@ Dr Stephen Jones
I'm sorry, I am really not sure I follow you here...
El Rupester>"Lets start with the simple facts: CO2 absorbs infra-red. More CO2 => more heat aborbed and the temperature goes up. CO2 levels have gone up 50% and are accelerating, so heat will go up more."
Dr Stephen> The facts pertain to a hypothesis, which is an interesting one. But there is no indication that that recent rapid rises in CO2 have *caused* the predicted effects: the CO2 and temperatures are out of phase. Your challenge is to demonstrate proof that human agency has significant effects on climate that cannot be explained by variance in natural phenomena. (The key here is significant). Correlation does not equal causation, however, and unless your hypothesis can find this evidence to support it, then it's as useful or worthless as any other hypothesis.
You missed the point. You (and a lot of people on this thread) seem to assume that the only basis for AGW is some observed rise in temperature, which is then retrofitted onto a rationale. If that were the case, then your "Correlation does not equal causation" would obviously be a valid point.
But it isn't.
The physics is that CO2 absorbs IR re-radiated from the earth
If you have any observations to disprove that, I'd be intrigued...
So (all other things being equal), more CO2 = more heat absorbed. That's not "hypothesis" it is simple logic.
Indeed, it is accepted: that is why Venus is hotter than it "ought" to be, and if it were not for greenhouse gases (water, CO2, methane) thanb earth would be far colder.
Again, if you have any observations to disprove that, I'd be intrigued...
Then comes the hypothesis, which dates back to Arrhenius in 1896 who put numbers to the "rise" and estimated that halving of CO2 would decrease temperatures by 4 - 5 °C and a doubling of CO2 would cause a temperature rise of 5 - 6 degrees Celsius
This is not searching for a carrelation. Nor is it epidemiology where we see a pattern and try to derive a hidden, underlying cause. What we are doing is getting (noisy, inaccurate) data to test a prediction based on simple, verified physics.
Now, the latest data does not exactly align to Arhhenius' predictions. The key words "all other things being equal" - because they aren't. we have other factors: solar cycles, El Nino, positive feedback from albedo, negative feedback, etc etc
But the huge fallacy is in assuming this is seaching for cause from a correlation: it is starting with physics predicting a correlation. If we do not see one, then we still know the physics is there, but there are other factors going on too which swamp it.
But no-one I have seen as told me what those things are which mean the earth is actually cooling at precidsely (fortuitously) the rate to balance the heating
So, if I worry about AGW I have:
Basic physics + predictive theory + measured data on imputs + observed (if noisy data) on outputs confirm causaility" => all of which confirm why I ought to be worried
I would describe that as "a rational response to a quantifiable risk"
If you want to tell me I'm wrong, I'd be delighted. But to do, I'd like to see an explanation that explains why the greenhouse effect that observably worked from 0 to 260ppm of CO2 suddently stopped working as we rise to 450ppm or beyond.
"Correlation does not imply causality" is a good slogan.
But "Agreed physics + Predictive model + hard data confirms causality" is a better one