Centennial scale climate instabilities in a wet early Holocene West African monsoon

Weldeab, Syee, Lea, D. W., Schneider, Ralph and Andersen, Nils (2007) Centennial scale climate instabilities in a wet early Holocene West African monsoon Geophysical Research Letters, 34 . L24702. DOI 10.1029/2007GL031898.

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Abstract

A Holocene Gulf of Guinea record of riverine runoff, based on Ba/Ca in tests of a shallow-dwelling planktic foraminifer, and sea surface temperature (SST), based on Mg/Ca, reveals centennial-scale instabilities in West African monsoon (WAM) precipitation and eastern equatorial Atlantic (EEA) thermal conditions. The long-term Holocene climate trend is characterized by a warm and wet early-mid Holocene and gradual drying and cooling during the late Holocene. Superimposed on this trend are numerous centennial scale drops in precipitation during the early-mid Holocene. The greatest declines in early Holocene monsoon precipitation were accompanied by significant SST cooling in the EEA and correlate with drops in air temperature over Greenland and fresh water outbursts into the North Atlantic (NA). This observation suggests that early Holocene climate instabilities in the NA were closely linked to changes in the WAM. The strong imprint of NA events in summer monsoon precipitation suggests that these events were not confined to winter-time. The late Holocene does not show large amplitude changes in riverine runoff at the centennial level. The relatively stable late Holocene conditions likely reflect a weakening and stabilization of the monsoon system, probably due to diminished influence of the NA region due to a reduction in ice sheet.

Document Type: Article
Keywords: Climatology; West African monsoon, riverine discharges, planktic foraminiferal Ba/Ca and Mg/Ca
Research affiliation: OceanRep > The Future Ocean - Cluster of Excellence
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Kiel University
Kiel University > Other > Leibniz-Laboratory for Radiometric Dating and Isotope Research
Refereed: Yes
DOI etc.: 10.1029/2007GL031898
ISSN: 0094-8276
Projects: Future Ocean
Date Deposited: 03 Dec 2008 16:51
Last Modified: 06 Jul 2012 15:02
URI: http://eprints.uni-kiel.de/id/eprint/7649

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