Data Description

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Bock, M et al. (2010): Methane concentration and delta deuterium of methane from the NGRIP ice core. doi:10.1594/PANGAEA.756715,
Supplement to: Bock, Michael; Schmitt, Jochen; Möller, Lars; Spahni, Renato; Blunier, Thomas; Fischer, Hubertus (2010): Hydrogen isotopes preclude marine hydrate CH4 emissions at the onset of Dansgaard-Oeschger Events. Science, 328(5986), 1686-1689, doi:10.1126/science.1187651
The causes of past changes in the global methane cycle and especially the role of marine methane hydrate (clathrate) destabilization events are a matter of debate. Here we present evidence from the North Greenland Ice Core Project ice core based on the hydrogen isotopic composition of methane [dD(CH4)] that clathrates did not cause atmospheric methane concentration to rise at the onset of Dansgaard-Oeschger (DO) events 7 and 8. Box modeling supports boreal wetland emissions as the most likely explanation for the interstadial increase. Moreover, our data show that dD(CH4) dropped 500 years before the onset of DO 8, with CH4 concentration rising only slightly. This can be explained by an early climate response of boreal wetlands, which carry the strongly depleted isotopic signature of high-latitude precipitation at that time.
Latitude: 75.001000 * Longitude: -42.300000
Date/Time Start: 1996-07-01T00:00:00 * Date/Time End: 1996-07-01T00:00:00
Minimum DEPTH, ice/snow: 1993.48 m * Maximum DEPTH, ice/snow: 2129.88 m
NGRIP * * Latitude: 75.001000 * Longitude: -42.300000 * Date/Time: 1996-07-01T00:00:00 * Elevation: 2925.0 m * Campaign: NGRIP * * Basis: Sampling/drilling ice * * Device: Ice drill (ICEDRILL) *
Uncertainty for dD of CH4 is 3.4 per mil as derived from standard measurements as described in: Bock, M. et al., 2010, doi:10.1002/rcm.4429
Please note, that the concentration data given here have a higher error (of 29 ppbv 1-sigma) compared to conventional methods due to the uncertainty of total air content determination of the dD isotope system.
#NameShort NameUnitPrincipal InvestigatorMethodComment
1Sample code/label *LabelBock, Michael *Bag number
2DEPTH, ice/snow *Depth ice/snowmGeocode
3Gas age *Gas ageka BPBock, Michael *based on age model GICC05
4Methane *CH4ppbvBock, Michael *Gas chromatography *
5delta Deuterium, methane *dD CH4per milBock, Michael *Mass spectrometry *as measured, with respect to VSMOW, 1-sigma uncertainty of dD of CH4: 3.4 per mil
6delta Deuterium, methane *dD CH4per milBock, Michael *Mass spectrometry *corrected using d15N, with respect to VSMOW, 1-sigma uncertainty of dD of CH4: 3.4 per mil
288 data points

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