Central Greenland was nearly 14°C (24.5°F) colder during the Younger Dryas than it is today.
Notes on verification
Confirmed by multiple independent peer-reviewed ice-core studies (Buizert et al. 2014, Science; PNAS reconstructions) and corroborated by Wikipedia's synthesis of Alley (2000). Magnitude estimates converge in the 9-15°C range depending on methodology and baseline. [cascade flags: wikipedia_dropped_other_sources_exist | tier=silver indep_score=0.77 clusters=2 claim_tier=notable]
Sources
- Younger Dryas | Definition, Causes, & Termination (seed:history_and_archaeology)
- https://www.pnas.org/doi/10.1073/pnas.1202183109 (corroboration)
- https://www.science.org/doi/abs/10.1126/science.1254961 (corroboration)