If a planet has a lot of oxygen to support mega flora and fauna, how much would be too much?
My planet has the oxygen content about that of the carboniferous(as a starter example), which had a about 35 percent oxygen atmosphere.
During that period, giant bugs, massive plants, etc. all existed. My planet's atmosphere is at least 40 and/or 45 percent oxygen. Can all of that oxygen kill life and, if it could, how can I combat it?
One of my solutions was super volcanoes, or geysers, that spew carbon into the atmosphere.
I can't, however, have volcanoes erupting every day, so how can I fix this problem? I eventually want the oxygen to start killing all life, so how can I have that, too?
edit - What would happen to a human living on the planet? Would the oxygen kill them,or something else entirerly