Ice Ages: What Causes the Earth to Freeze Over Every Few Million Years?

At least five major ice ages have been documented in Earth's history. And guess what? You're living in an ice age right now. But don’t expect the planet to chill over from pole to pole.

By Avery Hurt
Feb 3, 2021 5:25 PMFeb 3, 2021 5:34 PM
Ice Age photo
(Credit: A.Hornung/Shutterstock)

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Periodically, global temperatures drop, ice sheets form at the poles, then the ice creeps down to cover the continents. We call these ice ages. There have been five major ice ages in Earth’s 4.5-billion-year history. The last one began about 2.5 to 3 million years ago. And get this: it’s still going on. That’s right, we’re living in an Ice Age.

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