title: 16 degrees C rapid temperature variation in central greenland 70,000 years Ago
abstract: Variations in the (29)N(2)/(28)N(2) ratio of air bubbles trapped in polar ice cores and their relation to variations of the (18)O/(16)O of the ice allow past surface temperature variations and ice age-gas age differences to be determined. High-resolution measurements of (29)N(2)/(28)N(2) 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 delta(18)O(ice)-temperature coefficient alpha 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 delta(18)O(ice)-surface temperature correlations.
authors.affiliation: Climate and Environmental Physics, Physics Institute, University of Bern, Sidlerstrasse 5, Bern CH-3012, Switzerland. Niels Bohr Institute, Department of Geophysics, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Copenhagen, Den.
authors.initials: C
authors.lastname: Lang
authors.initials: M
authors.lastname: Leuenberger
authors.initials: J
authors.lastname: Schwander
authors.initials: S
authors.lastname: Johnsen