Drier tropical and subtropical Southern Hemisphere in the mid-Pliocene Warm Period


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Christian.Stepanek [ at ] awi.de

Abstract

Thermodynamic arguments imply that global mean rainfall increases in a warmer atmosphere; however, dynamical effects may result in more significant diversity of regional precipitation change. Here we investigate rainfall changes in the mid-Pliocene Warm Period (~ 3 Ma), a time when temperatures were 2–3ºC warmer than the pre-industrial era, using output from the Pliocene Model Intercomparison Projects phases 1 and 2 and sensitivity climate model experiments. In the Mid-Pliocene simulations, the higher rates of warming in the northern hemisphere create an interhemispheric temperature gradient that enhances the southward cross-equatorial energy flux by up to 48%. This intensified energy flux reorganizes the atmospheric circulation leading to a northward shift of the Inter-Tropical Convergence Zone and a weakened and poleward displaced Southern Hemisphere Subtropical Convergences Zones. These changes result in drier-than-normal Southern Hemisphere tropics and subtropics. The evaluation of the mid-Pliocene adds a constraint to possible future warmer scenarios associated with differing rates of warming between hemispheres.



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Article
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ISI/Scopus peer-reviewed
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Published
Eprint ID
52825
DOI 10.1038/s41598-020-68884-5

Cite as
Pontes, G. M. , Wainer, I. , Taschetto, A. S. , Sen Gupta, A. , Abe-Ouchi, A. , Brady, E. C. , Chan, W. L. , Chandan, D. , Contoux, C. , Feng, R. , Hunter, S. J. , Kame, Y. , Lohmann, G. , Otto-Bliesner, B. L. , Peltier, W. R. , Stepanek, C. , Tindall, J. , Tan, N. , Zhang, Q. and Zhang, Z. (2020): Drier tropical and subtropical Southern Hemisphere in the mid-Pliocene Warm Period , Scientific Reports, 10 (13458) . doi: 10.1038/s41598-020-68884-5


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