This is actually still a reasonable concern to have. Coincidentally, just yesterday I came across a reference to the book Nuclear War: A Scenario by Annie Jacobsen, speculating on how a global thermonuclear war could start in modern times.

https://en.wikipedia.org/wiki/Nuclear_War:_A_Scenario

The scenario she presents is fictional, but it’s all based on current nuclear arsenals and response protocols. While what I’ve read of it certainly makes it seem like a worst-case scenario in a “nearly everything that can go wrong does” sense, it’s disturbing how relatively few things going wrong it actually takes—in a span of under two hours—to reach “civilizational collapse” level outcomes.