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Modelling abrupt glacial North Atlantic freshening: Rates of change and their implications for Heinrich events

Bigg, G.R., Levine, R.C. and Green, C.L. (2011) Modelling abrupt glacial North Atlantic freshening: Rates of change and their implications for Heinrich events. Global and Planetary Change, 79 (3-4). pp. 176-192. ISSN 0921-8181

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Abstract

The abrupt delivery of large amounts of freshwater to the North Atlantic in the form of water or icebergs has been thought to lead to significant climate change, including abrupt slowing of the Atlantic Ocean meridional overturning circulation. In this paper we examine intermediate complexity coupled modelling evidence to estimate the rates of change, and recovery, in oceanic climate that would be expected for such events occurring during glacial times from likely sources around the North Atlantic and Arctic periphery. We show that rates of climate change are slower for events with a European or Arctic origin. Palaeoceanographic data are presented to consider, through the model results, the origin and likely strength of major ice-rafting, or Heinrich, events during the last glacial period. We suggest that Heinrich events H1-H3 are likely to have had a significant contribution from an Arctic source as well as Hudson Strait, leading to the observed climate change. In the case of H1 and H2, we hypothesise that this secondary input is from a Laurentide Arctic source, but the dominant iceberg release for H3 is hypothesised to derive from the northern Fennoscandian Ice Sheet, rather than Hudson Strait. Earlier Heinrich events are suggested to be predominantly Hudson Strait in origin, with H6 having the lowest climate impact, and hence iceberg flux, but H4 having a climate signal of geographically variable length. We hypothesise that this is linked to a combination of climate-affecting events occurring around the globe at this time, and not just of Laurentide origin. (C) 2010 Elsevier B.V. All rights reserved.

Item Type: Article
Copyright, Publisher and Additional Information: © 2011 Elsevier. This is an author produced version of a paper subsequently published in Global and Planetary Change. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: Heinrich events; modelling; Quaternary; icebergs
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Social Sciences (Sheffield) > Department of Geography (Sheffield)
Depositing User: Miss Anthea Tucker
Date Deposited: 20 Feb 2012 13:15
Last Modified: 08 Feb 2013 17:37
Published Version: http://dx.doi.org/10.1016/j.gloplacha.2010.11.001 ...
Status: Published
Publisher: Elsevier
Refereed: Yes
Identification Number: 10.1016/j.gloplacha.2010.11.001
URI: http://eprints.whiterose.ac.uk/id/eprint/43722

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