Routing of western Canadian Plains runoff during the 8.2 ka cold event

• Main Authors: Carlson, Anders E., Clark, Peter U., 1956-, Haley, Brian A., Klinkhammer, Gary P.
• Other Authors: Geosciences, College of Oceanic and Atmospheric Sciences
• Format: Article in Journal/Newspaper
• Language: English; unknown
• Published: American Geophysical Union
• Subjects: Hudson Bay; Ice Sheet; Labrador Sea; Planktonic foraminifera
• Online Access: https://ir.library.oregonstate.edu/concern/articles/vq27zt628

The collapse of the Laurentide Ice Sheet over Hudson Bay ∼8.47 ka allowed the rapid drainage of glacial Lake Agassiz into the Labrador Sea, an event identified as causing a reduction in Atlantic meridional overturning circulation (AMOC) and the 8.2 ka cold event. Atmosphere‐ocean models simulations based on this forcing, however, fail to reproduce several characteristics of this event, particularly its duration. Here we use planktonic foraminifera U/Ca records to document the routing of western Canadian Plains runoff that accompanied ice‐sheet collapse. Geochemical modeling of the ∼7 nmol/mol increase in U/Ca at the opening of Hudson Bay indicates an increase in freshwater discharge of 0.13 ± 0.03 Sverdrups (106 m3 s−1) from routing, a sufficient magnitude to cause an AMOC reduction. We suggest that this routing event suppressed AMOC strength for several centuries after the drainage of Lake Agassiz, explaining multi‐centennial climate anomalies associated with the 8.2 ka cold event.