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.
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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20 June 2025
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.
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).
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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sciadv.ads3149
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Submitted date: 7 August 2024
Accepted/In Press date: 16 May 2025
Published date: 20 June 2025
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Local EPrints ID: 504092
URI: http://eprints.soton.ac.uk/id/eprint/504092
ISSN: 2375-2548
PURE UUID: 4a4795dd-1bf5-46a7-aa7f-5c0b7c2ded98
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Date deposited: 22 Aug 2025 17:02
Last modified: 23 Aug 2025 02:09
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Author:
Bryce A. Mitsunaga
Author:
Solana Buchanan
Author:
Timothy D. Herbert
Author:
James M. Russell
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