Millennial-scale oscillations in the Southern Ocean in response to atmospheric CO2 increase



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Álvarez Solas, Jorge and Charbit, Sylvie and Ramstein, Gilles and Paillard, Didier and Dumas, Christophe and Ritz, Catherine and Roche, Didier M. (2011) Millennial-scale oscillations in the Southern Ocean in response to atmospheric CO2 increase. Global and Planetary Change, 76 (03-abr). pp. 128-136. ISSN 0921-8181

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A coupled climate-ice-sheet model is used to investigate the response of climate at the millennial time scale under several global warming long-term scenarios, stabilized at different levels ranging from 2 to 7 times the pre-industrial CO2 level. The climate response is mainly analyzed in terms of changes in temperature, oceanic circulation, and ice-sheet behaviour. For the 4 x CO2 scenario, the climate response appears to be highly non-linear: abrupt transitions occur in the Southern Ocean deep water formation strength with a period of about 1200 yr. These millennial oscillations do not occur for both lower and larger CO2 levels. We show that these transitions are associated with internal oscillations of the Southern Ocean, triggered by the Antarctic freshwater budget. We first analyse the oscillatory mechanism. Secondly, through a series of 420 sensitivity experiments we also explore the range of temperature and freshwater flux for which such oscillations can be triggered.

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© 2010 Elsevier B.V. We are very grateful to the editor and to three anonymous referees who helped us to improve the manuscript. We also thank Masa Kageyama, Yannick Donnadieu, Marisa Montoya and Frank Pattyn for the many stimulating and fruitful discussions in the field. This work is supported by the French nationals LEFE/CASTOR and ANR/IDEGLACE projects and by the Research Training Network NICE. Didier M. Roche and Catherine Ritz are supported by INSU/CNRS.

Uncontrolled Keywords:Coupled Climate Model, Antarctic Ice-Sheet, Deep-Water Formation, Thermohaline Circulation, Intermediate Complexity, Multiple Equilibria, Rapid Transitions, Greenland Ice, System Model, North
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Atmospheric physics
Sciences > Physics > Astronomy
ID Code:24208
Deposited On:16 Jan 2014 10:49
Last Modified:10 Dec 2018 15:05

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