Well, we did spec.fic and mine was about the world overheating - some thought the sun was expanding millions of years too early, but one scientist dude thought it was just a "solar radiation mega-storm" (*shudders at corny sci fi language*). And he has a special blue elixir that, when released into the earth, causes lots of endothermic chemical reactions, slowing down all the surrounding life forms, reducing the world's temperature, eventually causing an ice-age-DayAfterTomorrow-type-thing.... so yeah, those markers won't know what hit them