1 degree C.
In what part of your voluminous contributions does that figure appear?
from reply #35, which you conveniently overlooked in your hurry, however just for you straight from the presses:
... we revisit the Geophysical record of CO2 and it's correlation to global temperture, this time we remove the catastrophic initiations of ice ages due to factors clearly not associated with CO2 concentration.
From the geological record, we can see a remainder trendline of CO2 concentration with respect to temperature by running a trend through the peak global tempertures.
As you have acknowleged the initiation of the deep iceages are clearly due to other factors such as plate tectonics, Gamma Ray Bursts, Meteoric events, etc.which initiate atmospheric cooling incident to the creation of high altitude cloud cover & icefields altering the mean albedo of the earth. Such effects lower overall irradiation of the earths surface and hence cools the surface. Under such conditions the major multi-million year iceages are induced. Remove their effects on the overall record, and what is left behind is a residual that can be perceived, to the first order, as a correlation of CO2 and temperature if we assume an essentially constant Solar radiation flux, which the IPCC modellers insist as being true.
I bring your attention to the two redline additions to our favorite chart:
:
The upper horizontal red line represents a peak temperature of 22.8oC as represented at the chart Cambrian CO2 peak of 7000ppm. The second and descending redline is a rough approximation of the average peak temperatures which should be somewhat representative of any residual correlation between CO2 & temperature, we note that the downtrending redline terminates at approximately 21.6oC and today's 320ppm CO2 concentration.
It should also be noted here that the relationship between CO2 radiant absorption capacity varies logrithmically with concentration of the gas under consideration in the atmosphere. For any fixed multiplier of change in concentration there is a linear incremental change in absorbed energy of the gas. Thus doubling, or halving, the concentration of CO2 will result in a linear increment in the absorbed radiation at the wavelengths CO2 is responsive to where incident radiative flux is constant.
7000ppm/320ppm = 21.9 (~ 4.45 doublings) with 22.8-21.6 = 1.2oC change in temperature.
Overall atmospheric correlation between CO2 & increment of energy absorbed of necessity includes any temperature/concentration linkages that may actually occur in the atmosphere.
for 1.2oC & 4.45 doublings, CO2 doubles for ~ 0.27oC increase in global temperature
A value which is much less than the lowest 1.5to2.5oC/doubling estimate built into the UN/IPCC global climate models, which suggests the relationship between CO2 and temperature built into the IPCC models is substantially overstated and in error.
Somes just mere observation of published information is sufficient to see the relationships and their magnitude for one's self.
OK. This will be a shorter reply than I had planned; I have numerous activities pressing on me both professional and personal (foremost among them a birthday party for toddler twins) as well as coping with a nasty respiratory infection that just will not let go. Let this provide some talking points for next week.
Number 1: is the derivation of average global temperature something that you did as an analysis, or is it taken from an accessible publication? I.e., is there any justification other than your own ideas for your running a trendline through peak global temperatures to show the correspondence of CO2 and temperature? The main reason that I'm asking this is that I will contrast it with the CO2 + sun forcing plot that is provided in the aforementioned Crowley and Berner paper. Radiative forcing varies from a minimum value of -13.5 W m-2 to a maximum of 10+ W m-2 over the Phanerozoic. On the same plot they provide a scaled del oxygen 18 temperature data from deep-sea sediments over the past 100 million years, which shows a temperature decrease from the Cretaceous of about 4.5 C. (The decrease into the Holocene is right on the edge of the graph.) The latter data agrees with what we see on the right side of your graph.
Sooo... while Crowley and Berner show major variations in net forcing due to CO2 variability, your analysis does not. I do not know how to reconcile this discrepancy. In essence, the radiative forcing during glacial periods is shown as roughly 20 W/m -2 compared to non-glacial periods.
Your analysis indicates that for a 20 W m-2 forcing difference, which corresponds to a 10 deg C change in global temperature over the same time period, only 1 deg C of that change is due to CO2? That's the BIG discrepancy of which I speak. Feel free to explain; please concentrate on this point.
Two short points. Crowley and Berner say this directly about the Ordovician glaciation:
"In the case of the relatively short-lived Ordovician glaciation (about 440 Ma) which occurred at a time of high net radiative forcing, climate models suggest that the unusual continental configuration of Gondwanaland (essentially a large landmass tangent to the South Pole) could result in conditions where high CO2 and glaciation can co-exist. A brief negative excursion of CO2 at this time may also have contributed to this glaciation. *" (Latter text also refers to other processes that could have affected ocean heat transport.)
* not very large, according to the graph
Last point, regarding the temperature and CO2 variability over the past 420,000 years. It is indeed true that temperature increase preceded CO2 rise each time. This is fairly obvious, and likely primarily due to release of CO2 from a warmer ocean. The current situation, however, is without precedent, as the CO2 concentration has exceeded the boundary conditions for atmospheric CO2 concentrations over that interval by about 80 ppmv. This is why predictions of what will happen are difficult to compare to the paleoclimate record.
Next week I want to re-examine the relationship between radiative forcing and climate sensitivity, and determine if what I mean by "climate sensitivity" is the same or different than what you mean by it.
Sorry for the necessary brevity of this response; we will continue next week.