We're going to have a hard time dumping enough anything into the atmosphere (or causing some other kind of pollution) to kill ourselves entirely. We'd osculate around an equilibrium where we dump some pollutant into our environment to the point where our population decreases, natural processes remove it and our population increases, wash, rinse, repeat. You can see similar population and resource usage patterns in many ecosystems.
And before anyone tries to twist my words to saying global warming isn't a bad thing, that's not what I'm saying. I'm just saying that humans as a species will likely survive it.