Isotope data indicates that central Greenland was nearly 14 °C (24.5 °F) colder during the Younger Dryas than it is today.
Notes on verification
Confirmed by peer-reviewed gas-isotope paleothermometry (Severinghaus et al. 1998, Nature) and corroborated by subsequent literature (Alley 2000, Buizert et al. 2014). Minor uncertainty remains on exact magnitude but order of ~14-15°C cooling is well supported. [cascade flags: wikipedia_dropped_other_sources_exist | tier=silver indep_score=1.0 clusters=2 claim_tier=notable]
Sources
- Greenland Ice-core Project/Greenland Ice Sheet Project 2 | geochronology | Britannica (seed:history_and_archaeology)
- https://www.pnas.org/doi/10.1073/pnas.1202183109 (corroboration)
- https://web.gps.caltech.edu/classes/ge140a/Stable_Isotope_W19/Readings_files/Severinghaus1998Nature.pdf (corroboration)