The atmosphere is a local, regional, and global commons. Many scientists have described the atmosphere as suffering from a “tragedy of the commons,” and environmentalists widely claim that the tragedy has become more of a horror film due to the threats of (1) transboundary air pollution, (2) stratospheric ozone depletion, and (3) climate change. While this course examines these three threats from a wide range of perspectives, it mostly takes a combined historical and policy approach to understanding international conflict and cooperation over the atmosphere. The course primarily aims to answer two overarching questions: First, what has the international community done in order to protect the atmosphere, and what should it be doing now? An important part of answering this question is to discern what we mean by “international community,” and to emphasize that it does not only refer to countries and international organizations. Second, and very importantly, what does “protecting the atmosphere” actually mean from the perspective of international environmental policy? One response to the latter question will constitute a key theme of the course—viz., that there are inextricable ties between "atmospheric health" and other environmental media (viz., land, water, and the biosphere—not to mention human health).