A continuous measure of public environmental concern was created using the appearance of environmental content in mass-circulation magazines between January 1956 and December 2005 to investigate Downs' "Issue Attention Cycle", the public response to physical and non-physical episodic events, and the relationship between sectors of environmental concern. The results indicated that environmental concern follows discernible cycles peaking in 1970, 1990, and 2000. Each cycle exhibits an asymmetrical decrease in concern resulting in a ratcheting of environmental concern upwards over the study period. A multivariate regression analysis was used to test for physical and non-physical episodic events was not found to be a strong predictor of environmental concern. The dynamics of these cycles of environmental concern will have far-reaching implications for policy makers.