Magnitude and temporal evolution of Dansgaard-Oeschger event 8 abrupt temperature change inferred from nitrogen and argon isotopes in GISP2 ice using a new least-squares inversion

TitleMagnitude and temporal evolution of Dansgaard-Oeschger event 8 abrupt temperature change inferred from nitrogen and argon isotopes in GISP2 ice using a new least-squares inversion
Publication TypeJournal Article
Year of Publication2014
AuthorsOrsi A.J, Cornuelle BD, Severinghaus JP
JournalEarth and Planetary Science Letters
Volume395
Pagination81-90
Date Published2014/06
Type of ArticleArticle
ISBN Number0012-821X
Accession NumberWOS:000336110300008
Keywordsabrupt climate change; climate-change; core record; east antarctica; firn; greenland; greenland ice; grip; ice; ice cores; inverse; last glacial period; methods; noble gases; polar; thermal fractionation; thermal-diffusion constants; trapped air
Abstract

Polar temperature is often inferred from water isotopes in ice cores. However, non-temperature effects on 3180 are important during the abrupt events of the last glacial period, such as changes in the seasonality of precipitation, the northward movement of the storm track, and the increase in accumulation. These effects complicate the interpretation of 8180 as a temperature proxy. Here, we present an independent surface temperature reconstruction, which allows us to test the relationship between delta O-18(ice) and temperature, during Dansgaard-Oeschger event 8, 38.2 thousand yrs ago using new delta N-15 and delta Ar-40 data from the GISP2 ice core in Greenland. This temperature reconstruction relies on a new inversion of inert gas isotope data using generalized least-squares, and includes a robust uncertainty estimation. We find that both temperature and delta O-18 increased in two steps of 20 and 140 yrs, with an overall amplitude of 11.80 +/- 1.8 degrees C between the stadial and interstadial centennial-mean temperature. The coefficient alpha = d delta O-18/dT changes with each time-segment, which shows that non-temperature sources of fractionation have a significant contribution to the delta O-18 signal. When measured on century-averaged values, we find that alpha = d delta O-18/dT = 0.32 +/- 0.06%(0)/degrees C, which is similar to the glacial/Holocene value of 0.328%(o)/degrees C. (C) 2014 Elsevier B.V. All rights reserved.

DOI10.1016/j.epsl.2014.03.030
Short TitleEarth Planet. Sci. Lett.
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