Only in the ice ages..............

Geologic history[edit]

Ice cap climates have only existed in ice ages. There have been at least five such ice ages in the Earth's past. Outside these ages, the Earth seems to have been ice-free even in high latitudes.^[6][7] By the geologic definition, Earth is currently in an ice age, in that the planet has permanent ice caps. Factors that cause ice ages include changes to the atmosphere, the arrangement of continents, the energy received from the sun, volcanos, and meteor impacts.

The current era is believed to be the only time in the last 600 million years of Earth's history with ice caps at both poles.^{[citation needed]} The Antarctic ice cap was formed after Antarctica split from South America, allowing the formation of the Antarctic Circumpolar Current. The Arctic ice cap was partially caused by the Azolla event, where a large number of ferns in the ocean died, sank, and never decayed, which trapped carbon dioxide beneath the ocean.^{[citation needed]}

There is a hypothesis that around 650 million years ago, the entire planet was frozen, called Snowball Earth. Essentially the entire planet had an ice cap climate. However, this theory is disputed, and even proponents suggest there was an area of periodic melting near the equator.^[cit