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Influence of El Niño on the equatorial Pacific contribution to atmospheric CO2 accumulation

Abstract

The equatorial oceans are the dominant oceanic source of CO2 to the atmosphere, annually amounting to a net flux of 0.7–1.5 Pg (1015 g) of carbon, up to 72% of which emanates from the equatorial Pacific Ocean1,2,3. Limited observations indicate that the size of the equatorial Pacific source is significantly influenced by El Niño events4,5,6,7,8,9,10, but the effect has not been well quantified. Here we report spring and autumn multiannual measurements of the partial pressure of CO2 in the surface ocean and atmosphere in the equatorial Pacific region. During the 1991–94 El Niño period, the derived net annual sea-to-air flux of CO2 was 0.3 Pg C from autumn 1991 to autumn 1992, 0.6 Pg C in 1993, and 0.7 Pg C in 1994. These annual fluxes are 30–80% of that of 1996, a non-El-Niño year. The total reduction of the regional sea-to-air CO2 flux during the 1991–94 El Niño period is estimated to account for up to one-third of the atmospheric anomaly (the difference between the annual and long-term-average increases in global atmospheric CO2 content) observed over the same period.

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Figure 1: CO2 disequilibria and sea-to-air fluxes in the equatorial Pacific.
Figure 2: Time series of p CO 2 ω .
Figure 3: Long time series of seawater and atmospheric p CO 2 .

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References

  1. Houghton, J. et al. (eds) Climate Change 1994: Radiative Forcing of Climate Change and an Evaluation of the IPCC 1992 Emission Scenarios(Cambridge Univ. Press, 1994).

    Google Scholar 

  2. Tans, P. P., Fung, I. Y. & Takahashi, T. Observational constraints on the global atmospheric CO2budget. Science 247, 1431– 1438 (1990).

    Article  ADS  CAS  Google Scholar 

  3. Takahashi, T. et al.Global air–sea flux of CO2: An estimate based on measurements of sea–air pCO2difference. Proc. Natl Acad. Sci. USA 94, 8292–8299 (1997).

    Article  ADS  CAS  Google Scholar 

  4. Feely, R. A. et al.CO2distributions in the equatorial Pacific during the 1991–92 ENSO event. Deep-Sea Res. II 42(2–3), 365–386 (1995).

    Article  ADS  Google Scholar 

  5. Wanninkhof, R., Feely, R. A., Chen, H., Cosca, C. & Murphy, P. P. Surface water fCO2values in the eastern equatorial Pacific during the 1992–93 El Niño. J. Geophys. Res. 101, 16333–16343 ( 1996).

    Article  ADS  Google Scholar 

  6. Murray, J. W., Barber, R. T., Roman, M., Bacon, M. & Feely, R. A. Physical and biological controls on carbon cycling in the equatorial Pacific. Science 266, 58– 65 (1994).

    Article  ADS  CAS  Google Scholar 

  7. Feely, R. A. et al.Distribution of chemical tracers in the eastern equatorial Pacific during and after the 1982–1983 El Niño/Southern Oscillation event. J. Geophys. Res. 92, 6545– 6558 (1987).

    Article  ADS  CAS  Google Scholar 

  8. Inoue, H. & Sugimura, Y. Variations and distributions of CO2in and over the equatorial Pacific during the period from 1986/88 El Niño event to the 1988/89 La Niña event. Tellus B 44, 1–22 ( 1992).

    Article  ADS  Google Scholar 

  9. Goyet, C. & Peltzer, E. T. Comparison of the August–September 1991 and 1979 surface partial pressure of CO2distribution in the Equatorial Pacific Ocean near 150° W. Mar. Chem. 45, 257–266 (1994).

    Article  CAS  Google Scholar 

  10. Archer, D. E. et al.Seasonal and interannual variability of sea-surface carbon and nutrient concentration in the equatorial Pacific Ocean. Deep-Sea Res. II 43(4–6), 779–808 (1996).

    Article  ADS  Google Scholar 

  11. McPhaden, M. J. TOGA-TAO and the 1991–92 ENSO event. Oceanography 6(2),36–44 (1993).

    Article  Google Scholar 

  12. Harrison, D. E. Vertical velocity in the central tropical Pacific—a circulation model perspective for JGOFS. Deep-Sea Res. II 43(4–6), 687–705 (1996).

    Article  ADS  Google Scholar 

  13. Toggweiler, J. R. & Carson, S. in Upwelling the Ocean: Modern Processes and Ancient Records(eds Summerhayes, C. et al.) 337–360 (Wiley, Chichester, 1995).

    Google Scholar 

  14. Wanninkhof, R. Relationship between wind speed and gas exchange over the ocean. J. Geophys. Res. 97, 7373–7382 (1992).

    Article  ADS  Google Scholar 

  15. Inoue, H. Y., Ishii, M., Matsueda, H. & Ahoyama, M. Changes in longitudinal distributions of partial pressure of CO2(pCO2) in the central and western equatorial Pacific, west of 160 °W. Geophys. Res. Lett. 23(14),1781–1784 (1996).

    Article  ADS  Google Scholar 

  16. Francey, R. J. et al.Changes in oceanic and terrestrial carbon uptake since 1982. Nature 373, 326–330 (1995).

    Article  ADS  CAS  Google Scholar 

  17. Ciais, P. et al.Partitioning of ocean and land uptake of CO2as inferred by CO2measurements from the NOAA/CMDL global air sampling network. J. Geophys. Res. 100, 5051– 5070 (1995).

    Article  ADS  CAS  Google Scholar 

  18. Keeling, C. D., Whorf, T. P., Wahlen, M. & Vander Plicht, J. Interannual extremes in the rate of rise of atmospheric carbon dioxide since 1980. Nature 375, 666–670 ( 1995).

    Article  ADS  CAS  Google Scholar 

  19. Ciais, P., Tans, P. P., Trolier, M., White, J. W. & Francey, R. J. Alarge northern hemisphere terrestrial CO2sink indicated by the 13C/12C ratio of atmospheric CO2. Science 269, 1098– 1102 (1995).

    Article  ADS  CAS  Google Scholar 

  20. Maier-Reimer, E. & Hasselmann, K. Transport and storage of CO2in the ocean—An inorganic ocean-circulation carbon cycle model. Clim. Dyn. 2, 63– 90 (1987).

    Article  Google Scholar 

  21. Tsuchiya, M., Lukas, R., Fine, R. A., Firing, E. & Lindstrom, E. Source waters of the Pacific Equatorial Undercurrent. Prog. Oceanogr. 23, 101– 147 (1990).

    Article  ADS  Google Scholar 

  22. Toggweiler, J. R., Dixon, K. & Broecker, W. S. The Peru upwelling and the ventilation of the South Pacific thermocline. J. Geophys. Res. 96, 20467–20497 (1991).

    Article  ADS  CAS  Google Scholar 

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

    Article  Google Scholar 

  24. 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 

  25. Murphy, P. P., Kelly, K. C., Feely, R. A. & Gammon, R. H. Carbon Dioxide Concentrations in Surface Water and the Atmosphere: PMEL Cruises 1986–1989(Tech. Memo. ERL PMEL-101 (DE95-009659), NOAA, Seattle, (1994).

    Google Scholar 

  26. Feely, R. A., Wanninkhof, R., Goyet, C., Archer, D. E. & Takahashi, T. Variability of CO2distributions and sea–air fluxes in the central and eastern equatorial Pacific during the 1991–94 El Niño. Deep-Sea Res. II 44, 1851–1867

  27. Inoue, H. Y. et al.Long-term trend of the partial pressure of carbon dioxide (pCO 2) in surface waters of the western North Pacific, 1984–1993. Tellus B 47, 391–413 (1995).

    Article  ADS  Google Scholar 

  28. Winn, C. D., Li, Y.-H., Mackenzie, F. & Karl, D. M. Rising surface dissolved inorganic carbon at the Hawaii Ocean Time-series site. Mar. Chem. 60(1–2), 33–48 (1998).

    Article  Google Scholar 

  29. Wanninkhof, R. & Thoning, K. Measurement of CO2in surface water using continuous and discrete sampling methods. Mar. Chem. 44, 189–205 (1993).

    Article  CAS  Google Scholar 

  30. Keeling, C. D., Rakestraw, N. W. & Waterman, L. S. Carbon dioxide in the surface waters of the Pacific Ocean, 1—Measurements of the distribution. J. Geophys. Res. 70, 6087–6097 ( 1965).

    Article  ADS  CAS  Google Scholar 

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Acknowledgements

The assistance of the officers and crew of NOAA ships Discoverer, Malcolm Baldrig, and Ka'imimoana is acknowledged. We thank D.E. Harrison for wind data, and C. Cosca, M. Steckley and D. Ho for the p CO 2 ω measurements and data reduction. We also thank the NOAA TAO Project Office (director M. McPhaden) for support. This work was supported by the NOAA Climate and Global Change Program as part of the Ocean–Atmosphere Carbon Exchange Study.

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Correspondence to Richard A. Feely.

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Feely, R., Wanninkhof, R., Takahashi, T. et al. Influence of El Niño on the equatorial Pacific contribution to atmospheric CO2 accumulation. Nature 398, 597–601 (1999). https://doi.org/10.1038/19273

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