Sure painther, it's happened before. We are helping accelerate the process. It's a cyclic process like you said. Dinosaurs got extinct last time, this time it might be the Human Race. No big deal, the earth will keep on going. It might not necessarily be suitable for life, but it will continue.

So yes, lets continue. Let the tigers die, let the next Ice age or Ultraviolet radiation wipe of human population. It's all just a cycle anyway.