Climate of the Past Discussions www.clim-past-discuss.net 1814-9340 1814-9359 1 2 2005 10.5194/cpd-1-193-2005 http://www.clim-past-discuss.net/1/193/2005/ http://www.clim-past-discuss.net/1/193/2005/cpd-1-193-2005.html http://www.clim-past-discuss.net/1/193/2005/cpd-1-193-2005.pdf 193 214 2005-09-23 Orbital forcings of the Earth’s climate in wavelet domain A. V. Glushkov V. N. Khokhlov N. S. Loboda V. D. Rusov V. N. Vaschenko Institute for Applied Mathematics, Department of Computational Mathematics, Odessa, Ukraine Innovative Geosciences Research Centre, Department of Hydrometeorology, Odessa, Ukraine Odessa National Polytechnic University, Department of Theoretical Physics, Odessa, Ukraine Kiev National University, Department of Antarctic Sciences, Kiev, Ukraine We examine two paleoclimate proxy records – the temperature differences from the Antarctic Vostok ice core and the composite δ¹⁸O record from three sites (V19-30, ODP 677, and ODP 846) – in order to search for indications of orbital forcings. We demonstrate that the non-decimated wavelet transform is an appropriate tool for investigating temporarily changing spectral properties of records. Our results indicate that abrupt climate warmings with cyclicity of ~100 kiloyears during the last 400 kiloyears were caused by the combined unidirectional influences of three orbital parameters and the eccentricity can be considered as a modulator defining transitions from the Ice Ages to the periods of comparative warmings. Non-decimated wavelet transform avails discovering the possible part played in climate change by the eccentricity-forced variations. Up to approximately 1.7 million years BP, the influence of this variations of eccentricity appears in increasing for almost all local maxima of δ¹⁸O. Since the ~1.7 million years BP, minor and significant maxima alternated and this not affected as much the variations of δ¹⁸O.