In case you were wondering, we still don't know the answers to, well just about any global warming questions. But it sort of makes you wonder: would we change any of our behaviors if we knew we were "killing" the planet? And what degree of certainty would we require? If scientists told us "well, we can't possibly say with 100% certainty, but we are 90% sure that global warning is caused by our emissions," would we say "bah! Get back to me when you're at 95% and we'll talk."
And even if science gave us an unequivocal 100%? Hey, we've always got Hume and the problem of induction.
I guess my point is, maybe we should stop obsessing over the degree of certainty, and start asking ourselves whether and what changes we'd be willing to make, and whether they would actually result in a reduction of utility--of the level of happiness in our lives. In other words, the famous pseudo-pragmatic Pascal's wager, applied to our ecological behaviors.
(I realize this post sounds pretty "green"--it's not really intended to be. I'm just being critical about how we tend to frame the debate.)