Rapid coastal deoxygenation due to ocean circulation shift in the northwest Atlantic
Claret Cortes, Mariona (Joint Institute for the Study of the Atmosphere and the Ocean)
Galbraith, Eric (Universitat Autònoma de Barcelona. Institut de Ciència i Tecnologia Ambientals)
Palter, Jaime B. (University of Rhode Island. Graduate School of Oceanography)
Bianchi, Daniele (University of California. Department of Atmospheric and Oceanic Sciences)
Fennel, Katja (Dalhousie University. Department of Oceanography)
Gilbert, Denis (Maurice Lamontagne Institute)
Dunne, Johan (NOAA Geophysical Fluid Dynamics Laboratory)

Date:	2018
Abstract:	Global observations show that the ocean lost approximately 2% of its oxygen inventory over the past five decades1,2,3, with important implications for marine ecosystems4,5. The rate of change varies regionally, with northwest Atlantic coastal waters showing a long-term drop6,7 that vastly outpaces the global and North Atlantic basin mean deoxygenation rates5,8. However, past work has been unable to differentiate the role of large-scale climate forcing from that of local processes. Here, we use hydrographic evidence to show that a Labrador Current retreat is playing a key role in the deoxygenation on the northwest Atlantic shelf. A high-resolution global coupled climate-biogeochemistry model9 reproduces the observed decline of saturation oxygen concentrations in the region, driven by a retreat of the equatorward-flowing Labrador Current and an associated shift towards more oxygen-poor subtropical waters on the shelf. The dynamical changes underlying the shift in shelf water properties are correlated with a slowdown in the simulated Atlantic Meridional Overturning Circulation (AMOC)10. Our results provide strong evidence that a major, centennial-scale change of the Labrador Current is underway, and highlight the potential for ocean dynamics to impact coastal deoxygenation over the coming century.
Grants:	European Commission 682602 Ministerio de Economía y Competitividad MDM-2015-0552
Note:	Unidad de excelencia María de Maeztu MdM-2015-0552
Rights:	Tots els drets reservats.
Language:	Anglès
Document:	Article ; recerca ; Versió acceptada per publicar
Published in:	Nature climate change, Vol. 8 (September 2018) , p. 868-872, ISSN 1758-6798

DOI: 10.1038/s41558-018-0263-1
PMID: 30416585

Postprint 43 p, 8.2 MB

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