> Eugene Leitl <email@example.com> wrote:
> Actually, there is a known abiogenic mechanism (water photolysis, with
> the hydrogen escaping into space) which constantly replenishes the
> oxygen pool, and some not well characterized mechanisms which removes
the oxygen from the atmosphere (probably mostly oxidation of volcanic material).
True, but I suspect most of the oxygen in the atmosphere comes from the plants grabing the Carbon away from the CO2. Carbon and Oxygen are in relative equal abundance in the sun & solar system. However, hydrogen is hugely overabundant. So when the system starts out, everything is going to be in a "reduced" chemical state, e.g. mostly CH4 and H2O. There may only be a little CO2 available.
Over time, if "normal" life is present, it will harvest the C from CH4 or CO2 meaning that Hydrogen and Oxygen get released. That makes more water (or if the hydrogen escapes), it leaves oxygen which gets sucked up by any unoxidized metals (e.g. iron).
If you are a *true believer*, you want "them" to burn all the oil and coal they can get their hands on.... Why? Because oil or coal in the ground is carbon that belongs to someone else. Carbon dioxide in the atmosphere is carbon that is free for me (and my very close friends)... :-) [And before somebody jumps *all* over me, by "free", I mean that I can harvest it out of the atmosphere for "free" *iff* I have the solar power to do it.]