r/climatechange • u/srmcmahon • 5d ago

"retired plant scientist" claim

This was in a letter to the editor locally:

"There is no real evidence that global warming is due to atmospheric CO2. Controlled experiments indicate that the addition of CO2 in air up to 10,000 ppm have little or no effect on warming under atmospheric conditions."

Entire letter is here: https://www.inforum.com/opinion/letters/letter-co2-and-global-warming

I was going to write a comment. I think he might be talking about experiments where they added CO2 to experimental plant plots (but don't remember the mechanics). "Under atmospheric conditions"--means exactly what?

Can you help me out here? I have not figured out how to phrase a search that brings me to what he is referring to.

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u/Infamous_Employer_85 5d ago

H2O vapor is the main weather forming component

Correct, but water vapor, at 0.25% of the atmosphere, is a condensible gas, the mean amount in the atmosphere is determined by temperature

Controlled experiments indicate that the addition of CO2 in air up to 10,000 ppm have little or no effect on warming under atmospheric conditions.

Incorrect, we have directly measured changes in absorption in the atmosphere.

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u/PoolQueasy7388 5d ago

They've been measuring it for years up on Mauna Loa thru Scripps Inst. for years.( Keeling Curve)

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u/Infamous_Employer_85 5d ago

That's a measurement of CO2, i was referencing direct measurements of the effect of CO2 in the atmosphere.https://acp.copernicus.org/articles/24/6375/2024/