High-resolution glacial and deglacial record of atmospheric methane by continuous-flow and laser spectrometer analysis along the NEEM ice core

Chappellaz, L.; Stowasser, C.; Blunier, T.; Baslev-Clausen, D.; Brook, E. J.; Dallmayr, R.; Faïn, X.; Lee, J. E.; Mitchell, L. E.; Pascual, O.; Romanini, D.; Rosen, J.; Schüpbach, Simon (2013). High-resolution glacial and deglacial record of atmospheric methane by continuous-flow and laser spectrometer analysis along the NEEM ice core. Climate of the past, 9(6), pp. 2579-2593. Copernicus Publications 10.5194/cp-9-2579-2013

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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.

Item Type:

Journal Article (Original Article)

Division/Institute:

08 Faculty of Science > Physics Institute > Climate and Environmental Physics
10 Strategic Research Centers > Oeschger Centre for Climate Change Research (OCCR)

UniBE Contributor:

Schüpbach, Simon

Subjects:

500 Science > 530 Physics

ISSN:

1814-9324

Publisher:

Copernicus Publications

Language:

English

Submitter:

Doris Rätz

Date Deposited:

18 Aug 2014 10:29

Last Modified:

26 Jun 2016 01:50

Publisher DOI:

10.5194/cp-9-2579-2013

BORIS DOI:

10.7892/boris.47747

URI:

https://boris.unibe.ch/id/eprint/47747

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