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Comment by aidenn0 | Hacker News Reader

The US has been moving away from high-yield bombs for a while; here's the highest yield bombs in the US arsenal and the dates of their retirement:

B41: 25MT, retired in 1976

B53: 9MT retired in 2011

B83: 1.2MT retired 2022

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in the world of nuclear weapons i didn't think 1.2MT was that particularly high of a yield. Wikipedia leads me to believe that the majority of nuclear weapons deployed in the US are in the 100-500KT range. Given that yields are shrinking (i assume globally as well) I wonder how that impacts fallout prediction maps that probably haven't been updated in a long time. Also, assuming the number of warheads is staying constant or going down then the total energy on tap is going down too. I guess increases in stealth, detection, and accuracy make up for the decrease in power when it comes to a nuclear deterrent.

https://en.wikipedia.org/wiki/Nuclear_weapon_yield

A bomb's blast radius increases with the cube-root of its energy, so 10 500KT bombs cover a larger ground area than one 5MT bomb; my understanding is that this was a big reason for having more smaller bombs compared to fewer larger bombs.

Despite its dearth of tactical (or strategic) uses, the B41 is a marvel of engineering assuming it does what it claims; 25MT from 5T of mass is crazy efficient.

It's mostly increases in targeting and accuracy -- in the era of air-dropped bombs, and early ICBMs and cruise missiles, having a reasonable probability of kill on a hardened target required an absolutely enormous warhead. With the minuscule circular error probables of modern weapons, the "city killers" of the 1950s and '60s simply aren't necessary in modern nuclear doctrine.

As you mentioned, fallout is greatly decreased by the reduction in warhead size. Additionally, as airbursts are more effective at causing damage, they have taken precedence over ground bursts, and have a substantial impact on the reduction in fallout.

The concept of a nuclear winter is primarily related to the expected firestorms in cities and forests, which would throw colossal amounts of soot into the air. With infrastructure devastated by the strategic weapons exchange, the resources to effectively fight the fires weren't expected to be in place, so it was thought they'd burn out of control. While there has been debate over how realistic it is that a nuclear winter would occur from a strategic nuclear exchange, nobody doubts that it would be catastrophic.

When precision weapons exist that can pick which window in your house to put a weapon through from the other side of the planet… the enormous nukes just aren’t really all that necessary any more. Smaller weapons have less fallout so your opponent will think you more likely to use them.

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