[pfdietz]

Actually, burning of trees helped reduce CO2 over the long term. That's because burning is incomplete and produces charcoal. Charcoal doesn't decay, so when it is buried it semi-permanently takes carbon out of the biosphere. Over extended time, this would draw down atmospheric CO2. Some coal deposits from that period have a significant fraction of charcoal in them.

[EdwardDiego]

IIRC, that's lignite coal?

[pfdietz]

I don't think so? The charcoal would remain identifiable as the coal is matured by burial and heating (perhaps not all the way to anthracite).

[EdwardDiego]

Ah true. It'd be more of a structural thing I guess.