[gondramB]

Thank you for the responses. This will take some reading/digesting.

I clearly don't know a great deal about atmospheric dynamics and I'll have to refresh - I took three undergrad courses in AD 20 years ago.

I also worked all night so in my addled state it sounds to me like you are saying that a paper on the DOE site (and the science, as you present it) means that CO2 is only a small part of the cause of extreme temperatures on Venus. The paper even claims this was already the scientific consensus in the reference it cites from 1984.

In my sweep I can't find any scientific sources that agree with your conclusion except that one paper. If they correctly quoted their source at the time then their source has been revised and in any case it does not appear to be te consensus. You would also think that such an earth shaking conclusion by the DOE would have been followed up on...

I appreciate you investing all this effort in me and will follow up when I've had some sleep.

[ancient_geezer]

In my sweep I can't find any scientific sources that agree with your conclusion except that one paper.

You apparently are not looking at the volumes of peer-reviewed studies associated with the Pioneer & Venera venus flyby and landing projects, as well as the multitude of limb microwave studies that all confirm precisely what I have been saying.

The lack of water vapor on Venus precludes the kind of "greenhouse" that is evoked by the popularization of the concept.

I have found literally dozens of such studies all citing nil water vapor and high level clouds as the dominant factor in the Venus temperature environment.

Even basic themodynamics makes the case clear. We have the knowm logarithmic relationship for CO2 forcing which hold for high concentrations of CO2 and any gas at high concentrations that make very clear that CO2 can only contribute to a limited extent absorbing incident IR.

A sobering fact about CO2 and any other molecule for that matter is that the ultimate limit is established by it's IR spectrographic absorption which when at maximum concentrations approaches the exponential limiting form, R(1-e^(-kC)) as available IR photons are overwhelmed in relation to the number of CO2 molecules. In otherwords, a CO2 atmosphere cannot absorb more IR radiation than is present as represented by the equilibrium blackbody temperature conditions. You can't get energy for nowhere.

If CO2 forcing were near linear as a climate driver, the upper maximum envelope of earth's surface temperatures would have a curve similar to the CO2 the concentration curve over geological time.

The measurable limit in climate sensitivity to increasing CO2 is clearly represented in the average surface temperature of the earth in the following graphical presentation of the earth's geological history providing a clear demonstration of the limits of CO2 as a driver of global temperature as well as its lack of correlation to the large swings in earth's temperatures:

 

Global Surface Temperature and Atmospheric CO2 over Geologic Time 

Late Carboniferous to Early Permian time (315 mya -- 270 mya) is the only time period in the last 600 million years when both atmospheric CO2 and temperatures were as low as they are today (Quaternary Period ).

Temperature after C.R. Scotese
CO2 after R.A. Berner, 1994

•     There has historically been much more CO2 in our atmosphere than exists today. For example, during the Jurassic Period (200 mya), average CO2 concentrations were about 900 ppm or about 2.5 times higher than today. The highest concentrations of CO2 during all of the Paleozoic Era occurred during the Ordovician Period, exceeding 6000 ppm -- more than 16 times higher than today.

•     The Carboniferous Period and the Ordovician Period were the only geological periods during the Paleozoic Era when global temperatures were as low as they are today.
  
  To the consternation of global warming proponents, the Late Ordovician Period was also an Ice Age, with CO2 concentrations nearly 15 times higher than today-- 5500 ppm. According to greenhouse theory, Earth should have been exceedingly hot. Instead, global temperatures were no warmer than today. Clearly, other factors besides atmospheric carbon influence earth temperatures and global warming.

 

 

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Using the above chart and knowing the logarithmic relationship of direct radiative forcing we can test what the forcing for CO2 is at the extremes represented above in geological history must be.

To due so, I took the above chart and did a bit of digitizing and overlaid a linear response line across the envelope of temperatures depicted in the geological history:

A 0.24^oC change in Earth's surface temperature per CO₂ doubling is depicted in the resulting graphic:

 

• The upper horizontal redline represents a temperature of 22.8^oC at the chart Cambrian CO₂ peak of 7000ppm.

• The second and descending redline is a rough approximation of the average peak temperatures connecting similar conditions of albedo and other climate factors, the downtrending redline terminates at approximately 21.6^oC, with roughly deep ice age conditions of ~200 ppmv CO₂ concentration from ice core studies yielding for ~5 doublings of CO2 concentration.

   

Given ~5 doublings of CO2 in the above graphic, and using DF = 5.35 ln(C/C₀) wm^-2 [Myhre et al. 1998, Geophys.Res.Lett., 25:2715-2718].

We get ~8.6 w/m² change in radiative flux due to the change in CO2 concentrations above.

Applying Boltzman once again, using initial 22.8^oC (i.e. 295.8K @ T_o) we get

F_o = 1*5.67*10^-8(295.8^oK)⁴ = 434.09 w/m²

Subtracting 8.6 w/m² for cooling due to decreasing CO2 we get

434.1-8.6 = 425.5 w/m²

Calculating a final CO2 delta T as

T = (E/s)^0.25 = (425.5/5.67*10^-8)^0.25 = 294.32K

computing the difference we get (295.8-294.32) = 1.48 K (i.e 1.48^oC)

Which conforms very closely with the 22.8-21.6 = 1.2^oC change in max temperatures of the graphic, confirming of what we can determine from first principles in regards surface heating affects,