Collapse of the North American ice saddle 14, 500 years ago caused widespread cooling and reduced ocean overturning circulation. Issue 1 (9th January 2017)

• Record Type: Journal Article
• Authors: Ivanovic, Ruza F.; Gregoire, Lauren J.; Wickert, Andrew D.; Valdes, Paul J.; Burke, Andrea
• Is Part Of: Geophysical research letters. Volume 44:Issue 1(2017)
• Page Start: 383
• Page End: 392
• Publication Date: 2017-01-09
• Subjects: AMOC -- ice sheet melt -- saddle collapse -- Older Dryas; Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/2016GL071849
• Languages: English
• ISSNs: 0094-8276

Abstract

Abstract: Collapse of ice sheets can cause significant sea level rise and widespread climate change. We examine the climatic response to meltwater generated by the collapse of the Cordilleran‐Laurentide ice saddle (North America) ~14.5 thousand years ago (ka) using a high‐resolution drainage model coupled to an ocean‐atmosphere‐vegetation general circulation model. Equivalent to 7.26 m global mean sea level rise in 340 years, the meltwater caused a 6 sverdrup weakening of Atlantic Meridional Overturning Circulation (AMOC) and widespread Northern Hemisphere cooling of 1–5°C. The greatest cooling is in the Atlantic sector high latitudes during Boreal winter (by 5–10°C), but there is also strong summer warming of 1–3°C over eastern North America. Following recent suggestions that the saddle collapse was triggered by the Bølling warming event at ~14.7–14.5 ka, we conclude that this robust submillennial mechanism may have initiated the end of the warming and/or the Older Dryas cooling through a forced AMOC weakening. Key Points: Around 50% of the melt from the Cordilleran‐Laurentide ice saddle collapse directly entered the Arctic Ocean The resulting freshwater cap reduced Atlantic Overturning in the model by 6 Sv (40%) This caused widespread Northern Hemisphere cooling (1–5°C), but strong winter warming over eastern North America