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Circulation and CO2 in the deglacial North Pacific
William Gray
LSCE
Jeudi 28/03/2019, 11h00-12h00
Bât. 714 P. 118, LSCE Orme des Merisiers

As the largest store of carbon in the global ocean, changes in the circulation of the North Pacific Ocean could have a substantial impact on atmospheric CO2. Despite 20 years since a more vigorous overturning circulation in the glacial North Pacific was first proposed, the view persists that the North Pacific Ocean played only a passive role in glacial-interglacial carbon cycling. I will present records of surface ocean pH and CO2 derived from boron isotopes in planktic foraminifera from two cores in the subpolar North Pacific which demonstrate the region was a substantial source of CO2 to the atmosphere over deglaciation. Using a compilation of proxy data and earth system modelling I suggest the observed changes in CO2 outgassing over deglaciation are driven by changes in both overturning circulation and Ekman suction within the basin. In the second part of the talk, I will focus on proxy evidence for changes in gyre circulation over deglaciation, and using general circulation models, relate these changes to large scale reorganisation of the atmosphere during glacial times in response to ice sheet forcing.

Contact : Aline Govin
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