Change Your Snake-Oil Filters Every 3000 Miles

The college idealists who fill the ranks of the environmental movement seem willing to do absolutely anything to save the biosphere, except take science courses and learn something about it.
-- P.J. O'Rourke, Parliament of Whores

Most save-the-planet "ecologists" were just born a century too late to be evangelical prohibitionists.

The one at your door, asking you to sign her petition opposing some environmental catastrophe: is she real, or is she just Paul Erlich on Memorex?

Try asking her this question:

A pine seed is tiny. The ponderosa pine right behind you weighs a couple of tons. Where'd it get all that mass?

If she knows, or can reason her way to the answer, she may be worth listening to. If not, she ain't.