The twentieth century brought about sweeping environmental, economic, social, and political change. Each type of change was itself substantial, but collectively these changes collaborated to produce unprecedented impacts on the Earth and the human way of life. In this lecture, Nay Htun, Deputy Director of the United Nations Environmental Programme, addresses these changes and places them in the context of global environmental change. Dr. Htun describes the forces negatively affecting the global environment and talks about possible solutions to these impacts.

The enactment of the Montreal Protocol in 1987 is hailed as a success for international cooperation in general, and environmental policy in particular. In this talk, Dr. Peter Thacher, a retired UN diplomat, explains the circumstances surrounding the identification of the ozone hole problem and the subsequent agreement to curb CFC emissions, the leading contributor to ozone depletion. Dr. Thacher argues that there are lessons to be learned from this case-study that can be applied to future cases of cooperation on environmental issues.