Freshwater Outburst from Lake Superior as a Trigger for the Cold Event 9300 Years Ago

• Published in: Science
• Main Authors: Yu, Shi-Yong, Colman, Steven M., Lowell, Thomas V., Milne, Glenn A., Fisher, Timothy G., Breckenridge, Andy, Boyd, Matthew, Teller, James T.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science (AAAS) 2010
• Subjects: Lawrence River; North Bay; Ice Sheet; North Atlantic
• Online Access: http://dx.doi.org/10.1126/science.1187860; https://www.science.org/doi/pdf/10.1126/science.1187860

Down the Drain A pervasive cooling event affected much of the Northern Hemisphere approximately 9300 years ago. This event was accompanied by changes in ocean circulation in the North Atlantic, forced presumably by a large injection of fresh water produced by melting of the Laurentide Ice Sheet, but the source, magnitude, and routing of the meltwater remain unknown. Yu et al. (p. 1262 , published online 29 April) present evidence that the trigger for this cooling episode was an outburst flood from Lake Superior. Reconstructing lake-level changes in the Superior basin suggests that a rapid fall of lake level of about 45 meters occurred 9300 years ago, possibly due to the sudden failure of a drift dam. Rapid drainage through the North Bay–Ottawa River–St. Lawrence River valleys into the North Atlantic should have been sufficient to disturb ocean circulation in line with the geologic record.