期刊
HOLOCENE
卷 10, 期 3, 页码 293-302出版社
SAGE PUBLICATIONS LTD
DOI: 10.1191/095968300678141274
关键词
lake sediments; aeolian dust; ostracods; palaeolimnology; sahel; West Africa; Holocene
A high-resolution, multiproxy palaeolimnological record from the Manga Grasslands, northeastern Nigeria, spanning the last 5500 calendar years, reveals the episodic deterioration in Sahelian climate as significant biogeophysical thresholds were crossed. Desert-dust deposition began to increase similar to 4700 cal. BP. Rainfall during the summer-monsoon season declined permanently after 4100 cal. BP. A further significant change in atmospheric circulation, giving rise to multidecadal to centennial-scale droughts and enhanced dust deposition, occurred similar to 1500 cal. BP. Hence, the post-1968 Sahel drought is not unique. The prolonged arid episode that occurred around 1200-1000 cal. BP in Ethiopia, the Sahel and tropical Mexico may have been linked to an abrupt cooling event in the North Atlantic and to a cluster of intense El Nino-Southern Oscillation events in the Eastern Equatorial Pacific.
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