CO2 Band-Saturation Explained

10/14/2019 22:23 - Posted by Tom van Leeuwen
Professor at the Geophysical Sciences department at the University of Chicago David Archer describes the band-saturation of the CO2 greenhouse effect.

After that, everything goes wrong.

The first part of the lecture is very informative. Professor Archer explains in great detail how the CO2 greenhouse absorption works, it's logarithmic nature and the band-saturation. He even shows on a working instance of the MODTRAN model how adding the first ppm of CO2 to the atmosphere has a huge impact on the atmosphere's energy balance. Adding more CO2, the effect fades away.

"If you go up higher and higher in CO2-concentrations it decreases the rate at which energy is lost to space but you get less bang for your buck the more CO2 you have in the atmosphere. It never becomes insensitive to CO2 but the sensitivity goes down the more of the gas you have in the atmosphere."

Perfect! This explains why the IPCC models do not work. It's because adding more CO2 has no measurable effect on the temperature. It also explains why there is no observed correlation between CO2-concentration and global temperatures in the real world. In fact, his explanation up to this point solves the whole "Global Warming" controversy. There is almost no human-caused global warming. Period.

The CO2 band-saturation effect defuses the whole Climate Change scare. That's why so few people talk about it.

Unfortunately, things start to take a different course after 09:35 minutes into the lecture when Professor Archer starts talking about a supposed Doppler effect between the radiation and a moving receiving CO2 molecule.
The point he tries to make is that the CO2 molecule can absorb photons with a frequency slightly different because of the Doppler effect. What he does not take into account is the huge difference in speeds between these two types of objects. A convecting CO2 molecule might be moving at a speed of 300 to 400 km/hour at most, while the photon moves at the speed of light, 299,702 km/second in the Earth's atmosphere. So:
  • CO2 speed: 400 km/h ~ 111 m/s
  • Photon speed: 299,702,547 m/s
If the direction of the two objects is the same, the CO2 molecule perceives the photon's frequency as 1.00000037 times its real frequency. If both objects move in the opposite direction the perceived frequency is 0,99999963 times the real frequency. If the photon comes from any other direction the perceived frequency is in between these two values. So, the difference in perceived frequency between a steady molecule and a convecting molecule is neglectable.
As the photon is absorbed even if "the frequency, the vibration of the gas is sort of the same as the frequency of the light that's coming in (07:40)", the Doppler effect does not affect at all on the absorption frequency band. Professor Archer should know this, and I'm sure he does.

Edit 10/17/2019
A reader wrote me that there exists a Doppler-effect between the photon frequency and the "spinning" and "vibrating" movements of the CO2 molecule. That makes sense, but that's not what Professor Archer is telling us.

The analogy with the moving train is invalid as well. A photon travels at the speed of light, so the correct analogy would be a train traveling at the speed of sound. You do not hear a train moving towards you in a straight line at the speed of sound because the sound it emits reaches you at the same moment the train itself reaches you.

Somehow, this absurd assertion marks a sudden rupture in his lecture, because shortly after, Professor Archer pronounces the most conflictive statement (10:20):

"It turns out that even if the gas absorbed everything, adding more of the greenhouse gas would still affect the climate."

This, of course, is impossible. If the gas absorbs everything, then there's nothing left to be absorbed and adding more gas will not affect the climate.

He tries to explain his statement comparing the greenhouse effect with a layer model in which panes of completely saturated glass are stacked one on another, but he admits that they can not explain how this works on Venus. That's not a great start for his model.

The truth is that you can only stack a finite number of saturated glass panes. You can't go on and on and on as he describes it because this modeled analogy only works up to the top of the atmosphere. But this is just a minor flaw because the photon won't make it past the first pane anyway.

The main problem with this model is that a completely saturated glass pane is completely opaque from the infrared photon's point of view, it can't get through. In his model you see photons coming out of the first pane and enter the second one. But if a photon can traverse the first pane, that pane is not completely opaque by definition. That's a contradiction because a glass pane can't be both completely opaque and not completely opaque at the same time.

During the whole explanation of his model, Professor Archer seems much less confident than during the rest of the lecture. He hesitates, searching for words and at 10:52 minutes the video is edited. Even the written text on the blackboard is edited (chalk dust below "the") and still contains an error: "but even if it (sic) the gas absorbed everything," All this indicates confusion and doubt at the moment he prepared this section of the presentation.

He closes this part with the phrase: "that's how we defined it, to make it simple". This can be interpreted as a reference to the climate science doctrine. They define that CO2 is the climate control knob and start building their hypothesis from that definition on.

After that, he quickly returns to the first part of the lecture saying: "so, the band-saturation effect is a very, very important effect for understanding how the climate of the Earth responds to greenhouse gasses like CO2", completely contradicting the points he said just seconds before.

His closing phrase emphasizes his fixed "CO2-equals-warming-by-definition" mindset: "It's a good thing we already had CO2 in the atmosphere before the Industrial Revolution because if there wasn't and we started putting CO2 into a virgin atmosphere, it would have just totally melted down the climate".

No, Professor Archer! If we would have started adding CO2 into a virgin atmosphere we would actually have a lower concentration than the 420 ppm of CO2 we have right now, and the temperature might be slightly lower depending on the degree of saturation of the CO2 greenhouse effect. But in no case, the temperature would be higher.

A better final phrase would have been: "It's a good thing we already had CO2 in the atmosphere because with a virgin atmosphere life on earth would not have developed, and therefore, the Industrial Revolution would never have happened."


During the first 9 minutes of this lecture, Professor Archer presents a solid explanation of the CO2 greenhouse effect, its logarithmic progression, and its band saturation effect. Unfortunately, in the last part of his lecture, he spoils it all contradicting his own explanation with a failing analogy, an impossible statement, an ill-constructed model, and a bogus conclusion remark.

Tom van Leeuwen, October 14th, 2019.


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The fingerprints of the greenhouse effect

The hypothesis of "man-made climate change" tells us that the increase in the concentration of CO2 enhances the greenhouse effect of the atmosphere and has global warming as a final result.

Since the beginning of the industrialized era around 1850, man emits relatively large amounts of CO2 into the atmosphere through the use of fossil fuels. The consequence of these emissions is that during that period, the concentration of CO2 in the atmosphere increased sharply from about 300 parts per million to more than 400 ppm, an increase of almost 40%. The average temperature increased in the same period more or less 1.5 °C with a small variation depending on the data source used.

Why did the warming stop?

The political reports of the IPCC are based on the hypothesis that CO2 is the most important control knob of the Earth's temperature. The problem is that this hypothesis does not correspond at all with the empirical data available to science. Forecasts are made using models that are not capable of 'predicting' the past.

Temperature versus CO2 – the big picture

When discussing “Climate Change” it’s good to have an understanding of how the Earth’s climate has changed in the past. That will give us a reference to decide whether the current changes are normal or not.

Global temperatures have varied a lot over the last 500 million years. Depending on the timescale used, the current temperature is either cold or hot, so when you want to know the “normal temperature” you’ll have to indicate what timescale you’re using.

Dutch Warming

In the Netherlands, the day-to-day whether depends heavily on the direction the wind is coming from. Being a small country, the wind direction is quite homogeneous for the whole country, specially on higher altitudes where the bulk of heat convection is taking place.

Due to its geographical position, midway between the icy-cold Arctic to the north, the dry and hot Sahara to the south, the Eurasian land-mass to the east and the Atlantic Ocean to the west, every wind direction comes with unique weather characteristics.

North - cold,
East - dry,
South - warm,
West - wet whether.

Satellite temperature observations

This month of January 2023, the average satellite temperature published, by Dr. Christy and Dr. Spencer (University Alabama Huntsfield) had a negative deviation, compared with the average monthly measures between 1991 and 2000.

Of course, this value does not mean much, it's definition is full of arbitrary begin and endpoints, but anyway it doesn't sound like a lot of warming has taken place over the past 30 years, and even less "catastrophic warming" we're reading about in the Mainstream Media, newspapers and TV stations.

CO2 saturation

This graph is all you need to understand that CO2 is not the Earth's Climate Control Knob.

On the horizontal axis, we see the Infra-red (IR) spectrum wavelengths, that is like "IR colors" were this kind of radiation visible to the human eye.
The vertical axis shows to energy flux, that is the energy emitted by the Earth, as seen from outer space.

The graph itself shows how the Earth's atmosphere filters the IR radiation emitted by the Earth's surface and the role of the various greenhouse gases in that filtering process. The green line is the filter of the Earth's atmosphere without any greenhouse gases.

Video - Who are the real climate deniers?

The climate has shown many fluctuations during the Holocene. The difference between the highest and lowest average temperature of the past 10 thousand years is about 3 °C.

Climate alarmists, led by the IPCC, are trying to deny this, and understandably so. This variation means that without human influence there was climate change as well.

This undermines their hypotheses and often their jobs depend on it.

Climate change seen from a historical perspective.

Satellite Earth temperature February 2022

The satellite temperature departure measurement for February 2022 is exactly 0° C.

This means that Earth temperature during February 2022 was exactly the same as the average from 1991 to 2020.

Satellites are the best way to have insight into the short-term temperature variations. They measure the whole surface, independent of weather station distribution, Heat Islands, measurement failures, surface condition (land or water).

There is a step-wise increase in temperature, triggered by two very strong El Niño events (1998 and 2016.) The energy that welled up from the deep oceans established a new level in these two ocasions, where the warming paused. This is a natural phenomenon and has nothing to do with CO2, or human activity.

Where is the Climate Emergency? It just does not exist.

Wake up and spread this information to your government!

Tom van Leeuwen, March 1st, 2022.