Atlantic Ocean CO2 uptake reduced by weakening of the meridional overturning circulation

Type Article
Date 2013-02
Language English
Author(s) Perez Fiz F.1, Mercier HerleORCID2, 4, 5, Vazquez-Rodriguez Marcos1, Lherminier PascaleORCID2, 5, Velo Anton1, Pardo Paula C.1, Roson Gabriel3, Rios Aida F.1
Affiliation(s) 1 : CSIC, IIM, Vigo 36208, Spain.
2 : UBO, IRD, IFREMER, Lab Phys Oceans,UMR6523,CNRS, F-29280 Plouzane, France.
3 : Univ Vigo, Fac Marine Sci, Vigo 36200, Spain.
Source Nature Geoscience (1752-0894) (Nature Publishing Group), 2013-02 , Vol. 6 , N. 2 , P. 146-152
DOI 10.1038/NGEO1680
WOS© Times Cited 71
Abstract Uptake of atmospheric carbon dioxide in the subpolar North Atlantic Ocean declined rapidly between 1990 and 2006. This reduction in carbon dioxide uptake was related to warming at the sea surface, which-according to model simulations-coincided with a reduction in the Atlantic meridional overturning circulation. The extent to which the slowdown of this circulation system-which transports warm surface waters to the northern high latitudes, and cool deep waters south-contributed to the reduction in carbon uptake has remained uncertain. Here, we use data on the oceanic transport of volume, heat and carbon dioxide to track carbon dioxide uptake in the subtropical and subpolar regions of the North Atlantic Ocean over the past two decades. We separate anthropogenic carbon from natural carbon by assuming that the latter corresponds to a pre-industrial atmosphere, whereas the remaining is anthropogenic. We find that the uptake of anthropogenic carbon dioxide-released by human activities-occurred almost exclusively in the subtropical gyre. In contrast, natural carbon dioxide uptake-which results from natural Earth system processes-dominated in the subpolar gyre. We attribute the weakening of contemporary carbon dioxide uptake in the subpolar North Atlantic to a reduction in the natural component. We show that the slowdown of the meridional overturning circulation was largely responsible for the reduction in carbon uptake, through a reduction of oceanic heat loss to the atmosphere, and for the concomitant decline in anthropogenic CO2 storage in subpolar waters.
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Perez Fiz F., Mercier Herle, Vazquez-Rodriguez Marcos, Lherminier Pascale, Velo Anton, Pardo Paula C., Roson Gabriel, Rios Aida F. (2013). Atlantic Ocean CO2 uptake reduced by weakening of the meridional overturning circulation. Nature Geoscience, 6(2), 146-152. Publisher's official version : , Open Access version :