Thank you, Andrew.
Yes, there are two big scientific unknowns, and Andrew mentioned them. One is the carbon cycle, which will actually tell you how emissions translate into atmospheric concentrations. The other one is how do ice sheets behave? Both of them will have feedbacks on the climate system. Both of them could lead to an acceleration of the climate system.
My hope is that with the fourth assessment we've been able to put a line under the scientific debate about whether climate change is real or not. I think we have to move from science that's been useful in defining the problem to science that's going to be useful in defining the solutions.
This doesn't mean to say that we have done all the science necessary, and there are many reasons for that. Let me just add one. That is because we don't know yet what we've missed. There may be some things in the climate system that we've missed up to now. We won't know them until we do the research, and we don't really want those sorts of surprises.
But I think Andrew is right. We've got to understand better how we adapt, and that's not just a matter for the natural scientists. Surely we do need better regional scale climate models, but we need to know how societies work, how societies have adapted to today's variability, and how they can adapt to the increasing variability in the future.
Thank you.