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Fundamentally unchanged northwestern African rainfall regimes across the Plio-Pleistocene transition

Fundamentally unchanged northwestern African rainfall regimes across the Plio-Pleistocene transition
Fundamentally unchanged northwestern African rainfall regimes across the Plio-Pleistocene transition
Northern African climate is characterized by strongly contrasting wet summers and dry winters. Dust exported by the northeasterly trade (Harmattan) winds creates marine sedimentary records that have been long interpreted to show that northern African climate became drier and more variable across the Pliocene-Pleistocene boundary [2.58 million years ago (Ma)], when global climate cooled and high-latitude glacial-interglacial cycles intensified. However, questions about the impact of summer rainfall on winter dust fluxes and thus the history of the African summer monsoons remain. We present a leaf wax hydrogen isotope record from offshore northwestern Africa that demonstrates that rainfall regimes remained stable and varied solely in response to 21,000-year cycles in summer insolation from 3.5 to 2.5 Ma. We infer that the summer rains and winter winds respond to different climate forcings, with summer rainfall driven by solar radiation over the northern African landmass and the winter trades affected by high-latitude climate and meridional temperature gradients.
2375-2548
Mitsunaga, Bryce A.
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Jewell, Amy M.
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Buchanan, Solana
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Crocker, Anya
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Wilson, Paul A.
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Herbert, Timothy D.
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Russell, James M.
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Mitsunaga, Bryce A.
63ab4d56-0ac9-4c56-bc89-eeab9e9933b6
Jewell, Amy M.
3de1a5a3-b62c-4069-a06e-b2fedb6456e7
Buchanan, Solana
78852e7e-2663-494d-a4b2-cdea5bddbcb8
Crocker, Anya
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Wilson, Paul A.
f940a9f0-fa5a-4a64-9061-f0794bfbf7c6
Herbert, Timothy D.
d839b710-dbca-4be2-b8c6-c11ace756e91
Russell, James M.
cd58a70f-7997-4313-9c92-cff811825e76

Mitsunaga, Bryce A., Jewell, Amy M., Buchanan, Solana, Crocker, Anya, Wilson, Paul A., Herbert, Timothy D. and Russell, James M. (2025) Fundamentally unchanged northwestern African rainfall regimes across the Plio-Pleistocene transition. Science Advances, 11 (25), [eads3149]. (doi:10.1126/sciadv.ads3149).

Record type: Article

Abstract

Northern African climate is characterized by strongly contrasting wet summers and dry winters. Dust exported by the northeasterly trade (Harmattan) winds creates marine sedimentary records that have been long interpreted to show that northern African climate became drier and more variable across the Pliocene-Pleistocene boundary [2.58 million years ago (Ma)], when global climate cooled and high-latitude glacial-interglacial cycles intensified. However, questions about the impact of summer rainfall on winter dust fluxes and thus the history of the African summer monsoons remain. We present a leaf wax hydrogen isotope record from offshore northwestern Africa that demonstrates that rainfall regimes remained stable and varied solely in response to 21,000-year cycles in summer insolation from 3.5 to 2.5 Ma. We infer that the summer rains and winter winds respond to different climate forcings, with summer rainfall driven by solar radiation over the northern African landmass and the winter trades affected by high-latitude climate and meridional temperature gradients.

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Submitted date: 7 August 2024
Accepted/In Press date: 16 May 2025
Published date: 20 June 2025

Identifiers

Local EPrints ID: 504092
URI: http://eprints.soton.ac.uk/id/eprint/504092
ISSN: 2375-2548
PURE UUID: 4a4795dd-1bf5-46a7-aa7f-5c0b7c2ded98
ORCID for Anya Crocker: ORCID iD orcid.org/0000-0001-9561-5750
ORCID for Paul A. Wilson: ORCID iD orcid.org/0000-0001-6425-8906

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Date deposited: 22 Aug 2025 17:02
Last modified: 23 Aug 2025 02:09

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Contributors

Author: Bryce A. Mitsunaga
Author: Amy M. Jewell
Author: Solana Buchanan
Author: Anya Crocker ORCID iD
Author: Paul A. Wilson ORCID iD
Author: Timothy D. Herbert
Author: James M. Russell

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