I'll try to respond to the first of these questions concerning the completeness of science.
I very strongly agree with you that science is an ongoing enterprise. I commented at the end of my presentation, for example, that we are unable to predict what may be one of the most important impacts of global climate change, namely the stability of the cryosphere. The implication of that is that our scientific understanding is incomplete. We're unable to embody sufficient understanding in our models to make credible predictions.
What we can say on the basis of the AR4—and I don't think I would go further than this, and I don't think my colleague intended to go further than this—is that the science is unequivocal. I think what he meant to say was that it is unequivocal in the sense of the conclusion reached. With a high level of confidence, humankind is responsible for the majority of the warming that has occurred over the past four decades.
I think that's the guts of the comment in the AR4 report, but that doesn't mean the science is over. There is still a great deal that we have to understand if we're able to make credible predictions of very important aspects of the climate system.