Rapid coastal deoxygenation due to ocean circulation shift in the northwest Atlantic

Authors

Mariona Claret
Eric D. Galbraith
Jaime B. Palter, University of Rhode IslandFollow
Daniele Bianchi
Katja Fennel
Denis Gilbert
John P. Dunne

Document Type

Article

Date of Original Version

2018

Department

Oceanography

Abstract

Global observations show that the ocean lost approximately 2% of its oxygen inventory over the past five decades^1,2,3, with important implications for marine ecosystems^4,5. The rate of change varies regionally, with northwest Atlantic coastal waters showing a long-term drop^6,7 that vastly outpaces the global and North Atlantic basin mean deoxygenation rates^5,8. 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.

Citation/Publisher Attribution

Claret, M., Galbraith, E. D., Palter, J. B., Bianchi, D., Fennel, K., Gilbert, D., & Dunne, J. P. (2018). Rapid coastal deoxygenation due to ocean circulation shift in the northwest Atlantic. Nature Climate Change, 8, 868-872. doi: 10.1038/s41558-018-0263-1

Available at: http://dx.doi.org/10.1038/s41558-018-0263-1