Geophysical processes and biosphere: article

Аnnotation: The results of the new astronomical theory of the paleoclimate are studied for intervals of 1, 5 and 20 million years ago. On the interval of 1 million years, the evolution of the obliquity ε, insolation Qs65N for the summer half-year, insolation I in equivalent latitudes and the evolution of these parameters according to the former theory are considered. The range of the obliquity oscillation ε according to the new theory is from 14.7° to 32.1°, and in the previous theory from 22.08° to 24.45°. That is, the amplitude of the oscillations is increased 7-8 times. In the same respect, the insolation variations increased too. On the basis of the summer insolation Qs65N the six gradations of the climate have been introduced from very cold to very warm. For the interval of 5 million years, the oscillations of the orbital and rotational motion parameters of the Earth and various components of insolation, their periods and amplitudes are considered. The eccentricity of the orbit e varies with periods of 94.6 thousand years, 413 thousand years and 2.31 million years, and the periods of perihelion rotation relative to the equator are uneven and vary from 13.8 to 41.8 thousand years. These periods are also present in changes of the obliquity and insolation. The latitude distributions of the insolation for the summer and the winter caloric half-years and of the annual insolation in three different epochs are considered: the modern, the coldest and the warmest. The greatest changes in summer and annual insolation occur in high latitudes. Statistics of very cold and very warm periods are considered for 20 million years. On average, for 1 million years there can be 6 such periods. In restless intervals of time they can occur 10, and in quiet intervals can be 2. The measuring results of the oxygen isotope 18O content in marine sediments are analyzed. It is shown that they do not agree with the change in the insolation of the Earth, both in the previous theory and in the new one. In addition, variations in the isotope 18O contradict known changes of the paleoclimate. From the analysis of short-period variations of radioactive isotopes, as well as 18O in stalagmites and glacial cores, it follows that variations in 18O in marine sediments can be caused not by fluctuations in the paleoclimate, but by the 18O changes in the Earth’s atmosphere.