Robert Maxwell wrote:
I don't think humans are 100% extinction-proof, however, I do think we could survive a lot of things that most other species could not. Besides, there are billions of us. Even if you whittle that down to a few thousand, that is a survivable number of people to prevent extinction.
I think our ultimate limit, given current technology, would be the destruction of our atmosphere (that is, making it unbreathable by us.) Even then, I suppose we could make indoor environments and grow plants. However, none of the Biosphere projects actually panned out, so it's debatable whether we could really survive this way long-term.
100% of anything is not possible, and we are certainly not extinction proof...related to the existence of aliens...think of the Kardashev scale of technological development. What if we can control the entire output of energy of our planet, then solar system and sun. These would be lofty advances, and a seriously powerful civilization, but even those could fall prey to cosmic catastrophes...let's go further beyond: what if our major cultural goal is to survive, well..everything
! Can we harness the energy of a galaxy? Can we force evolve ourselves to live beyond the extinction of the universe...into multiverses? It's problematic, if a new universe has new physical laws, even if we survive the "end of the universe" we might me winked out of existence.
Taking it way back to modern Earth...man has the power to change much of what he has done, and space travel is a fact, we just need advancements to take us to another level..resource exploitation, habitat expansion, etc. It's my oipinion that a totally renewable human civilization is not possible within this biosphere
, we can make some inroads to being responsible and renewable, but if man progresses as he has shown to, he will expand. It's inevitable. Early native populations destroyed their habitats, many disappeared, same with animal populations...we have the brain to take evolution out of the realm of nature and go beyond it. We can never avoid threats of extinction, but we can mitigate it if we spread out!