# Toward a mechanistic understanding of the decadal trends in the Southern Ocean carbon sink

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Author(s) Lovenduski, Nicole S., Gruber, Nicolas, Doney, Scott C.
Publication Type Journal Items, Publication Status: Published
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Title Toward a mechanistic understanding of the decadal trends in the Southern Ocean carbon sink
Author(s) Lovenduski, Nicole S.
Gruber, Nicolas
Doney, Scott C.
Journal or Series Title Global biogeochemical cycles
Volume Number 22
Issue Number 3
Start Page GB3016-1
End Page GB3016-9
ISSN 0886-6236
1944-9224
Publisher American Geophysical Union
Publication Place Washington, D.C.
Publication Date 2008
Abstract We investigate the multidecadal and decadal trends in the flux of CO2 between the atmosphere and the Southern Ocean using output from hindcast simulations of an ocean circulation model with embedded biogeochemistry. The simulations are run with NCEP-1 forcing under both preindustrial and historical atmospheric CO2 concentrations so that we can separately analyze trends in the natural and anthropogenic CO2 fluxes. We find that the Southern Ocean (<35 degrees S) CO2 sink has weakened by 0.1 Pg C a(-1) from 1979-2004, relative to the expected sink from rising atmospheric CO2 and fixed physical climate. Although the magnitude of this trend is in agreement with prior studies (Le Quere et al., 2007), its size may not be entirely robust because of uncertainties associated with the trend in the NCEP-1 atmospheric forcing. We attribute the weakening sink to an outgassing trend of natural CO2, driven by enhanced upwelling and equatorward transport of carbon-rich water, which are caused by a trend toward stronger and southward shifted winds over the Southern Ocean (associated with the positive trend in the Southern Annular Mode (SAM)). In contrast, the trend in the anthropogenic CO2 uptake is largely unaffected by the trend in the wind and ocean circulation. We regard this attribution of the trend as robust, and show that surface and interior ocean observations may help to solidify our findings. As coupled climate models consistently show a positive trend in the SAM in the coming century [e. g., Meehl et al., 2007], these mechanistic results are useful for projecting the future behavior of the Southern Ocean carbon sink.
DOI 10.1029/2007GB003139
Additional Notes Received 8 November 2007, Revised 4 May 2008, Accepted 5 June 2008, Published 16 August 2008
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03731
Organisational Unit(s)
NEBIS System Number 000041178
Source Database ID PP-43390
WOS-000258510400001
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@article{Lvndsk2008,
author = "Lovenduski, Nicole S. and Gruber, Nicolas and Doney, Scott C.",
title = "{T}oward a mechanistic understanding of the decadal trends in the {S}outhern {O}cean carbon sink",
journal = "Global biogeochemical cycles",
year = 2008,
volume = "22",
number = "3",
pages = "GB3016-1--GB3016-9",
}


E-Citations record created: Fri, 02 Apr 2010, 00:13:29 CET