"The world's problems are pressing in on us all. The scale and impact of human activities now affects a great portion of the global resources important to human welfare. These activities are putting growing, often destructive pressure on the global environment, pressure that appears likely to increase as human numbers swell toward the doubling of the world's population that evidently lies ahead. These pressures can spawn or aggravate conflict that. in a world with so much destructive weaponry, generates important national security problems. Great changes are necessary to help ensure a humane future for the generations to come. Most of the world's scientific community and many people in the environmental movement are aware of the gravity of the problems. Yet despite sober warnings from these and other groups, in both the industrial and the developing world, re- medial efforts frequently appear powerless and ineffectual. The scientific community has not taken a sustained, powerful role in the public arena where this great cluster of issues is debated and where the problems must be resolved. There is much more that our community can contribute to assessment, warning, and proposals for new patterns of behavior."