7. John Denver, 'Sunshine on My Shoulders'
Denver wrote scores of pro-environment pop songs in his career, and was a recognizable spokesman for conservation ecology; the last song he wrote before his death in 1997 was called "Yellowstone, Coming Home." This finger-picked ballad to temperate days went to Number One on the Billboard charts in 1974. It also includes the mushy line "sunshine almost always makes me high," which has united generations of college students in their snickering.
Listen to "The Corniest Pro-Environment Songs" Playlist: