UK Company Develops Climate Change Masks for Cows

The fundamental question here, notwithstanding the fact that this article is udder nonsense, is the accuracy and meaning of the statement CH4 is (894%) more powerful than CO2 as a greenhouse gas. An exhaustive search of the literature available on the internet produced no articles or explanation of the physics and chemistry showing just how CH4 is more powerful than CO2. Does this mean it emits 84 times as much energy per than CO2 when irradiated with infrared in the respective wavelengths of the various “greenhouse gases?” And lest not forget the big “greenhouse gas.” water vapor or H2O. In the absence of such a scientific explanation I asked my associate, Bud Bromley, to explain. Bud is the absolute best analytical physical chemist I have ever worked with in 40 years.

Bud’s thoughtful explanation follows:

The short answer is that no other greenhouse gas is absorbing at CH4’s LWIR wavelength. If water vapor has already absorbed the LWIR coming up from the surface, then that radiation is not there to be absorbed by CO2 or CH4.

In the case of CO2, most of the LWIR emitted by earth’s is absorbed by water vapor because water vapor is 10 times more concentrated and the absorption bands overlap. But water vapor is not absorbing much LWIR at the main absorption wavelengths of CH4 around 7.69 microns.

The LWIR absorption bands are different among the different greenhouse gases because the dipole moments of the molecules are different, which means the vibration modes are different for each gas molecule. The C-0 bonds in CO2 have different vibration frequencies compared to the H-0 bonds in water vapor and compared to the C-H bonds in CH4. These different vibrational frequencies correspond to the wavelengths/frequencies of LWIR that are definitively characteristic of each gas molecule. If the spectrum of one of the pure greenhouse gases is taken at low concentration, that spectrum will be one or more straight lines at precisely known, experimentally measured, and precise wavelengths. As the pressure increases, either by adding more of that pure gas or adding other atmospheric gases, the straight lines become spread out bell curves and then as pressure increases further blobs spread over many wavelengths … due to collisions …collision induced absorption (CIA). The absorption bands are spreading and forming “wings” centered around the original absorption line. H20 vapor at STP in air is ~10 times more concentrated that CO2 and ~200 times more concentrated that CH4. The absorption lines of H20 vapor are spread out into a blob that extends over a broad range of the LWIR spectrum. This blob overlaps with the two main LWIR absorption bands of CO2…thus CO2 absorption is relatively weak. But the CH4 line around 7.69 microns is in a region where H2O vapor absorption is declining.

The processes of absorption and emission are the same in H2O, CO2 and CH4. The characteristic wavelengths/frequencies of each molecule is determined by the various dipole moments of the vibrations of the atoms relative to each other within the molecule. BUT, detecting the IR light which is absorbed and emitted by the molecules is an entirely different matter complicated by the temperature/pressure and the other gas molecules. CH4 in normal air STP at the surface is easily measured by an IR spectrometer. CO2 Is not easily measured, because water vapor in normal air is absorbing most of the IR radiation.

Further detail:
One of CH4’s main IR absorption bands is ~ 7.69 microns. This band does not overlap with the IR absorption bands of water vapor or CO2. The bands of CO2 mostly overlap with water vapor and water vapor concentration is of course much 10X or more higher than CO2, so water vapor cancels out most CO2 absorption and almost all radiative emission from CO2 is absorbed by water vapor.  

In fact, it is extremely difficult or impossible to measure by IR spectroscopy the atmospheric concentration of CO2 due to the presence of water vapor in a normal air sample. The air sample must be dried first or the CO2 is converted to CH4 by passing it over a catalyst. 
As you already know, the IR absorption of CH4 has undetectable effect on temperature and climate because its concentration is so low. While it is true that CH4 on a molecule by molecule comparison with CO2 will absorb and re-emit 20 to 30 times more intensity (watt/m^2) of IR, it is also true that CO2 is 200 times more concentrated in air than CH4. Furthermore, all CH4 in air spontaneously combines with O2 at STP in collisions in the presence of trace Cl2 as catalyst over the oceans to form CO2. Ultimately, CH4 converted (oxidized) in this way is the largest source of atmospheric CO2. CH4 exists in 50-60 times higher concentration as gaseous CH4 in ocean, controlled by Henry’s Law constant, just as CO2 is. But the CH4 emitted by oceans converts to CO2.  

Both gases are continuously outgassed at the surface of ocean water and re-absorbed at the surface of ocean water and a partition rate determined by temperature, pressure and salinity at the surface. However, in air trace concentration CH4 collides with high concentration of O2 in the presence of Cl2 and concerts to CO2 and H20. In other words, the lifetime of CH4 is air is short, which is another reason CH4 has no significant warming effect.
        
I have been arguing against AGW from the basis of Atomic, Molecular and Optical physics (AMO) for over 30 years. The myriad theoretical assumptions (e.g. blackbody radiation) and the math involved in the physics of weather change and earth’s energy balance results mostly in glazed over eyes of listeners and readers. I believe AMO is a far more understandable, known and more certain basis for argument than the overlapping and less understood theories of climatology. 

Roy Spencer pointed out over a decade ago that radiative emissions from greenhouse gases do not result in positive feedback (or positive climate forcing) which is assumed in climate models and that this mistake was a reason climate models were notoriously wrong. 
Looking at AMO, the sequence of: (1) infrared emission (IR) from the surface (2) absorption of that IR by a greenhouse gas molecule in air, (3) near instantaneous collision of that greenhouse gas molecule most probably with a non-IR-absorbing N2 or O2 molecule, and (4) emission of that IR from that greenhouse molecule in a pulse into 3D Steradian space, means that the intensity (watts/m^2) of that IR radiative emission received at any subsequent point is at least 50% less than the intensity absorbed initially at the greenhouse gas molecule. The intensity is further reduced by the inverse square of the distance between the emitting greenhouse gas molecule and receiving point. In sum, it is a cascade of emission-absorption-collision-emission sequences progressively dividing the intensity of the LWIR by more than 50% in each subsequent sequence of events. Radiative emissions of IR from greenhouse gas molecules reaching earth’s surface are minor, infinitely small if any, since the density of air and IR absorbing molecules are increasing a, and the collision frequency is increasing, thus the rate of progressive Steradian divisions of intensity is increasing, as the earthward-direct radiation approaches the surface. 

Similar to approaching a wall by taking steps in succession with each step 50% of the distance to wall, you never reach the wall.

Consider one of several exceptional situations: a greenhouse gas molecule moving in air at the velocity commensurate with the surrounding air temperature and density and only one wavelength distance above the surface. The surface is non-coherently radiating across a broad spectrum of IR light, but the molecule only absorbs coherently at its characteristic IR wavelengths/frequencies until its quantum bands are saturated. The molecule’s velocity does not change due to either the absorption or emission events, therefore these events are not thermal events; radiative absorption and emission by greenhouse gases are not thermal events in AMO. The energy increase within the greenhouse gas molecule is potential not kinetic. The atoms within the greenhouse gas molecule are vibrating relative to each other at a higher frequency due to the absorption and a lower frequency after emission, but the vector velocity of the gas molecule in air does not change. Following a collision, an IR pulse is emitted and the gas molecule relaxes to its ground state. A 100% reversible energy transition has occurred between absorption and emission, conserving the laws of thermodynamics. But the IR intensity received at the surface (only one IR wavelength away and a only fraction of a second later) following the radiative emission is only about half the intensity that was originally received at the same, characteristic IR wavelengths. IR received off axis is at longer wavelengths determined by its solid Steradian angle and is at more than 50% reduced intensity. Meanwhile, the surface is still non-coherently emitting IR at the same spectrum of wavelengths/frequencies but at much higher intensity than the gas molecule’s pulse. In a probability distribution, the tiny coherent one wavelength pulse of coherent IR from the gas molecule probably will be harmonically cancelled by much more intense IR emission from the surface which are 180 degrees out of phase with the LWIR pulse from the molecule. Thus, in the most likely case for radiative emission of IR downward toward earth’s surface, the IR radiative emission from the gas molecule never reaches the surface even if it is very near earth’s surface. 

Thus IR emissions from the surface into the atmosphere and eventually into space are cooling the surface of the earth, not warming. The concentration of greenhouse gases above the surface does not warm the surface by radiative emissions but delays the rate of cooling of the atmosphere due to LWIR emission from gases into space. The same will be true for any greenhouse gas. 

That’s how I see it.