Certain characteristics, such as high levels of tin, identify a comet as the origin of the alien dust, Abbott said
This is total speculation if not total BS. Comets are supposed to be dirty snow balls or snowy dirt balls. Astrophysicists still can't make up their minds which.
“Certain characteristics such as”
Read: “I haven't got a clue but I’ll clutch at any straw that help my theory”
Ice core data record evidence of a volcanic eruption in 536, but it almost certainly wasn't big enough to change the climate so dramatically, Abbott said.
“almost certainly wasn’t big enough”
Read: I haven’t got a clue but if it was my theory is toast
"There was, I think, a small volcanic effect," she said. "But I think the major thing is that something hit the ocean."
Virtually every literate culture around in AD 536 recorded the devastating effect of the change of climate. Not one of them mentions seeing a comet as a precursor to the disasters. The most feared harbinger of danger in ancient and medieval times would have been front and centre in the chronicles of the times.
She and her colleagues have found circumstantial evidence of such an impact. The Greenland ice cores contain fossils of tiny tropical marine organisms — specifically, certain species of diatoms and silicoflagellates.
If the volcanic eruption was massive, was tropical and the caldera collapsed into the sea (like Santorini) what would you expect to find in the ice core samples: Perhaps “certain fossils of marine organisms”.
An extraterrestrial impact in the tropical ocean likely blasted these little low-latitude organisms all the way to chilly Greenland, researchers said.
A terrestrial volcanic eruption in a tropical ocean likely blasted these little low-latitude organisms all the way to chilly Greenland.
Specifically a volcanic eruption in the Sunda Straight that was so powerful it not only blasted millions of tonnes of debris into the atmosphere it turned a former single island into two new islands Sumatra and Java.
Maybe Dallas Abbot should read more and speculate less. I suggest he starts with Catastrophe, by David Keys. It outlines a very plausible theory based on factual geological evidence and written testimony from multiple cultural sources throughout the world that existed in the Sixth Century.