How many Ice Ages on Earth?
5 Ice Ages
According to scientific evidence, five major Ice Age periods have been established, beginning with the earliest in the Proterozoic Eon. The next Ice Age occurred in the Cryogenian period. This is probably the most severe in the last billion years. This is followed by a minor Ice Age called the Andean-Saharan, which occurred during the Late Orduvician and the Silurian period. The fourth and fifth Ice Ages are the Karoo Ice Age, which occurred during the Devonian period, and the Pliocene-Quaternary glaciations, which occurred during the late Pliocene period.