Abstract
If three assumptions shown in the text are adopted, we can replicate the δ18O-derived observations of ice mass evolution. Our results suggest that the large free oscillations with 100 kyr period may be governing the most predominant oscillations in the actual climate, and that the effect of variation in CO2 which would be induced by the link between biological action and the Milankovitch insolation variation would be superposed non-linearly on the free oscillation system with phase lock of the major variation, and play an important role in an apprearance of the real δ18O data.
