Book excerpt: The Earth as Transformed by Human Action is the culmination of a mammoth undertaking involving the examination of the toll our continual strides forward, technical and social, take on our world. The purpose of such a study is to document the changes in the biosphere that have taken place over the last 300 years, to contrast global patterns of change to those appearing on a regional level, and to explain the major human forces that have driven these changes. The first section deals strictly with the major human forces of the past 300 years and the second is a detailed account of the transformations of the global environment wrought by human action. The final section examines a range of perspectives and theories that purport to explain human actions with regard to the biosphere.