If you were born in the 1970s, then there's more than a fair chance you're as deeply scarred/inspired by the “Crying Indian” commercial—the most effective public service announcement ever made—as I was. All the Earth Days in the world can't match what you knew at first glance watching that commercial... litterbugs are the worst sort of people and if you didn't give a hoot and went ahead and polluted, well... you'd make the Indian cry. (It turned out the tearful one was an Italian American named Iron Eyes Cody, now buried at Hollywood Forever Cemetery . . . oh well, them's the shits.)
These days people need more than a one-minute PSA to get the message about protecting the planet. Between the Discovery Channel, Animal Planet, and others, there are currently airing (as in, right this second) a zillion programs that relay the incredible diversity of life on Earth. Of course, the subtext for many is the nasty effect that we humans are having on it. Think it means anything? It does. But I personally still see people chucking things out of their car windows, or discarding plastic sacks directly onto the sidewalk, at which time violent atavistic urges course through me and I see that tear trickling down that sad, betrayed cheek.