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

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...

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Bibliographic Details
Published in:Geophysical Research Letters
Main Authors: Carlson, A. E., Clark, P. U., Haley, Brian A., Klinkhammer, G. P.
Format: Article in Journal/Newspaper
Language:English
Published: AGU (American Geophysical Union) 2009
Subjects:
Glacial Lake
Hudson
Hudson Bay
Ice Sheet
Labrador Sea
Planktonic foraminifera
Online Access:https://oceanrep.geomar.de/id/eprint/6165/
https://oceanrep.geomar.de/id/eprint/6165/1/695_Carlson_2009_RoutingOfWesternCanadianPlains_Artzeit_pubid12118.pdf
https://doi.org/10.1029/2009GL038778
Description
Summary: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.

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