The End of The World

[dukealien]

Sunlight drips over roads  for your first line, perhaps a grabber stronger than "drips over."  Something ike, "Sunlight rapes raddled roads," but better.
lined with skeletons of trees
bearing damage in their tresses.  these two lines are very good

The air is laden with requiem and apathy.  Always question "the" - how about "Through air deep in.."?
We walk in somber silence  "we trudge somberly," perhaps
watching a charcoal sky crawl down   another suggestion - "watching charcoal sky dissolve"
until it kisses a drying earth, maybe you could restrict use of "a"?  Less can be more.
defeat tucked in its crevasses. perhaps "worn" rather than "tucked," which seems a bit gentle

I remember sonnets written for the sky  See below.
centuries ago
calling her a limpid pool of blue.
Azure, cerulean.
Some words will fade into the ebony smog, forgotten. Have trouble visualizing ebony smog - "sable" or "fly-ash?"

If only people had realized sooner perhaps, "If only people then had realized/that.."
time was barmecidal
and the shadows of their mistakes, to ease the reading, perhaps "and their errors' shades"?
perennial.

I can't, in Basic, say how you *should* have answered the challenge, but will critique how you *did* answer it.

In general, watch "the" and "a" - eliminating them often smooths the flow (and too many can sound a bit pretentious).

Also in general, though this is free verse a consistent rhythmic flow may have value, depending on what you're trying to do.  For example, and my apologies for the rewrite, this is only an example for S3:

  I remember sonnets written to
  a blue sky centuries ago
  calling her a limpid azure pool,
  cerulean.
  Such words fade in this ashy smog, 
  forgotten. 

So, again in general, look for alternative, more striking words that also create a regular rhythm.

Hope that was not excessive for Basic.  It's got good images that could be made even stronger with fewer words, tells the story by showing, and meets the challenge.