This result may help explain why we see such large plants in the fossil record. In fact, some have suggested that if our pre-flood atmosphere was like a hyperbaric chamber today, not only would it produce the large vegetation seen in fossils but, it may also have contributed as one factor of why people had such long lifespans before the flood of Noah.
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Around 10800 BC North America principally was hit by comet debris for over 100 years causing massive firestorms which burned off vegetation leaving a deep layer called black mat. All the huge and lasting firestorms likely burned off equally massive amounts of O2 which may be why it disappeared. The geological result was the Younger Dryas Age - so cold the once melting Northern Ice Cap reformed. 1000 years later or around 9800 BC, another comet debris barrage ended the YDA; the melt was very sudden - that may be the true origin of the “Flood” as sea levels rose drastically by hundreds of feet worldwide in a few years.
I'd think that Noah; etal; would have noticed and commented.