måndag 18 februari 2013

Modtran: High Emissivity of 1 ppm CO2!

The uchicago modtran solver produces the following outgoing long wave radiation OLR spectra for a dry atmosphere with varying concentrations of CO2: 0 ppm, 1 ppm, 400 ppm and 600 ppm:

We see an effect of reducing OLR from 379 W/m2 to 373 W/m2 by adding 1 ppm CO2 to a carbon free atmosphere: Thus a warming effect of 6 W/m2 by adding 0.0001% CO2 to a dry atmosphere!!

We see warming effect of about 2 W/m2 by increasing CO2 to 600 ppm from present 400 ppm.

We see the effect of 6 W/m2 from the ditch in the spectrum (second graph from top) centered at the main resonance of CO2 at wave number 667, developing by adding just 1 ppm of CO2!

We thus see a very big effect from a very small cause, which directly triggers sound scientific skepticism: If one grain of salt can change the world, then either 10 grains will end it, or the effect quickly saturates maybe to no effect by adding more. Since the first option is absurd, only the second is thinkable and this is the IPCC logarithmic saturation effect: 6 W/m2 from 0 to 1 ppm, and 2 W/m2  from 400 to 600 ppm.

We compare with the absorption spectrum for 1000 m of 1 ppm CO2 computed by spectralcalc showing extreme sparsity of the absorption away from the narrow interval 667-669:

We thus find good reason to question the spectra produced by Modtran which serve as the main scientific evidence of a warming effect of CO2.

8 kommentarer:

  1. Hi Claes,

    Just for fun, what is the result for 0.001 ppm CO2 i.e. 1 part per billion CO2?

    What Modtran parameters are you using e.g. for 1 ppm CO2?

    CO2 (ppm)
    CH4 (ppm)
    Trop. Ozone (ppb)
    Strat. Ozone scale
    Ground T offset, C
    hold water vapor
    Water Vapor Scale

    Sensor Altitude km

  2. Water vapor = 0, sensor 70 km, ground offset = 0.

  3. I'm not reproducing your results from

    CO2 (ppm) 1
    CH4 (ppm) 1.7
    Trop. Ozone (ppb) 28
    Strat. Ozone scale 1
    Ground T offset, C 0
    hold water vapor pressure
    Water Vapor Scale 0
    Locality tropical atmosphere, no clouds or rain
    Sensor Altitude km 70 km looking down


  4. I think the difference is that I used Trop Ozone = 800.

  5. I linked to this post in the comments at Science of Doom and we are discussing it there if you'd like to join in...


  6. Thanks, but the reception is so hostile that I leave it to you. In any case I think there is substantial evidence showing that 0.039% CO2 cannot block radiation from the Earth surface in the whole band 600 - 800 as given by Modtran, only effectively in 667-669 say, and thus that the total emissivity is very small, smaller than 0.002, and vey little is gained by doubling the concentration. Radiative forcing of 3.7 W/m2 appears to be at least a factor 10 too big, and without those 3.7 W/m2, CO2 alarmism collapses to zero.

  7. Here’s an analysis done with Spectralcalc which determines doubling of current CO2 levels could only raise surface temperature < 0.2 C, i.e. that climate sensitivity is exaggerated by more than a factor of 10.


  8. In the Spectralcalc analysis above Bryce Johnson finds "heat to atmosphere" of 244.64 W/m2 for 400 ppm CO2 and 249.58 W/m2 for 800 ppm CO2.

    a. is this plausible?
    b. do you agree with the method he used to determine surface temp?