The North Atlantic Ocean is in a state of reduced overturning

• Published in: Geophysical Research Letters
• Main Authors: Smeed, D.A., Josey, S.A., Beaulieu, C., Johns, W.E., Moat, B.I., Frajka-Williams, Eleanor, Rayner, D., Meinen, C.S., Baringer, M.O., Bryden, H.L., McCarthy, G.D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: North Atlantic
• Online Access: http://nora.nerc.ac.uk/id/eprint/519229/; https://nora.nerc.ac.uk/id/eprint/519229/7/Smeed_et_al-2018-Geophysical_Research_Letters.pdf; https://doi.org/10.1002/2017GL076350

The Atlantic Meridional Overturning Circulation (AMOC) is responsible for a variable and climatically important northward transport of heat. Using data from an array of instruments that span the Atlantic at 26°N, we show that the AMOC has been in a state of reduced overturning since 2008 as compared to 2004-2008. This change of AMOC state is concurrent with other changes in the North Atlantic such as a northward shift and broadening of the Gulf Stream, and altered patterns of heat content and sea-surface temperature. These changes resemble the response to a declining AMOC predicted by coupled climate models. Concurrent changes in air-sea fluxes close to the western boundary reveal that the changes in ocean heat transport and SST have altered the pattern of ocean-atmosphere heat exchange over the North Atlantic. These results provide strong observational evidence that the AMOC is a major factor in decadal scale variability of North Atlantic climate.