Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 3 2 2007 10.5194/cpd-3-679-2007 http://www.clim-past-discuss.net/3/679/2007/ http://www.clim-past-discuss.net/3/679/2007/cpd-3-679-2007.html http://www.clim-past-discuss.net/3/679/2007/cpd-3-679-2007.pdf 679 692 2007-03-26 The origin of the 1500-year climate cycles in Holocene North-Atlantic records M. Debret debret@lgge.obs.ujf-grenoble.fr V. Bout-Roumazeilles F. Grousset M. Desmet J. F. McManus N. Massei D. Sebag J.-R. Petit Y. Copard A. Trentesaux Laboratoire de Glaciologie et de Géophysique de l'Environnement, UMR CNRS 5183, BP96, 38402, St Martin d'Hères, France PBDS Laboratoire, UMR 8110 CNRS, Université de Lille 1, 59 655 Villeneuve d'Ascq, France EPOC, UMR CNRS 5805, Univ. de Bordeaux I, Avenue des Facultés, 33405 Talence, France EDYTEM Laboratoire, UMR 5204, Université de Savoie, CISM, Campus Scientifique 73376 Le Bourget du Lac Cedex, France Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA Laboratoire de Morphodynamique Continentale et Côtière, UMR CNRS 6143, Département de Geologie, Université of Rouen, 76821 Mont-Saint-Aignan Cedex, France Since the first suggestion of 1500-year cycles in the advance and retreat of glaciers (Denton and Karlen, 1973), many studies have uncovered evidence of repeated climate oscillations of 2500, 1500, and 1000 years. During last glacial period, natural climate cycles of 1500 years appear to be persistent (Bond and Lotti, 1995) and remarkably regular (Mayewski et al., 1997; Rahmstorf, 2003), yet the origin of this pacing during the Holocene remains a mystery (Rahmstorf, 2003), making it one of the outstanding puzzles of climate variability. Solar variability is often considered likely to be responsible for such cyclicities, but the evidence for solar forcing is difficult to evaluate within available data series due to the shortcomings of conventional time-series analyses. However, the wavelets analysis method is appropriate when considering non-stationary variability. Here we show by the use of wavelets analysis that it is possible to distinguish solar forcing of 1000- and 2500- year oscillations from oceanic forcing of 1500-year cycles. 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