#1-5 appear to be orthogonal to the issue at hand. http://climate.nasa.gov/scientific-consensus/ http://climate.nasa.gov/scientific-consensus/ From a "earth w

#1-5 appear to be orthogonal to the issue at hand. http://climate.nasa.gov/scientific-consensus/ http://climate.nasa.gov/scientific-consensus/ From a "earth will always be habitable by humans" perspective, #6 may be a valid point. On a "cosmic scale", however, this is far from a certainty. To give a little perspective, light travels at approximately 5,865,696,000,000 miles per year. The hubble telescope apparently has seen things in space up to around 10-15 billion light years away. So this means that hubble telescope has seen things as far as 8.7985x10^22 miles away from earth. And to this day we have yet to observe real evidence that intelligent life exists beyond this planet, so we have no strong evidence that there is even a single place in the universe besides earth that humans could possibly exist. Now, recent evidence suggests that there are hundreds of thousands of earth-like planets even within our own galaxy, which is great news, but we don't know with certainty if they would be habitable on a similar scale like earth is for humans. So, for the time being, I think a safe perspective is to assume that this is "all we got". And we just don't know what the real implications would be for humans should the earth start changing too dramatically. Perhaps what would happen is earth simply becomes uninhabitable by humans and wipes us into extinction. The universe seems to be very unassuming, but at the same time evidence suggests that it's also unforgiving, as we don't know just how rare we are and just how special the circumstances need to be in order to sustain intelligent life.