Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Recent slowing of Atlantic overturning circulation as a recovery from earlier strengthening

Abstract

The Atlantic meridional overturning circulation (AMOC) has weakened substantially over the past decade1. Some weakening may already have occurred over the past century2, and global climate models project further weakening in response to anthropogenic climate change3. Such a weakening could have significant impacts on the surface climate4. However, ocean model simulations based on historical conditions have often found an increase in overturning up to the mid-1990s, followed by a decrease5. It is therefore not clear whether the observed weakening over the past decade is part of decadal variability or a persistent weakening6. Here we examine a state-of-the-art global-ocean reanalysis product, GloSea5, which covers the years 1989 to 2015 and closely matches observations of the AMOC at 26.5° N, capturing the interannual variability and decadal trend with unprecedented accuracy. The reanalysis data place the ten years of observations—April 2004 to February 2014—into a longer-term context and suggest that the observed decrease in the overturning circulation is consistent with a recovery following a previous increase. We find that density anomalies that propagate southwards from the Labrador Sea are the most likely cause of these variations. We conclude that decadal variability probably played a key role in the decline of the AMOC observed over the past decade.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Time series of AMOC strength.
Figure 2: Profiles in the central Labrador Sea.
Figure 3: Propagation of density anomalies in the GloSea5 reanalysis.
Figure 4: Density anomalies at 1,795 m.

References

  1. Smeed, D. A. et al. Observed decline of the Atlantic meridional overturning circulation 2004–2012. Ocean Sci. 10, 29–38 (2014).

    Article  Google Scholar 

  2. Rahmstorf, S. et al. Exceptional twentieth-century slowdown in Atlantic ocean overturning circulation. Nature Clim. Change 5, 475–480 (2015).

    Article  Google Scholar 

  3. Collins, M. et al. in Climate Change 2013: The Physical Science Basis (eds Stocker, T. F. et al.) Ch. 12, 1029–1136 (IPCC, Cambridge Univ. Press, 2013).

    Google Scholar 

  4. Jackson, L. C. et al. Global and European climate impacts of a slowdown of the AMOC in a high resolution GCM. Clim. Dynam. 45, 3299–3316 (2015).

    Article  Google Scholar 

  5. Danabasoglu, G. et al. North Atlantic simulations in coordinated ocean-ice reference experiments phase II (CORE-II). Part II: inter-annual to decadal variability. Ocean Model. 97, 65–90 (2015).

    Article  Google Scholar 

  6. Roberts, C. D., Jackson, L. & McNeall, D. Is the 2004-2012 reduction of the Atlantic meridional overturning circulation significant? Geophys. Res. Lett. 41, 3204–3210 (2014).

    Article  Google Scholar 

  7. Smeed, D. et al. Atlantic meridional overturning circulation observed by the RAPID-MOCHA-WBTS (RAPID-Meridional Overturning Circulation and Heatflux Array-Western Boundary Time Series) array at 26N from 2004 to 2014 (British Oceanographic Data Centre-Natural Environment Research Council, UK, 2015); http://dx.doi.org/10/6qb

    Google Scholar 

  8. Roemmich, D. et al. Argo: the challenge of continuing 10 years of progress. Oceanography 22, 46–55 (2009).

    Article  Google Scholar 

  9. Tett, S., Sherwin, T., Shravat, A. & Browne, O. How much has the North Atlantic Ocean overturning circulation changed in the last 50 years? J. Clim. 27, 6325–6342 (2014).

    Article  Google Scholar 

  10. Karspeck, A. R. et al. Comparison of the Atlantic meridional overturning circulation between 1960 and 2007 in six ocean reanalysis products. Clim. Dynam. http://dx.doi.org/10.1007/s00382-015-2787-7 (2015).

  11. Roberts, C. D. et al. Atmosphere drives recent interannual variability of the Atlantic meridional overturning circulation at 26.5° N. Geophys. Res. Lett. 40, 5164–5170 (2013).

    Article  Google Scholar 

  12. Bentsen, M., Drange, H., Furevik, T. & Zhou, T. Simulated variability of the Atlantic meridional overturning circulation. Clim. Dynam. 22, 701–720 (2004).

    Article  Google Scholar 

  13. Deshayes, J. & Frankignoul, C. Simulated variability of the circulation in the North Atlantic from 1953 to 2003. J. Clim. 21, 4919–4933 (2008).

    Article  Google Scholar 

  14. Robson, J., Sutton, R., Lohmann, K., Smith, D. & Palmer, M. D. Causes of the rapid warming of the North Atlantic Ocean in the mid-1990s. J. Clim. 25, 4116–4134 (2012).

    Article  Google Scholar 

  15. Yeager, S. & Danabasoglu, G. The origins of late-twentieth-century variations in the large-scale north atlantic circulation. J. Clim. 27, 3222–3247 (2014).

    Article  Google Scholar 

  16. Roberts, C. D., Garry, F. K. & Jackson, L. C. A multimodel study of sea surface temperature and subsurface density fingerprints of the atlantic meridional overturning circulation. J. Clim. 26, 9155–9174 (2013).

    Article  Google Scholar 

  17. Robson, J., Hodson, D., Hawkins, E. & Sutton, R. Atlantic overturning in decline? Nature Geosci. 7, 2–3 (2014).

    Article  Google Scholar 

  18. Good, S. A., Martin, M. J. & Rayner, N. A. EN4: quality controlled ocean temperature and salinity profiles and monthly objective analyses with uncertainty estimates. J. Geophys. Res. 118, 6704–6716 (2013).

    Article  Google Scholar 

  19. Curry, R. G., McCartney, M. S. & Joyce, T. M. Oceanic transport of subpolar climate signals to mid-depth subtropical waters. Nature 391, 575–577 (1998).

    Article  Google Scholar 

  20. Pickart, R. S., Torres, D. J. & Clarke, R. A. Hydrography of the Labrador Sea during active convection. J. Phys. Oceanogr. 32, 428–457 (2002).

    Article  Google Scholar 

  21. Eden, C. & Willebrand, J. Mechanism of interannual to decadal variability of the North Atlantic circulation. J. Clim. 14, 2266–2280 (2001).

    Article  Google Scholar 

  22. Dickson, R. et al. Current estimates of freshwater flux through Arctic and subarctic seas. Progr. Oceanogr. 73, 210–230 (2007).

    Article  Google Scholar 

  23. Riser, S. C. et al. Fifteen years of ocean observations with the global Argo array. Nature Clim. Change 6, 145–153 (2016).

    Article  Google Scholar 

  24. Hodson, D. & Sutton, R. The impact of resolution on the adjustment and decadal variability of the Atlantic meridional overturning circulation in a coupled climate model. Clim. Dynam. 39, 3057–3073 (2012).

    Article  Google Scholar 

  25. Blanke, B., Speich, S., Madec, G. & Döös, K. A global diagnostic of interocean mass transfers. J. Phys. Oceanogr. 31, 1623–1632 (2001).

    Article  Google Scholar 

  26. Bower, A. S. et al. Interior pathways of the North Atlantic meridional overturning circulation. Nature 459, 243–247 (2009).

    Article  Google Scholar 

  27. Molinari, R. L. et al. The arrival of recently formed Labrador Sea water in the deep western boundary current at 26.5° N. Geophys. Res. Lett. 25, 2249–2252 (1998).

    Article  Google Scholar 

  28. MacLachlan, C. et al. Global seasonal forecast system version 5 (GloSea5): a high resolution seasonal forecast system. Q. J. R. Meteorol. Soc. 141, 1072–1084 (2014).

    Article  Google Scholar 

  29. Blockley, E. W. et al. Recent development of the Met Office operational ocean forecasting system: an overview and assessment of the new global FOAM forecasts. Geosci. Model Dev. 7, 2613–2638 (2014).

    Article  Google Scholar 

  30. Megann, A. et al. GO5.0: the joint NERC–Met Office NEMO global ocean model for use in coupled and forced applications. Geosci. Model Dev. 7, 1069–1092 (2014).

    Article  Google Scholar 

  31. Mirouze, I., Blockley, E., Lea, D., Martin, M. & Bell, M. A multiple length scale correlation operator with application to ocean data assimilation. Tellus A 68, 29744 (2016).

    Article  Google Scholar 

  32. Dee, D. P. et al. The ERA-Interim reanalysis: configuration and performance of the data assimilation system. Q. J. R. Meteorol. Soc. 137, 553–597 (2011).

    Article  Google Scholar 

  33. Altimeter products were produced by Ssalto/Duacs and distributed by AVISO, with support from CNES. (2015); http://www.aviso.altimetry.fr/duacs

  34. Casey, K., Brandon, T., Cornillon, P. & Evans, R. in Oceanography from Space: Revisited (eds Barale, V., Gower, J. & Alberotanza, L.) Ch. 16, 273–287 (Springer, 2010).

    Book  Google Scholar 

  35. Data from the (A)ATSR instruments are provided courtesy of the Natural Environment Research Council, STFC Rutherford Appleton Laboratory, the European Space Agency and Defra, through the NERC Earth Observation Data Centre (NEODC). (NERC, 2015); http://neodc.nerc.ac.uk

  36. EUMETSAT Ocean and Sea Ice Satelitte Application Facility. Global sea ice concentration reprocessing dataset 1978–2009 (v1.1, 2011) (EUMETSAT, 2011); http://osisaf.met.no

  37. GHRSST: The Group for High Resolution Sea Surface Temperature (2015); https://www.ghrsst.org

Download references

Acknowledgements

This work was supported by the Joint UK DECC/Defra Met Office Hadley Centre Climate Programme (GA01101), the Public Weather Service Research programme, and the EU SPECS project (GA308378). The authors also wish to thank the Met Office Ocean Forecasting, Research and Development team for providing the FOAMv13 system, and B. Blanke and N. Grima for developing and supporting the use of Ariane.

Author information

Authors and Affiliations

Authors

Contributions

L.C.J. led the writing of the paper, K.A.P. developed and performed the GloSea5 reanalysis, and L.C.J. and C.D.R. performed the analysis. All authors, including R.A.W., contributed to writing and editing the paper.

Corresponding author

Correspondence to Laura C. Jackson.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 875 kb)

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Jackson, L., Peterson, K., Roberts, C. et al. Recent slowing of Atlantic overturning circulation as a recovery from earlier strengthening. Nature Geosci 9, 518–522 (2016). https://doi.org/10.1038/ngeo2715

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/ngeo2715

This article is cited by

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing