Deep Arctic Ocean warming during the last glacial cycle

Cronin, T. M., Dwyer, G. S., Farmer, J., Bauch, Henning A., Spielhagen, Robert F., Jakobsson, M., Nilsson, J., Briggs, W. M. and Stepanova, A. (2012) Deep Arctic Ocean warming during the last glacial cycle Nature Geoscience, 5 (9). pp. 631-634. DOI 10.1038/ngeo1557.

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In the Arctic Ocean, the cold and relatively fresh water beneath the sea ice is separated from the underlying warmer and saltier Atlantic Layer by a halocline. Ongoing sea ice loss and warming in the Arctic Ocean1, 2, 3, 4, 5, 6, 7 have demonstrated the instability of the halocline, with implications for further sea ice loss. The stability of the halocline through past climate variations8, 9, 10 is unclear. Here we estimate intermediate water temperatures over the past 50,000 years from the Mg/Ca and Sr/Ca values of ostracods from 31 Arctic sediment cores. From about 50 to 11 kyr ago, the central Arctic Basin from 1,000 to 2,500 m was occupied by a water mass we call Glacial Arctic Intermediate Water. This water mass was 1–2 °C warmer than modern Arctic Intermediate Water, with temperatures peaking during or just before millennial-scale Heinrich cold events and the Younger Dryas cold interval. We use numerical modelling to show that the intermediate depth warming could result from the expected decrease in the flux of fresh water to the Arctic Ocean during glacial conditions, which would cause the halocline to deepen and push the warm Atlantic Layer into intermediate depths. Although not modelled, the reduced formation of cold, deep waters due to the exposure of the Arctic continental shelf could also contribute to the intermediate depth warming.

Document Type: Article
Additional Information: WOS:000308211300018
Keywords: Palaeoceanography; palaeoclimate; oceanography; Arctic Ocean warming; NORTH-ATLANTIC; ICE-SHELF; SEA-ICE; WATERS; CIRCULATION; EVOLUTION; HISTORY; SURFACE; EVENT
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
DOI etc.: 10.1038/ngeo1557
ISSN: 1752-0894
Projects: Frühwarnsysteme für globale Umweltveränderungen und ihre historische Dokumentation in natürlichen Klimaarchiven, US Geological Survey Global Change Program, Academy of Sciences, Humanities, and Literature Mainz, Akademienprogramm, Future Ocean
Date Deposited: 29 Nov 2012 15:03
Last Modified: 23 May 2017 06:39

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