Originally Posted by AlTekhasski
Here we are again. The real issue is that you cannot name any "other forcing mechanisms" that could be possibly different today from 18,000 years ago. I asked Dana1981 to answer this simple question, [s]he cannot.
Since you claim to know the answer, why don't you simmarize what the "proper interpretation" is instead of pointing me to inaccessible piece of literature? Upon some digging, I still see no calculations there but a pile of different opinions on how unphysical mechanism of radiative forcings might or might not operate. Also why do you think that the interpretation of Schmidt-Mann-Annan, or Rahmstorf/Ganopolski is more proper than the original interpretations of Schwartz or Chylek-Lohmann? After all we know what is the right idea of interpretation of climate issues in the Schmidt-Mann-Annan-Rahmstorf team at RealCilmate.org, don’t we?
I am sorry, but didn’t we already dismissed possible differences in albedo changes, and CO2 changes?
Here we are again. I do not have any theory of ice ages. As I agued, CO2 change is CO2 change regardless when this change did occur, today or 18,000, 140,000, or 250,000 years back. The change is registered, and proper proportional response (with all associated feedbacks, including changes in ice covers) must be observed. Please note that I am not comparing absolute responces, I am comparing differential properties of responses that should not be that different, unless some other fundamental strong factor is present.
No, I am arguing that even the enhanced hypothesis of radiative forcing from GH gases, aerosols, and ice-albedo, all allegedly triggered by something small, cannot explain the difference between today’s behavior of climate and climate behavior during deglaciations. I am arguing that modern climatology still failed to explain natural ice ages, and therefore all speculations regarding “unnatural” climate change are completely unfounded. You keep repeating that "other factors are involved", and I am asking you to name what these factors are.
I am certain of nothing; it is your official climatology that is certain that climate is in crisis due to CO2. And I simply object to this ridiculous certainty.
You are missing the point that if you want to use the paleo record to infer climate sensitivity to increases in CO2, you have to first estimate the changes in the surface forcings. This is the point of the article I cited, and even the skeptics Chylek and Lohmann use this method. Estimating sensitivity cannot be done without estimating the forcings, and those forcings are planetary albedo (surface from ice and atmospheric from clouds and aerosols) and longwave forcing from CO2 (and methane and H2O vapor). That the mix of those forcings is different in the paleo record than today is not shocking news since humans are driving only one part of that equation, the CO2 (and methane). However, not even the skeptics argue that the fundamental forcings operating over the course of a glacial cycle are different than what are operating today. At best, they jigger around the magnitude of those forcings (for instance decreasing the albedo effect of aerosols to decrease the climate sensitivity to an increase in the surface forcing (where this sensitivity is given in terms of temperature increase per increase in surface forcing, with surface forcing defined as *anything* that changes the net amount of energy deposited at the surface of the planet (i.e., it could be increases/decreases in the shortwave solar flux, increases in the downwelling longwave flux))), but as a rule they do not invoke radically different mechanisms. Your plot says nothing about climate sensitivity.
The idea is relatively simple and goes like this:
A. From the ice core observations infer changes in global mean temperatures over a glacial cycle
B. From ice core data and other sources, including model results, estimate the net changes in total surface forcing over the glacial cycle
C. Combine A and B to calculate the climate sensitivity in terms of temperature change per change in total energy flux to the surface (so that the climate sensitivity will have a value like +0.7 K/W/m^2)
D. Using radiative transfer theory, calculate the increase in longwave surface forcing due to a doubling of atmospheric CO2, that number is something like 5 W/m^2.
E. Multiply the result of D by the result of C and get a projected increase in mean surface temperature of around 3 K.
This isn't rocket science and the tricky part is B, where the paleo forcings must be estimated from proxy data and model runs. But even the most hardened skeptics do not argue that albedo and longwave forcing are not critical in ice ages. Nor do the skeptics argue that the drivers for the paleo climate are identical to what is going on today. Modern climate is being forced primarily by increases in the radiatively active tracer gases, the paleo climate was forced (initially at least) by changes in planetary albedo with further amplification of those changes by CO2.
If you cannot be bothered to dig this out from the scientific literature for yourself in the midst of a technical debate, that is your problem. However, you are looking very scientifically illiterate at this point because you won't do the minimum background work to understand why your plot of temperature for CO2 is incorrect as an assessment of climate sensitivity, and why it says nothing about what will happen to global mean temperatures in the modern era if atmospheric CO2 concentrations are doubled over the pre-industrial levels.
The final point is that you are basing your belief that CO2 is irrelevant in the modern era on your misunderstanding that the paleo climate operated in a manner different than today. What I am arguing is that there is no disconnect, that the same forcing mechanisms were in play then as today, and if you would take the time to go through the data objectively you would see that. Then we could argue whether Chylek and Lohmann drastically underestimate the aerosol albedo effect over an ice age rather than this nonsense that the forcings from albedo and CO2 don't explain the gross features of ice ages.
Dana, Dawei, and others here have been extremely patient with you. It is time for you to do your homework. I suggest starting with the Chylek and Lohmann paper (it's cited in the link I provided) since they are skeptics so you will like what they are saying and maybe understand the points that they are making. That they are wrong will be beside the point as far as you are concerned. But at least you will be arguing semi-coherently from a scientific standpoint. As it is you're just getting angry because you don't like having multiple people tell you that you're wrong.