Science et changements planétaires / Sécheresse


Events of persistent dryness in the Mediterranean throughout the last 50 000 years Volume 20, issue 2, avril-mai-juin 2009


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Laboratoire des sciences du climat et de l’environnement UMR 1572 CNRS-UVSQ-CEA domaine du CNRS Avenue de la Terrasse bâtiment 12 91198 Gif-sur-Yvette cedex France, UMR CNRS 8157 Géosystèmes, université de Lille-I 59655 Villeneuve-d’Ascq cedex France, Laboratoire de chronoenvironnement UMR 8249 CNRS 25030 Besançon France

Recent drought and heat waves in the Mediterranean have brought increased attention to high population density and the weakness of water resources. Studying past droughts may supply information to help understand their mechanisms. Mineralogy, pollen records and pollen-based reconstruction from Site ODP 976, collected in the Alboran Sea, show that several droughts occurred during the past 50 kyr. These events correspond to a significant development of semi desertic environments and increased wind from the Saharan arid area. This situation implies atmospheric conditions close to the present day positive situation of the North Atlantic Oscillation (NAO) during these droughts that resulted in a high level of stability over the west Mediterranean and favoured wind transport from the South.