Health as defined in the World Health Organization's constitution is "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity." The state of health of an individual or population depends upon complex i nteractions of the physical, biological, political, and social domains. Over the past century, human activities and behavior have played a major role in global environmental change, with increases in atmospheric greenhouse gases, depletion of the stratosp heric ozone layer, loss of biodiversity, pollution of water resources, and degradation of soils. In turn, these and other global environmental changes are beginning to affect the health and welfare of human populations. According to the United Nations Env ironment Programme (1992) in Saving Our Planet, "All constituents of the environment of our planet ultimately exert an influence on human health and well-being." Only recently have scientists begun to explore these influences, and most of the liter ature currently available focuses on the effects of climate change.
This guide contains a Human Health Overview that provides information on documents which offer general background. Topics important to human health and global environmental change include loss of biodiversity, malnutrition, population growth, and urbanization. Subsections of this guide present detailed information on several other key issues: