I've just found a very interesting lecture by the legendary physicist Freeman Dyson.
There is a video here, and some of the text here.
My favourite contribution from Dyson is of course the Dyson Sphere.
Anyway, in this lecture from 2005, he is reminding us that heretics in science are important and that we shouldn't always blindly believe the common popular view. He goes on to try to put the problems of global warming into some perspective to try to pull us away from the current popular hysteria in the media. It really is worth a read.
(thanks to Neal Asher who linked this recently)