Steve Jackson Games Forums - View Single Post - How long would the air on a dead world stay breathable?

Johnny1A.2 · 07-06-2022, 01:52 AM

Here's a bit of a geeky question: assume an Earth-like world with an Earth-like overall biosphere and atmosphere, one that would be well-suited to human habitation 'as is'.

Now assume that Something (a nearby supernova, a curse, whatever) kills all the biological life, including the unicellular forms, in a short time (a few hours, days, or less than a year, anyway).

What I was wondering was how long after the Event that the air would remain breathable to later visiting humans, since the free oxygen is no longer being biologically replenished (and probably a lot of dead biomatter is gonna burn, there's still lightning, after all, to start fires, volcanoes, etc, and no microorganisms to break down dead biomatter, so it'll sit there until something destroys it). Plus of course there's ongoing inorganic reactions with minerals and so forth taking O2 out of the air as well.

If a ship comes by a century or two later, would the air still have enough O2 to be breathable?

(Recognizing that the answer is necessarily a guesstimate.)

07-06-2022, 01:52 AM	#1
Johnny1A.2 Join Date: Feb 2007	How long would the air on a dead world stay breathable? Here's a bit of a geeky question: assume an Earth-like world with an Earth-like overall biosphere and atmosphere, one that would be well-suited to human habitation 'as is'. Now assume that Something (a nearby supernova, a curse, whatever) kills all the biological life, including the unicellular forms, in a short time (a few hours, days, or less than a year, anyway). What I was wondering was how long after the Event that the air would remain breathable to later visiting humans, since the free oxygen is no longer being biologically replenished (and probably a lot of dead biomatter is gonna burn, there's still lightning, after all, to start fires, volcanoes, etc, and no microorganisms to break down dead biomatter, so it'll sit there until something destroys it). Plus of course there's ongoing inorganic reactions with minerals and so forth taking O2 out of the air as well. If a ship comes by a century or two later, would the air still have enough O2 to be breathable? (Recognizing that the answer is necessarily a guesstimate.) __________________ HMS Overflow-For conversations off topic here.