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| Titel |
NGRIP CH4 concentration from 120 to 10 kyr before present and its relation to a δ15N temperature reconstruction from the same ice core |
| VerfasserIn |
M. Baumgartner, P. Kindler, O. Eicher, G. Floch, A. Schilt, J. Schwander, R. Spahni, E. Capron, J. Chappellaz, M. Leuenberger, H. Fischer, T. F. Stocker |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 10, no. 2 ; Nr. 10, no. 2 (2014-04-30), S.903-920 |
| Datensatznummer |
250116961
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| Publikation (Nr.) |
 copernicus.org/cp-10-903-2014.pdf |
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| Zusammenfassung |
| During the last glacial cycle,
Greenland temperature showed many rapid temperature variations, the so-called
Dansgaard–Oeschger (DO) events. The past atmospheric methane concentration
closely followed these temperature variations, which implies that the
warmings recorded in Greenland were probably hemispheric in extent. Here we
substantially extend and complete the North Greenland Ice Core Project
(NGRIP) methane record from the Preboreal Holocene (PB) back to the end of
the last interglacial period with a mean time resolution of 54 yr. We relate
the amplitudes of the methane increases associated with DO events to the
amplitudes of the local Greenland NGRIP temperature increases derived from
stable nitrogen isotope (δ15N) measurements, which have been
performed along the same ice core (Kindler et al., 2014). We find the ratio to
oscillate between 5 parts per billion (ppb) per °C and
18 ppb °C−1 with the approximate frequency of the precessional
cycle. A remarkably high ratio of 25.5 ppb °C−1 is reached
during the transition from the Younger Dryas (YD) to the PB. Analysis of the
timing of the fast methane and temperature increases reveals significant lags
of the methane increases relative to NGRIP temperature for DO events 5, 9,
10, 11, 13, 15, 19, and 20. These events generally have small methane
increase rates and we hypothesize that the lag is caused by pronounced
northward displacement of the source regions from stadial to interstadial. We
further show that the relative interpolar concentration difference (rIPD) of
methane is about 4.5% for the stadials between DO events 18 and 20, which
is in the same order as in the stadials before and after DO event 2 around
the Last Glacial Maximum. The rIPD of methane remains relatively stable
throughout the full last glacial, with a tendency for elevated values during
interstadial compared to stadial periods. |
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