Collapse of the North American ice saddle 14,500 years ago caused widespread cooling and reduced ocean overturning circulation
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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 Sv 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 sub-millennial mechanism may have initiated the end of the warming and/or the Older Dryas cooling through a forced AMOC weakening.
Ivanovic , R F , Gregoire , L J , Wickert , A D , Valdes , P J & Burke , A 2017 , ' Collapse of the North American ice saddle 14,500 years ago caused widespread cooling and reduced ocean overturning circulation ' Geophysical Research Letters . DOI: 10.1002/2016GL071849
Geophysical Research Letters
© 2016 The Authors. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
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).
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