Re: IPCC blaming heretics again? - @ribosome
I hate to break it to you, but you're wrong and the guy you respond to was at least partly right.
"During the Devonian, which is when plants were really dominant, levels dropped from about 5000 to 500 parts per million. 20%? Pull the other one. Between 40 and 400 times too high."
Photosynthesis was not "invented" by plants but by cyanobacteria. When these evolved there was 0% O2 in the atmosphere and quite a lot of CO2 indeed, 20% isn't far off the mark.
"The pH would simply be too low. Even at 5% you wouldn't be getting any dinosaurs or fish."
Your pH assumption is bullshit, 5% CO2 is what we give to cultured mammalian cells in labs, precisely to keep the pH exactly right for them. That pH of course depends also on the bicarbonate concentration in the medium. With common lab media we achieve pH 7.4 with 5% CO2. Of course the sea is not a "common lab medium", but still 5% CO2 is not what I would call incompatible with life. Actually a lot -most- of your own cells are seeing 5% CO2 as you read this, and some (though much fewer) are seeing 20% indeed.
When correcting someone else's percieved mistakes, try not to make huger ones.