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Centennial-scale evolution of Dansgaard-Oeschger events in the northeast Atlantic Ocean between 39.5 and 56.5 ka B.P

Dickson, Alexander J.; Austin, William E. N.; Hall, Ian R.; Maslin, Mark A. and Kucera, Michal (2008). Centennial-scale evolution of Dansgaard-Oeschger events in the northeast Atlantic Ocean between 39.5 and 56.5 ka B.P. Paleoceanography, 23(3) PA3206.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1029/2008PA001595
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Abstract

There is much uncertainty surrounding the mechanisms that forced the abrupt climate fluctuations found in many palaeoclimate records during Marine Isotope Stage (MIS)-3. One of the processes thought to be involved in these events is the Atlantic Meridional Overturning Circulation (MOC), which exhibited large changes in its dominant mode throughout the last glacial period. Giant piston core MD95-2006 from the northeast Atlantic Ocean records a suite of palaeoceanographic proxies related to the activity of both surface and deep water masses through a period of MIS-3 when abrupt climate fluctuations were extremely pronounced. A two-stage progression of surface water warming during interstadial warm events is proposed, with initial warming related to the northward advection of a thin warm surface layer within the North Atlantic Current, which only extended into deeper surface layers as the interstadial progressed. Benthic foraminifera isotope data also show millennial-scale oscillations but of a different structure to the abrupt surface water changes. These changes are argued to partly be related to the influence of low-salinity deepwater brines. The influence of deepwater brines over the site of MD95-2006 reached a maximum at times of rapid warming of surface waters. This observation supports the suggestion that brine formation may have helped to destabilize the accumulation of warm, saline surface waters at low latitudes, helping to force the MOC into a warm mode of operation. The contribution of deepwater brines relative to other mechanisms proposed to alter the state of the MOC needs to be examined further in future studies.

Item Type: Journal Article
Copyright Holders: 2008 American Geophysical Union
ISSN: 0883-8305
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Item ID: 27664
Depositing User: Alexander Dickson
Date Deposited: 01 Feb 2011 11:38
Last Modified: 17 Jul 2013 08:40
URI: http://oro.open.ac.uk/id/eprint/27664
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