I don't know if I'd call it "the Most Urgent Crisis in World History", since he was just complaining about how nobody's neighborly anymore. I get what he was going for, people keep to themselves, they don't know the people they live next to, and if something weird is going on in the street they just draw the curtains and hope it goes away. "As though under siege". He pins it on the population explosion, and then indicates that soon there'll be too many people and we'll all die forever. He predicted that within 30 years. The book's 50 years old.
Ah well.