It's not a matter of believing it or not, it is a theory based on lots and lots of hard data and research. It would be like choosing not to believe in Gravitational Theory.

I think we need more science education in this country so people understand the scientific method- scientists don't arrive at conclusions based on a whim, it takes years of valid testing and retesting hypotheses to arrive at a theory. That is actually what I am completing my master's thesis on- science education for the first 3 chapters and for my project, a unit on the scientific method and global warming. I will hopefully be done shortly!