The end could begin with a missile launched by accident.
And then the response would be deliberate, as would be
the counter-response, and on and on until we were all

gone.

Or, it could be deliberate from the outset, an act
of madness by a suicidal leader, setting the end in motion.

First, the blasts and mushroom clouds.  Then the fires
and burning cities and the winds driving the fires, turning
humans into projectiles, and all of it mixed with deadly
radiation.  Finally, for the last act, the soot from destroyed
cities rising into the upper stratosphere, blocking the sunlight
and the temperatures falling into a frozen Ice Age, followed
by mass starvation.

If any humans were left to name it, they might call it
“Global Hiroshima,” but none would be left.
It would be ugly for a while, eerily still and silent
for some stretch of time, but no one would be there
to observe.  Still, the Earth would go on rotating
around the sun and the universe would go on expanding.

Only we humans would be off the not-so-merry-go-round.