I guess you're talking about "nuclear winter", where the ash from the nuclear explosions gets into the upper atmosphere, blocks some of the sunlight and leads to a global famine.

I'm not sure what's "a small number of nukes" in your book. Last I read about it, estimates suggest e.g. India and Pakistan dropping their entire arsenals on each other would indeed cause a nuclear winter.

Go look at the Nevada Test Site on Google maps. About 1000 nukes were set off there. Las Vegas is only about 100 miles away and by all accounts seems to be thriving.

In a nuclear attack, it's unlikely "we'll" be fine, but someone will be.

What on earth are you downplaying

There never ever has been an above-ground test of a modern enhanced hydrogen bomb in the USA

The Bikini Atoll test in the 1950s using 75 year old technology killed people via radiation over 130 miles away

Modern ICBMs carry several much more powerful warheads than that

Even a few of them would make life on earth a permanent hell like peak covid pandemic but forever

Even the "smallest" nuclear war would be one-and-we're-done event

Eventually some tyrant on their deathbed will do it though

So hold on. You are saying Tsar Bomba would have potentially been an extinction event at ground level?

Holy shit.