Fifty million years ago, the Arctic Ocean was a warm sea, bounded by lush vegetation of the warm-temperate shores of Scandinavia, Siberia, Alaska and the Northwest Territories. Wind and storms were rare because Atlantic weather systems had not developed but, as today, polar day length added a hostile element to this otherwise tranquil climate. With the aid of scientists from all the countries close to the Arctic Circle, this book describes the palaeontology, the statistical analysis of vegetational features, comparisons with atmospheric, marine, and geological features and some of the first models of plant migration developed from newly constructed databases.