What does that have to do with CO2 levels 18 times higher in the ancient past than it is now?
It was to question the argument that the CO2 level , now or 10 million years ago, was consistent around the planet.
The argument that CO2 was at such a high level in what we believe was a heavily overgrown tropical jungle, and therefore it was the same everyone on Earth, seems questionable.
Outside, it can be 50 degrees. A cloud passes by and the temperature drops to 40 degrees.
This happens in two minutes. What was the temperature, then, 40 or 50 ?
If you take a measurement of CO2 over a dense Amazonian forest, and take a measurement of CO2 at the side of a backed up interstate highway, will the measurement be the same ?