Question: What causes ice ages?

Amy Birch answered on 19 Jun 2012:

Hi meg123,
That’s an interesting question, and scientists have different opinions about it!
Usually what happens is that we stop having summers, or our summer start to get a lot cooler rather than winters getting a lot colder.
The earth spins on it’s axis in a wobbly way (like a spinning top) which means that there is quite a big variation in which part and how much of the earth is facing the sun which then affects the temperature of the earth. This wobble, and the fact that the earth is tilted on its axis, can cause an increase summers that happen when the sun is further away from the earth, which makes the summers a lot colder.
Once it’s already cold, it’s harder for the earth to heat up again because the ice that has built up reflects away the sun’s energy instead of absorbing it, meaning that the earth stays colder for longer.
Another factor could be the amount of dust and smoke in the atmosphere – if there were a lot a volcano eruptions or big meteor strikes, this may cause dust and smoke to be trapped in the air for a long time which would block out the sun and cause the earth to cool down.
Hope this answers your question! 🙂