My honest opinion is that we don't really know if we're seeing global warming, nor do we know why it's happening, if it is. There's just WAY too much money and power tied up in the concept of Global Warming to believe we're getting any real information about it. On one hand, Gore is trumpeting an alarm. On the other hand, he's doing next to nothing about it in his own life, despite having ample funds to drastically lower his personal impact on the environment. On top of that, he's making a ton of cash selling "carbon offsets". When I take those 2 facts into account, I have a hard time believing him. I don't believe what most sales and marketing people say about their products, either, so take that into account too.
There are lots of good reasons to do "the right thing" where the environment is concerned, I just don't think that a panic inspired by "The Brothers and Sisters of The Church of Global Warming" is one of them.
And yes, I'm the guy that, at every bookstore he goes in, moves all the copies of "An Inconvenient Truth" to the "Religion and Spirituality" section. I'll post the pictures sometime ;)