In rec.crafts.metalworking DBM wrote:
"...name any example of human engineering that could "kill the entire
world with one accident..."

I accept the challenge! (He said, with tongue in cheek...)

#1 - Famous 'Software Maker' discovers 'error' in their operating
system for medical nanobots (nanotechnology).

(snip description)

Assuming that there would be no way to deal with this you still don't kill
the world. You don't even wipe out humans. You just wind up with
hemophillia in all of humanitys genetic code.

#2 - Genetically engineered food stuffs endowed with 'Human Genes'
(Google for it), result in plant diseases 'jumping species'.

'It was horrible', the Chief of Operations said, 'All those people
with 'rust' disease, we had no choice but to flame-thrower them all!'

Not only not able to kill the world, not even very likely to do major
damage.

#3 - GM (Genetically Modified) Mousepox, but done 'differently'.

(snip)
Answered in another post.

--
Yours, DBM -
From Somewhere in Australia, the Land of Tree-hugging Funnelwebs...