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Interhemispheric coupling, the West Antarctic Ice Sheet and warm Antarctic interglacials

Holden, P. B.; Edwards, N. R.; Wolff, E. W.; Lang, N. J.; Singarayer, J. S.; Valdes, P. J. and Stocker, T. F. (2010). Interhemispheric coupling, the West Antarctic Ice Sheet and warm Antarctic interglacials. Climate of the Past, 6(4) pp. 431–443.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.5194/cp-6-431-2010
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Abstract

Ice core evidence indicates that even though atmospheric CO2 concentrations did not exceed ~300 ppm at any point during the last 800,000 years, East Antarctica was at least ~3-4ºC warmer than preindustrial (CO2 ~280 ppm) in each of the last four interglacials. During the previous three interglacials, this anomalous warming was short lived (~3,000 years) and apparently occurred before the completion of Northern Hemisphere deglaciation. Hereafter, we refer to these periods as 'Warmer than Present Transients' (WPTs). We present a series of experiments to investigate the impact of deglacial meltwater on the Atlantic Meridional Overturning Circulation (AMOC) and Antarctic temperature. It is well known that a slowed AMOC would increase southern sea surface temperature (SST) through the bipolar seesaw and observational data suggests that the AMOC remained weak throughout the terminations preceding WPTs, strengthening rapidly at a time which coincides closely with peak Antarctic temperature. We present two 800 kyr transient simulations using the Intermediate Complexity model GENIE-1 which demonstrate that meltwater forcing generates transient southern warming that is consistent with the timing of WPTs, but is not sufficient (in this single parameterisation) to reproduce the magnitude of observed warmth. In order to investigate model and boundary condition uncertainty, we present three ensembles of transient GENIE-1 simulations across Termination II (135,000 to 124,000 BP) and three snapshot HadCM3 simulations at 130,000 BP. Only with consideration of the possible feedback of West Antarctic Ice Sheet (WAIS) retreat does it become possible to simulate the magnitude of observed warming.

Item Type: Journal Article
Copyright Holders: 2010 The Authors
ISSN: 1814-9332
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetNot SetNERC
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 22651
Depositing User: Philip Holden
Date Deposited: 04 Aug 2010 11:08
Last Modified: 21 Mar 2014 16:56
URI: http://oro.open.ac.uk/id/eprint/22651
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