EDIT: For clarification, I feel that the current situation on the ground in the war (vs. say a year ago) might indicate that an attack on Russia might not result in instant nuclear war, which is what prompted my question. I am well aware of the “instant nuclear Armageddon” opinion.
Serious question. I don’t need to be called stupid. I realize nuclear war is bad. Thanks!
Short answer: the end of the world.
The resultant nuclear war would kill a good portion of Earth’s population, but it’s likely far more would die from the chaos of civilisation being instantly forced back to the iron age by the EMP frying every silicon transistor.
I used to be a Boy Scout. That just means I’ll die a bit slower.
The end of the northern hemisphere*
For anyone interested in some light fiction on the subject, may I direct you to On the Beach by Neville Shute.
The film Threads is also relevant.