The Younger Dryas cold period began about 12,900 years ago, when glacial temperatures returned within decades, and ended abruptly around 11,700 years ago after roughly 1,200 years.
Sources
- GICC05 (Rasmussen et al. 2006) - Greenland ice-core chronology (NOAA NCEI paleo archive) (ncei.noaa.gov)
- Did a Comet Really Kill the Mammoths 12,900 Years Ago? (nationalgeographic.com)
- https://www.pnas.org/doi/10.1073/pnas.2007869117 (pnas.org)
- https://www.sciencedirect.com/topics/earth-and-planetary-sciences/younger-dryas (sciencedirect.com)