Abstract: The major lines of scientific debate, research progress, and controversy over stratospheric ozone depletion from the mid 1970s to the mid 1980s are examined. Begins with the initial qualitative confirmation of the main points of the chlorine-ozone depletion claim in 1976, which coincided with the resolution of the US policy debate over aerosols. It proceeds through 1985, with the seeming contradiction between slowly growing confidence that the main processes operating in the stratosphere were coming to be understood, and two shocking new claims of observed ozone losses that sharply called this confidence into question. In addition to reviewing substantive debates in stratospheric science, the chapter examines the multiple attempts over this period to synthesize and communicate the state of scientific understanding in assessments to inform policy making, culminating in 1985 with the first assessment that significantly influenced international policy debates.

Keywords: aerosols, chlorine, environmental policy, international cooperation, ozone depletion, research, scientific assessment, stratospheric science, USA,