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| Titel |
High-resolution glacial and deglacial record of atmospheric methane by continuous-flow and laser spectrometer analysis along the NEEM ice core |
| VerfasserIn |
J. Chappellaz, C. Stowasser, T. Blunier, D. Baslev-Clausen, E. J. Brook, R. Dallmayr, X. Faïn, J. E. Lee, L. E. Mitchell, O. Pascual, D. Romanini, J. Rosen, S. Schüpbach |
| 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 ; 9, no. 6 ; Nr. 9, no. 6 (2013-11-14), S.2579-2593 |
| Datensatznummer |
250085261
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| Publikation (Nr.) |
 copernicus.org/cp-9-2579-2013.pdf |
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| Zusammenfassung |
| The Greenland NEEM (North Greenland Eemian Ice Drilling) operation in 2010
provided the first opportunity to combine trace-gas measurements by laser
spectroscopic instruments and continuous-flow analysis along a freshly
drilled ice core in a field-based setting. We present the resulting
atmospheric methane (CH4) record covering the time period from 107.7 to
9.5 ka b2k (thousand years before 2000 AD). Companion discrete CH4
measurements are required to transfer the laser spectroscopic data from a
relative to an absolute scale. However, even on a relative scale, the
high-resolution CH4 data set significantly improves our knowledge of
past atmospheric methane concentration changes. New significant
sub-millennial-scale features appear during interstadials and stadials,
generally associated with similar changes in water isotopic ratios of the
ice, a proxy for local temperature. In addition to the midpoint of
Dansgaard–Oeschger (D/O) CH4 transitions usually used for cross-dating,
sharp definition of the start and end of these events brings precise depth
markers (with ±20 cm uncertainty) for further cross-dating with other
palaeo- or ice core records, e.g. speleothems. The method also provides an
estimate of CH4 rates of change. The onsets of D/O events in the
methane signal show a more rapid rate of change than their endings. The rate
of CH4 increase associated with the onsets of D/O events progressively
declines from 1.7 to 0.6 ppbv yr−1 in the course of marine isotope stage 3.
The largest observed rate of increase takes place at the onset of D/O event
#21 and reaches 2.5 ppbv yr−1. |
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