Ice on Earth

This is a New Scientist article – go to www.newscientist.com/articles/dn-18949-the-history-of-ice-on-earth.html … which concerns the history of ice on Earth (according to mainstream theory). Again, another learning exercise that allows us to understand the thinking behind the consensus. We are told our planet has three settings. The first one is the greenhouse – when tropical temperatures extend to the poles and ice sheets vanish. Of course, as the Earth is a close system we may suspect something else was going on in order for tropical vegetation to grow in the Arctic circle – something like pole shift (or rapid movement of the continents). The same may apply to the second option – snowball earth. Was this theory dreamed up after the discovery of ice at what is now the equatorial regions? The third option of course is the ice house – where there is some permanent ice (as nowadays) although its extent may vary.