Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 6 3 2010 10.5194/cpd-6-1229-2010 http://www.clim-past-discuss.net/6/1229/2010/ http://www.clim-past-discuss.net/6/1229/2010/cpd-6-1229-2010.html http://www.clim-past-discuss.net/6/1229/2010/cpd-6-1229-2010.pdf 1229 1265 2010-06-29 Sea-surface salinity variations in the Northern Caribbean Sea across the mid-Pleistocene transition S. Sepulcre sepulcre@cerege.fr L. Vidal K. Tachikawa F. Rostek E. Bard CEREGE, UMR6635, Université Aix-Marseille, CNRS, Collège de France, IRD, Europôle de l'Arbois, BP80, 13545 Aix-en-Provence, France This study aimed at documenting climate changes in tropical area in response to the Mid-Pleistocene Transition (MPT) by reconstructing past hydrologic variations in the Northern Caribbean Sea and its influence on the stability of the Atlantic Meridional Overturning Circulation (AMOC) during the last 940 kyr. Using core MD03-2628, we estimated past changes in sea surface salinity (SSS) using Δ<i>δ</i>¹⁸O, the difference between the modern and the past <i>δ</i>¹⁸O of seawater (obtained by combining alkenone thermometer data with the <i>δ</i>¹⁸O of the planktonic <i>foraminifera</i> <i>Globigerinoides ruber</i> (white) and corrected for ice-sheet volume effects). Today, the lowest SSS values in the studied area are associated with the northernmost location of the Inter-Tropical Convergence Zone (ITCZ). The Δ<i>δ</i>¹⁸O record exhibits glacial/interglacial cyclicity with higher values during all glacial periods spanning the last 940 kyr, indicating increased SSS. At a longer timescale, the Δ<i>δ</i>¹⁸O exhibits a shift toward lower values for interglacial periods during the last 450 kyr, when compared to interglacial stages older than 650 kyr. 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