Future changes in the position of the intertropical convergence zone (ITCZ; a narrow band of heavy precipitation in the tropics) with climate change could affect the livelihood and food security of billions of people. Although models predict a future narrowing of the ITCZ, uncertainties remain large regarding its future position, with most past work focusing on zonal-mean shifts. Here we use projections from 27 state-of-the-art climate models and document a robust zonally varying ITCZ response to the SSP3-7.0 scenario by 2100, with a northward shift over eastern Africa and the Indian Ocean and a southward shift in the eastern Pacific and Atlantic oceans. The zonally varying response is consistent with changes in the divergent atmospheric energy transport and sector-mean shifts of the energy flux equator. Our analysis provides insight about mechanisms influencing the future position of the tropical rain belt and may allow for more-robust projections of climate change impacts.
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The data we use in our analysis are all freely available. We use satellite data (monthly precipitation series on a 0.25° × 0.25° grid96 and OLR series on a 1° × 1° grid97 for 1983–2005) and climate model outputs from the sixth phase of the Coupled Model Intercomparison Project39 (CMIP6); see Supplementary Table 1.
Upon reasonable request, the code that supports the findings of this study can be provided by the corresponding author.
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Partial support for this research was provided to E.F.-G., J.T.R. and P.S. by the National Science Foundation (NSF) under the TRIPODS+ programme (DMS-1839336). Moreover, the work of E.F.-G. was supported by NSF under the EAGER programme (grant ECCS-1839441) and by NASA’s Global Precipitation Measurement (GPM) programme (grant 80NSSC19K0684). J.T.R. received support from DOE’s Office of Science RUBISCO Science Focus Area and NASA’s IDS and CMS programmes. J.-Y.Y. and M.S.P. were supported by the NSF Climate and Large-scale Dynamics (CLD) programme under grants AGS-1833075, AGS-173416 and AGS-1912134. The work of P.S., M.S.P., P.A.L. and J.T.R. was also partially supported by NSF under the DGE-1633631 grant. S.Y. was supported by a generous gift to Yale from T. Sandoz. A research grant from UCI to advance these research ideas is also acknowledged. We thank the climate modelling groups around the world for producing and making their model outputs available. We also acknowledge the help from O. Adam and B. Lintner in discussing parts of this analysis.
The authors declare no competing interests.
Peer review information Nature Climate Change thanks Michael Byrne and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Mamalakis, A., Randerson, J.T., Yu, JY. et al. Zonally contrasting shifts of the tropical rain belt in response to climate change. Nat. Clim. Chang. 11, 143–151 (2021). https://doi.org/10.1038/s41558-020-00963-x
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