"Earth Then and Now" records the dramatic way in which our planet has changed in just the past hundred years. It draws on the combined photographic archives of print, picture, and space agencies to create a powerful collection of images. Each pair of photographs has been selected to tell a compelling story - of a melting glacier, an ever-rising cityscape or a natural disaster - presenting a stark visual comparison. On one page, we are shown a part of the world as it was, five, ten, twenty, fifty, or even more than one hundred years ago. On the facing page, we have the same place as it looks today. Concise captions explain the facts and then leave us to draw our own conclusions about the Earth then and now and about the Earth to come.