Partly Cloudy

A few days ago I had the opportunity to meet an interesting character at the uni. He was supposed to have retired about a decade ago, but he's not the type to retire. He's an engineer and has many decades of experience in academia.
He brought a photocopied graph that he found in an article in Scientific American from a couple of years ago. It shows levels of CO2 and methane in the atmosphere, as well as the change in temperature from the previous millennium, on a scale of about half a million years. Every 100,000 years or so, the earth goes through a period of warming that lasts about 7200 years. We're now smack in the middle of one of these periods.
Now, he wasn't arguing for or against man-induced global warming. He just thought that this was an interesting graph, based on precise measurements, that raises some questions that he thinks should lead to good scientific debate. Are we putting off the next ice age? How can we rely on recent measurements and predictions of small changes in temperature and sea level, when the sea level at the same point in this climate cycle has varied by nearly 200 meters, without any human intervention?
He told of a recent presentation that he gave, in which he showed this graph and asked some of these questions. He asked why we don't hear more debate on this. What was the response? The session chair told him that his time was up (it wasn't) and that he should step down and end his talk. He was stunned. Afterwards he asked why he was silenced like that, and was told that there are so many applications for government grants that nobody wants to say something that "they" don't want to hear.
The graph is from this article, written by James Hansen, who is by no means a global warming skeptic. On the contrary.
So what do I think of global warming? Well, I'm no climatologist, and there are plenty of people who know more than me on the subject. Unlike many journalists and pundits, I have no problem saying this. But I am a scientist and an engineer, and I know about modeling. I know how hard it is to get a good model of, say, a biological system. The model is only as good as what you put in it.
Planetary climate on a long-term time scale is just so immensely, utterly complicated, that I doubt that any of the current climate models are worth much, and especially not predicting global temperatures 100 years from now. There are so many variables, we have no idea how many there are and how they interact. We're learning new things about what affects climate on this earth every day. Each of these things factors in. We can't even explain past climate changes adequately; how can we claim to predict the future?
The big question is not whether climate change is happening or not (it is and always has) or if humans affect it (we do and always have). The question is what are we going to do about it. And that's where politics, biases, money and a host of other things unrelated to science, come into the equation. Academics wanting grant money. Journalists wanting a headline. Hollywood producers wanting to sell movies. Bush-haters will blame Bush, Howard-haters will blame Howard. The Greens will blame everyone.
I personally don't give much of a damn about it all, but I do care when scientists and academics are silenced.