re: #1044 Charles

If you are seriously interested in this issue and not just repeating anti-AGW talking points, there’s a very good explanation in this video:

The video is excellent but the explanation of the 800 year lag is flawed.

Let me state the skeptic’s objection a different way. The video, like lots of things, constrains itself by avoiding the vocabulary of Calculus. Thus, I wouldn’t say that he just handwaived the issue away, but he didn’t really explain it.

The video uses the word “triggers” to describe events that start a process which then supposedly self-sustains through feedback mechanisms (e.g. the CO2 change). I agree that these mechanisms are there. It’s how the feedback equations (differential equations, really) play out that’s the problem.

Suppose temperature is falling and then some trigger reverses it. While it was falling, CO2 was also falling and passed through a value X. This value X is part of the feedback and is driving the temperature lower.

After the trigger, temperature rises and then CO2 starts to rise too. Eventually it gets back up to X but now the theory says that a CO2 level of X is driving temperature UP. That’s a problem as X cannot do both. At this point I can only go on using Calculus.

The feedback term in the differential equation is that the derivative of temp with respect to time (dT/dt) is a function of X, not dX/dt. I think the technical folks here who are not skeptics/deniers will confirm this. There are other forms of feedback beside dT/dt being a function of X but this is the one everyone’s thinking of. So, Houston, we gotta problem.

The only way I can see this working out is if the trigger isn’t transient. That is, whatever force started the reversal is still pushing the whole way up. Then the response of the system makes sense.

But if the trigger is durative, then we no longer need the CO2 feedback to sustain the process. The trigger is just pushing it up (or down in the next phase). These swings neither prove nor disprove the feedback (which is fine since everyone agrees that there’s some feedback).