Rapid termination of the African Humid Period triggered by northern high-latitude cooling

James A. Collins*, Matthias Prange, Thibaut Caley, Luis Gimeno, Britta Beckmann, Stefan Mulitza, Charlotte Skonieczny, Didier Roche, Enno Schefuß

*Corresponding author for this work

Research output: Contribution to JournalArticleAcademicpeer-review

Abstract

The rapidity and synchrony of the African Humid Period (AHP) termination at around 5.5 ka are debated, and it is unclear what caused a rapid hydroclimate response. Here we analysed the hydrogen isotopic composition of sedimentary leaf-waxes (δDwax) from the Gulf of Guinea, a proxy for regional precipitation in Cameroon and the central Sahel-Sahara. Our record indicates high precipitation during the AHP followed by a rapid decrease at 5.8-4.8 ka. The similarity with a δDwax record from northern East Africa suggests a large-scale atmospheric mechanism. We show that northern high- and mid-latitude cooling weakened the Tropical Easterly Jet and, through feedbacks, strengthened the African Easterly Jet. The associated decrease in precipitation triggered the AHP termination and combined with biogeophysical feedbacks to result in aridification. Our findings suggest that extratropical temperature changes, albeit smaller than during the glacial and deglacial, were important in triggering rapid African aridification during the Holocene.

Original languageEnglish
Article number1372
Number of pages11
JournalNature Communications
Volume8
Issue number1
DOIs
Publication statusPublished - 2017

Funding

J.A.C. was supported by the Helmholtz Postdoc Programme (PD-001) and the Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Bremerhaven. E.S., B.B. and M.P. were supported by the German Science Foundation (DFG) within the Priority Programme (SPP) 1266“Interdynamic” (Sche903/9; PR1050/4) and the DFG Research Center/Cluster of Excellence “The Ocean in the Earth System” at MARUM–Center for Environmental Sciences. T.C. and D.R. are supported by CNRS-INSU. C.S. was partly supported by a Grant from the French government through Agence Nationale de la Recherche (ANR) under the ‘Investissements d’Avenir’ programme, reference ANR-10-LABX-19-0. CCSM3 model experiments were performed on the HLRN supercomputer. We thank Raquel Nieto for her assistance with the FLEX-PART computations. J.A.C. is grateful to Yannick Garcin and Jule Müller for discussion.

FundersFunder number
German Science Foundation
Helmholtz Postdoc ProgrammePD-001
MARUM
Deutsche ForschungsgemeinschaftPR1050/4, Sche903/9
Agence Nationale de la RechercheANR-10-LABX-19-0
Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research

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