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.

  • Article
  • Published:

Slowdown of the meridional overturning circulation in the upper Pacific Ocean

Nature volume 415, pages 603–608 (2002)Cite this article

Abstract

Decadal temperature fluctuations in the Pacific Ocean have a significant effect on marine ecosystems and the climate of North America. The physical mechanisms responsible for these fluctuations are poorly understood. Some theories ascribe a central role to the wind-driven meridional overturning circulation between the tropical and subtropical oceans. Here we show, from observations over the past 50 years, that this overturning circulation has been slowing down since the 1970s, causing a decrease in upwelling of about 25% in an equatorial strip between 9° N and 9° S. This reduction in equatorial upwelling of relatively cool water, from 47 × 106 to 35 × 106 m3 s-1, is associated with a rise in equatorial sea surface temperatures of about 0.8 °C. Another effect of the slowing circulation is a reduction in the outgassing of CO2 from the equatorial Pacific Ocean–at present the largest oceanic source of carbon dioxide to the atmosphere.

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

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Mean circulation and potential vorticity averaged over 50 years (1950–99) in the upper pycnocline of the Pacific Ocean.
Figure 2: Meridional transports in the pycnocline and smoothed sea surface temperatures over the past 50 years.
Figure 3: Decadal differences in the tropical Pacific between 1990–99 and 1970–77.

Similar content being viewed by others

References

  1. Minobe, S. Spatio-temporal structure of pentadecadal variability over the North Pacific. Prog. Oceanogr. 47, 381–408 (2000).

    Article  ADS  Google Scholar 

  2. Trenberth, K. E. & Hurrell, J. W. Decadal atmosphere-ocean variations in the Pacific. Clim. Dyn. 9, 303–319 (1994).

    Article  Google Scholar 

  3. Mantua, N. J., Hare, S. J., Zhang, Y., Wallace, J. M. & Francis, R. C. A Pacific interdecadal oscillation with impacts on salmon production. Bull. Am. Meteorol. Soc. 76, 1069–1079 (1997).

    Article  Google Scholar 

  4. Zhang, Y., Wallace, J. M. & Battisti, D. S. ENSO-like interdecadal variability: 1900–93. J. Clim. 10, 1004–1020 (1997).

    Article  ADS  Google Scholar 

  5. Hare, S. R. & Mantua, N. Empirical evidence for North Pacific regime shifts in 1977 and 1989. Prog. Oceanogr. 47, 103–145 (2000).

    Article  ADS  Google Scholar 

  6. Cayan, D. R., Kammerdiener, S. A., Dettinger, M. D., Caprio, J. M. & Peterson, D. H. Changes in the onset of spring in the western United States. Bull. Am. Meteorol. Soc. 82, 399–415 (2001).

    Article  ADS  Google Scholar 

  7. Miller, A. J. & Schneider, N. Interdecadal climate regime dynamics in the North Pacific Ocean: theories, observations, and ecosystem impacts. Prog. Oceanogr. 47, 355–379 (2000).

    Article  ADS  Google Scholar 

  8. Latif, M. & Barnett, T. P. Cause of decadal variability over the North Pacific and North America: Dynamics and predictability. J. Clim. 9, 2407–2423 (1996).

    Article  ADS  Google Scholar 

  9. Lindsey, B. K., Wellington, G. M. & Schrag, D. P. Decadal sea surface temperature variability in the subtropical South Pacific from 1726 to 1997 A. D. Science 290, 1145–1148 (2001).

    ADS  Google Scholar 

  10. Garreaud, R. E. & Battisti, D. S. Interannual (ENSO) and interdecadal (ENSO-like) variability in the Southern Hemisphere tropospheric circulation. J. Clim. 12, 2113–2123 (1999).

    Article  ADS  Google Scholar 

  11. Gu, D. & Philander, S. G. H. Interdecadal climate fluctuations that depend on exchanges between the tropics and extratropics. Science 275, 805–807 (1997).

    Article  CAS  Google Scholar 

  12. Schneider N., Miller, A. J., Alexander, A. & Deser, C. Subduction of decadal North Pacific temperature anomalies: Observations and dynamics. J. Phys. Oceanogr. 29, 1056–1070 (1999).

    Article  ADS  Google Scholar 

  13. Schneider, N. et al. Pacific thermocline bridge revisited. Geophys. Res. Lett. 26, 1329–1332 (1999).

    Article  ADS  Google Scholar 

  14. Liu, Z. & Shin, S.-I. On thermal ventilation of active and passive tracers. Geophys. Res. Lett. 26, 357–360 (1999).

    Article  ADS  Google Scholar 

  15. Nonaka, M., Xie, S.-P. & Takeuchi, K. Equatorward spreading of a passive tracer with application to North Pacific interdecadal temperature variations. J. Oceanogr. 56, 173–183 (2000).

    Article  Google Scholar 

  16. Kleeman, R., McCreary, J. P. & Klinger, B. A mechanism for generating ENSO decadal variability. Geophys. Res. Lett. 26, 1743–1746 (1999).

    Article  ADS  Google Scholar 

  17. Johnson, G. C. & McPhaden, M. J. Interior pycnocline flow from the subtropical to the equatorial Pacific Ocean. J. Phys. Oceanogr. 29, 3073–3089 (1999).

    Article  ADS  Google Scholar 

  18. Huang, B. & Liu, Z. Pacific subtropical-tropical thermocline water exchange in the National Centers for Environmental Prediction ocean model. J. Geophys. Res. 104, 11065–11076 (1999).

    Article  ADS  Google Scholar 

  19. McPhaden, M. J. & Fine, R. A. A dynamical interpretation of the tritium maximum in the central equatorial Pacific. J. Phys. Oceanogr. 18, 1454–1457 (1988).

    Article  ADS  Google Scholar 

  20. Quay, P. D., Stuiver, M. & Broecker, W. S. Upwelling rates for the equatorial Pacific Ocean derived from the bomb 14C distribution. J. Mar. Res. 41, 769–792 (1983).

    Article  Google Scholar 

  21. Fine, R. A., Maillet, K. A., Sullivan, K. F. & Willey, D. Circulation and ventilation flux of the Pacific Ocean. J. Geophys. Res. 106, 22159–22178 (2001).

    Article  ADS  Google Scholar 

  22. Sverdrup, H. U. Wind-driven currents in a baroclinic ocean: with application to the equatorial currents of the eastern Pacific. Proc. Natl Acad. Sci. USA 33, 318–326 (1947).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  23. Liu, Z. & Huang, B. Cause of tropical Pacific warming trend. Geophys. Res. Lett. 27, 1935–1938 (2000).

    Article  ADS  Google Scholar 

  24. Wallace, J. M. et al. On the structure and evolution of ENSO-related climate variability in the tropical Pacific: Lessons from TOGA. J. Geophys. Res. 103, 14241–14259 (1998).

    Article  ADS  Google Scholar 

  25. McCreary, J. P. & Lu, P. On the interaction between the subtropical and the equatorial oceans: The subtropical cell. Phys. Oceanogr. 24, 466–497 (1994).

    Article  Google Scholar 

  26. Ralph, E. A. & Niiler, P. P. Wind-driven currents in the tropical Pacific. J. Phys. Oceanogr. 29, 2121–2129 (1999).

    Article  ADS  Google Scholar 

  27. Gordon, A. L., Susanto, R. D. & Ffield, A. Throughflow within the Makassar Strait. Geophys. Res. Lett. 26, 3325–3328 (1999).

    Article  ADS  Google Scholar 

  28. Philander, S. G. H. Variability of the tropical oceans. Dyn. Atmos. Oceans 3, 191–208 (1979).

    Article  ADS  Google Scholar 

  29. Johnson G. C., McPhaden, M. J. & Firing, E. Equatorial Pacific Ocean horizontal velocity, divergence, and upwelling. J. Phys. Oceanogr. 31, 839–849 (2001).

    Article  ADS  Google Scholar 

  30. Chavez, F. P. & Toggweiler, J. R. in Upwelling in the Ocean: Modeling Processes and Ancient Records (eds Summerhayes, C. P. et al.) 313–320 (Wiley, New York, 1995).

    Google Scholar 

  31. Wyrtki, K. An estimate of equatorial upwelling in the Pacific. J. Phys. Oceanogr. 11, 1205–1214 (1981).

    Article  ADS  Google Scholar 

  32. Meinen, C. S., McPhaden, M. J. & Johnson, G. C. Vertical velocities and transports in the equatorial Pacific during 1993–1999. J. Phys. Oceanogr. 31, 3230–3248 (2001).

    Article  ADS  Google Scholar 

  33. Guilderson, T. P. & Schrag, D. P. Abrupt shift in subsurface temperatures in the tropical Pacific associated with changes in El Niño. Science 281, 240–243 (1998).

    Article  ADS  CAS  Google Scholar 

  34. Chang, P., Giese, B. S., Ji, L., Seidel, H. F. & Wang, F. Decadal change in the south tropical Pacific in a global assimilation analysis. Geophys. Res. Lett. 28, 3461–3464 (2001).

    Article  ADS  Google Scholar 

  35. Knutsen, T. R. & Manabe, S. Model assessment of decadal variability and trends in the tropical Pacific Ocean. J. Clim. 11, 2273–2296 (1998).

    Article  ADS  Google Scholar 

  36. Federov, A. V. & Philander, S. G. H. Is El Niño changing? Science 288, 1997–2001 (2000).

    Article  ADS  Google Scholar 

  37. Urban, F. E., Cole, J. E. & Overpeck, J. T. Influence of mean climate change on climate variability from a 155-year tropical Pacific coral record. Nature 407, 898–993 (2000).

    Article  Google Scholar 

  38. Kirtman, B. P. & Schopf, P. S. Decadal variability in ENSO predictability and prediction. J. Clim. 11, 2843–2822 (1998).

    Article  Google Scholar 

  39. Meehl, G. A. & Washington, W. M. El Niño-like climate change in a model with increased CO2 concentrations. Nature 382, 56–60 (1995).

    Article  ADS  Google Scholar 

  40. Feely, R. A., Wanninkhof, R., Takahashi, T. & Tans, P. Influence of El Niño on the equatorial Pacific contribution to atmospheric CO2 accumulation. Nature 398, 597–601 (1999).

    Article  ADS  CAS  Google Scholar 

  41. Feely, R. A. et al. Seasonal and interannual variability of CO2 in the equatorial Pacific. Deep-Sea Res. (in the press).

  42. Conkright, M. E. et al. World Ocean Database 1998 Version 2.0 (National Oceanographic Data Center Internal Report 14, National Oceanic and Atmospheric Administration, Silver Spring, Maryland, 1999).

    Google Scholar 

  43. da Silva, A. M., Young, C. C. & Levitus, S. Atlas of Surface Marine Data Vol. 1, Algorithms and Procedures (NOAA Atlas NESDIS 6, US Dept. of Commerce, Washington DC, 1994).

    Google Scholar 

  44. Goldenberg, S. B. & O'Brien, J. J. Time and space variability of tropical Pacific wind stress. Mon. Weath. Rev. 109, 1190–1207 (1981).

    Article  ADS  Google Scholar 

  45. Kalnay, E. et al. The NCEP/NCAR 40-year reanalysis project. Bull. Am. Meteorol. Soc. 77, 437–471 (1996).

    Article  ADS  Google Scholar 

  46. European Centre for Medium-Range Weather Forecasts – ECMWF Data Archive (http://www.ecmwf.int/services/data/archive/) (February 2001).

  47. Hackert, E. C., Busalacchi, A. J. & Murtugudde, R. A. A wind comparison study using an ocean general circulation model for the 1997–98 El Niño. J. Geophys. Res. 106, 2345–2362 (2001).

    Article  ADS  Google Scholar 

  48. Godfrey, J. S. A Sverdrup model of the depth-integrated flow for the World Ocean allowing for island circulations. Geophys. Astrophys. Fluid Dyn. 45, 89–112 (1989).

    Article  ADS  Google Scholar 

  49. Schneider, N. The Indonesian throughflow and the global climate system. J. Clim. 11, 676–689 (1998).

    Article  ADS  Google Scholar 

  50. Smith, T. M., Reynolds, R. W. & Ropelewski, C. F. Optimal averaging of seasonal sea surface temperatures and associated confidence intervals. J. Clim. 7, 949–964 (1994).

    Article  ADS  Google Scholar 

Download references

Acknowledgements

We thank J. Potemra for advice on Indonesian throughflow calculations. We also thank W. Kessler, G. Johnson and R. Kleeman for comments on an earlier version of this manuscript. This work was supported by the NOAA Office of Oceanic and Atmospheric Research and by the Joint Study for the Atmosphere and Ocean (JISAO) at the University of Washington.

Author information

Authors and Affiliations

  1. NOAA/Pacific Marine Environmental Laboratory, Seattle, 98115, Washington, USA

    Michael J. McPhaden & Dongxiao Zhang

  2. Joint Institute for the Study of the Atmosphere and Ocean, University of Washington, Seattle, 98115, Washington, USA

    Dongxiao Zhang

Authors
  1. Michael J. McPhaden
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Dongxiao Zhang
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Michael J. McPhaden.

Rights and permissions

Reprints and permissions

About this article

Cite this article

McPhaden, M., Zhang, D. Slowdown of the meridional overturning circulation in the upper Pacific Ocean. Nature 415, 603–608 (2002). https://doi.org/10.1038/415603a

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/415603a

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced 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