You would have to be pretty far away, somewhere in the Southern Hemisphere on the other side of the globe to escape the fireball and shock wave. And that would only work until the "fallout" (remember when that word was in wide usage?) reaches the upper atmosphere and disperses globally. A nuclear winter would definitely significantly slow down the global warming processes but very few humans would live to enjoy seeing the cool-down in action.
And that's just if whoever is being the nukeslinger only sends one bomb, and what would be the point of doing that if one has a whole multi warhead "nuclear arsenal"? Got to use enough of them to knock out all the US retaliatory missiles before the automated "launch on warning" mechanisms could set them coming right back at 'em.
It's disturbing that the Nuclear War Industrial Complex is again talking about a survivable nuclear war. Every documentary I've watched and every book and article I've read casts deep doubt on this idea. It's hard to picture the president and the chiefs of staff, Joint or otherwise, climbing out of their safety tunnels, looking around at the smoldering ruins stretching as far as the eye can see, and saying: ."OK, find some generators so we can fire up some computers and get the economy going again, create us some walking around money. If you happen across any survivors, make sure they're clear on who's in charge -- us!"
A friend of mine, a back to the land guy living in the hills in a wind and solar powered deep mountain hideaway, emailed me and said he was worried that the only people with an actual memory of Hiroshima and Nagasaki are in their nineties and that this makes the use of nukes less unthinkable. So the sabre rattling grows more threatening almost daily, almost hourly. A preemptory first strike is back on that "terrible table" under the doctrine of "we better get 'em first while we've still got an unexploded upper hand."
If it happens and I'm one of the survivors, one that still has working hearing after the shock wave has hit, I will say (or write using what will be the abundant charcoal that will be lying around everywhere -- don't know what I'd use for for paper, fried human flesh perhaps?) And I will apologize profusely for underestimating the chances of survival. But I'm not sure how "refusing to be targets" would work. Take that finger off that button RIGHT NOW!!