It is widely accepted that there is a relationship between ice volume and the solar insolation in summer in the northern hemisphere. The Earth's glacial cycles are driven by cyclic changes in the Earth's orbital elements. This conclusion is based on the strong coherence between the approx. 20000 and 40000 year spectral components of ice volume and insolation (Milankovitch-curve) records. These frequencies are determined by the variation of the obliquity of the Earth's axis and by its position relative to the Earth's orbit around the sun. The degree of sum mer insolation on the Earth's...