Mid-Pliocene El Niño/Southern Oscillation suppressed by Pacific intertropical convergence zone shift
Pontes, Gabriel M.; Taschetto, Andrea S.; Sen Gupta, Alex; Santoso, Agus; Wainer, Ilana; Haywood, Alan M.; Chan, Wing-Le; Abe-Ouchi, Ayako; Stepanek, Christian; Lohmann, Gerrit; Hunter, Stephen J.; Tindall, Julia C.; Chandler, Mark A.; Sohl, Linda E.; Peltier, W. Richard; Chandan, Deepak; Kamae, Youichi; Nisancioglu, Kerim H.; Zhang, Zhongshi; Contoux, Camille; Tan, Ning; Zhang, Qiong; Otto-Bliesner, Bette L.; Brady, Esther C.; Feng, Ran; von der Heydt, Anna S.; Baatsen, Michiel L. J.; Oldeman, Arthur M.
(2022) Nature Geoscience, volume 15, issue 9, pp.
(Article)
Abstract
The El Niño/Southern Oscillation (ENSO), the dominant driver of year-to-year climate variability in the equatorial Pacific Ocean, impacts climate pattern across the globe. However, the response of the ENSO system to past and potential future temperature increases is not fully understood. Here we investigate ENSO variability in the warmer climate
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of the mid-Pliocene (~3.0–3.3 Ma), when surface temperatures were ~2–3 °C above modern values, in a large ensemble of climate models—the Pliocene Model Intercomparison Project. We show that the ensemble consistently suggests a weakening of ENSO variability, with a mean reduction of 25% (±16%). We further show that shifts in the equatorial Pacific mean state cannot fully explain these changes. Instead, ENSO was suppressed by a series of off-equatorial processes triggered by a northward displacement of the Pacific intertropical convergence zone: weakened convective feedback and intensified Southern Hemisphere circulation, which inhibit various processes that initiate ENSO. The connection between the climatological intertropical convergence zone position and ENSO we find in the past is expected to operate in our warming world with important ramifications for ENSO variability.
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Keywords: Taverne
ISSN: 1752-0894
Publisher: Nature Publishing Group
Note: Funding Information: This work was supported by the São Paulo Research Foundation (FAPESP-Brazil grants no. 2016/23670-0, no. 2019/0882-1 and no. 2021/11035-6), the Australian Research Council (ARC FT160100495) including the ARC Centre of Excellence for Climate Extremes (CE110001028) and the NCI National Facility, Canberra. A.S. is supported by CSHOR, a joint research centre between QNLM and CSIRO, and the Australian Government’s National Environmental Science Program. PlioMIP2 experiments were supported by FP7 Ideas Programme: European Research Council, Past Earth Network, CEMAC—University of Leeds, JSPS, Earth Simulator at JAMSTEC, Helmholtz Climate Initiative REKLIM, Alfred Wegener Institute’s research programme Marine, Coastal and Polar Systems, Swedish Research Council, Swedish National Infrastructure for Computing, Canadian Innovation Foundation, UNINETT Sigma2—the National Infrastructure for High Performance Computing and Data Storage in Norway, Très Grand Centre de calcul du CEA—GENCI, National Science Foundation (NSF—USA), SURFsara Dutch National Computing and Netherlands Organisation for Scientific Research, Exact Sciences. This research is sponsored by National Science Foundation Grants 2103055 to R.F. and 1418411 to B.O.-B. The CESM project is supported primarily by the National Science Foundation. This material is based on work supported by NCAR, which is a major facility sponsored by the National Science Foundation under Cooperative Agreement 1852977. Computing and data storage resources, including the Cheyenne supercomputer (https://doi.org/10.5065/D6RX99HX), were provided by the Computational and Information Systems Laboratory (CISL) at NCAR. Funding Information: This work was supported by the São Paulo Research Foundation (FAPESP-Brazil grants no. 2016/23670-0, no. 2019/0882-1 and no. 2021/11035-6), the Australian Research Council (ARC FT160100495) including the ARC Centre of Excellence for Climate Extremes (CE110001028) and the NCI National Facility, Canberra. A.S. is supported by CSHOR, a joint research centre between QNLM and CSIRO, and the Australian Government’s National Environmental Science Program. PlioMIP2 experiments were supported by FP7 Ideas Programme: European Research Council, Past Earth Network, CEMAC—University of Leeds, JSPS, Earth Simulator at JAMSTEC, Helmholtz Climate Initiative REKLIM, Alfred Wegener Institute’s research programme Marine, Coastal and Polar Systems, Swedish Research Council, Swedish National Infrastructure for Computing, Canadian Innovation Foundation, UNINETT Sigma2—the National Infrastructure for High Performance Computing and Data Storage in Norway, Très Grand Centre de calcul du CEA—GENCI, National Science Foundation (NSF—USA), SURFsara Dutch National Computing and Netherlands Organisation for Scientific Research, Exact Sciences. This research is sponsored by National Science Foundation Grants 2103055 to R.F. and 1418411 to B.O.-B. The CESM project is supported primarily by the National Science Foundation. This material is based on work supported by NCAR, which is a major facility sponsored by the National Science Foundation under Cooperative Agreement 1852977. Computing and data storage resources, including the Cheyenne supercomputer ( https://doi.org/10.5065/D6RX99HX ), were provided by the Computational and Information Systems Laboratory (CISL) at NCAR. Publisher Copyright: © 2022, The Author(s), under exclusive licence to Springer Nature Limited.
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