NGRIP CH<sub>4</sub> concentration from 120 to 10 kyr before present and its relation to a δ<sup>15</sup>N temperature reconstruction from the same ice core

Baumgartner, Matthias; Kindler, Philippe; Eicher, Olivier; Floch, G.; Schilt, Adrian; Schwander, Jakob; Spahni, Renato; Capron, E.; Chappellaz, J.; Leuenberger, Markus; Fischer, Hubertus; Stocker, Thomas (2014). NGRIP CH<sub>4</sub> concentration from 120 to 10 kyr before present and its relation to a δ<sup>15</sup>N temperature reconstruction from the same ice core. Climate of the past, 10(2), pp. 903-920. Copernicus Publications 10.5194/cp-10-903-2014

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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.

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:

Baumgartner, Matthias; Kindler, Philippe; Eicher, Olivier; Schilt, Adrian; Schwander, Jakob; Spahni, Renato; Leuenberger, Markus; Fischer, Hubertus and Stocker, Thomas

Subjects:

500 Science > 530 Physics

ISSN:

1814-9324

Publisher:

Copernicus Publications

Language:

English

Submitter:

Doris Rätz

Date Deposited:

18 Aug 2014 15:06

Last Modified:

13 Jul 2015 15:03

Publisher DOI:

10.5194/cp-10-903-2014

BORIS DOI:

10.7892/boris.53692

URI:

https://boris.unibe.ch/id/eprint/53692

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