Global environmental change occupies a central niche in the pantheon of modern sciences. There is an urgent need to know and understand the way in which global biogeochemical cycles have changed over different time scales in the past and are likely to do so in the future. Equally important, it is necessary to determine the extent to which natural variability and that induce by anthropogenic activities are bringing about change. A number of international co-operative scientific programmes ad­ dress these issues. Chief among them are the International Geosphere-Biosphere Programme (IGBP), the World Climate Research Programme (WCRP) and the Inter­ national Human Dimensions Programme (IHDP) for global change. This book is one of a series of IGBP syntheses drawing together findings in global environmental change over the past decade or so. One focus of IGBP activities is the System for Analysis, Research and Training (START). Co-sponsored by the WCRP and IHDP, START establishes regional research networks for global change science in developing countries, stimulates and carries out global change research in developing regions of the world, and builds capacity to undertake such research at personal, institutional and regional levels. Several regional global change networks have been established, and much regional research has been accomplished in the last five years or so. In this book, work relating to four of the older START regions, Southern Africa, South Asia, Southeast Asia and East Asia, will be used as case studies to illustrate regional-global linkages in Earth System Science.