Zero Hour said:
If you consider the kind of pathetic, dependant, low-gravity non self-sustaining habitats we could build in our own solar system (offering space to what? 1000, 10000 people>) we could conceivably build 'fit for human habitation', let alone a serious way to enable mankind's survival, I think I'll take my chances with global warming.
You really need to read The High Frontier by Gerard O'Neill. Here's a site that summarizes a lot of its ideas:
http://www.dyarstraights.com/msgundam/frontier.html