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.

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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.

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

Author information


  1. Center for Climate Physics, Institute for Basic Science (IBS), Busan, South Korea

    • Axel Timmermann
    • , Karl Stein
    • , Kyung-Sook Yun
    • , June-Yi Lee
    •  & Elke Zeller
  2. Pusan National University, Busan, South Korea

    • Axel Timmermann
    • , Karl Stein
    • , Kyung-Sook Yun
    • , June-Yi Lee
    •  & Elke Zeller
  3. International Pacific Research Center, University of Hawaii at Manoa, Honolulu, HI, USA

    • Axel Timmermann
    •  & Tim Li
  4. Department of Atmospheric Sciences, Yonsei University, Seoul, South Korea

    • Soon-Il An
  5. Division of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang, South Korea

    • Jong-Seong Kug
    • , Sunyong Kim
    •  & Woo-Hyun Yang
  6. Department of Atmospheric Science, SOEST, University of Hawaii at Manoa, Honolulu, HI, USA

    • Fei-Fei Jin
    • , Michiya Hayashi
    •  & Tim Li
  7. CSIRO Oceans and Atmosphere, Aspendale, Victoria, Australia

    • Wenju Cai
    • , Harun Rashid
    •  & Guojian Wang
  8. Physical Oceanography Laboratory/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao, China

    • Wenju Cai
  9. Centre for Southern Hemisphere Oceans Research (CSHOR), CSIRO Oceans and Atmosphere, Hobart, Tasmania, Australia

    • Wenju Cai
  10. Cooperative Institute for Research in Environmental Science, University of Colorado, Boulder, CO, USA

    • Antonietta Capotondi
  11. Physical Sciences Division, NOAA Earth System Research Laboratory, Boulder, CO, USA

    • Antonietta Capotondi
  12. Earth and Atmospheric Sciences, Georgia Tech, Atlanta, GA, USA

    • Kim Cobb
  13. LOCEAN/IPSL, Sorbonne Universités/UPMC-CNRS-IRD-MNHN, Paris, France

    • Matthieu Lengaigne
  14. Pacific Marine Environmental Laboratory/NOAA, Seattle, WA, USA

    • Michael J. McPhaden
  15. Department of Atmospheric Sciences, University of Washington, Seattle, WA, USA

    • Malte F. Stuecker
  16. Cooperative Programs for the Advancement of Earth System Science, University Corporation for Atmospheric Research, Boulder, CO, USA

    • Malte F. Stuecker
  17. Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, NJ, USA

    • Andrew T. Wittenberg
  18. GEOMAR Helmholtz Centre for Ocean Research, Kiel, Germany

    • Tobias Bayr
  19. Department of Atmospheric Sciences, National Taiwan University, Taipei, Taiwan

    • Han-Ching Chen
  20. Department of Plants, Soils, and Climate, Utah State University, Logan, UT, USA

    • Yoshimitsu Chikamoto
  21. Centro de Estudios Avanzado en Zonas Áridas (CEAZA), Coquimbo, Chile

    • Boris Dewitte
  22. Laboratoire d’Etudes en Géophysique et Océanographie Spatiale, Toulouse, France

    • Boris Dewitte
  23. School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria, Australia

    • Dietmar Dommenget
    •  & Shayne McGregor
  24. Department of Earth and Environmental Sciences, University of Mary Washington, Fredericksburg, VA, USA

    • Pamela Grothe
  25. Laboratoire d’Océanographie et du Climat: Expérimentation et Approches Numériques (LOCEAN), IRD/UPMC/CNRS/MNHN, Paris, France

    • Eric Guilyardi
    •  & Yann Planton
  26. NCAS-Climate, University of Reading, Reading, UK

    • Eric Guilyardi
  27. Department of Oceanography, Chonnam National University, Gwangju, South Korea

    • Yoo-Geun Ham
  28. Met Office Hadley Centre, Exeter, UK

    • Sarah Ineson
  29. School of Urban and Environmental Engineering, Ulsan National Institute of Science and Technology, Ulsan, South Korea

    • Daehyun Kang
  30. Climate Prediction Department, APEC Climate Center, Busan, South Korea

    • WonMoo Kim
  31. Australian Bureau of Meteorology, Melbourne, Victoria, Australia

    • Jing-Jia Luo
    • , Scott Power
    •  & Guomin Wang
  32. Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, Beijing, China

    • Hong-Li Ren
  33. ARC Centre of Excellence for Climate System Science, Faculty of Science, University of New South Wales, Sydney, New South Wales, Australia

    • Agus Santoso
  34. Instituto Geofisico del Peru, Lima, Peru

    • Ken Takahashi
  35. University of Exeter College of Engineering, Mathematics and Physical Sciences, Exeter, UK

    • Alexander Todd
  36. Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China

    • Ruihuang Xie
  37. Department of Marine Sciences and Convergent Technology, Hanyang University, Ansan, South Korea

    • Sang-Wook Yeh
  38. School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology, Gwangju, South Korea

    • Jinho Yoon
  39. CSIRO Ocean and Atmosphere, Hobart, Tasmania, Australia

    • Xuebin Zhang


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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.C., M.L., M.J.M, M.F.S and A.T.W. served as coordinating lead authors for various sections.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Axel Timmermann.

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