[anoncow]

Will this result in an increase in O2 levels? If yes, what risk does that bring?

[IshKebab]

Not an issue. The oxygen release is just oxygen that was already in the atmosphere before it was used to burn oil.

Even if that weren't the case, the atmosphere is 21% oxygen and 0.04% CO2.

[nominatronic]

Giant predatory dragonflies the size of seagulls, if the fossil record is anything to go by.

https://www.sciencedaily.com/releases/2010/10/101029132924.h...

[ClumsyPilot]

O2 levels are currently decreasing. In a thousand years we will run out

[jjcon]

Try >1 billion years from now