Jumbo, vastly overpowered weapons, like the 50MT Tsar Bomba were invented & tested before there were precise, GPS guided missile navigation systems. Nukes were designed to be physically dropped by plane (like the Tsar test), and were big because you couldn’t guarantee if they’d get their target, so bigger boom = more chance you’d obliterate your intended target.
Unfortunately, a lot of maps in the mainstream press use sites like NukeMap, where you can choose your yield and it up to the Tsar Bomba size (or above to the original 100MT Tsar Bomba yield, the Russians ‘dialed back’ to 50MT on the test bomb) because it makes for a more impressive map to scaremonger the public! There were 2 Tsars made, one went boom & one’s in a museum (minus the boom-y bit, obviously).
Modern weapons are smaller, in the kiloton to single digit megaton range. Satellite navigation & modern guidance systems mean you can hit the target with a greater guarantee, and since each weapon costs bloody millions to design, maintain, produce the plutonium fission component (which sets off the fusion, or thermonuclear bigger bang), keep replacing the fusion core due to the short half life of the isotopes you need, storage, submarine costs (all UK Trident nukes are on the V series of subs, we don’t deploy via air or land based missile), security… why make them bigger than you need?
Since Russia (and the UK, US, possibly France) deploy using subs as part of their defence, there’s a chance we won’t even get that 4 minutes. Combatant subs in the North Sea, the missiles would be over target before the bods at RAF Fylingdales (our detection dudes) have put the kettle on.
As PPs have said before, it all depends on air bursts or ground bursts (generally ground = fallout), weapon yield, area of detonation. If you had food, water, good shelter, and each nuke was an air burst, there’s a good chance if you aren’t in the blast overpressure & firestorm range then you’d be grand, could come out of your shelter after a couple of weeks, safe & alive.
But the real question you need to ask, would you want to?
In terms of a nuclear winter, a worldwide detonation of everyone’s stockpiles would cause a nuke winter, and that would probably be goodnight humanity. There have been thousands of nukes exploded in the names of weapons testing since 1945. Not defending any of the tests, nor stockpiles. but it’s worth knowing the facts. North Korea are happily testing the bloody things even now.
As for me, sod all that survival stuff. Years spend researching & studying (and campaigning against) the bloody things, if I survived I would probably envy the dead. I don’t know if that’s because I’m now a 50 year old fart with adult kids, or I know it’d be all so bloody bleak. I’d rather sit on the roof with a joint, a whiskey, and let it be the last thing I see as my eyeballs melt & I’m blown into the wind.
I’m a Nuke Nerd. Make power, not bombs!