What is a nother theory for.....?

Question

the cause of ice ages except the Milankovitch theory?

Answer 1

Nobody really knows. Variability of the Sun and other factors have been put forward.

Answer 2

There are a lot of ideas, really, and most of them are pretty viable.

Given how many ice ages Earth has gone through, it's really not likely to be any one factor, but a combonation of a collection of factors.

If a few of these variables get too far out of whack, we get an ice age.

That's my take on it, anyhow.