Digression #3 - The "Greenhouse effect"
This digression article is needed to avoid comment threads being derailed by the basics again and again. I can send commenters here and move comments here.
Many people who don’t understand atmospheric physics dispute the basic idea that adding CO2 to the atmosphere increases the surface temperature of the planet. The idea is known by the imperfect name, “the greenhouse effect”.
There isn’t a simple conceptual idea that we can put in someone’s head to explain why the greenhouse effect is real. Too bad.
Plenty of people try to explain it to the general public. However, give too brief an explanation and you miss out important details.
Ah ha, these idiots don’t understand this subject, look at their lack of attention to detail. It’s much more complicated than that!
Give too long an explanation and no one outside the field can understand it.
Too long and boring. Too nebulous. Too much maths. Give me a simple demonstration of why this is true.
Maybe try basket weaving instead. Or go into politics. Or journalism.
There are some basic ideas that together are used to prove the “greenhouse effect”.
The temperature of the atmosphere decreases as you go up in altitude. Everyone seems familiar with this point.
Gases absorb radiation at various wavelengths, depending on the gas in question. The higher the concentration of the gas, the more the absorption.
Gases emit radiation at various wavelengths. The higher the temperature of the gas, the more the emission. The higher the concentration of the gas, the more the emission.
If we take the temperature profile of the atmosphere as a given, we can write down equations using points 2 and 3. This wasn’t invented by climate scientists. Famous names from history and Nobel prize winners came up with this stuff a long time ago.
It’s in all the textbooks that cover this level of detail. There isn’t an alternative set of equations.
I’ve explained the derivation of the equations in Understanding Atmospheric Radiation and the “Greenhouse” Effect – Part Six – The Equations.
It’s very boring and tedious, and if you don’t have a maths or hard science background you won’t follow it.
Emission and absorption of radiation are not fanciful or unproven ideas. The equations are used in cosmology for working out, for example, the temperatures of gas and dust clouds. The equations are used in satellite observations of the earth, for example, in measuring ocean temperatures and atmospheric humidity. They are solid.
We have spectroscopic measurements of the absorption lines of CO2, water vapor, methane, and other gases. They aren’t some fanciful idea either. The Journal of Quantitative Spectroscopy & Radiative Transfer contains the tedious details in the reference below.
Here’s an example of radiation vs wavelength. We’re comparing the calculation from the physics I’ve just outlined with observations from a satellite. The gap is artificial to make it easier to see the comparison, the lines match:
The big “bite” in the middle is the effect of CO2 - reducing radiation emitted to space. If there was no CO2 this “bite” wouldn’t exist. Radiation to space would increase, meaning the planet would cool down.
It’s just lines on a page, so ignore it if you like. Maybe someone just made it up.
And the equations of absorption and emission, used by countless disciplines, they are probably made up as well.
Over to the enlightened ones.
Further Reading
Here are some references from the old blog, explaining these ideas in more detail:
The “Greenhouse” Effect Explained in Simple Terms – summarizing the effect, attempting to “make it simple but not too simple” with many links to other articles
Theory and Experiment – Atmospheric Radiation – real values of total flux and spectra compared with the theory
Visualizing Atmospheric Radiation - a series
References
The HITRAN 2008 molecular spectroscopic database, by L.S. Rothman et al, Journal of Quantitative Spectroscopy & Radiative Transfer (2009)
I'm moving this comment here from "Natural Variability, Attribution and Climate Models #12" - https://scienceofdoom.substack.com/p/natural-variability-attribution-and-469
Robert Hisey
All of these models assume the truth of the hypothesis that adding more CO2 to the atmosphere will increase ir absorption and thus raise the temperature. Two facts are obviously ignored. First, no one has ever put forward a proof of this hypothesis! Could it be that the hypothesis is false? Is the entire war on fossil fuel based on an unproven hypothesis?
Second, the 1991 NASA project on the Infra-red transmission/absorbtion of the atmosphere in 1991 shows total absorption of all the energy in the only band where CO2 is effective is already cleaned of all energy. True, this information was kept hidden until 1992 and still recieves no publicity. Thus, more CO2 can not absorb any energy, so does not affect gloal warming. The climate sensitivity to CO2 addition is zero. All the models are thus fatally corrupted.
The arguement is made that doubling the CO2 will cause crowding, and thus broaden the band. No citation or reference. An analogy. A quart of beans is like 2,500 beans. Present atmosphere has one black bean. Doubling is adding 1 more black bean. Now 2 black beans in a quart jar of 2,500 beans is not very crowded.
I uncovered the NASA data at "Nasa Technical Memorandum 103957, Appendices E and F", all 100 pages of it. It is also available on Kindle. The salient 15 micron part is available in a more convenient form, with discussion, in my little booklet on Kindle "Carbon Dioxide-Not Guilty". This has been searchable for a year now. It is 99c and in interest of clarity, I get 6c each! It is also available as a free PDF to anyone who sends me an e-mail address.
I'm moving a comment from "Natural Variability, Attribution and Climate Models #11" - https://scienceofdoom.substack.com/p/natural-variability-attribution-and-f99
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Will Pratt
Writes The Perpetual Lightbulb
But natural climate variability shows clear unequivocal signs of patterns that are directly attributable to solar cycles.
There is absolutely no human signal in the CO2 data let alone climate variability.
You first need to show through experiment that CO2 traps heat. As heat is a vector and cannot be trapped, that’s never going to happen.