Publication Date:
2023-07-10
Description:
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during the 35-41 ka cal BP interval covering three Dansgaard-Oeschger cycles and including Heinrich event 4, in a new unpublished marine record, i.e. the MD99-2285 core (62.69°N; -3.57°E).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.
Keywords:
2065N; AGE; Bitectatodinium tepikiense; CALYPSO; Calypso Corer; DEPTH, sediment/rock; Dinoflagellate cyst reworked per volume; Diversity; Dominance; Foraminifera, planktic; Halodinium spp.; Ice rafted debris; IMAGES V; Islandinium minutum var. minutum; Marion Dufresne (1995); MD114; MD99-2285; N.Faeroes; Neogloboquadrina pachyderma sinistral; Neogloboquadrina pachyderma sinistral, δ18O; Operculodinium centrocarpum; Pediastrum spp., coenobia; Primary production of carbon; Sea ice cover duration; Sea surface salinity, summer; Sea surface salinity, winter; Sea surface temperature, summer; Sea surface temperature, winter
Type:
Dataset
Format:
text/tab-separated-values, 647 data points
Permalink