HR: 10:50h
AN: PP12B-03    [Abstracts]
TI: Effects Of The Thermohaline Circulation Slowdown On Vegetation And Climate Around The Tropical Atlantic During The Younger Dryas Period
AU: * Hermann, B
EM: Hermann.Behling@uni-bremen.de
AF: University of Bremen, Department of Geosciences P.O. Box 330440, Bremen, 28334 Germany
AU: Lydie, D M
EM: dupont@uni-bremen.de
AF: University of Bremen, Department of Geosciences P.O. Box 330440, Bremen, 28334 Germany
AB: The Younger Dryas (YD) event is thought to be caused by a slowdown of the thermohaline circulation as a result of large input of freshwater into the Arctic Ocean (Tarasov and Peltier 2005). Decreased heat transport to the Arctic region would have resulted in higher sea surface temperatures of the tropical Atlantic (Rühlemann et al. 1999). Modelling studies show that a weaker Atlantic overturning circulation thus has consequences for the amount and geographical distribution of rain fall over and around the tropical Atlantic (Lohmann 2003). According to this study, northern South America would have become drier and eastern Brazil wetter. No significant changes in rainfall were predicted for Africa. We test these predictions comparing pollen studies from Africa, South America and the tropical Atlantic. Terrestrial and marine pollen sequences record changes in the tropical vegetation which responds to changes in precipitation. In south and south-eastern Brazil, a transect of three pollen sequences document the southern limit of a positive precipitation anomaly during the latter part of the YD period (Behling et al. 2004, 2005, unpublished data). In Africa, a dry YD period is recorded in Nigeria and Ghana (Talbot and Johannessen 1992, Salzmann et al. 2002). However, in Cameroon (Maley and Brenac 1998) and offshore Angola (Dupont and Behling in press) vegetation records are unambiguous or do not show changes in precipitation regime during the YD period.
DE: 1620 Climate dynamics (0429, 3309)
DE: 4901 Abrupt/rapid climate change (1605)
DE: 4950 Paleoecology
DE: 4952 Palynology
DE: 4962 Thermohaline
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005