An ice age requires a combination of astronomical and terrestrial causes.

Astronomer-mathematician Milutin Milanković pointed out the periodic changes in the Sun-Earth relationship that occur over short periods of time. Modifications to the Earth’s orbital elements alter the Earth’s climate by changing the angle of incidence of the sun’s rays and the amount of heat radiated to Earth. Thus, we have a succession of wet, cold, snowy winters and cool summers when the snow does not melt in the north.

However, these astronomical (orbital) cycles are not sufficient to cause or stop an ice age, and their effect is only reflected in the alternation of colder and warmer periods. The main causes of ice accumulation are terrestrial factors, and an ice age can develop only if:

– there are seas at the Earth’s poles more or less surrounded by land, i.e. where ice can accumulate; it is also important that there are oceans at the poles or near land of sufficient extent to play a role in the formation of precipitation, which can accumulate as snow;

– the rise of mountain ranges, the position of continents and underwater trenches change the movement of wind and sea currents in such a way that the Earth’s equable climate is broken, and snow and ice accumulation can occur on the high (elevated) landmasses located at middle latitudes;

– the amount of carbon dioxide and other greenhouse gases in the atmosphere decreases, i.e. the greenhouse effect is reduced, and therefore the Earth’s surface temperature is lowered.