Well here's the problem: it's the other way around. The fact that our population has grown far beyond the capacity of our planet is contributing to the upcoming extinction, not averting it. Exactly like bacteria growing uncontrollably in a Petri dish we're now consuming all available resources at an alarming rate, without regard for future generations. Perhaps the word "extinction" is what's bothering you. We tend to use the term "collapse", because it more accurately describes the most likely outcome.