Chapter 1. Geophysical and Geochemical Aspects of Environmental Degradation The environmental system is characterized by an interplay of geophysical and geochemical processes that provide a setting for life. Now that human interventions are affecting the global system as a whole it is important to distinguish between changes of natural origin and changes brought about by human activities. Major difficulties arise in doing this because of the nonlinear and chaotic nature of the interactions between the environmental and human systems. Following an initial review of basic earth science principles this chapter focuses on five fundamental issues that are important in all quarters of the world. Two sections deal with purely atmospheric issues air pollution near the earth’s surface and depletion of ozone in the stratosphere. These sections are followed by a closer look at water pollution and water management. A specific issue acidification of freshwaters and soils is next dealt with in more detail. The final issue addressed in the chapter global climate change requires an analysis of the total environmental system. All of these environmental issues have a bearing on how humankind might be able to secure sustainable development for the future which is touched upon in the concluding section.