Skip to main content

Thank you for visiting 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.

Opposing decadal changes for the North Atlantic meridional overturning circulation

A Corrigendum to this article was published on 14 October 2010

This article has been updated


The hydrographic properties of the North Atlantic Ocean changed significantly from 1950 to 2000: the subtropics warmed and became more saline, whereas the subpolar ocean cooled and freshened. These changes directly affect the storage of heat and fresh water in the ocean, but their consequences for ocean dynamics are determined by the resultant changes in seawater density. Here we use historical hydrographic data to show that the overall seawater density in the North Atlantic basin decreased during this 50-year period. As a result of these density changes, sea-surface heights changed in a spatially varying pattern with typical rates of 2 mm yr−1, in broad agreement with tide-gauge measurements. Melding the observed density fields within a numerical model we find a slight weakening in the overturning of the subtropical gyre by −1.5±1 Sv and a slight strengthening in the overturning of the subpolar gyre by +0.8±0.5 Sv. These gyre-specific changes run counter to the canonical notion of a single, basin-scale overturning cell and probably reflect interannual and decadal trends rather than any long-term climate trend. We conclude that gyre dynamics strongly affect temperature and salinity changes that translate into changes in the meridional overturning circulation.

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.


All prices are NET prices.

Figure 1: Historical hydrographic data analysis.
Figure 2: Spatial fields of temperature, salinity and density changes.
Figure 3: Sea-surface height changes.
Figure 4: Changes in the meridional overturning circulation.
Figure 5: Relationship of MOC changes to observed density field.

Change history

  • 14 October 2010

    In the version of this Letter originally published, "-0.8 ± 0.5 Sv" in the fifth sentence of the abstract should have read "+0.8 ± 0.5 Sv". This error has now been corrected in the HTML and PDF versions of the text.


  1. Sabine, C. L. et al. The oceanic sink for anthropogenic CO2 . Science 305, 367–371 (2004).

    Article  Google Scholar 

  2. Levitus, S., Antonov, J. I., Boyer, T. P. & Stephens, C. Warming of the world ocean. Science 287, 2225–2229 (2000).

    Article  Google Scholar 

  3. Levitus, S., Antonov, J. & Boyer, T. Warming of the world ocean, 1955–2003. Geophys. Res. Lett. 32, L02604–L02607 (2005).

    Google Scholar 

  4. Dickson, B. et al. Rapid freshening of the deep North Atlantic Ocean over the past four decades. Nature 416, 832–837 (2002).

    Article  Google Scholar 

  5. Curry, R., Dickson, B. & Yashayaev, I. A change in the freshwater balance of the Atlantic Ocean over the past four decades. Nature 426, 826–829 (2003).

    Article  Google Scholar 

  6. Boyer, T. et al. Changes in freshwater content in the North Atlantic Ocean 1955–2006. Geophys. Res. Lett. 34, L16603–L16607 (2007).

    Article  Google Scholar 

  7. Bi, D., Budd, W. F., Hirst, A. C. & Wu, X. Collapse and reorganisation of the Southern Ocean overturning under global warming in a coupled model. Geophys. Res. Lett. 28, 3927–3930 (2001).

    Article  Google Scholar 

  8. Gregory, J. M. et al. A model intercomparison of changes in the Atlantic thermohaline circulation in response to increasing atmospheric CO2 concentration. Geophys. Res. Lett. 32, L12703–L12707 (2005).

    Article  Google Scholar 

  9. Cunningham, S. A. et al. Temporal variability of the Atlantic meridional overturning circulation at 26.5° N. Science 317, 935–938 (2007).

    Article  Google Scholar 

  10. Bryden, H. L., Longworth, H. R. & Cunningham, S. A. Slowing of the Atlantic meridional overturning circulation at 25 N. Nature 438, 655–657 (2005).

    Article  Google Scholar 

  11. Lumpkin, R., Speer, K. G. & Koltermann, K. P. Transport across 48° N in the Atlantic Ocean. J. Phys. Oceanogr. 38, 733–752 (2008).

    Article  Google Scholar 

  12. Cunningham, S. A. & Marsh, R. Observing and modeling changes in the Atlantic MOC. Wiley Interdiscip. Rev. Clim. Change 1, 180–191 (2010).

    Article  Google Scholar 

  13. Biastoch, A., Böning, C. W., Getzlaff, J., Molines, J-M. & Madec, G. Causes of interannual–decadal variability in the meridional overturning circulation of the midlatitude North Atlantic Ocean. J. Clim. 21, 6599–6615 (2008).

    Article  Google Scholar 

  14. Bingham, R. J., Hughes, C. W., Roussenov, V. & Williams, R. G. Meridional coherence of the North Atlantic meridional overturning circulation. Geophys. Res. Lett. 34, L23606–L23611 (2007).

    Article  Google Scholar 

  15. Baehr, J., Stroup, A. & Marotzke, J. Testing concepts for continuous monitoring of the meridional overturning circulation in the South Atlantic. Ocean Modelling 29, 147–153 (2009).

    Article  Google Scholar 

  16. Lozier, M. S. et al. The spatial pattern and mechanisms of heat-content change in the North Atlantic. Science 319, 800–803 (2008).

    Article  Google Scholar 

  17. Boyer, T. et al. in NOAA Atlas NESDIS 60 (ed. Levitus, S.) 190–190 (US Government Printing Office, 2006).

    Google Scholar 

  18. Gregory, D. N. Canadian Science Advisory Secretariat Research Document—2004/075 (2004).

  19. Hurrell, J. W. Decadal trends in North Atlantic oscillation: Regional temperatures and precipitation. Science 269, 676–679 (1995).

    Article  Google Scholar 

  20. Hurrell, J. W., Kushnir, Y., Ottersen, G. & Visbeck, M. (eds) The North Atlantic Oscillation: Climate Significance and Environmental Impact (Geophysical Monograph Series 134, American Geophysical Union, 2003).

  21. Church, J. A., White, N. J., Coleman, R., Lambeck, K. & Mitrovica, J. X. Estimates of the regional distribution of sea level rise over the 1950–2000 period. J. Clim. 17, 2609–2625 (2004).

    Article  Google Scholar 

  22. Church, J. et al. Understanding global sea levels: Past, present and future. Sustain. Sci. 3, 9–22 (2008).

    Article  Google Scholar 

  23. Marotzke, J. et al. Construction of the adjoint MIT ocean general circulation model and application to Atlantic heat transport sensitivity. J. Geophys. Res. 104, 529–547 (1999).

    Article  Google Scholar 

  24. Baehr, J., Hirschi, J. J. M., Beismann, J-O. & Marotzke, J. Monitoring the meridional overturning circulation in the North Atlantic: A model-based array design study. J. Mar. Res. 62, 283–312 (2004).

    Article  Google Scholar 

  25. Kanzow, T. et al. Observed flow compensation associated with the MOC at 26.5° N in the Atlantic. Science 317, 938–941 (2007).

    Article  Google Scholar 

  26. Marshall, J., Hill, C., Perelman, L. & Adcroft, A. Hydrostatic, quasi-hydrostatic, and nonhydrostatic ocean modeling. J. Geophys. Res. 102, 5733–5752 (1997).

    Article  Google Scholar 

  27. Koehl, A., Dommenget, D., Ueyoshi, K. & Stammer, D. Ocean Synthesis. Report No. 40, (2006).

  28. Roussenov, V. M., Williams, R. G., Hughes, C. W. & Bingham, R. J. Boundary wave communication of bottom pressure and overturning changes for the North Atlantic. J. Geophys. Res. 113, C08042–C08053 (2008).

    Article  Google Scholar 

  29. Willis, J. K. Can in situ floats and satellite altimeters detect long-term changes in Atlantic Ocean overturning? Geophys. Res. Lett. 37, L06602 (2010).

    Article  Google Scholar 

  30. Bingham, R. J. & Hughes, C. W. Signature of the Atlantic meridional overturning circulation in sea level along the east coast of North America. Geophys. Res. Lett. 36, L02603–L02607 (2009).

    Article  Google Scholar 

  31. Hatun, H., Sando, A. B., Drange, H., Hansen, B. & Valdimarsson, H. Influence of the Atlantic subpolar gyre on the thermohaline circulation. Science 309, 1841–1844 (2005).

    Article  Google Scholar 

  32. Fofonoff, N. P. & Millard, R. C. J. Algorithms for Computation of Fundamental Properties of Seawater Vol. 44, 53 (Unesco Technical Papers in Marine Science, 1985).

  33. Lozier, M. S., Owens, W. B. & Curry, R. G. The climatology of the North Atlantic. Prog. Oceanogr. 36, 1–44 (1995).

    Article  Google Scholar 

Download references


The authors gratefully acknowledge support from the US National Science Foundation and the UK Natural Environment Research Council.

Author information

Authors and Affiliations



M.S.L. led the data study and its interpretation and R.G.W. led the modelling study and interpretation. V.R. conducted the modelling study and developed the model-data analysis. M.S.C.R. conducted the historical-data analysis. M.S.L. and R.G.W. jointly wrote the paper.

Corresponding authors

Correspondence to M. Susan Lozier or Richard G. Williams.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 889 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Lozier, M., Roussenov, V., Reed, M. et al. Opposing decadal changes for the North Atlantic meridional overturning circulation. Nature Geosci 3, 728–734 (2010).

Download citation

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


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