Insolation Cause of Long-Period Climate Changes

In the middle of the 19th century, insolation oscillations at high latitudes, which are due to the precession of the Earthʼs axis of rotation, were put forward as the cause of the Ice Ages. A quarter of a century later, the eccentricity of the orbit was proposed as an additional factor. In the first third of the 20th century, M. Milanković developed the astronomical theory of climate change, which determines insolation fluctuations depending on three parameters of the Earth’s orbit. However, the insolation oscillations were small, and the extremes did not coincide with warming and cooling of the paleoclimate. At the end of the 20th century, this theory was analyzed by me; the problems included in it had been solved in a new way. Later, I additionally solved the problem of the evolution of the Earthʼs rotation axis. Taking it into account, insolation fluctuations increased 7–8 times, and extremes coincided with cooling and warming of the paleoclimate. This article considers insolation periods of climate change over 20 million years and the epochs of their onset and their duration. Insolation periods are compared with paleoclimate fluctuations over 250 000 years, and their coincidence is established. Changes in annual insolation and average annual temperature are considered. Based on various characteristics of insolation, the main properties of insolation periods are formulated. Annual and summer temperatures vary within such limits that can lead either to glaciations of territories almost to the middle latitudes or to the complete melting of polar ice. In the process of climate fluctuations, certain territories are flooded, both within the continents and on the shores of the seas. As a result, alternating layers of deposits and soil are formed. They capture the frequency of changes in insolation.