[joe_the_user]

The problem with any overpopulation or growth-limit push argument is that since interstellar travel is a very, very difficult to achieve, there's no reason to expect either humans or aliens to achieve interstellar travel at the point that they've encountered some limit to a process of out-of-control growth. Space colonization is certainly not going to solve global warming, etc.

Indeed, if human society is a guide, a society that develops interstellar travel would have to have reached a stable situation, so stable I'm not sure if massive expansion would seem desirable.