Reduced North Atlantic Deep Water Coeval with the Glacial Lake Agassiz Freshwater Outburst

• Published in: Science
• Main Authors: Kleiven, Helga (Kikki) Flesche, Kissel, Catherine, Laj, Carlo, Ninnemann, Ulysses S., Richter, Thomas O., Cortijo, Elsa
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science (AAAS) 2008
• Subjects: Glacial Lake; North Atlantic Deep Water; North Atlantic; Northwest Atlantic
• Online Access: http://dx.doi.org/10.1126/science.1148924; https://www.science.org/doi/pdf/10.1126/science.1148924

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.