Universität zu Köln

Norstrom, Elin, Noren, Gabriel, Smittenberg, Rienk H., Massuanganhe, Elidio A. and Ekblom, Anneli ORCID: 0000-0001-9248-5516 (2018). Leaf wax delta D inferring variable medieval hydroclimate and early initiation of Little Ice Age (LIA) dryness in southern Mozambique. Glob. Planet. Change, 170. S. 221 - 234. AMSTERDAM: ELSEVIER SCIENCE BV. ISSN 1872-6364

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Abstract

A sediment sequence from a coastal, hydrologically isolated lake in southern Mozambique was analysed for leaf wax delta D, n-alkane abundance (ACL) and bulk organic geochemistry (delta C-13, TOC, %N), providing a record of past rainfall variability and savanna dynamics over the last 1500 years. The delta D-wax a rainfall reconstruction reveals a stable hydroclimate between 500-700 CE, while ACL and delta C-13 together with previous pollen data suggest savanna vegetation was characterized by a relatively dense woody cover. Highly variable hydroclimate conditions are inferred by delta D-wax between 800-1350 CE, with repeated centennial scale intervals of extreme dry and wet conditions overlapping the Medieval Climate Anomaly (MCA; 950-1250 CE). Savanna tree cover stayed relatively intact over this phase. After ca 1250 CE, a progressive change towards drier conditions was initiated, leading up to maximum aridity during the AD 1700s, a period associated with the Little Ice age (LIA; 1500-1850 CE). Tree cover was now replaced by a more grass-dominated savanna. The clear antiphase rainfall patterns between Nhaucati and equatorial East African proxy records gives support to the notion that Indian Ocean sea surface temperature (SST) gradients act as modulator of southern African climate on a multi-decadal time scale, possibly forced by long-term El Nino Southern Oscillation (ENSO) variability. We suggest that strong ENSO variability and greater occurrence of La Nina events triggered the generally wet and unstable MCA in southern Africa. From around 1250 CE, a shift towards a predominance of El Nino induced drier conditions in south-east Africa during the LIA. Our study of vegetation and hydroclimate proxies in parallel suggests that savanna tree and shrub cover was relatively resilient to the abrupt shifts in hydroclimate over the MCA, but more sensitive to the long-term progressive drying over the LIA.

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Norstrom, Elin UNSPECIFIED UNSPECIFIED UNSPECIFIED Noren, Gabriel UNSPECIFIED UNSPECIFIED UNSPECIFIED Smittenberg, Rienk H. UNSPECIFIED UNSPECIFIED UNSPECIFIED Massuanganhe, Elidio A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Ekblom, Anneli UNSPECIFIED orcid.org/0000-0001-9248-5516 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-166946
DOI:	10.1016/j.gloplacha.2018.09.004
Journal or Publication Title:	Glob. Planet. Change
Volume:	170
Page Range:	S. 221 - 234
Date:	2018
Publisher:	ELSEVIER SCIENCE BV
Place of Publication:	AMSTERDAM
ISSN:	1872-6364
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language BREONADIA-SALICINA TREES; WINTER RAINFALL ZONE; N-ALKANES RECORD; EL-NINO; CLIMATE VARIABILITY; VEGETATION DYNAMICS; INDIAN-OCEAN; PRECIPITATION VARIABILITY; TERRESTRIAL PLANTS; ESTUARINE SYSTEM Multiple languages Geography, Physical; Geosciences, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/16694