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

Baker, Andy; Asrat, Asfawossen; Fairchild, Ian J.; Leng, Melanie J. ORCID: https://orcid.org/0000-0003-1115-5166; Thomas, Louise; Widmann, Martin; Jex, Catherine N.; Dong, Buwen; van Calsteren, Peter; Bryant, Charlotte. 2010 Decadal-scale rainfall variability in Ethiopia recorded in an annually laminated, Holocene-age, stalagmite. The Holocene, 20 (6). 827-836. https://doi.org/10.1177/0959683610365934

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Abstract/Summary

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:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1177/0959683610365934
Programmes:	BGS Programmes 2010 > NERC Isotope Geoscience Laboratory
ISSN:	0959-6836
NORA Subject Terms:	Earth Sciences
Date made live:	10 Sep 2010 15:30 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/10961

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1177/0959683610365934

Programmes:

BGS Programmes 2010 > NERC Isotope Geoscience Laboratory

ISSN:

0959-6836

NORA Subject Terms:

Earth Sciences

Date made live:

10 Sep 2010 15:30 +0 (UTC)