The scientific evidence behind CO2 alarmism consists of OLR spectra produced by a combination of modeling and measurement (Modtran/Hitran/IRIS) predicting a radiative forcing of 3.7 W/m2 by doubling the concentration of atmospheric CO2 from a preindustrial level of 300 ppm to 600 ppm (with 390 ppm the present level) with an estimated warming effect of 1 C.
The OLR spectra are computed by radiative transfer models based on models of spectral emissivity of atmospheric CO2 determined by line spectra combined with line broadening models, which determine a warming effect of 3.7 W/m2 from doubled CO2 resulting from an increase of the effective altitude of emission on the "shoulders" of the line spectrum of CO2 around the main resonance at wave number 667 forming a ditch in the spectrum between 550 and 800 with a total area representing a warming of about 20 W/m2, about one tenth of a total of about 200 W/m2 as shown in a previous post.
This effect can be studied more closely by the online Gas-Cell Simulator by Spectral Calc, which gives the following absorptivity for an atmosphere at 0.5 bar with 300 and 600 ppm of CO2 at a path length of 2000 m:
The Gas-Cell Simulator shows an absorptivity increasing with p x L, where p is the partial pressure of CO2 and L the path length, with a switch to absorptivity greater than 0.5 (defining an effective emission altitude) occurring between 300 and 600 ppm CO2 at a path length of 2000 m (with full saturation between wave numbers 640 and 700).
The effective altitude of OLR emission for wave numbers 580 - 620 on the left shoulder may thus be estimated to increase by 2000 m upon doubling of CO2 until the tropopause is reached, which could mean a temperature drop of 13 C. With a shoulder width of 80 out of a total width of 250 the CO2 ditch between 550 and 800 and 13 C about one fifth of the total temperature drop in the ditch of about 65 C, this gives a warming effect of about 0.3 x 0.2 x 20 = 1.2 W/m2 for one shoulder.
We thus arrive at a warming effect of about 2 - 3 W/m2 from an increase of CO2 from 300 to 600 ppm, which gives an insight into the background of the crucial 3.7 W/m2 as the starting point of climate alarmism.
We see that the effect comes from a simple model of line broadening of the weak spectral real lines on the shoulders of the CO2 spectrum around the main resonance at 667. The model is simplistic and the effect is so small that it cannot be measured, and so from scientific point of view it can only be viewed as a speculation which could as well be half or twice as big, thus without much substance.
Yet this is the main scientific evidence put forward in support of CO2 alarmism. Note that the fact that the number 3.7 W/m2 cannot be trusted as scientific evidence, does not itself give reason to restrictions on CO2 emissions putting more burdens on humanity. Lack of evidence is not a reason to put someone in jail. What would be needed is positive scientific evidence that CO2 can cause global warming with observable negative effects, but that is missing.
PS When climate skeptics state that for sure they understand very well that there is a CO2 greenhouse effect, as any knowledgable scientist must do, they refer to the radiative forcing of 3.7 W/m2 with 1 C warming from doubled concentration, but then forget that this effect has very weak scientific support. They seem to get caught in an argument stating that even if the effect is too small to ever be detected, the effect is undeniably real as an expression of the line spectrum of CO2.
But this means violating the essential principle of science to not give a negligible effect a major role, which is required in order to be able to make meaningful predictions as the goal of science.
PS When climate skeptics state that for sure they understand very well that there is a CO2 greenhouse effect, as any knowledgable scientist must do, they refer to the radiative forcing of 3.7 W/m2 with 1 C warming from doubled concentration, but then forget that this effect has very weak scientific support. They seem to get caught in an argument stating that even if the effect is too small to ever be detected, the effect is undeniably real as an expression of the line spectrum of CO2.
But this means violating the essential principle of science to not give a negligible effect a major role, which is required in order to be able to make meaningful predictions as the goal of science.
Inlägg
Claes. The fabrication of all radiative and greenhouse paradigms can be completely demolished because it is not energy budget considerations which ultimately determine supported planetary temperatures in their atmosphere, surfaces, crusts, mantles and cores - anywhere in the Universe.
SvaraRaderaIt is the non-radiative process which spontaneously evolves that does so. This process is in all statements of the Second Law of Thermodynamics and the reasons are in my paper "Planetary Core and Surface Temperatures" in the PROM menu at PSI.
Try explaining Uranus temperatures with any radiative model. There is 3W/m^2 received and re-emitted in the very top of its atmosphere where temperatures are about 53K and the radiating temperature for the planet is 59K. Then 350K below that it is 320K (following a temperature gradient extremely close to the quotient of the acceleration due to gravity and the weighted mean specific heat of the 83% hydrogen and 15% helium atmosphere.
Then, the depths of the 20,000Km deep atmosphere temperatures get up well into thousands of degrees.
How does the required energy get down there, unless by the method I explain in the paper?
Doug Cotton
The "old paradigm" is smashed when you consider Venus. Each Venus 4-month-long day the surface temperature rises by about 5 degrees, and it cools by 5 degrees at night. Obviously the energy which increases the temperature in the day comes from the Sun. We have only about 20W/m^2 of direct solar radiation getting through the Venus atmosphere in the day, and yet the Stefan-Boltzmann Law tells us we would need about 16,100W/m^2 of radiation to increase the temperature of the Venus surface when it is in the vicinity of 730K. Obviously radiation from the colder atmosphere cannot increase the temperature of the surface, for that would be an outright violation of the Second Law of Thermodynamics. In any event, there is not enough radiative flux entering the atmosphere. So the energy cannot get there by radiation alone and in fact radiation can play only a very small role.
SvaraRaderaSo that leaves only non-radiative processes, and clearly it gets narrowed down to diffusion and convection. The reasons why (and the process whereby) downward diffusion and convection ("heat creep") can in fact increase the temperature are explained in my paper "Planetary Core and Surface Temperatures."
For radiation to make a surface temperature increase from 730K to 735K each 4-month long Venus day it has to comply with both these requirements, as per standard physics ...
SvaraRadera(a) It has to have a flux based on the Stefan-Boltzmann Law, namely about 16,100W/m^2 for 730K. The flux coming into the Venus atmosphere is far less, and hardly any gets through to the surface. How can the atmosphere multiply the flux and how can such flux do so much better at penetrating the atmosphere? Where are the calculations that at least obey the First Law, even though they don't have a hope of obeying the Second Law, so the whole radiation exercise is hypothetical anyway.
(b) The radiation has to come from a hotter source. That only leaves the Sun. So the only radiation that can have a hope of doing so is the mere 10 to 20W/m^2 of Solar radiation that gets through the atmosphere. So we have about one-tenth of the radiative flux which reaches Earth's surface. So if that really could heat a surface to 720K, then why wouldn't Earth be much hotter still? The whole thing is ludicrous.
Only the new paradigm in my paper explains what really happens, and it is certainly not radiation that is doing most of the heating, I can assure you. How could it be?
Low frequency, low energy radiation does not undergo atomic absorption in a warmer target, as Claes Johnson also points out, and so its electro-magnetic energy is not converted back to thermal energy in the target. Radiation in a microwave oven demonstrates this point when it passes through opaque plastic, following a random path involving multiple "pseudo scattering" events. The plastic is not transparent in the normal sense of the term in physics. The radiation does not pass straight through like x-rays, or light passing through glass. If it did you could patent a new safe medical imaging device.
SvaraRaderaHeat is not energy itself, and is not a property of an object. Heat is always associated with a process in which thermal energy is transferred from source to target. In the case of radiation, thermal energy is converted to electromagnetic energy in the source, and then it may or may not be completely or partially converted back to thermal energy in the target. This is explained in my PSI reviewed paper "Radiated Energy and the Second Law of Thermodynamics" in the publications menu since March 2012, and based on the work of Prof Claes Johnson.
I have put up an alternative to the greenhouse radiative forcing models, rather than just saying they are wrong because the world is not still warming as much, or back radiation only slows radiative cooling without transferring heat to the surface. I have firstly shown that radiative flux cannot be used to determine planetary surface temperatures because those surfaces act nothing like a true blackbody, and then I have shown, with valid physics, how such temperatures are supported by the autonomous gravitationally-induced temperature gradient and the resulting "heat creep" process, which I doubt that many understand, even if they disagree.
The process I am talking about is explained in sufficient detail in Sections 4 to 9 of my paper "Planetary Core and Surface Temperatures" in the PSI PROM menu. It is not hard to understand if you have an understanding of the process described in statements of the Second Law of Thermodynamics, whereby a state of thermodynamic equilibrium evolves spontaneously with maximum accessible entropy.
When new energy is absorbed it disturbs the thermodynamic equilibrium, and so the process I describe in my paper is nothing more nor less than the same process described in statements of the Second Law of Thermodynamics in which thermodynamic equilibrium evolves spontaneously. Hence such thermodynamic equilibrium is restored when it has been disturbed. To prove me wrong you would have to prove the Second Law wrong.
Planetary surface temperatures have very little to do with incident radiation. At the base of the theoretical troposphere of Uranus it is about 320K but virtually no Solar radiation reaches down through 350Km of its atmosphere to that altitude.
SvaraRaderaThe Sun cannot heat the surfaces of planets like Earth and Venus to the observed temperatures with direct radiation. So it doesn't matter how much the atmosphere slows cooling if we can't explain how the temperature gets to 288K on Earth or 730K on Venus before any such cooling begins.
In fact it is energy from the Sun which does the warming by first heating the atmosphere with incident radiation. That absorbed energy then disturbs the thermodynamic equilibrium and this leads to convective heat transfer down towards the surface. In physics "convective heat transfer" can comprise diffusion as well as advection, but advection is not necessary. We don't need to explain such heat transfer by imagining air moving up or down. We need to understand the process described in the Second Law of Thermodynamics, as in Sections 4 to 9 here.