Arctic Ocean meltwater outflow as a trigger for the Younger Dryas event – a review of available evidence from sediment cores.

Spielhagen, Robert F., Nørgaard-Pedersen, Niels and Telesinski, Maciej (2014) Arctic Ocean meltwater outflow as a trigger for the Younger Dryas event – a review of available evidence from sediment cores. [Talk] In: 2. PAST Gateways International Conference and Workshop. , 19.05.-23.05.2014, Trieste, Italy . Proceedings of the II PAST Gateways International Conference and Workshop : Trieste, May 19-­23, 2014 / Istituto Nazionale di Oceanografia e di Geofisica Sperimentale. Eds.: Renata G. Lucchi ; Colm O’Cofaigh ; Michele Rebesco ; Carlo Barbante. ; p. 47 .

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The Younger Dryas event at ca. 12.8-11.5 ka was a severe fall-back to quasi-glacial conditions during the last glacial termination in much of the northern hemisphere. For more than a decade since the late 1980s the widely accepted theory was that this event was triggered by a major meltwater ejection to the North Atlantic through the Gulf of St.Lawrence which caused a slowdown of the meridional overturning circulation and a diminished heat transport to the northern latitudes. However, field evidence from the potential meltwater route in North America has been discussed controversially in the last years, and the detection of a freshwater signal in marine sediments off the St.Lawrence river rendered difficult. The idea of an "Arctic route" of the meltwater was then put forward by Tarasov and Peltier (2005) and has gained further attraction through evidence from radiogenic isotopes (Not and Hillaire-Marcel, 2012) and through modelling results of Condron and Winsor (2012) which showed that only a freshwater outflow through Fram Strait was capable of triggering a climate perturbation like the Younger Dryas.
Here we review isotopic records from the Arctic Ocean, the Fram Strait, and the Greenland Sea in search of evidence for a strong freshwater event in the Arctic Ocean at the onset of the Younger Dryas event that could support an Arctic origin of the trigger. There are now a number of cores which show a light planktic oxygen isotope spike at 13 ka. For several of them the age model is detailed enough to exclude a confusion with other deglacial spikes. On the central Arctic Lomonosov Ridge there is even evidence for a diminshed intermediate/bottom water circulation immediately following the freshwater event. On the other hand, many records do not hold a meltwater spike in the critical time interval, possible bcause of low temporal reolution, a thick ice cover and/or a habitat change of the planktic foraminifers. The largest uncertainty is introduced by arguable reservoir corrections which may need to be applied to radiocarbon datings from the last glacial termination. Nevertheless, the accumulating evidence from Arctic sediment cores makes an "Arctic trigger" even more likely and may add to the establishment of a new paradigm for the origin of the Younger Dryas cold event.

Essential bibliography
Condron, A., Winsor, P., 2012. Meltwater routing and the Younger Dryas. Proc. Nat. Acad. Sciences (PNAS), 109 (49), 19928-19933, doi: 10.1073/pnas.1207381109.
Not, C., Hillaire-Marcel, C., 2012. A trigger from the Arctic: the most plausible scenario for the Younger Dryas cold spell. Nature Comm.. 3, 647.
Tarasov, L., Peltier, W.R., 2005. Arctic freshwater forcing of the Younger Dryas cold reversal. Nature 435, 662–665.

Document Type: Conference or Workshop Item (Talk)
Keywords: Younger Drias; Meltwater outflow; North Atlantic Ocean; Gulf of St. Lawrence; Arctic sediment
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
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Projects: Laptev Sea System, Transdrift
Date Deposited: 23 Feb 2015 12:51
Last Modified: 23 Feb 2015 13:05

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