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Climate of East Africa 6000 14C Yr B.P. as Inferred from Pollen Data

Published online by Cambridge University Press:  20 January 2017

Odile Peyron
Affiliation:
CEREGE, Europôle de I'Arbois, B.P. 80, 13545 Aix-en-Provence cedex 04, France, and Institut Méditerranéen d'Ecologie et de Paléoécologie, CNRS, Case 451, 13397 Marseille cedex 20, France
Dominique Jolly
Affiliation:
Dpt Paléoenvironnements et Palynologie, case 61, ISEM, Université Montpellier 2, 34095, Montpellier cedex 5, France
Raymonde Bonnefille
Affiliation:
CEREGE, Europôle de I'Arbois, B.P. 80, 13545, Aix-en-Provence cedex 04, France
Annie Vincens
Affiliation:
CEREGE, Europôle de I'Arbois, B.P. 80, 13545, Aix-en-Provence cedex 04, France
Joël Guiot
Affiliation:
Institut Méditerranéen d'Ecologie et de Paléoécologie, CNRS, Case 451, 13397, Marseille cedex 20, France

Abstract

This paper presents a spatial reconstruction of climate in East Africa at 6000 14C yr B.P. Two different approaches using pollen data have been used, the standard “best modern analogues” method and the new “plant functional type” method, based on groups of pollen taxa. Both methods have been applied to 32 fossil pollen spectra dated at 6000 14C yr B.P. For each site, we have estimated two climatic parameters (annual precipitation and mean annual temperature), three bioclimatic parameters (ratio of actual to potential evapotranspiration, and the mean temperature of the coldest and warmest months). Results show that the temperature lapse rate was less steep at 6000 14C yr B.P. than it is today. The climate was wetter north of 3°S (precipitation anomalies >+50 mm/yr) and slightly drier farther south (precipitation anomalies ≤+50 mm/yr). The ratio of actual to potential evapotranspiration also indicates conditions similar to or wetter than today north of 3°S (anomalies >10%). The climate was warmer than today by 2°C north of the equator and was cooler southward (≤−1°C). Although both methods indicate similar climatic patterns, the plant functional type method provides more consistent results.

Type
Research Article
Copyright
University of Washington

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