Results from a recent survey: One in three schoolchildren fears that the Earth will no longer exist and over half believe it will be a nasty place by the time they grow up. (Thanks to Chris for the link.)
Much of modern environmentalism strikes me as very Old Testament psychologically: use fear and guilt to induce desired behavior. Note the first minute of this TED talk by John Doerr: the first 30 seconds of his talk is all fear and the next 30 seconds is all guilt.
All of this is aside from the issue of sorting out the complicated science. The issues here are the psychological set (negative emotionalism versus we-can-handle-it confidence) and the educational methods used (indoctrination versus informed critical thinking).
On this very topic, my short Wall Street Journal article from some years ago about neither indoctrinating nor overloading children — “Global Problems Are Too Big for Little Kids” — is online in text [pdf] and audio [mp3].