Ice Ages: When the World Chills Out

Imagine the Earth: temperatures below freezing and covered completely in ice. Our last ice age may have ended around 12 000 years ago but it wasn't the only one. The earth has had many ice ages, constantly changing from hot to cold and back again. But what causes this to happen ? and most importantly, are we due for another one? Russ Ferrett, author of Builders of the Past and When the Earth Moves: Earthquakes & Volcanoes, takes us on an icy journey through what really happened in the ice ages. Where does snow and ice come from? How do glaciers form, grow and move? And what happens when an ice age ends and everything begins to melt?