This issue crosses my mind sometimes too. But what can one do ?
Most likely South America, large portion of Africa, Mexico etc. will survive relatively unharmed. Nothing interesting to nuke there. So will smaller towns. A global disaster -- yes, for sure, risk to the survival of the entire mankind -- no, not even close.
This is a very unfortunate reality.
This is a very fortunate reality. There has been no major war in Europe for over 70 years, unbelievable.
Best regards, Piotr