Proposes and explicates a classification scheme of world environmental problems. Identifies research questions requiring answers. Physical-linkage effects, subdivided into global and regional problems, and social-linkage effects, subdivided into pecuniary and non-pecuniary effects, are each illustrated by examples. (AL)

This entire issue is devoted to the problem of producing enough food for the world population and of distributing it equitably. Areas covered include reports on the latest agricultural research, biological research concerned with more efficient photosynthesis, nutrition, and the world social structure, politics, and economics of food. (MA)