16°C rapid temperature variation in Central Greenland 70,000 years ago

• Published in: Science
• Main Authors: Lang, C., Leuenberger, M., Schwander, J., Johnson, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science 1999
• Subjects: 530 Physics; Greenland
• Online Access: https://boris.unibe.ch/158271/1/lang99sci.pdf; https://boris.unibe.ch/158271/

Variations in the 29N2/28N2 ratio of air bubbles trapped in polar ice cores and their relation to variations of the 18O/16O of the ice allow past surface temperature variations and ice age–gas age differences to be determined. High-resolution measurements of29N2/28N2 in Dansgaard-Oeschger event 19 (around 70,000 years before the present) in ice from Central Greenland show that at the beginning of the event, the ice age–gas age difference was 1090 ± 100 years. With the use of a combined firn densification, temperature, and gas diffusion model, the δ18Oice-temperature coefficient α was determined to be 0.42 ± 0.05 per mil per kelvin. This coefficient implies a mean surface temperature change of 16.0 kelvin (between 14.3 and 18.1 kelvin), which differs substantially from values derived from borehole temperatures and modern spatial δ18Oice–surface temperature correlations.