A New Theory of Change in the Insolation of the Earth over Millions of Years against Marine Isotope Stages

Abstract

Results from a new astronomical theory of paleoclimate for the last 1, 5, and 20 Myr are presented. Evolutions of obliquity e and insolation at 65°N $$Q_{s}^{{65\,{\text{N}}}}$$ are considered for the summer half year and insolation I at equivalent latitudes over the last 1 Myr; the results are compared with the evolution of these parameters obtained from the former theory. The oscillations in the obliquity e range from 14.7° to 32.1° according to the new theory and from 22.08° to 24.45° according to the former theory; i.e., the amplitude of oscillations have increased 7–8 times. The insolation oscillations have increased to the same extent. The summer insolation $$Q_{s}^{{65\,{\text{N}}}}$$ was used to introduce six (from very cold to very warm) climate gradations. Oscillations in the parameters of orbital and rotational motions of the Earth and various insolation components, as well as their periods and amplitudes, are considered for the last 5 Myr. Orbit eccentricity e varies with periods of 94.6 kyr, 413 kyr, and 2.31 Myr, while the periods of perihelion rotation relative to the equator are nonuniform and vary from 13.8 to 41.8 kyr. These periods can also be found in changes in the obliquity and insolation. The distribution of insolation over the Earth’s latitude for the summer and winter caloric half-years and for the year in three different (modern, coldest, and warmest) epochs is considered. The maximum changes in summer and annual insolation occur at high latitudes. The statistics of coldest and warmest periods are considered for the last 20 Myr. On average, there can be six such periods per 1 Myr; their number can reach 10 in unquiet time intervals and can decrease to 2 in quiet time intervals. The results of measurements of the oxygen isotope 18O content in marine sediments are analyzed. The content of 18O is shown to be inconsistent with the change in the Earth’s insolation according to both the former theory and the new one; in addition, the variation in 18O is inconsistent with known paleoclimate changes. An analysis of short-period variations in radioactive isotopes, as well as 18O in stalagmites and glacial cores, indicates that variations in 18O in marine sediments can be caused by a change in the 18O content in the Earth’s atmosphere, rather than by climate fluctuations.