El Niño–Southern Oscillation complexity

An Author Correction to this article was published on 20 February 2019

This article has been updated


El Niño events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years. Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities. The alternation of warm El Niño and cold La Niña conditions, referred to as the El Niño–Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system. Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: ENSO cycle.
Fig. 2: Schematic representation of ENSO temporal complexity.
Fig. 3: Spatio-temporal complexity of ENSO.
Fig. 4: Probabilistic ENSO precursors and predictive skill.
Fig. 5: Mechanisms of ENSO complexity.

Change history

  • 20 February 2019

    In this Review, the middle initial of author Kim M. Cobb was omitted. The original Review has been corrected online.


  1. 1.

    Carrillo, C. N. Hidrografía oceánica. Bol. Soc. Geogr. Lima 1, 72–110 (1893).

    Google Scholar 

  2. 2.

    Bjerknes, J. Atmospheric teleconnections from the equatorial Pacific. Mon. Weath. Rev. 97, 163–172 (1969).

    ADS  Google Scholar 

  3. 3.

    McPhaden, M. J., Busalacchi, A. J. & Anderson, D. L. T. A TOGA retrospective. Oceanography 23, 86–103 (2010).

    Google Scholar 

  4. 4.

    Cai, W. J. et al. More extreme swings of the South Pacific convergence zone due to greenhouse warming. Nature 488, 365–369 (2012).

    ADS  CAS  PubMed  Google Scholar 

  5. 5.

    Capotondi, A. et al. Understanding ENSO diversity. Bull. Am. Meteorol. Soc. 96, 921–938 (2015).

    ADS  Google Scholar 

  6. 6.

    Kug, J. S., Jin, F. F. & An, S. I. Two types of El Niño events: cold tongue El Niño and warm pool El Niño. J. Clim. 22, 1499–1515 (2009). This study demonstrates that the two types of El Niño (CP and EP) have different dynamical structures, including discharge processes and dominant SST feedbacks.

    ADS  Google Scholar 

  7. 7.

    Ashok, K., Behera, S. K., Rao, S. A., Weng, H. Y. & Yamagata, T. El Niño Modoki and its possible teleconnection. J. Geophys. Res. Oceans 112, C11007 (2007).

    ADS  Google Scholar 

  8. 8.

    Takahashi, K., Montecinos, A., Goubanova, K. & Dewitte, B. ENSO regimes: reinterpreting the canonical and Modoki El Niño. Geophys. Res. Lett. 38, L10704 (2011).

    ADS  Google Scholar 

  9. 9.

    Tziperman, E. & Yu, L. S. Quantifying the dependence of westerly wind bursts on the large-scale tropical Pacific SST. J. Clim. 20, 2760–2768 (2007).

    ADS  Google Scholar 

  10. 10.

    Lengaigne, M. et al. Triggering of El Niño by westerly wind events in a coupled general circulation model. Clim. Dyn. 23, 601–620 (2004).

    Google Scholar 

  11. 11.

    Choi, J., An, S. I. & Yeh, S. W. Decadal amplitude modulation of two types of ENSO and its relationship with the mean state. Clim. Dyn. 38, 2631–2644 (2012).

    Google Scholar 

  12. 12.

    L’Heureux, M. L. et al. Observing and predicting the 2015/16 El Niño. Bull. Am. Meteorol. Soc. 98, 1363–1382 (2017).

    ADS  Google Scholar 

  13. 13.

    Jin, F. F., Kim, S. T. & Bejarano, L. A coupled-stability index for ENSO. Geophys. Res. Lett. 33, L23708 (2006).

    ADS  Google Scholar 

  14. 14.

    Hoerling, M. P. & Kumar, A. Why do North American climate anomalies differ from one El Niño event to another? Geophys. Res. Lett. 24, 1059–1062 (1997).

    ADS  Google Scholar 

  15. 15.

    Karoly, D. J. & Hoskins, B. J. 3 dimensional propagation of planetary waves. J. Meteorol. Soc. Jpn 60, 109–123 (1982).

    Google Scholar 

  16. 16.

    Ropelewski, C. F. & Halpert, M. S. Global and regional scale precipitation patterns associated with the El-Niño Southern Oscillation. Mon. Weath. Rev. 115, 1606–1626 (1987).

    ADS  Google Scholar 

  17. 17.

    Larkin, N. K. & Harrison, D. E. On the definition of El Niño and associated seasonal average US weather anomalies. Geophys. Res. Lett. 32, L13705 (2005).

    ADS  Google Scholar 

  18. 18.

    Cobb, K. M. et al. Highly variable El Niño-Southern Oscillation throughout the holocene. Science 339, 67–70 (2013).

    ADS  CAS  PubMed  Google Scholar 

  19. 19.

    McGregor, S., Timmermann, A., England, M. H., Timm, O. E. & Wittenberg, A. T. Inferred changes in El Niño–Southern Oscillation variance over the past six centuries. Clim. Past 9, 2269–2284 (2013). This study uses multi-proxy data to demonstrate that ENSO variance has increased over the past century relative to the previous 500 years.

    Google Scholar 

  20. 20.

    Cai, W. J. et al. ENSO and greenhouse warming. Nat. Clim. Change 5, 849–859 (2015).

    ADS  Google Scholar 

  21. 21.

    Rasmusson, E. M. & Carpenter, T. H. Variations in tropical sea-surface temperature and surface wind fields associated with the Southern Oscillation El-Niño. Mon. Weath. Rev. 110, 354–384 (1982).

    ADS  Google Scholar 

  22. 22.

    Wang, C. Z. On the ENSO mechanisms. Adv. Atmos. Sci. 18, 674–691 (2001).

    Google Scholar 

  23. 23.

    Jin, F. F. An equatorial ocean recharge paradigm for ENSO. Part I: conceptual model. J. Atmos. Sci. 54, 811–829 (1997). This paper introduces a heuristic model that explains key features of ENSO dynamics, such as the important role of recharge and discharge processes in ENSO.

    ADS  Google Scholar 

  24. 24.

    Roberts, A., Guckenheimer, J., Widiasih, E., Timmermann, A. & Jones, C. Mixed-mode oscillations of El Niño-Southern Oscillation. J. Atmos. Sci. 73, 1755–1766 (2016).

    ADS  Google Scholar 

  25. 25.

    Levine, A. F. Z. & Jin, F. F. Noise-induced instability in the ENSO recharge oscillator. J. Atmos. Sci. 67, 529–542 (2010).

    ADS  Google Scholar 

  26. 26.

    Rayner, N. A. et al. Global analyses of sea surface temperature, sea ice, and night marine air temperature since the late nineteenth century. J. Geophys. Res. Atmos. 108, 4407 (2003).

    ADS  Google Scholar 

  27. 27.

    Giese, B. S. & Ray, S. El Niño variability in simple ocean data assimilation (SODA), 1871–2008. J. Geophys. Res. Oceans 116, (2011).

  28. 28.

    Johnson, N. C. How many ENSO flavors can we distinguish? J. Clim. 26, 4816–4827 (2013).

    ADS  Google Scholar 

  29. 29.

    Kug, J. S. & Ham, Y. G. Are there two types of La Niña? Geophys. Res. Lett. 38, L16704 (2011).

    ADS  Google Scholar 

  30. 30.

    Kao, H. Y. & Yu, J. Y. Contrasting eastern-Pacific and central-Pacific types of ENSO. J. Clim. 22, 615–632 (2009).

    ADS  Google Scholar 

  31. 31.

    Lengaigne, M. & Vecchi, G. A. Contrasting the termination of moderate and extreme El Niño events in coupled general circulation models. Clim. Dyn. 35, 299–313 (2010).

    Google Scholar 

  32. 32.

    An, S.-I., Kug, J.-S., Timmermann, A., Kang, I.-S. & Timm, O. The influence of ENSO on the generation of decadal variability in the North Pacific. J. Clim. 20, 667–680 (2007).

    ADS  Google Scholar 

  33. 33.

    Deser, C., Simpson, I. R., McKinnon, K. A. & Phillips, A. S. The Northern Hemisphere extratropical atmospheric circulation response to ENSO: how well do we know it and how do we evaluate models accordingly? J. Clim. 30, 5059–5082 (2017).

    ADS  Google Scholar 

  34. 34.

    Fedorov, A. V., Hu, S. N., Lengaigne, M. & Guilyardi, E. The impact of westerly wind bursts and ocean initial state on the development, and diversity of El Niño events. Clim. Dyn. 44, 1381–1401 (2015).

    Google Scholar 

  35. 35.

    Seiki, A. & Takayabu, Y. N. Westerly wind bursts and their relationship with intraseasonal variations and ENSO. Part I: statistics. Mon. Weath. Rev. 135, 3325–3345 (2007).

    ADS  Google Scholar 

  36. 36.

    Jin, F. F., Lin, L., Timmermann, A. & Zhao, J. Ensemble-mean dynamics of the ENSO recharge oscillator under state-dependent stochastic forcing. Geophys. Res. Lett. 34, L03807 (2007).

    ADS  Google Scholar 

  37. 37.

    Vimont, D. J., Battisti, D. S. & Hirst, A. C. The seasonal footprinting mechanism in the CSIRO general circulation models. J. Clim. 16, 2653–2667 (2003). This article presents a coupled air-sea mechanism by which extratropical Pacific climate anomalies can propagate into the tropics.

    ADS  Google Scholar 

  38. 38.

    Hong, L. C. L Ho & Jin, F. F. A Southern Hemisphere booster of super El Niño. Geophys. Res. Lett. 41, 2142–2149 (2014).

    ADS  Google Scholar 

  39. 39.

    Ham, Y. G., Kug, J. S., Park, J. Y. & Jin, F. F. Sea surface temperature in the north tropical Atlantic as a trigger for El Niño/Southern Oscillation events. Nat. Geosci. 6, 112–116 (2013).

    ADS  CAS  Google Scholar 

  40. 40.

    Chikamoto, Y. et al. Skilful multi-year predictions of tropical trans-basin climate variability. Nat. Commun. 6, 6869 (2015). This article documents the impact of Atlantic SSTAs on the generation of CP El Niño events.

    CAS  PubMed  PubMed Central  Google Scholar 

  41. 41.

    Yu, J. Y. & Kim, S. T. Relationships between extratropical sea level pressure variations and the central Pacific and eastern Pacific types of ENSO. J. Clim. 24, 708–720 (2011).

    ADS  Google Scholar 

  42. 42.

    Lee, T. & McPhaden, M. J. Increasing intensity of El Niño in the central-equatorial Pacific. Geophys. Res. Lett. 37, L14603 (2010).

    ADS  Google Scholar 

  43. 43.

    Wittenberg, A. T., Rosati, A., Delworth, T. L., Vecchi, G. A. & Zeng, F. R. ENSO modulation: is it decadally predictable? J. Clim. 27, 2667–2681 (2014).

    ADS  Google Scholar 

  44. 44.

    Yeh, S. W. et al. El Niño in a changing climate. Nature 461, 511–514 (2009); erratum 462, 674 (2009).

    ADS  CAS  PubMed  Google Scholar 

  45. 45.

    Capotondi, A. & Sardeshmukh, P. D. Optimal precursors of different types of ENSO events. Geophys. Res. Lett. 42, 9952–9960 (2015).

    ADS  Google Scholar 

  46. 46.

    Xie, R. & Jin, F.-F. Two leading ENSO modes and El Niño Types in the Zebiak–Cane Model. J. Clim. (2018). This study provides theoretical evidence for two coupled modes that resemble EP and CP El Niño events with different timescales and background-state sensitivities.

  47. 47.

    Ham, Y. G. & Kug, J. S. How well do current climate models simulate two types of El Niño? Clim. Dyn. 39, 383–398 (2012). This work shows that current climate models tend to underestimate the diversity of El Niño owing to dry and cold biases in the equatorial central Pacific.

    Google Scholar 

  48. 48.

    Bellenger, H., Guilyardi, E., Leloup, J., Lengaigne, M. & Vialard, J. ENSO representation in climate models: from CMIP3 to CMIP5. Clim. Dyn. 42, 1999–2018 (2014).

    Google Scholar 

  49. 49.

    Bayr, T. et al. Mean-state dependence of ENSO atmospheric feedbacks in climate models. Clim. Dyn. 50, 3171–3194 (2017).

    Google Scholar 

  50. 50.

    Li, T. Phase transition of the El Niño Southern Oscillation: a stationary SST mode. J. Atmos. Sci. 54, 2872–2887 (1997). This study applied seasonally varying instability to model coupled ENSO dynamics.

    ADS  Google Scholar 

  51. 51.

    Zhang, W. J. et al. Unraveling El Niño’s impact on the East Asian monsoon and Yangtze River summer flooding. Geophys. Res. Lett. 43, 11375–11382 (2016).

    ADS  Google Scholar 

  52. 52.

    Trenberth, K. E. et al. Progress during TOGA in understanding and modeling global teleconnections associated with tropical sea surface temperatures. J. Geophys. Res. Oceans 103, 14291–14324 (1998).

    ADS  Google Scholar 

  53. 53.

    Risbey, J. S., Pook, M. J., McIntosh, P. C., Wheeler, M. C. & Hendon, H. H. On the remote drivers of rainfall variability in Australia. Mon. Weath. Rev. 137, 3233–3253 (2009).

    ADS  Google Scholar 

  54. 54.

    McPhaden, M. J. Genesis and evolution of the 1997–98 El Niño. Science 283, 950–954 (1999).

    CAS  PubMed  Google Scholar 

  55. 55.

    Vecchi, G. A. & Harrison, D. E. Tropical Pacific sea surface temperature anomalies, El Niño, and equatorial westerly wind events. J. Clim. 13, 1814–1830 (2000).

    ADS  Google Scholar 

  56. 56.

    Wengel, C., Latif, M., Park, W., Harlass, J. & Bayr, T. Seasonal ENSO phase locking in the Kiel Climate Model: the importance of the equatorial cold sea surface temperature bias. Clim. Dyn. 50, 901–919 (2017).

    Google Scholar 

  57. 57.

    Zebiak, S. E. & Cane, M. A. A model El-Niño Southern Oscillation. Mon. Weath. Rev. 115, 2262–2278 (1987).

    ADS  Google Scholar 

  58. 58.

    Tziperman, E., Zebiak, S. E. & Cane, M. A. Mechanisms of seasonal–ENSO interaction. J. Atmos. Sci. 54, 61–71 (1997).

    ADS  Google Scholar 

  59. 59.

    Galanti, E. et al. The equatorial thermocline outcropping—a seasonal control on the tropical Pacific Ocean–atmosphere instability strength. J. Clim. 15, 2721–2739 (2002).

    ADS  Google Scholar 

  60. 60.

    Dommenget, D. & Yu, Y. S. The seasonally changing cloud feedbacks contribution to the ENSO seasonal phase-locking. Clim. Dyn. 47, 3661–3672 (2016).

    Google Scholar 

  61. 61.

    Harrison, D. E. & Vecchi, G. A. On the termination of El Niño. Geophys. Res. Lett. 26, 1593–1596 (1999).

    ADS  Google Scholar 

  62. 62.

    Lengaigne, M., Boulanger, J. P., Menkes, C. & Spencer, H. Influence of the seasonal cycle on the termination of El Niño events in a coupled general circulation model. J. Clim. 19, 1850–1868 (2006).

    ADS  Google Scholar 

  63. 63.

    McGregor, S., Timmermann, A., Schneider, N., Stuecker, M. F. & England, M. H. The effect of the south Pacific convergence zone on the termination of El Niño events and the meridional asymmetry of ENSO. J. Clim. 25, 5566–5586 (2012). This work demonstrates that the southward wind shift that leads to the rapid decay of El Niño events is related to the seasonal formation of the South Pacific Convergence Zone.

    ADS  Google Scholar 

  64. 64.

    Stuecker, M. F., Timmermann, A., Jin, F. F., McGregor, S. & Ren, H. L. A combination mode of the annual cycle and the El Niño/Southern Oscillation. Nat. Geosci. 6, 540–544 (2013).

    ADS  CAS  Google Scholar 

  65. 65.

    Stuecker, M. F., Jin, F. F., Timmermann, A. & McGregor, S. Combination mode dynamics of the anomalous northwest Pacific anticyclone. J. Clim. 28, 1093–1111 (2015).

    ADS  Google Scholar 

  66. 66.

    Meinen, C. S. & McPhaden, M. J. Observations of warm water volume changes in the equatorial Pacific and their relationship to El Niño and La Niña. J. Clim. 13, 3551–3559 (2000).

    ADS  Google Scholar 

  67. 67.

    Barnston, A., Tippett, M. K., Ranganathan, M. & L’Heureux, M. Deterministic skill of ENSO predictions from the North American Multimodel Ensemble. Clim. Dyn. https://doi.org/10.1007/s00382-017-3603-3 (2017); erratum https://doi.org/10.1007/s00382-017-3814-7 (2017)

  68. 68.

    Ramesh, N. & Murtugudde, R. All flavours of El Niño have similar early subsurface origins. Nat. Clim. Change 3, 42–46 (2013).

    ADS  Google Scholar 

  69. 69.

    Ballester, J., Bordoni, S., Petrova, D. & Rodo, X. Heat advection processes leading to El Niño events as depicted by an ensemble of ocean assimilation products. J. Geophys. Res. Oceans 121, 3710–3729 (2016).

    ADS  Google Scholar 

  70. 70.

    Izumo, T. et al. Influence of the state of the Indian Ocean Dipole on the following year’s El Niño. Nat. Geosci. 3, 168–172 (2010).

    ADS  CAS  Google Scholar 

  71. 71.

    Ham, Y. G., Kug, J. S. & Park, J. Y. Two distinct roles of Atlantic SSTs in ENSO variability: North Tropical Atlantic SST and Atlantic Niño. Geophys. Res. Lett. 40, 4012–4017 (2013).

    ADS  Google Scholar 

  72. 72.

    Takahashi, K. & Dewitte, B. Strong and moderate nonlinear El Niño regimes. Clim. Dyn. 46, 1627–1645 (2016).

    Google Scholar 

  73. 73.

    Barnston, A. G., Tippett, M. K., L’Heureux, M. L., Li, S. H. & DeWitt, D. G. Skill of real-time seasonal ENSO model predictions during 2002–11: is our capability increasing? Bull. Am. Meteorol. Soc. 93, 631–651 (2012).

    ADS  Google Scholar 

  74. 74.

    Newman, M. & Sardeshmukh, P. D. Are we near the predictability limit of tropical Indo-Pacific sea surface temperatures? Geophys. Res. Lett. 44, 8520–8529 (2017).

    ADS  Google Scholar 

  75. 75.

    Petrova, D., Koopman, S. J., Ballester, J. & Rodo, X. Improving the long-lead predictability of El Niño using a novel forecasting scheme based on a dynamic components model. Clim. Dyn. 48, 1249–1276 (2017).

    Google Scholar 

  76. 76.

    Kessler, W. S. Is ENSO a cycle or a series of events? Geophys. Res. Lett. 29, 2125 (2002). This study challenges the notion of ENSO as a cycle and highlights the fact that the ENSO system can lose its dynamical memory during long La Niña events.

    ADS  MathSciNet  Google Scholar 

  77. 77.

    Barnston, A. G. & Tippett, M. K. Do statistical pattern corrections improve seasonal climate predictions in the North American Multimodel Ensemble models? J. Clim. 30, 8335–8355 (2017).

    ADS  Google Scholar 

  78. 78.

    DiNezio, P. N., Deser, C., Okumura, Y. & Karspeck, A. Predictability of 2-year La Niña events in a coupled general circulation model. Clim. Dyn. 49, 4237–4261 (2017).

    Google Scholar 

  79. 79.

    McPhaden, M. J. A. 21st century shift in the relationship between ENSO SST and warm water volume anomalies. Geophys. Res. Lett. 39, L09706 (2012).

    ADS  Google Scholar 

  80. 80.

    Jeong, H. I. et al. Assessment of the APCC coupled MME suite in predicting the distinctive climate impacts of two flavors of ENSO during boreal winter. Clim. Dyn. 39, 475–493 (2012).

    Google Scholar 

  81. 81.

    Larson, S. & Kirtman, B. The Pacific Meridional Mode as a trigger for ENSO in a high-resolution coupled model. Geophys. Res. Lett. 40, 3189–3194 (2013).

    ADS  Google Scholar 

  82. 82.

    Zhang, H. H., Clement, A. & Di Nezio, P. The south Pacific meridional mode: a mechanism for ENSO-like variability. J. Clim. 27, 769–783 (2014).

    ADS  Google Scholar 

  83. 83.

    An, S. I. Interannual variations of the Tropical Ocean instability wave and ENSO. J. Clim. 21, 3680–3686 (2008).

    ADS  Google Scholar 

  84. 84.

    Larson, S. M. & Kirtman, B. P. Linking preconditioning to extreme ENSO events and reduced ensemble spread. Clim. Dyn. https://doi.org/10.1007/s00382-017-3791-x (2017).

  85. 85.

    Chen, N. & Majda, A. J. Simple dynamical models capturing the key features of the Central Pacific El Niño. Proc. Natl Acad. Sci. USA 113, 11732–11737 (2016).

    CAS  PubMed  Google Scholar 

  86. 86.

    Hao, Z., Neelin, J. D. & Jin, F. F. Nonlinear tropical air-sea interaction in the fast-wave limit. J. Clim. 6, 1523–1544 (1993).

    ADS  Google Scholar 

  87. 87.

    Schneider, N. The response of tropical climate to the equatorial emergence of spiciness anomalies. J. Clim. 17, 1083–1095 (2004).

    ADS  Google Scholar 

  88. 88.

    McGregor, S., Sen Gupta, A., Holbrook, N. J. & Power, S. B. The modulation of ENSO variability in CCSM3 by extratropical Rossby waves. J. Clim. 22, 5839–5853 (2009).

    ADS  Google Scholar 

  89. 89.

    Xue, Y. et al. A real-time ocean reanalyses intercomparison project in the context of tropical pacific observing system and ENSO monitoring. Clim. Dyn. 49, 3647–3672 (2017).

    Google Scholar 

  90. 90.

    Widlansky, M. J. et al. Changes in South Pacific rainfall bands in a warming climate. Nat. Clim. Change 3, 417–423 (2013).

    ADS  Google Scholar 

  91. 91.

    Kirtman, B. P., Straus, D. M., Min, D. H., Schneider, E. K. & Siqueira, L. Toward linking weather and climate in the interactive ensemble NCAR climate model. Geophys. Res. Lett. 36, (2009).

  92. 92.

    Vecchi, G. A. et al. On the seasonal forecasting of regional tropical cyclone activity. J. Clim. 27, 7994–8016 (2014).

    ADS  Google Scholar 

  93. 93.

    Cook, E. R., Seager, R., Cane, M. A. & Stahle, D. W. North American drought: reconstructions, causes, and consequences. Earth Sci. Rev. 81, 93–134 (2007).

    ADS  Google Scholar 

  94. 94.

    Nicholson, S. E. & Selato, J. C. The influence of La Niña on African rainfall. Int. J. Climatol. 20, 1761–1776 (2000).

    Google Scholar 

  95. 95.

    McPhaden, M. J., Zebiak, S. E. & Glantz, M. H. ENSO as an integrating concept in Earth science. Science 314, 1740–1745 (2006).

    ADS  CAS  PubMed  Google Scholar 

  96. 96.

    Balmaseda, M. A., Mogensen, K. & Weaver, A. T. Evaluation of the ECMWF ocean reanalysis system ORAS4. Q. J. R. Meteorol. Soc. 139, 1132–1161 (2013).

    ADS  Google Scholar 

  97. 97.

    Huang, B. Y. et al. Extended reconstructed sea surface temperature, version 5 (ERSSTv5): upgrades, validations, and intercomparisons. J. Clim. 30, 8179–8205 (2017).

    ADS  Google Scholar 

  98. 98.

    Penny, S. G., Behringer, D. W., Carton, J. A. & Kalnay, E. A hybrid global ocean data assimilation system at NCEP. Mon. Weath. Rev. 143, 4660–4677 (2015).

    ADS  Google Scholar 

  99. 99.

    Puy, M., Vialard, J., Lengaigne, M. & Guilyardi, E. Modulation of equatorial Pacific westerly/easterly wind events by the Madden–Julian oscillation and convectively-coupled Rossby waves. Clim. Dyn. 46, 2155–2178 (2016).

    Google Scholar 

  100. 100.

    Adler, R. F. et al. The version-2 global precipitation climatology project (GPCP) monthly precipitation analysis (1979–present). J. Hydrometeorol. 4, 1147–1167 (2003).

    ADS  MathSciNet  Google Scholar 

Download references


A.T., K.S., K.-S.Y. and E.Z. were supported by the Institute for Basic Science (project code IBS-R028-D1). B.D. was funded by Fondecyt (grant 1151185). S.-I.A. was supported by the Basic Science Research Program through the National Research Foundation of Korea (NRF-2017R1A2A2A05069383). J.-S.K. was supported by the National Research Foundation of Korea (NRF-2017R1A2B3011511). F.-F.J.’s contribution was sponsored through the US NSF Grant AGS-1406601 and the US Department of Energy Grant DE-SC0005110. T.B. receives funding from SFB 754, project ‘Climate–Biochemistry Interactions in the tropical Ocean’. M.J.M. is supported by the US National Oceanic and Atmospheric Administration (NOAA). H.-L.R. is supported by the China Meteorological Special Research Project (grant number GYHY201506013). S.I. was supported by the UK–China Research & Innovation Partnership Fund through the Met Office Climate Science for Service Partnership (CSSP) China as part of the Newton Fund. M.F.S. acknowledges support from the NOAA Climate and Global Change Postdoctoral Fellowship Program, administered by UCAR’s Cooperative Programs for the Advancement of Earth System Sciences (CPAESS). H.R. was partly funded by the National Environmental Science Program, Australia. This is PMEL contribution number 4723. The authors thank the TAO Project Office of NOAA/PMEL for providing the TAO/TRITON 20 °C isotherm depth anomaly data shown in Fig. 5.

Reviewer information

Nature thanks M. L'Heureux, X. Rodo and A. Tudhope for their contribution to the peer review of this work.

Author information




The manuscript was written as a group effort during the ‘El Niño Complexity workshop’, held at Pusan National University from 16 to 20 October 2017. All authors contributed to the manuscript preparation and the discussions that led to the final figure selection. A.T., J.-S.K., S.-I.A. and F.-F.J. designed the study and served as coordinating lead authors for the sections ‘ENSO predictability’, ‘Space–time complexity of ENSO’, ‘A conceptual view of ENSO dynamics’ and ‘A unifying framework’, respectively. A.T. oversaw the writing of each section, preparation of figures and selection of references. W.C., A.C. K.M.C., M.L., M.J.M, M.F.S and A.T.W. served as coordinating lead authors for various sections.

Corresponding author

Correspondence to Axel Timmermann.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Timmermann, A., An, SI., Kug, JS. et al. El Niño–Southern Oscillation complexity. Nature 559, 535–545 (2018). https://doi.org/10.1038/s41586-018-0252-6

Download citation

Further reading


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.


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