Methane in NEEM-2011-S1 ice core from North Greenland, 1800 years continuous record: Version 2

DOI

Changes to original version posted at NOAA (https://www.ncdc.noaa.gov/paleo-search/study/14173): Chronology has been updated to most recent NEEM-2011-S1 ice age and NEEM delta age. Age scale now constructed from annual-layer-counted ice age (Sigl et al., 2015, Nature). Two options for delta age provided a) constant delta age of 188 yr (Buizert et al. 2012, ACP & 2014 corrigendum), b) variable delta age transferred from main NEEM core (Rasmussen et al., 2013, COP) using offsets between GICC05 and NEEM-2011-S1 ice age provided by Sigl et al. 2015. Outliers at 387.2-387.4 m and 335.1-335.3 m depth removed. Publication abstract: Ancient air trapped inside bubbles in ice cores can now be analysed for methane concentration utilising a laser spectrometer coupled to a continuous melter system. We present a new ultra-high resolution record of atmospheric methane variability over the last 1800 yr obtained from continuous analysis of a shallow ice core from the North Greenland Eemian project (NEEM-2011-S1) during a 4-week laboratory-based measurement campaign. Our record faithfully replicates the form and amplitudes of multi-decadal oscillations previously observed in other ice cores and demonstrates the detailed depth resolution (5.3 cm), rapid acquisition time (30 m day-1) and good long-term reproducibility (2.6%, 2s) of the continuous measurement technique.In addition, we report the detection of high frequency ice core methane signals of non-atmospheric origin. Firstly, measurements of air from the firn-ice transition region and an interval of ice core dating from 1546-1560 AD (gas age) resolve apparently quasi-annual scale methane oscillations. Traditional gas chromatography measurements on discrete ice samples confirm these signals and indicate peak-topeak amplitudes of ca. 22 parts per billion (ppb). We hypothesise that these oscillations result from staggered bubble close-off between seasonal layers of contrasting density during time periods of sustained multi-year atmospheric methane change. Secondly, we report the detection of abrupt (20-100 cm depth interval), high amplitude (35-80 ppb excess) methane spikes in the NEEM ice that are reproduced by discrete measurements. We show for the first time that methane spikes present in thin and infrequent layers in polar, glacial ice are accompanied by elevated concentrations of carbon and nitrogen-based chemical impurities, and suggest that biological in-situ production may be responsible.Funding: * US National Science Foundation, Grant: 0944552, 0909541, 0968391 ANR France, Grant: ANR-10-RPDOC-002-01, ANR-07-VULN-09-001 European Research Council, Grant: FP7/2007-2013 Grant Agreement 291062

CHANGES TO ORIGINAL VERSION POSTED AT NOAA (https://www.ncdc.noaa.gov/paleo-search/study/14173) Chronology has been updated to most recent NEEM-2011-S1 ice age and NEEM delta age. Age scale now constructed from annual-layer-counted ice age (Sigl et al., 2015, Nature). Two options for delta age provided a) constant delta age of 188 yr (Buizert et al. 2012, ACP & 2014 corrigendum). b) variable delta age transferred from main NEEM core (Rasmussen et al., 2013, COP) using offsets between GICC05 and NEEM-2011-S1 ice age provided by Sigl et al. 2015 Outliers at 387.2-387.4 m and 335.1-335.3 m depth removed.

Supplement to: Rhodes, Rachael H; Faïn, Xavier; Stowasser, Christopher; Blunier, Thomas; Chappellaz, Jérôme A; McConnell, Joseph R; Romanini, Daniele; Mitchell, Logan E; Brook, Edward J (2013): Continuous methane measurements from a late Holocene Greenland ice core: Atmospheric and in-situ signals. Earth and Planetary Science Letters, 368, 9-19

Identifier
DOI https://doi.org/10.1594/PANGAEA.899040
Related Identifier https://doi.org/10.1016/j.epsl.2013.02.034
Related Identifier https://doi.org/10.25921/BFTN-XA29
Related Identifier https://doi.org/10.5194/acp-12-4259-2012
Related Identifier https://doi.org/10.5194/acp-14-3571-2014
Related Identifier https://doi.org/10.5194/cp-9-2713-2013
Related Identifier https://doi.org/10.1038/nature14565
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.899040
Provenance
Creator Rhodes, Rachael H ORCID logo; Brook, Edward J
Publisher PANGAEA
Publication Year 2019
Funding Reference Agence Nationale de la Recherche https://doi.org/10.13039/501100001665 Crossref Funder ID 07-VULN-09-001 North Greenland Eemian Ice Drilling
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 4 datasets
Discipline Earth System Research
Spatial Coverage (-51.060 LON, 77.450 LAT); Greenland