Abstract
The termination of the African Humid Period in northern Africa has been described as abrupt, occurring within centuries, as well as gradual, in response to incremental decreases in summer insolation. This study examined the rapidity of the change in diatom assemblages over the period from 6.5 to 4.5 cal ka BP, in a core studied previously at a coarser resolution. This transition was characterized by high variability of assemblages, which could be related, in part, to changes in water conductivity, and potentially enhanced by a site-specific hydrological threshold or ecological salinity threshold. We hypothesize that the variations in diatom assemblages reflect climate fluctuations, which may have been an early warning signal of an impending climate regime shift.
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Acknowledgements
We thank Jean-Charles Mazur (CEREGE) for slide preparation of the new analyzed samples. Sediment core samples were collected under the auspices of CNRS-INSU Programs PNEDC-ERICA (‘Environmental Research for Intertropical Climate in Africa’, R.Bonnefille, coord.), and ECLIPSE-CLEHA (‘CLimat, Environnement et dynamique des populations Humaines en Afrique de l’Est depuis 20,000 ans’, D. Williamson coord.). We are grateful to Keely Mills for valuable comments and suggestions that greatly improved the manuscript, and to an anonymous reviewer for helpful comments.
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Roubeix, V., Chalié, F. New insights into the termination of the African Humid Period (5.5 ka BP) in central Ethiopia from detailed analysis of a diatom record. J Paleolimnol 61, 99–110 (2019). https://doi.org/10.1007/s10933-018-0047-7
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DOI: https://doi.org/10.1007/s10933-018-0047-7