Regardless of political motives, scientific data (which on large scales can be remarkably in-credible), I think the more poinient question is; does it matter?
I personally find it a bit comical that a person could look at the billions of barrels of oil and millions of acres of vegetation loss that happen daily, then look at the thick layers of smog in cities, and then turn around and say, "its not even a possibility that global warming is our fault." Of course its possible. To say its not possible is rather ignorant.
But... all of that aside, we could very easily be headed for an energy crisis; either because we'll run out of petroleum without a sufficient new source of energy, or because we discover that it IS the human habit that is causing global warming and stopping gluttonous petroleum use would become legislated.
I have strong opinions on it, obviously, and like many humans I am equally hypocritical. I eat meat, but I also know that livestock farming is heavily destructive to the landscape and atmosphere. If we ate the grain we feed the cows instead of eating the cows themselves, we would cause a major shift for the better in the economy and environment... once we paid off the now very ticked off cattle farmers
But I eat meat. Hypocrite.
In summary, I don't care if we're causing global warming or not, but there is no reason for the gross environmental irresponsibility we are heaping on the earth right now. If we didn't "need" 46" plasma TVs, microwaves, Xboxes, security lighting, and air conditioning set at 70*, we could all get by with a bank of batteries and a photoelectric array on our roof. Have a week of clouds? Oh well, you don't get to watch Gilligan's Island on your 13" TV this friday. Would it be that bad?
We keep questioning if we're causing global warming. Here's an idea: STOP DOING THE THINGS WE THINK ARE CAUSING IT. Either global warming will start to reverse, or it won't, but either way we'll have our answer... AND we hopefully will have learned to get by with less in the meantime.