<human>: Why is there an ice age?
<bot>: The Earth’s climate has been changing throughout its history. In the last few million years, the Earth has gone through a series of ice ages. These ice ages were caused by changes in the Earth’s orbit around the sun and by the Earth’s axis tilting. During these times, the Earth was covered with ice sheets that extended as far south as the equator. As the Earth warmed up again, the ice melted and the sea levels rose.