manaker.
“The truth of the matter is that IPCC’s CAGW premise as stated in AR4, which is based on a climate sensitivity of 3.2C, is not supported by empirical scientific evidence (Feynman)”
The truth of the matter is that AR4 summarizes the empirical evidence for the estimation of climate sensitivity. That summary states that climate sensitivity for a doubling of C02 is anywhere between 1.5C and 6C. The mean of these estimates is close to 3.2. This figure is estimated using the following kinds of studies.
A) deep paleo studies. we estimate the temperatures in the past.
we estimate the evolution of forcing over time. we estimate the
temperature today. From these observations we can estimate a climate sensitivity number. Those numbers center around 3 C with
uncertainty bounds of +- 1.5C.
B) near term paleo. So for example the MWP and the LIA. here again,
we estimate the temperature, we estimate the forcing and we estimate a change in temp due to forcing. These studies tend to give
much wider confidence intervals on the high side.
C) Surface record. using the surface record as the data, one can aslo estimate the response due to changes in forcing. For some details on how thats done see Lucia’s blog. Here too we see numbers that fall
inside the range.
D) Volcanic response. The response after a volcano, how quickly the system recovers, gives you an estimate for the relaxation response. From this you have an estimate of sensitivity. Again, the numbers fall within the range I describe above.
E) satellite work. You must be familiar with Lindzen and Dessler and Spencer. Each of them uses observations to estimate sensitivity. Lots of interesting debates there.
F) first order estimates from physical law.
G) models.
Note I put F and G last because they can really only tell you that you are in the right ballpark.
So Feynman would be very happy that the theory is being investigated from the empirical standpoint. The principle theory ( that C02 blocks IR ) is something that Feynman knew. The principle theory, ( that blocking IR will warm the planet ) is something that Feynman knew. What we dont know so well is HOW MUCH. that number, climate sensitivity, isnt a theory. Its a quantity that must be estimated.
“In addition, you have not been able to state how it could be falsified (Popper)
1. You dont falsify the estimate of a parameter. Let me give you an example. The gravatational constant. This number is not something you falsify it is something you estimate or measure. The climate sensitivity is a parameter. basically if you increase forcing by 1 watt how much warmer does the earth get. That’s a constant NOT a hypothesis or a theory. The AGW Theory, which is really just a collection of science, uses this parameter.
2. You can use the parameter to create a hypothesis.
If you double C02 , then the world will respond by warming between 1.5C and 6C. This hypothesis is testable. We are testing it NOW, we are slowly but surely doubling C02. This passes the “falsifiable” principle. “Falsifiablity” refers to the feature of having observable consequences. Nothing more. Popper and those in his school of thought ( which itself was not falsifiable ) were concerned about separating science from metaphysics. Metaphysical “theories” have no observational consequences. Let’s take a old metaphysics. Reality consists of absolute ideals. Nice idea. Too bad there are no observations that count for it or against it.
3. You could falsify the science by going to the TOA measuring outgoing IR. If you saw that C02 did not block IR, then key tenets of the science would be undermined.
However you want to construe the science it is testable. we are testing it now. The key parameter, sensitivity, is estimate from several lines of empirical evidence. Nobody is reading tarot cards.
