Recipient of the ECI Prize 1991 in Limnetic ecology. This book details and summarizes Mooney's intimate and thorough knowledge on recent changes in the physical and biological properties of Planet Earth, their causes and consequences, and the responses to these changes by science and politics. Focal points are the roles played by governmental and non-governmental efforts, as well as by outstanding individuals ("heroes of global change research") in investigating and evaluating changes in climate, hydrological cycles, biodiversity, breakdown of biogrographical boundaries, and a variety of human activities threatening the delicate age-old balances essential for the development and continued existence of life on earth.