A genuine, abrupt climate catastrophe at the exact moment human civilization was stirring.
Documented
A real thousand-year cold snap
Around 12,900 years ago, temperatures in the Northern Hemisphere plunged within decades and stayed low for about 1,200 years, right as the Ice Age was ending. The cause is debated: a leading hypothesis involves a comet impact or airburst, marked by nanodiamonds, platinum spikes, and meltglass at sites across four continents; a rival explanation involves meltwater floods disrupting ocean circulation.
Assessment: The event is settled science. The cause is a live scientific controversy, rare and genuine.
Interesting claims
The day Atlantis actually died
Graham Hancock and others argue the Younger Dryas cataclysm destroyed an advanced Ice Age civilization, with survivors passing knowledge to hunter-gatherers, explaining Göbekli Tepe and global flood myths.
Assessment: The cataclysm is real; the advanced civilization remains unevidenced. But this is the fringe theory standing closest to legitimate science, which is exactly what makes it so effective, and worth watching as the impact debate resolves.
Stories
Every grandmother remembers the fire time
The traditions assembled for the case: indigenous accounts of burning skies and floods, the Norse Fimbulwinter, the flood epics, the sudden winters in the mythology of peoples a hemisphere apart. Hundreds of cultures, the argument goes, kept the memory of the same bad century.
Assessment: The myths are documented and their parallels are genuinely arresting. Whether they encode one event, many local disasters, or the universal human experience of catastrophe is the exact question the folk tier cannot settle and the science is still chasing.
Sources and further reading
Greenland GISP2 ice-core record of the Younger Dryas (Alley et al., 1993)
Firestone et al., Evidence for an extraterrestrial impact 12,900 years ago, PNAS 104, 2007
Pinter et al., The Younger Dryas impact hypothesis: a requiem, Earth-Science Reviews, 2011
Worth asking
What would human history look like if we knew for certain it began in the rubble of a cataclysm?