An Open Letter to an Alarmist Shill

Multiverse theory is a good way of attracting the attention of a viewer.
Its hardly a theory, at best an unproveable hypothesis.
That’s because such universes must, by definition, be unobservable from our universe.
They are a way of explaining ‘everything’.
Everything that possibly can exist or will exist, exists in at least one of these states, or so the theory plays out, despite a lack of any evidence.
That includes god, flying spaghetti monsters, fairies at the bottom of the garden and people with your sweater on.
Some of these universes may even contain people who demand empirical evidence and testable hypotheses.
Perhaps one will be discovered some day soon, right here.

Whoa, you shouldn’t begrudge a science-populiser his colourful turn of phrase. Agreed Cox is a McCarthyist where global warming is concerned, but he’s entitled to have a stab at explaining the multiverse theory.

The first thing to understand is that the MODTRAN spectrum available at https://en.wikipedia.org/wiki/Radiative_forcing very closely models an actual spectrum taken by a satellite looking down near Guam [see the third Fig. at http://climateaudit.org/?p=2572 . The models in molecular spectroscopy are really “settled science” (unlike those of the IPCC predicting climate change).
The next thing to understand is that these are “net absorption” spectra [ask any competent chemist], not “emission spectra”. This is the difference between the Fraunhofer lines in the Solar spectrum and the bright line emission spectra of a hydrogen discharge tube (or the bright mercury lines seen over diffuse phosphor emission from a fluorescent light – use any small hand spectroscope to see these).
I used the adjective “net” for absorption because there is a CO2 emission spectrum (at 220 K) at central frequencies superimposed on a CO2 absorption ditch that would otherwise go all the way down to zero transmission in the troposphere. This 220 K CO2 emission is powered by incoming Solar UV and visible radiation absorbed by ozone in the stratosphere and then transferred during inelastic molecular collisions to the main molecules N2, O2 and Ar that make up more than 99.9% of the atmosphere. A tiny part of that total energy excites CO2 molecules which can emit infrared (IR) frequencies around 667 cm^-1, and these are registered in the spectrum.
Doubling CO2 will increase absorption in the troposphere, and this occurs in the wings of the spectrum, centered at 618 and 721 cm^-1, since the main increase is in sidebands where the absorbing molecules are in the first excited state (about 3% of all CO2 molecules), and not in the ground (lowest energy) state, which is involved in the 667 cm^-1 absorption. 3% relative concentration means that these sideband frequencies are not “saturated”, so doubling CO2 will have a significant effect on absorption. You can see this extra absorption in the MODTRAN spectrum (it is the area between the green and blue curves that represent absorption at 300 ppmv CO2 and 600 ppmv). Most of the absorbed energy is transferred to the main molecules of the air (N2, O2, Ar) that are non-polar, with zero electric dipole moment, and therefore cannot and do not emit or absorb any significant IR photons. Because the heat capacity at constant pressure for linear molecules like N2, O2 and CO2 is Cp = 7k/2 per molecule, where k is Boltzmann’s constant, most of the heat content (enthalpy) is stored in non-radiating molecules that outnumber CO2 by 2500:1 (at 400 ppmv CO2). This is the molecular explanation for the greenhouse effect. This extra absorption would mean an energy imbalance: a decreased TOA (Top Of the Atmosphere) flux would no longer balance the net incoming Solar flux (after reflection or the albedo has been taken into account), so the same incoming flux would warm up the surface until the TOA flux again balanced the net incoming. The principle of adding equal amounts of energy to all molecules in the same energy state means that all molecules in a column of the troposphere (which have the same total U + H, where U is the gravitational potential energy and H is the enthalpy) will on average increase by the same temperature T [ since “delta H” = Cp .(“delta T”) ]. Therefore the new temperature profile will have the same slope as previously [the lapse rate remains at -6.8 K/km], but will be offset by the same temperature at each altitude. Extra absorption means an increased temperature.
The stratosphere is a different story. The heating by incoming Solar UV and visible radiation by ozone produces a temperature inversion: the temperature increases with increasing altitude. Central CO2 frequencies around 667 cm^-1 are essentially 100% saturated in the troposphere. Kirchhoff’s law says that a good absorber is also a good emitter, so those CO2 frequencies are 100% re-emitted, as per the usual theory of the greenhouse effect. This is mathematically handled with the Schwarzschild Equation, which adds an emission term to a Beer-Lambert absorption term. Doubling CO2 means that the region of 100% absorption is extended to higher altitudes, where the temperature is higher. So the final escape of IR photons to outer space occurs at higher temperatures, which means higher emission (using the Stefan-Boltzmann law for an effective Planck black body equivalent). This does not show up in the MODTRAN spectrum, which was calculated only to 20 km altitude. Jack Barrett has run the program to 70 km altitude [see the section “The hard bit” at his website http://www.barrettbellamyclimate.com/ ], which shows increasing emission around 667 cm^-1 on increasing CO2. Increasing emission at these frequencies means that the energy imbalance is now the other way: if more escapes per unit time while the incoming radiation (which excites ozone and heats the stratosphere) stays the same, then the stratosphere will cool with time.
The tropopause is the inflection point, where the lapse rate switches from negative in the troposphere to positive in the stratosphere. The net effect on temperature should be between the two cases, i.e. zero or very little change with time as CO2 increases.
QED

A better phrase than “monotonic” would be “increasing with curvature upward” for CO2, which for a time matched the increase in T [see Al Gore].