[Blood of Tyrants]

“400 parts per million (meaning that for every 400 molecules of air, one was carbon dioxide) “

Nice try, but WRONG. 400 ppm equates to 1 CO2 molecule per 2500 molecules of air. (Someone check my math.)

[al baby]

Define Air ?

[SunTzuWu]

You are correct...

[kitchen]

... atmospheric levels of carbon dioxide were similar to modern levels of 400 parts per million (meaning that for every 400 molecules of air, one was carbon dioxide) ...

There are two statements here which are purported to be true:

... 400 parts [of CO2] per million [parts of atmosphere]

= 400/1,000,000 = 0.0004

or 0.04% of the atmosphere.

Next,

... meaning that for every 400 molecules of air, one was carbon dioxide ...

= 1/400 = 0.0025

or 0.25% of the atmosphere.

Question for Becky: does 0.04% = 0.25%?

[MeanAsSnake]

Air is a mixture; there is no “air molecule”. 1 out of 2500 molecules is correct. O2, N2, H2O, CH4, AR, …etc.

[PA Engineer]

Nice try, but WRONG. 400 ppm equates to 1 CO2 molecule per 2500 molecules of air. (Someone check my math.)

Beat me to it. What would you expect from a "Journalista" versus a journalist.