Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
Clim. Past, 6, 245-264, 2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
14 Apr 2010
Abrupt climate changes of the last deglaciation detected in a Western Mediterranean forest record
W. J. Fletcher1,2, M. F. Sanchez Goñi1, O. Peyron3, and I. Dormoy3 1Ecole Pratique des Hautes Etudes, UMR 5805 CNRS EPOC, Université Bordeaux 1, Avenue des Facultés, 33405 Talence cedex, France
2Institute of Geosciences, Goethe-Universität, Frankfurt am Main 60438, Germany
3CNRS UMR 6249 Laboratoire Chrono-Environnement, Université de Franche-Comté, 16 route de Gray, 25030 Besançon, France
Abstract. Abrupt changes in Western Mediterranean climate during the last deglaciation (20 to 6 cal ka BP) are detected in marine core MD95-2043 (Alboran Sea) through the investigation of high-resolution pollen data and pollen-based climate reconstructions by the modern analogue technique (MAT) for annual precipitation (Pann) and mean temperatures of the coldest and warmest months (MTCO and MTWA). Changes in temperate Mediterranean forest development and composition and MAT reconstructions indicate major climatic shifts with parallel temperature and precipitation changes at the onsets of Heinrich stadial 1 (equivalent to the Oldest Dryas), the Bölling-Allerød (BA), and the Younger Dryas (YD). Multi-centennial-scale oscillations in forest development occurred throughout the BA, YD, and early Holocene. Shifts in vegetation composition and (Pann reconstructions indicate that forest declines occurred during dry, and generally cool, episodes centred at 14.0, 13.3, 12.9, 11.8, 10.7, 10.1, 9.2, 8.3 and 7.4 cal ka BP. The forest record also suggests multiple, low-amplitude Preboreal (PB) climate oscillations, and a marked increase in moisture availability for forest development at the end of the PB at 10.6 cal ka BP. Dry atmospheric conditions in the Western Mediterranean occurred in phase with Lateglacial events of high-latitude cooling including GI-1d (Older Dryas), GI-1b (Intra-Allerød Cold Period) and GS-1 (YD), and during Holocene events associated with high-latitude cooling, meltwater pulses and N. Atlantic ice-rafting. A possible climatic mechanism for the recurrence of dry intervals and an opposed regional precipitation pattern with respect to Western-central Europe relates to the dynamics of the westerlies and the prevalence of atmospheric blocking highs. Comparison of radiocarbon and ice-core ages for well-defined climatic transitions in the forest record suggests possible enhancement of marine reservoir ages in the Alboran Sea by 200 years (surface water age 600 years) during the Lateglacial.

Citation: Fletcher, W. J., Sanchez Goñi, M. F., Peyron, O., and Dormoy, I.: Abrupt climate changes of the last deglaciation detected in a Western Mediterranean forest record, Clim. Past, 6, 245-264, doi:10.5194/cp-6-245-2010, 2010.
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