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Robust decrease in El Niño/Southern Oscillation amplitude under long-term warming

Nature Climate Change volume 11, pages 752–757 (2021)Cite this article

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Abstract

El Niño/Southern Oscillation (ENSO) is the primary mode of interannual climate variability, and understanding its response to climate change is critical, but research remains divided on the direction and magnitude of that response. Some twenty-first-century simulations suggest that increased CO2 strengthens ENSO, but studies suggest that on palaeoclimate timescales higher temperatures are associated with a reduced ENSO amplitude and a weaker Pacific zonal temperature gradient, sometimes termed a ‘permanent El Niño’. Internal variability complicates this debate by masking the response of ENSO to forcing in centennial-length projections. Here we exploit millennial-length climate model simulations to disentangle forced changes to ENSO under transient and equilibrated conditions. On transient timescales, models show a wide spread in ENSO responses but, on millennial timescales, nearly all of them show decreased ENSO amplitude and a weakened Pacific zonal temperature gradient. Our results reconcile differences among twenty-first-century simulations and suggest that CO2 forcing dampens ENSO over the long term.

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Fig. 1: Methods used to analyse ENSO in LongRunMIP simulations.
Fig. 2: Percentage changes in ENSO amplitude after a sustained increase in CO2.
Fig. 3: Evolution of ENSO amplitude under increased CO2 for three representative LongRunMIP models.
Fig. 4: Relationship between zonal temperature gradient change and ENSO amplitude change.

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Data availability

All processed data required to reproduce the results of this study are available at https://github.com/ccallahan45/Callahan-et-al_NCC_2021/, archived on Zenodo at https://doi.org/10.5281/zenodo.4718010 (ref. 74). Raw LongRunMIP data are not provided due to large file sizes, but these data are publicly available at https://data.iac.ethz.ch/longrunmip/, with further information available at http://www.longrunmip.org.

Code availability

Analysis code required to reproduce the results of this study is available at https://github.com/ccallahan45/Callahan-et-al_NCC_2021/, archived on Zenodo at https://doi.org/10.5281/zenodo.4718010 (ref. 74).

References

  1. Cayan, D. R., Redmond, K. T. & Riddle, L. G. ENSO and hydrologic extremes in the Western United States. J. Clim. 12, 2881–2893 (1999).

    Article  Google Scholar 

  2. Lehodey, P., Bertignac, M., Hampton, J., Lewis, A. & Picaut, J. El Niño Southern Oscillation and tuna in the western Pacific. Nature 389, 715–718 (1997).

    Article  CAS  Google Scholar 

  3. Harger, J. R. E. ENSO variations and drought occurrence in Indonesia and the Philippines. Atmos. Environ. 29, 1943–1955 (1995).

    Article  CAS  Google Scholar 

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

    Article  CAS  Google Scholar 

  5. Philip, S. & Oldenborgh, G. J. V. Shifts in ENSO coupling processes under global warming. Geophys. Res. Lett. 33, L11704 (2006).

    Article  CAS  Google Scholar 

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

    Article  Google Scholar 

  7. Collins, M. et al. The impact of global warming on the tropical Pacific Ocean and El Nino. Nat. Geosci. 3, 391–397 (2010).

    Article  CAS  Google Scholar 

  8. Cai, W. et al. Increasing frequency of extreme El Niño events due to greenhouse warming. Nat. Clim. Change 4, 111–116 (2014).

    Article  Google Scholar 

  9. Cai, W. et al. Increased frequency of extreme La Niña events under greenhouse warming. Nat. Clim. Change 5, 132–137 (2015).

    Article  Google Scholar 

  10. Cai, W. et al. Increased variability of eastern Pacific El Niño under greenhouse warming. Nature 564, 201–206 (2018).

    Article  CAS  Google Scholar 

  11. Rashid, H. A., Hirst, A. C. & Marsland, S. J. An atmospheric mechanism for ENSO amplitude changes under an abrupt quadrupling of CO2 concentration in CMIP5 models. Geophys. Res. Lett. 43, 1687–1694 (2016).

    Article  CAS  Google Scholar 

  12. Kohyama, T. & Hartmann, D. L. Nonlinear ENSO warming suppression. J. Clim. 30, 4227–4251 (2017).

    Article  Google Scholar 

  13. Wittenberg, A. T. Are historical records sufficient to constrain ENSO simulations? Geophys. Res. Lett. 36, L12702 (2009).

    Article  Google Scholar 

  14. Chen, C., Cane, M. A., Wittenberg, A. T. & Chen, D. ENSO in the CMIP5 simulations: life cycle, diversity, and responses to climate change. J. Clim. 30, 775–801 (2017).

    Article  Google Scholar 

  15. Maher, N., Matei, D., Milinski, S. & Marotzke, J. ENSO change in climate projections: forced response or internal variability? Geophys. Res. Lett. 45, 11390–11398 (2018).

    Google Scholar 

  16. Sun, C. et al. Uncertainties in simulated El Niño–Southern Oscillation arising from internal climate variability. Atmos. Sci. Lett. 19, e805 (2018).

    Article  Google Scholar 

  17. Zheng, X.-T., Hui, C. & Yeh, S.-W. Response of ENSO amplitude to global warming in CESM large ensemble: uncertainty due to internal variability. Clim. Dyn. 50, 4019–4035 (2018).

    Article  Google Scholar 

  18. Meehl, G. A. & Washington, W. M. El Niño-like climate change in a model with increased atmospheric CO2 concentrations. Nature 382, 56–60 (1996).

    Article  CAS  Google Scholar 

  19. Vecchi, G. A. & Soden, B. J. Global warming and the weakening of the tropical circulation. J. Clim. 20, 4316–4340 (2007).

    Article  Google Scholar 

  20. An, S.-I., Kug, J.-S., Ham, Y.-G. & Kang, I.-S. Successive modulation of ENSO to the future greenhouse warming. J. Clim. 21, 3–21 (2008).

    Article  Google Scholar 

  21. Wara, M. W., Ravelo, A. C. & Delaney, M. L. Permanent El Niño-like conditions during the Pliocene warm period. Science 309, 758–761 (2005).

    Article  CAS  Google Scholar 

  22. Fedorov, A. V. et al. The Pliocene paradox (mechanisms for a permanent El Niño). Science 312, 1485–1489 (2006).

    Article  CAS  Google Scholar 

  23. Zhang, Y. G., Pagani, M. & Liu, Z. A 12-million-year temperature history of the tropical Pacific Ocean. Science 344, 84–87 (2014).

    Article  CAS  Google Scholar 

  24. Yang, H. & Zhang, Q. Anatomizing the ocean’s role in ENSO changes under global warming. J. Clim. 21, 6539–6555 (2008).

    Article  Google Scholar 

  25. Ivany, L. C., Brey, T., Huber, M., Buick, D. P. & Schone, B. R. El Niño in the Eocene greenhouse recorded by fossil bivalves and wood from Antarctica. Geophys. Res. Lett. 38, L16709 (2011).

    Article  CAS  Google Scholar 

  26. Seager, R. et al. Strengthening tropical Pacific zonal sea surface temperature gradient consistent with rising greenhouse gases. Nat. Clim. Change 9, 517–522 (2019).

    Article  Google Scholar 

  27. Chung, E.-S. et al. Reconciling opposing Walker circulation trends in observations and model projections. Nat. Clim. Change 9, 405–412 (2019).

    Article  Google Scholar 

  28. Rugenstein, M. et al. LongRunMIP: motivation and design for a large collection of millennial-length AOGCM simulations. Bull. Am. Meteorol. Soc. 100, 2551–2570 (2019).

    Article  Google Scholar 

  29. McPhaden, M. J., Lee, T. & McClurg, D. El Niño and its relationship to changing background conditions in the tropical Pacific Ocean. Geophys. Res. Lett. 38, L15709 (2011).

    Article  Google Scholar 

  30. Stevenson, S., Wittenberg, A. T., Fasullo, J., Coats, S. & Otto-Bliesner, B. Understanding diverse model projections of future extreme El Niño. J. Clim. 34, 449–464 (2020).

    Article  Google Scholar 

  31. Wang, B. et al. Historical change of El Niño properties sheds light on future changes of extreme El Niño. Proc. Natl Acad. Sci. USA 116, 22512–22517 (2019).

    Article  CAS  Google Scholar 

  32. Ng, B., Cai, W., Cowan, T. & Bi, D. Impacts of low-frequency internal climate variability and greenhouse warming on the El Niño-Southern Oscillation. J. Clim. 34, 2205–2218 (2020).

    Article  Google Scholar 

  33. Wyman, D. A., Conroy, J. L. & Karamperidou, C. The tropical pacific ENSO–mean state relationship in climate models over the last millennium. J. Clim. 33, 7539–7551 (2020).

    Article  Google Scholar 

  34. Kohyama, T., Hartmann, D. L. & Battisti, D. S. La Niña-like mean-state response to global warming and potential oceanic roles. J. Clim. 30, 4207–4225 (2017).

    Article  Google Scholar 

  35. Knutson, T. R. & Manabe, S. Time-mean response over the tropical Pacific to increased CO2 in a coupled ocean–atmosphere model. J. Clim. 8, 2181–2199 (1995).

    Article  Google Scholar 

  36. Zhang, L. & Karnauskas, K. B. The role of tropical interbasin SST gradients in forcing Walker circulation trends. J. Clim. 30, 499–508 (2017).

    Article  Google Scholar 

  37. Coats, S. & Karnauskas, K. A role for the equatorial undercurrent in the ocean dynamical thermostat. J. Clim. 31, 6245–6261 (2018).

    Article  Google Scholar 

  38. Olonscheck, D., Rugenstein, M. & Marotzke, J. Broad consistency between observed and simulated trends in sea surface temperature patterns. Geophys. Res. Lett. 47, e2019GL086773 (2020).

  39. Chemke, R. & Polvani, L. M. Opposite tropical circulation trends in climate models and in reanalyses. Nat. Geosci. 12, 528–532 (2019).

    Article  CAS  Google Scholar 

  40. Lloyd, J., Guilyardi, E., Weller, H. & Slingo, J. The role of atmosphere feedbacks during ENSO in the CMIP3 models. Atmos. Sci. Lett. 10, 170–176 (2009).

    Article  Google Scholar 

  41. Lloyd, J., Guilyardi, E. & Weller, H. The role of atmosphere feedbacks during ENSO in the CMIP3 models. Part III: the shortwave flux feedback. J. Clim. 25, 4275–4293 (2012).

    Article  Google Scholar 

  42. Wang, G. et al. Continued increase of extreme El Niño frequency long after 1.5 C warming stabilization. Nat. Clim. Change 7, 568–572 (2017).

    Article  Google Scholar 

  43. Guilyardi, E. et al. Atmosphere feedbacks during ENSO in a coupled GCM with a modified atmospheric convection scheme. J. Clim. 22, 5698–5718 (2009).

    Article  Google Scholar 

  44. Middlemas, E. A., Clement, A. C., Medeiros, B. & Kirtman, B. Cloud radiative feedbacks and El Niño–Southern Oscillation. J. Clim. 32, 4661–4680 (2019).

    Article  Google Scholar 

  45. Bloch-Johnson, J., Rugenstein, M. & Abbot, D. S. Spatial radiative feedbacks from internal variability using multiple regression. J. Clim. 33, 4121–4140 (2020).

    Article  Google Scholar 

  46. Cai, W. et al. Butterfly effect and a self-modulating El Niño response to global warming. Nature 585, 68–73 (2020).

    Article  CAS  Google Scholar 

  47. Tierney, J. E., Haywood, A. M., Feng, R., Battacharya, T. & Otto-Bleisner, B. L. Pliocene warmth consistent with greenhouse gas forcing. Geophys. Res. Lett. 46, 9136–9144 (2019).

    Article  Google Scholar 

  48. Stevenson, S., Fox-Kemper, B., Jochum, M., Rajagopalan, B. & Yeager, S. G. ENSO model validation using wavelet probability analysis. J. Clim. 23, 5540–5547 (2010).

    Article  Google Scholar 

  49. Yeager, S. G., Shields, C. A., Large, W. G. & Hack, J. J. The low-resolution CCSM3. J. Clim. 19, 2545–2566 (2006).

    Article  Google Scholar 

  50. Danabasoglu, G. & Gent, P. R. Equilibrium climate sensitivity: is it accurate to use a slab ocean model? J. Clim. 22, 2494–2499 (2009).

    Article  Google Scholar 

  51. Gent, P. R. et al. The Community Climate System Model version 4. J. Clim. 24, 4973–4991 (2011).

    Article  Google Scholar 

  52. Danabasoglu, G. et al. The CCSM4 ocean component. J. Clim. 25, 1361–1389 (2012).

    Article  Google Scholar 

  53. Rugenstein, M. A. A., Sedlacek, J. & Knutti, R. Nonlinearities in patterns of long-term ocean warming. Geophys. Res. Lett. 43, 3380–3388 (2016).

    Article  Google Scholar 

  54. Voldoire, A. et al. Evaluation of CMIP6 DECK experiments with CNRM-CM6-1. J. Adv. Model. Earth Syst. 11, 2177–2213 (2019).

    Article  Google Scholar 

  55. Donner, L. J., Wyman, B. L. & Hemler, R. S. et al. The dynamical core, physical parameterizations, and basic simulation characteristics of the atmospheric component AM3 of the GFDL Global Coupled Model CM3. J. Clim. 24, 3484–3519 (2011).

    Article  Google Scholar 

  56. Paynter, D., Frolicher, T. L., Horowitz, L. W. & Silvers, L. G. Equilibrium climate sensitivity obtained from multimillennial runs of two GFDL climate models. J. Geophys. Res. Atmos. 123, 1921–1941 (2018).

    Article  Google Scholar 

  57. Dunne, J. P. et al. GFDL’s ESM2 global coupled climate-carbon earth system models. Part I: physical formulation and baseline simulation characteristics. J. Clim. 25, 6646–6665 (2012).

    Article  Google Scholar 

  58. Miller, R. L. et al. CMIP5 historical simulations (1850–2012) with GISS ModelE2. J. Adv. Model. Earth Syst. 6, 441–478 (2014).

    Article  Google Scholar 

  59. Nazarenko, L. et al. Future climate change under RCP emission scenarios with GISS ModelE2. J. Adv. Model. Earth Syst. 7, 244–267 (2015).

    Article  Google Scholar 

  60. Rind, D. et al. Multicentury instability of the Atlantic meridional circulation in rapid warming simulations with GISS ModelE2. J. Geophys. Res. Atmos. 123, 6331–6355 (2018).

    Article  Google Scholar 

  61. Schmidt, G. A. et al. Configuration and assessment of the GISS ModelE2 contributions to the CMIP5 archive. J. Adv. Model. Earth Syst. 6, 141–184 (2014).

    Article  Google Scholar 

  62. Cox, P. M., Betts, R. A., Jones, C. D., Spall, S. A. & Totterdell, I. J. Acceleration of global warming due to carbon-cycle feedbacks in a coupled climate model. Nature 408, 184–187 (2000).

    Article  CAS  Google Scholar 

  63. Cao, L., Duan, L., Bala, G. & Caldeira, K. Simulated long-term climate response to idealized solar geoengineering. Geophys. Res. Lett. 43, 2209–2217 (2016).

    Article  Google Scholar 

  64. Dufresne, J.-L., Foujols, M.-A. & Denvil, S. et al. Climate change projections using the IPSL-CM5 Earth System Model: from CMIP3 to CMIP5. Clim. Dyn. 40, 2123–2165 (2013).

    Article  Google Scholar 

  65. Hasumi, H. & Emori, S. K-1 coupled GCM (MIROC) description. https://ccsr.aori.u-tokyo.ac.jp/~hasumi/miroc_description.pdf (2004).

  66. Yamamoto, A. et al. Global deep-ocean oxygenation by enhanced ventilation in the Southern Ocean under long-term global warming. Glob. Biogeochem. Cycles 29, 1801–1815 (2015).

    Article  CAS  Google Scholar 

  67. Yoshimori, M. et al. A review of progress towards understanding the transient global mean surface temperature response to radiative perturbation. Prog. Earth Planet. Sci. 3, 21 (2016).

    Article  Google Scholar 

  68. Mauritsen, T. et al. Developments in the MPI-M Earth System Model version 1.2 MPI-ESM1.2 and its response to increasing CO2. J. Adv. Model. Earth Syst. 11, 998–1038 (2019).

    Article  Google Scholar 

  69. Rohrschneider, T., Stevens, B. & Mauritsen, T. On simple representations of the climate response to external radiative forcing. Clim. Dyn. 53, 3131–3145 (2019).

    Article  Google Scholar 

  70. Vecchi, G. A. et al. Weakening of tropical Pacific atmospheric circulation due to anthropogenic forcing. Nature 441, 73–76 (2006).

    Article  CAS  Google Scholar 

  71. Rugenstein, M. et al. Equilibrium climate sensitivity estimated by equilibrating climate models. Geophys. Res. Lett. 47, e2019GL083898 (2020).

    Article  Google Scholar 

  72. Huang, P. W. et al. NOAA Extended Reconstruction Sea Surface Temperature (ERSST), Version 5. NOAA National Centers for Environmental Information https://doi.org/10.7289/V5T72FNM (2017).

  73. 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. 108, 4407 (2003).

    Article  Google Scholar 

  74. Callahan, C. W. Robust decrease in ENSO amplitude under long-term warming. Zenodo https://zenodo.org/record/4718010 (2021).

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Acknowledgements

We thank M. Jansen, N. Maher, J. Franke and K. Schwarzwald for helpful discussions and insights. This research was performed as part of the Center for Robust Decision-making on Climate and Energy Policy at the University of Chicago, funded by NSF through the Decision Making Under Uncertainty programme (grant no. SES-1463644 to E.J.M.). Computing resources were provided by the University of Chicago Research Computing Center and Dartmouth College Research Computing. M.R. is funded by the Alexander von Humboldt foundation. This project received funding from the European Research Council under the European Union’s Horizon 2020 research and innovation programme (grant agreement no. 786427, project Couplet) to J.B.-J. Finally, this work would not have been possible without the efforts of the contributors to the LongRunMIP project.

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Authors and Affiliations

  1. Program in Ecology, Evolution, Environment and Society, Dartmouth College, Hanover, NH, USA

    Christopher W. Callahan

  2. Program in Environmental Sciences, Northwestern University, Evanston, IL, USA

    Christopher W. Callahan

  3. Centre for Climate Research, Singapore, Singapore

    Chen Chen

  4. Department of the Geophysical Sciences, University of Chicago, Chicago, IL, USA

    Chen Chen, Jonah Bloch-Johnson & Elisabeth J. Moyer

  5. Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA

    Maria Rugenstein

  6. Max Planck Institute for Meteorology, Hamburg, Germany

    Maria Rugenstein

  7. National Centre for Atmospheric Science, University of Reading, Reading, UK

    Jonah Bloch-Johnson

  8. Danish Meteorological Institute, Copenhagen, Denmark

    Shuting Yang

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Contributions

C.W.C., C.C. and E.J.M. conceptualized the study. C.W.C. and C.C. performed the analyses. J.B.-J., M.R., S.Y. and E.J.M. provided data, analysis tools and feedback on results. C.W.C., C.C. and E.J.M. wrote the manuscript, with all authors providing feedback.

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Correspondence to Chen Chen or Elisabeth J. Moyer.

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Callahan, C.W., Chen, C., Rugenstein, M. et al. Robust decrease in El Niño/Southern Oscillation amplitude under long-term warming. Nat. Clim. Chang. 11, 752–757 (2021). https://doi.org/10.1038/s41558-021-01099-2

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