Absolutely something big happened 12800 years ago: a massive comet strike that melted much of the North American ice sheet and started continent-wide wildfires.

Absolutely something big happened 12800 years ago: a massive comet strike that melted much of the North American ice sheet and started continent-wide wildfires. The record is seen unambiguously in a spike of massively elevated platinum dust, and sulfur from fires, frozen into a layer of polar ice. 30+ genera of, mostly, big mammals went extinct suddenly, along with the Clovis culture. The big remaining mystery is what happened 1200 years later to end the Younger Dryas cold spell.