This paper addresses several issues concerning Milankovitch Theory and its relationship to paleoclimate data over the last 800,000 years. The approach taken treats the insolation as it is physically, a time-dependent wave. A parameter free model, based solely on the earth’s celestial motions and the sun’s rays, is presented that partitions the precession index (the precession modulated by the eccentricity) wave and the obliquity wave contributions to the percentage change between successive mean-daily-insolation minima and maxima at 65N latitude during the summer solstice.
The model predictions indicate that the precession index contribution dominates such insolation changes and correlates with the occurrences of interglacial and glacial periods and temperature trends over the last 800,000 years. The predictions also indicate that all interglacial terminations over this period occur in the same manner through synchronized constructive interference of the precession index and obliquity waves. Similarly, all interglacial inceptions coincide with synchronized constructive interference of the precession index and obliquity waves, except for the timing of two inceptions, Marine Isotope Stage (MIS) 18d and 13c.
These specific timing discrepancies are associated with deep ice cores, which have also been noted by Parrenin et al. through a comparison of Lisiecki and Raymo benthic 18O and EPICA Dome C (EDC) ice core datasets. Finally, the model enables the classification of interglacial periods into two distinct types based on wave interference that approximately accounts for their different durations. This classification strongly suggests that the current warm period, MIS 1, is very similar to MIS 19c that occurred about 787,000 years ago. When extended into the future, the repetitive wave pattern deduced from the model also enables an estimate for the Holocene warm period termination of 500 years from present.
Continue reading: Parmentola 2023 Celestial Mechanics Holocene Termination journal by John A. Parmentola.