Hmmmm....yes and no...
We are insignificant blips on the face of the planet that can and likely will be extinguished by even small changes in global climate and conditions...true...
...but we can and do have significant effects upon those conditions. The significance of the changes we bring about seems magnified to us due to our own insignificance. If we manage to accelerate changes in pollution, weather, etc. it won't take a huge alteration for us to feel the effects. It doesn't take some dramatic zombie apocalypse or vampire plague to wipe us out; something as seemingly minor as the extinction of honey bees, or a pandemic of some destructive plant disease would do nicely. Anybody remember the old horror film "No Blade Of Grass"?
But even if we manage to nuke every last person on earth along with most of the other existing lifeforms...the planet just shrugs and carries on with the process of evolving new stuff that is suited to the new conditions. Bring on the next contender.
By the way,
Backfromthedead
, I am officially stealing "Embrace the stink!" as one of life's perfect mottos.