Reduced north Atlantic deep water coeval with the glacial lake Agassiz freshwater outburst

Helga Flesche Kleiven (1) , Catherine Kissel (2, 3) , Carlo Laj (2, 3) , Ulysses Ninnemann (4) , Thomas Richter (5) , Elsa Cortijo (2, 6)

1 UiB - University of Bergen
2 LSCE - Laboratoire des Sciences du Climat et de l'Environnement [Gif-sur-Yvette]
3 CLIMAG - Climat et Magnétisme
4 UiB - Department of Earth Science [Bergen]
5 NIOZ - Royal Netherlands Institute for Sea Research
6 PALEOCEAN - Paléocéanographie

An outstanding climate anomaly 8200 years before the present (B.P.) in the North Atlantic is commonly postulated to be the result of weakened overturning circulation triggered by a freshwater outburst. New stable isotopic and sedimentological records from a northwest Atlantic sediment core reveal that the most prominent Holocene anomaly in bottom-water chemistry and flow speed in the deep limb of the Atlantic overturning circulation begins at ∼8.38 thousand years B.P., coeval with the catastrophic drainage of Lake Agassiz. The influence of Lower North Atlantic Deep Water was strongly reduced at our site for ∼100 years after the outburst, confirming the ocean's sensitivity to freshwater forcing. The similarities between the timing and duration of the pronounced deep circulation changes and regional climate anomalies support a causal link.

Domains: Atmospheric and Oceanic Physics [physics.ao-ph]

Helga Flesche Kleiven, Catherine Kissel, Carlo Laj, Ulysses Ninnemann, Thomas Richter, et al.. Reduced north Atlantic deep water coeval with the glacial lake Agassiz freshwater outburst. Science, 2008, 319 (5859), pp.60-64. ⟨10.1126/science.1148924⟩. ⟨cea-00817389⟩