Report

16°C Rapid Temperature Variation in Central Greenland 70,000 Years Ago

Science  29 Oct 1999:
Vol. 286, Issue 5441, pp. 934-937
DOI: 10.1126/science.286.5441.934

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Abstract

Variations in the29N2/28N2 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.

  • * To whom correspondence should be addressed. E-mail: lang{at}climate.unibe.ch (C.L.) or leuenberger{at}climate.unibe.ch(M.L.)

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