Collapse of the North American ice saddle 14,500 years ago caused widespread cooling and reduced ocean overturning circulation

• Published in: Geophysical Research Letters
• Main Authors: Ivanovic, Ruza F., Gregoire, Lauren J., Wickert, Andrew D., Valdes, Paul J., Burke, Andrea
• Other Authors: NERC, University of St Andrews. School of Earth & Environmental Sciences, University of St Andrews. St Andrews Isotope Geochemistry, University of St Andrews. Earth and Environmental Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: AMOC; Ice sheet melt; Saddle collapse; Older Dryas; GE Environmental Sciences; NDAS; BDC; SDG 13 - Climate Action; GE; Ice Sheet
• Online Access: http://hdl.handle.net/10023/10076; https://doi.org/10.1002/2016GL071849

RFI is funded by NERC grant #NE/K008536/1. Numerical climate model simulations made use of the N8 HPC Centre of Excellence (N8 consortium and EPSRC Grant #EP/K000225/1). 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 ~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. Publisher PDF Peer reviewed