“Some scientists have posited that ...
Some scientists have posited that manmade global warming is real and we are doomed.
Bogus science both”
The “some scientists” supporting the civilization window theory included Enrico Fermi, who many people considered to be a fairly clever guy.
Some people are cleaver sometimes and no so clever other times, particularly when they are dealing in aspects of science they are not familiar with, not to mention things have drastically changed since the 1950s.
So Fermi was talking through his hat on this subject.