[osacial]

Well, look again - some of the group of points reach right to 200ppm.

Equation of line has nothing to do with reaching 200ppm, as that is average - adapted to whole timeline. Would look completely different in a different scope.

[ceejayoz]

> Despite feedbacks with weathering rates, much smaller imbalances would have resulted in the complete removal of atmospheric CO2 in less than a million years. Without evidence of such dire consequences, lignin production in the absence of lignin decay for more than 100 million years into the early Permian is untenable.

The study addresses CO2 levels closely, as well as other significant pieces of evidence. I would tend to assume the peer reviewers at one of the world’s most prestigious journals thought to Google up historical CO2 levels.