Deglacial floods in the Beaufort Sea preceded Younger Dryas cooling

• Published in: Nature Geoscience
• Main Authors: Keigwin, Lloyd D., Klotsko, Shannon, Zhao, Ning, Reilly, Brendan, Giosan, Liviu, Driscoll, Neal W.
• Format: Report
• Language: English
• Published: 2018
• Subjects: Arctic; Mackenzie River; Beaufort Sea; Canadian Archipelago; Foraminifera*; Fram Strait; Ice Sheet; Mackenzie river; Nordic Seas; North Atlantic; Planktonic foraminifera
• Online Access: https://hdl.handle.net/1912/10543

Author Posting. © The Author(s), 2018. This is the author's version of the work. It is posted here under a nonexclusive, irrevocable, paid-up, worldwide license granted to WHOI. It is made available for personal use, not for redistribution. The definitive version was published in Nature Geosciencevolume 11 (2018): 599-604, doi:10.1038/s41561-018-0169-6. The Younger Dryas cooling at ~13 ka, after 2 kyr of postglacial warming, is a century-old climate problem. The Younger Dryas is thought to have resulted from a slow-down of the Atlantic meridional overturning circulation in response to a sudden flood of Laurentide Ice Sheet meltwater that reached the Nordic Seas. Although there is no oxygen isotope evidence in planktonic foraminifera from the open western North Atlantic for a local source of meltwater from the Gulf of St. Lawrence where it was predicted, we report here that the eastern Beaufort Sea contains the long-sought signal of 18O-depleted water. Beginning at ~12.94 ± 0.15 ka, oxygen isotopes in planktonic foraminifera from two sediment cores as well as sediment and seismic data indicate a flood of melt water, ice and sediment to the Arctic via Mackenzie River that lasted about 700 years. The minimum in oxygen isotope ratios lasted ~130 years. The floodwater would have travelled north along the Canadian Archipelago, and through Fram Strait to the Nordic Seas where freshening and freezing near sites of deepwater formation would have suppressed convection, and caused the Younger Dryas cooling by reducing the meridional overturning This research was funded by NSF grants ARC 1204045 to L.D.K., and ARC 1203944 to N.W.D.