Spatio-temporal dynamics of hydrographic reorganizations and iceberg discharges at the junction between the Northeast Atlantic and Norwegian Sea basins surrounding Heinrich event 4

Abstract

Dansgaard–Oeschger and Heinrich events constitute ones of the most enigmatic features of the last glacial period. Many studies have focused on their characteristic millennial climatic variability, testing atmospheric/cryospheric/oceanic couplings, but major uncertainties and discrepancies still remain. A new scenario, robustly supported by an approach coupling paleoreconstructions and freshwater hosing experiments simulating Heinrich-type perturbations, has recently emerged. Reconciling most of the up to now hypothesized theories, it suggests the occurrence of a regional seesaw between a cooled-down North Atlantic Ocean and warmed-up Nordic Seas during cold atmospheric phases, in relation to enhanced subsurface advection of warm Atlantic waters re-emerging in the Norwegian Sea. The associated ocean warming, thus reaching Nordic basins at a critical location beyond the Faeroe-Shetland sill, is proposed to be involved in the concomitant release of European icebergs. Here we further investigate this promising scenario over the 35–41 ka BP interval by (i) outlining its precise spatial pattern in a crucial area, i.e. the junction between the North Atlantic and the Norwegian Sea close to European ice-sheets, (ii) resolving its very fine temporal and regional evolution during critical transitions associated with the onset of warm advection, i.e. Greenland Interstadial to Greenland Stadial and Greenland Interstadial to Heinrich Stadial, and (iii) assessing its impact on the spatio-temporal dynamic of iceberg discharges from the European and Laurentide ice-sheets during cold stadial episodes especially including Heinrich event 4.