"In 2021 the CO2 Coalition submitted a public comment opposing climate change disclosure rules by the U.S. Securities and Exchange Commission. The Coalition asserted "There is no 'climate crisis' and there is no evidence that there will be one," and further "Carbon dioxide, the gas purported to be the cause of catastrophic warming, is not toxic and does no harm." Both assertions are at odds with the scientific consensus on climate change."
The spectrum still is like it is. Even Cancel culture won't change it. Please read some papers about the subject... I was pretty shocked to see what kind of quality you find there... (Nothing but a little bit of quibbling, and also a lot of name calling...). There is a reason why politics shuts down some institutions... Mainly those that have some kind of consensus, that doesn't have any foundation in physics. It's just a sect... Strong believes - and no science...
Low PPM CO2 concentrations in the atmosphere affects IR in the atmosphere much as thin steel plate affects a bullet fired 5,000 yards through air .. it absorbs and scatters despite being a 'mere' PPM.
The real world physics of doubling a low CO2 concentration in representative air samples has been performed many a time .. it works as the cited paper says .. trapping more of heat energy radiated upwards by the land and sea that would otherwise diffuse outwards.
1967 is pretty ancient... Nowadays there are databases and there are detailed calculations about the spectrum (line by line). There is HITRAN database. And people did the calculations. And have done so for years... There are pretty precise calculations how much energy is being trapped. And they fit with observations. There is a saturation effect, and it's pretty strong. On each frequency you can only absorb the total amount of energy that is available there. After that adding more CO2 won't make a difference.
People calculated precisely what exactly happens when you double CO2... And the effect it's logarithmic...
FWiW you appear to basing your take on a reading pushed by Dr. C.A. de Lange of CO2Coalition of an unaccepted paper by William. A. van Wijngaarden and William Happer.
That discussion on Stackexchange has something like 6 upvotes. And if you read it, the comments there are mostly ridiculous. The absorption is logarithmic beyond 8000 ppm, and someone there e.g. whines about that Wijngaarden doesn't explain the climate on Venus (> 90% CO2 atmosphere).
The thing about Venus is also something you'll find if you look for serious papers trying to criticise the paper. Nitpicking about the word logarithmic seems to be the only things that serious critics have found. The other main argument seems to be name calling and Cancel Culture... and that's all what critics so far have produced...
Claiming that things are unaccepted is also some kind of rumour. There are more papers, and if you read them you'll notice that they're of very high quality. Just compare the quality with that of papers of critics...
To me the most compelling argument for Wijngaarden is the incredible low quality of all the writings from people from climate-institutes that tried to find something against him. OMG...
First you claim to want science, now you're saying thermodynamics goes stale?
Maybe read the paper and those that followed, especially about the follow on increases in water vapor and methane and where trapped heat energy goes once there's little to no ice left to melt and act as a sink.
The people you are quoting are a known fossil fuel disinformation crew providing a pension plan to fossils like Clauser who have zero peer review papers in any part of the climate or geophysics field despite some sound work in unrelated fields contemporous with 1967.
https://en.wikipedia.org/wiki/CO2_Coalition