Smoke from human fires in the soil? It was probably global warming and overhunting of the species that killed off the mammoths. We humans are a destructive species with no regard for life.
/sarc
I’m sure the various so-called studies that have already purported to disprove the Clovis impact model — none of them have been worth a crap — came about in part to shore up the global warming hoax; regardless, they’ll get more attention (not necessarily grant money) for themselves and future research and their careers if they link their ‘research’ to something already well known.
What do you mean "no regard for life"?
Those of us who DO have a high regard for animal life have formed "P.E.T.A." (People Eating Tasty Animals) The world's FIRST great technology made this possible!
The SECOND made made it delightful!
The THIRD split us into waring tribes!
Global warming and a lack of socialized medicine conspired to cause it. /s