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Decadal-scale rainfall variability in Ethiopia recorded in an annually laminated, Holocene-age, stalagmite

Baker, Andy; Asrat, Asfawossen; Fairchild, Ian J.; Leng, Melanie J.; Thomas, Louise; Widmann, Martin; Jex, Catherine N.; Dong, Buwen; van Calsteren, Peter and Bryant, Charlotte (2010). Decadal-scale rainfall variability in Ethiopia recorded in an annually laminated, Holocene-age, stalagmite. The Holocene, 20(6) pp. 827–836.

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DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1177/0959683610365934
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Abstract

An annually laminated, uranium-series dated, Holocene stalagmite from southeast Ethiopia has been analysed for growth rate and δ13C and δ18O variations at annual to biennial resolution, in order to provide the first long duration proxy record of decadal-scale rainfall variability in this climatically sensitive region. Our study site (10°N) is climatically influenced by both summer (June—August) and spring (March—May) rainfall caused by the annual movement of the Inter-Tropical Convergence Zone (ITCZ) and modulated by large-scale anomalies in the atmospheric circulation and in ocean temperatures. Here we show that stalagmite growth, episodic throughout the last 7800 years, demonstrates decadal-scale (8—25 yr) variability in both growth rate and δ 18O. A hydrological model was employed and indicates that this decadal variability is due to variations in the relative amounts of rainfall in the two rain seasons. Our record, unique in its combination of length (a total of ~1000 years), annual chronology and high resolution δ18O, shows for the first time that such decadal-scale variability in rainfall in this region has occurred through the Holocene, which implies persistent decadal-scale variability for the large-scale atmospheric and oceanic driving factors.

Item Type: Journal Article
Copyright Holders: 2010 The Authors
ISSN: 1477-0911
Keywords: Ethiopia; Holocene; rainfall; speleothem
Academic Unit/Department: Science
Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 27708
Depositing User: Peter van Calsteren
Date Deposited: 01 Feb 2011 13:05
Last Modified: 24 Nov 2012 21:39
URI: http://oro.open.ac.uk/id/eprint/27708
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