An interesting, self-deprecating article on the neurotic state folks can get into if they start fretting over every environmental threat:
Green with worry | San Francisco online
I imagine it's the same way I, as a new parent, get when every single news story (so it seems) is about child abuse and neglect. The issues and their importance are all very real, but if you invest yourself personally in all of them, you quickly paralyze yourself from the overload. It's all just too much.
We need to care, it's our duty as a human community to care (on both counts), but we need to maintain our effectiveness and sometimes that means realizing some issues are far larger than ourselves, and we can only do our best in this life and hope that trickles down to everyone else we meet or touch in some way.