This book is an attempt to capture the messages in the reports from SCOPE and IPCC as well as some other information and in a way that is accessible to the non-expert reader. The ambition is also to provide the reader with a picture of the different factors that scientists enter into their scenarios of the future. It should particularly interest policy advisors, Scientists in other disciplines and teachers. The decisions called for in a global climate convention have to be made by policy makers worldwide, but the basis for those decisions is the picture painted by scientists.