 This is another figure from the IPCC from 2007, their fourth assessment report. The year 1000 is over here, so this is year, and it comes up to the year 2000, and then into the future going that way. This is how much CO2 was in the air. And so what we're looking at here is a long period of stability. These are ice core data from breaking bubbles in various cores in Antarctica, different levels of impurities, different snowfall, different temperature, but the same record. As we come in here, what we see is that the ice cores and the instrumental record, what's measured in the air today, actually agree just beautifully, and that we really, really have raised CO2. And these are various possible futures running off here to the right, depending on sort of how the economy grows and so on. None of these include a strong effort to reduce CO2. So far we've been tracking very near the highest of these or above it a little bit, but we haven't gone very far, and so it's a little hard to tell which way we're going. The things to notice are that the rise so far from human CO2 is unequivocal. It's beautifully clear scientifically, but it's not very big compared to what's coming in all the futures envisioned. We see a much larger change in the future than in the past, and all of these curves are still headed up as they get to the point where students today are getting old but are still not passed away. And our children and our grandchildren very clearly will live off of this. So if we don't do something about our CO2, the changes coming are very, very much bigger than the changes that have happened so far.