- Johnson, Erik W.; Scott Frickel. Ecological Threat and the Founding of U.S. National Environmental Movement Organizations, 1962–1998. Social Problems. 2011,. 58 (Aug. 2011) (3): 305–29. doi:10.1525/sp.2011.58.3.305.
This study examines the role of "ecological threat" in shaping the U.S. environmental movement. … Declines in wildlife populations are associated with the foundings of wildlife and wilderness protection organizations while increases in air pollution are associated with the foundings of organizations focused on ecosystem well-being and public health.