In article ,
Jim Yanik wrote:

Cobalt bombs were to be extremely DIRTY enhanced-fallout bombs,Cobalt-60
being a hi-level radioactivity isotope. I don't know what the half-life is
for it,though. Reasonably long,I suppose.

A little over five years, which makes for a very nasty fallout pattern.

The thing is, you would have needed a *lot* of cobalt bombs to kill (or
even seriously harm) all life on Earth. Outside of prompt fallout
patterns, you wouldn't see a lot of cobalt-60 contamination (the jacket
of cobalt would have been pretty inefficient at making the -60 isotope).

Basically, every Soviet warhead would have had to have been coated with
a hundred pounds or so of cobalt, and that was never going to happen.

You couldn't get a single bomb to vaporize enough cobalt, either, even
in the 100 megaton range.

Due to the way weather patterns work, the southern hemisphere would have
been mostly spared, too - you don't get a lot of mixing between north
and south.

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