Clim. Past Discuss., 9, 5391-5438, 2013
© Author(s) 2013. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper is under review for the journal Climate of the Past (CP).
Impact of precession on the climate, vegetation and fire activity in southern Africa during MIS4
M.-N. Woillez1,2,3, G. Levavasseur4, A.-L. Daniau3, M. Kageyama5, D. H. Urrego1,2,3, and M.-F. Sánchez-Goñi2
1Centre National de la Recherche Scientifique (CNRS), Environnements et Paléocenvironements Océaniques et Continentaux (EPOC), Unité Mixte de Recherche – UMR5805, Université Bordeaux 1, 33400 Talence, France
2Ecole Pratique des Hautes Etudes (EPHE), EPOC – UMR5805, 33400 Talence, France
3CNRS, de la Préhistoire à l'Actuel: Culture, Environnement et Anthropologie, ACEA – UMR5199, 33400 Talence, France
4Institut Pierre Simon Laplace, Pôle de Modélisation du Climat, Université Pierre et Marie Curie, 4 Place Jussieu, Paris, France
5LSCE/IPSL INSU – UMR8212, CE Saclay, l'Orme des Merisiers, 91191 Gif-sur-Yvette Cedex, France

Abstract. The relationships between climate, vegetation and fires are a major subject of investigation in the context of climate change. In southern Africa, fire is known to play a crucial role in the existence of grasslands and Mediterranean-like biomes. Microcharcoal-based reconstructions of past fire activity in that region have shown a tight correlation between grass-fueled fires and the precessional cycle, with maximum fire activity during maxima of the climatic precession index. These changes have been interpreted as the result of changes in fuel load in response to precipitation changes in eastern southern Africa. Here we use the general circulation model IPSL_CM5A and the dynamical vegetation model LPJ-LMfire to investigate the response of climate, vegetation and fire activity to precession changes in southern Africa during Marine Isotopic Stage 4. We perform two climatic simulations, for a maximum and minimum of the precession index, and use a statistical downscaling method to increase the spatial resolution of the IPSL_CM5A outputs over southern Africa and perform high-resolution simulations of the vegetation and fire activity. Our results show an anti-correlation between the North and South African monsoons in response to precession changes. A decrease of the precession climatic index leads to a precipitation decrease in the summer rainfall area of southern Africa. The drying of climate leads to a decrease of vegetation cover and fire activity. Our results are in qualitative agreement with data and confirm that fire activity in southern Africa is strongly dependent on the vegetation type.

Citation: Woillez, M.-N., Levavasseur, G., Daniau, A.-L., Kageyama, M., Urrego, D. H., and Sánchez-Goñi, M.-F.: Impact of precession on the climate, vegetation and fire activity in southern Africa during MIS4, Clim. Past Discuss., 9, 5391-5438, doi:10.5194/cpd-9-5391-2013, 2013.
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