[Muleteam1]

Without evidence of deposition from the comet's ash that corresponds to the timing of the Dark Ages, it seems like a huge leap in logic to go from evidence of cool summers, crop losses, and plague to a comet exploding in the earth's atmosphere.

Muleteam1

[blam]

Catastrophic Event Preceded Dark Ages - Scientist

[LibWhacker]

Here's an interesting post that explains some of that logic. In some cases, ancient scribes wrote about the effects they witnessed firsthand. And the tree ring data testifies to how widespread the effects were.