The periods in the Earth’s history where the planet is covered in much more ice than today are called ice ages or glacial periods. Currently, we are in between ice ages, we are in an interglacial period. An ice age lasts around 100 thousand years and an interglacial lasts between 15 thousand and 50 thousand years. The last ice age ended about 14 thousand years ago.
This is how the Earth looked – seen from directly above the North Pole – about 20 thousand years ago. The ice sheets are white. Can you see which countries are covered with ice? When the ice sheets are larger, as they are here, we are in an ice age.