CO2 acts as a mild greenhouse gas in lab spectroscopy experiments.
That suggests it is likely to cause mild, harmless global warming in the atmosphere.
The lab experiments use closed systems, unlike the atmosphere.
The air used in the experiments is artificially dried, because water vapor and CO2 have somewhat overlapping effects on infrared radiation.
The effect of CO2 in the atmosphere is unknown.
There are far too many variables to focus only on CO2. Such as:
The effect of greenhouse gases is not to heat anything -- they merely reduce the ability of our planet to cool itself.
CO2 is invisible to sunlight, so it does not block any incoming sunlight,
But it does interfere with outgoing infrared radiation of certain wavelengths (see chart below) that were heading toward space.
If you want a worst case estimate, you can compare actual warming since the 1950s with actual CO2 level increases -- then assume all warming is caused by CO2.
That worst case estimate suggests CO2 would cause mild harmless warming -- no more than the bottom of the IPCC range of +1.5 to +4.5 degrees C. warming per CO2 doubling.
The climate alarmists know this.
So how do they spin a small amount of lab science suggesting mild, harmless global warming, into a coming climate crisis?
They invented a water vapor positive feedback effect, that allegedly triples the lab estimate of CO2 alone.
That theory makes no sense, because a positive feedback is not stable.
A positive feedback would cause runaway global warming,
There would have been runaway warming millions of years ago, if not billions of years ago, that would have ended most life on this planet, when CO2 levels were much higher than today.
There is also the issue of saturation -- there are only so much infrared wavelengths of outgoing radiation for CO2 to interfere with. (see links below).
As a result, CO2 should become less and less effective as a greenhouse gas, as the concentration in the atmosphere increases.
Scientists often claim a logarithmic effect for CO2, but that's just a guess, like almost everything else claimed about the future climate.
https://arxiv.org/pdf/2006.03098.pdf
Richard Greene
Bingham Farms. Michigan
