Orbital forcings of the Earth’s climate in wavelet domain

Abstract. 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.