This book provides a new look at the climatic history of the last 2.6 million years during the ice age, a time of extreme climatic fluctuations that have not yet ended. This period also coincides with important phases of human development from Neanderthals to modern humans, both of whom existed side by side during the last cold stage of the ice age. The ice age has seen dramatic expansions of glaciers and ice sheets, although this has been interspersed with relatively short warmer intervals like the one we live in today. The book focuses on the changing state of these glaciers and the effects of associated climate changes on a wide variety of environments (including mountains, rivers, deserts, oceans and seas) and also plants and animals. For example, at times the Sahara was green and colonized by humans, and Lake Chad covered 350,000 km2 – larger than the United Kingdom. What happened during the ice age can only be reconstructed from the traces that are left in the ground. The work of the geoscientist is similar to that of a detective who has to reconstruct the sequence of events from circumstantial evidence. The book draws on the specialisms and experience of the authors who are experts on the glacial history of the Earth.