Sociologist that declares environmentalism is the most comprehensive, influential movement of our time is Sociologist Manuel Castells. The activist subculture of the late 1960s and early 1970s inspired people especially youth to participate in a direct action concerning social issues. Second, the dissemination of systematic knowledge about serious environmental difficulties like air pollution and oil spill frightened many Americans, and third, the increasing popularity of outdoor leisure enlarged the number of people who were worried about the environment.