions. Here, we investigate the evolution of sea-surface and subsurface conditions, in terms of temperature, salinity and sea ice cover, at very high-resolution (mean resolution between 55 and 155 years depending on proxies) during the 35–41 ka cal BP interval covering three Dansgaard-Oeschger cycles and including Heinrich event 4, in a new unpublished marine record, i.e. the MD99-2285 core (62.69°N; -3.57s°E). We use a large panel of complementary tools, which notably includes dinocyst-derived sea-ice cover duration quantifications. The high temporal resolution and multiproxy approach of this work allows us to identify the sequence of processes and to assess ocean-cryosphere interactions occurring during these periodic ice-sheet collapse events. Our results evidence a paradoxical hydrological scheme where (i) Greenland interstadials are marked by a homogeneous and cold upper water column, with intensive winter sea ice formation and summer sea ice melting, and (ii) Greenland and Heinrich stadials are characterized by a very warm and low saline surface layer with iceberg calving and reduced sea ice formation, separated by a strong halocline from a less warm and saltier subsurface layer. Our work also suggests that this stadial surface/subsurface warming started before massive iceberg release, in relation with warm Atlantic water advection. These findings thus support the theory that upper ocean warming might have triggered European ice-sheet destabilization. Besides, previous paleoceanographic studies conducted along the Atlantic inflow pathways close to the edge of European ice-sheets suggest that such a feature might have occurred in this whole area. Nonetheless, additional high resolution paleoreconstructions are required to confirm such a regional scheme. Highlights: Paradoxical hydrological scheme during the millennial climatic events. Stadials marked by higher SST and subsurface temperatures, and reduced sea ice cover. Temperature pattern linked to warm Atlantic water advection during stadials. Advection and ocean warming: potential trigger mechanisms of ice-sheet collapses.