How ice age happen?

Answer 1

The cause of ice ages remains controversial for both the large-scale ice age periods and the smaller ebb and flow of glacial/interglacial periods within an ice age. The general consensus is that it is a combination of several important factors: atmospheric composition (the relative amounts of water vapor, carbon dioxide, methane, sulfur dioxide, and various other gases and particulates in the atmosphere), changes in the Earth's orbit around the Sun known as Milankovitch cycles (and possibly the Sun's orbit around the galaxy), the motion of tectonic plates resulting in changes in the relative location and amount of continental and oceanic crust on the Earth's surface, variations in solar output, the orbital dynamics of the Earth-Moon system, the impact of relatively large meteorites, and eruptions of super volcanoes.