I am going to be out enjoying some snow skiing this week, but I will leave you with a thought that was a prominent part of this video:
The catastrophe that Al Gore and others prophesy as a result of greenhouse gasses is actually not, even by their admission, a direct result of greenhouse gas emissions. Even the IPCC believes that warming directly resulting from manmade CO2 emissions is on the order of 1 degree C for a doubling of CO2 levels in the atmosphere (and many think it to be less).
The catastrophe comes, not from a mere 1 degree of warming, but from the multiplication for this warming 3,4,5 times or more by hypothesized positive feedback effects in the climate. Greenhouse gas theory gives us warming numbers we might not even be able to find amidst the natural variations of our climate; it is the theory of strong positive climate feedback that gives us the apocalypse.
So, In a large sense, the proposition that we face environmental Armageddon due to CO2 rests not on greenhouse gas theory, which is pretty well understood, but on the theory that our climate system is dominated by strong positive feedbacks. This theory of positive feedback is almost never discussed publicly, in part because it is far shakier and less understood than greenhouse gas theory. In fact, it is very probable that we have the sign, much less the magnitude, of major feedback effects wrong. But if we are considering legislation to gut our economies in order to avoid a hypothesized climate catastrophe, we should be spending a lot more time putting scrutiny on this theory of positive feedback, rather than just greenhouse gas theory.
Tom Nelson quotes an email from S. Fred Singer that states my position well:
I believe a fair statement is that the GH [greenhouse] effect of CO2 etc must exist (after all, CO2 is a GH gas and is increasing) but we cannot detect it in the record of temp patterns.
So we must conclude that its contribution to climate change is swamped by natural changes.
Why do models suggest a much larger effect? Because they all incorporate a positive feedback from WV [water vapor], which in actuality is more likely to be negative. Empirical evidence is beginning to support this explanation.