From the “Oh Dear!” department of unsettling science…
It would seem that the basic notion of CO2 as an emitter of infrared radiation causing ever more “back radiation” to heat the planet with increasing temperatures, the very foundation of the Global Warming runaway greenhouse hypothesis has, er, “has issues”. Which is a polite way of saying it is deeply flawed.
It looks like the only thing with black body radiation is a real black body and that transparent things, like gasses, are not quite the same. In particular, CO2 likes to heat up instead of emit a photon. Now that also means they will tend to hold onto any energy input long enough to whack into one of the other gasses in the air and thermalize any IR they absorbed. Which in turn means that the bulk of the air (Nitrogen, Oxygen, Argon, Water Vapor) will be holding that energy, not the CO2. That, then, means were are back to “hot air rises” and all the convective processes of the troposphere as “what matters” and that “back radiation” just isn’t going to cut it. All the calculation and hand waving based on “black body” and “back radiation” needs a bit of a do-over.
This paper is the key, but a bit thick to read:
Way down at the end it says:
The belief that arbitrary materials can sustain black radiation
always results from an improper treatment of reflection
and energy influx. In Max Planck’s case, this involved the
mandatory insertion of a carbon particle within his cavities.
This acted to drive reflection. In the construction of laboratory
blackbodies, it involves departure from thermal equilibrium
as the inflow of energy enables the emissivity to drive
the reflection. In the belief that optically thick gases can emit
blackbody radiation , it centers upon the complete dismissal
of reflection and a misunderstanding with respect to
energy inflow in gases .
In fact, many cavities can never be filled with
black radiation, even if one attempts to drive the reflection
term. That is because certain materials are not conducive to
emission and prefer to increase their temperature rather than
drive reflection. Arbitrary cavities do not contain black radiation,
and that is the measure of the downfall of Kirchhoff’s
Taken in unison, all of these observations, even dating
back to the days of Kirchhoff himself, highlight that the universality
of blackbody radiation has simply been overstated.
The emissive characteristics of a cavity are absolutely dependent
on the nature of the cavity walls (see , [14, p. 747–
759], and references therein). This has broad implications
throughout physics and astronomy.
A more approachable write up of the whole issues is here:
However, climate scientists and climate models instead falsely assume that the Kirchhoff, Planck, and Stefan-Boltzmann laws can be applied to greenhouse gases and that they behave as blackbodies. Dr. Robitaille shows prior work from Hottel et al demonstrating that the emissivity of both of these greenhouse gases decrease with temperature [i.e. they become less of a ‘greenhouse gas’ as temperatures increase], the opposite of the climate science assumption that greenhouse gases increase emissivity and absorptivity with temperature. For conservation of energy, emissivity must equal absorptivity for all materials and gases, therefore increases in temperature decrease both emissions and absorption of infrared radiation by the greenhouse gases water vapor and CO2, i.e. they become less ‘greenhouse like’ gases as temperatures increase, a self-regulatory mechanism that suggests less climate sensitivity to CO2 with increasing temperature.
It is well worth reading all of both of those links.
I came to this chain of links via a comment by Rogerknights on WUWT here:
May 24, 2014 at 5:59 pm (Edit)
Steve Oregon says:
May 24, 2014 at 4:47 pm
A curious question.
If Mann and Trenberth discovered iron clad scientific evidence that CO2 emissions were meaningless to the climate would they tell anyone?
We’ll have a clue in their reaction to this paper:
May 11, 2014 at 1:46 pm
Thursday, May 8, 2014
New paper questions the ‘basic physics’ underlying climate alarm
A forthcoming paper published in Progress in Physics has important implications for the ‘basic physics’ of climate change. Physicist Dr. Pierre-Marie Robitaille’s paper(s) show the assumption that greenhouse gases and other non-blackbody materials follow the blackbody laws of Kirchhoff, Planck, and Stefan-Boltzmann is incorrect, that the laws and constants of Planck and Boltzmann are not universal and widely vary by material or different gases. Dr. Robitaille demonstrates CO2 and water vapor act in the opposite manner of actual blackbodies [climate scientists falsely assume greenhouse gases act as true blackbodies], demonstrating decreasing emissivity with increases in temperature. True blackbodies instead increase emissivity to the 4th power of temperature, and thus the blackbody laws of Kirchhoff, Planck, and Stefan-Boltzmann only apply to true blackbodies, not greenhouse gases or most other materials. The significance to the radiative ‘greenhouse effect’ is that the climate is less sensitive to both CO2 and water vapor since both are less ‘greenhouse-like’ emitters and absorbers of IR radiation as temperatures increase.
Somehow I think a few folks are going to be very unhappy about that paper…