Andrew Sullivan highlighted an article from the New York Times on Stewart Brand. I think Sullivan's comments and the original article are both worth a read. Brand is a lively creative thinker.
Pessimism is a powerful force, but optimism and creativity are important tools for our survival and evolution in our complex world. Even as scary as global warming can appear, most people I have talked with seem to have their heads on straight. They deal with the facts and do not seem to be pulled under by the fear of what could be. Rather, they have the motivation to create workable solutions to aid in our survival.