There's been a shortage of people and materials for three years now. Microprocessors building supplies metal all gone. Now food in particular proteins and eggs all gone, all would be needed to reconstruct after whatever happens happens. Also a strange uptick in suicides in the military particularly the NAVY. Could be some can't handle what they learn, alternatively there is likely initiation involving weird fetish where they pretend that they are dogs and force them to do "things" but that's a different issue.

From what I can gather they expect the inner planets of the solar system to become uninhabitable in the near future. There are likely colonies in the outer system they've kept hidden so nobody would discover the reason for abandoning the inner system. Probably made an expedition to Mars in the 70's and learned from them also rumors of moon mission around that time that confirmed what was occurring.

The "Fake" documentary alternative 3 covers some of this the book also expands on it. Apparently the author started to be spied on so he stopped looking into it. In the expanded novel the author posits it could be atmospheric damage due to nuclear testing done in the 50's and 60's that's plausible but just speculation.