GISP II Ice Core Holocene CH4 Isotope Data ----------------------------------------------------------------------- World Data Center for Paleoclimatology, Boulder and NOAA Paleoclimatology Program ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: GISP II Ice Core Holocene CH4 Isotope Data LAST UPDATE: 11/2009 (Original receipt by WDC Paleo) CONTRIBUTOR: Todd Sowers, Penn State University IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2009-125 WDC PALEO CONTRIBUTION SERIES CITATION: Sowers, T. 2009. GISP II Ice Core Holocene CH4 Isotope Data. IGBP PAGES/World Data Center for Paleoclimatology Data Contribution Series # 2009-125. NOAA/NCDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCE: Sowers, T. 2010. Atmospheric methane isotope records covering the Holocene period. Quaternary Science Reviews, Vol. 29, pp. 213-221 doi:10.1016/j.quascirev.2009.05.023 ABSTRACT: Records of the 13C/12C (d13CH4) and the D/H (dDCH4) ratio of atmospheric methane were recovered from the GISP II ice core covering the last 11,000 years. All totaled, 76 samples were analyzed for d13CH4 and 65 adjacent samples for dDCH4 between 86 and 1696 m below surface (mbs) providing a temporal resolution that is better than one pair of isotope samples every 200 years. The d13CH4 record exhibits a decreasing trend throughout the Holocene beginning at -46.4 per mil at 11,000 years BP (BP defined as 1950 AD = 11 ka), and decreasing to -48.4 per mil at 1 ka. The 2 per mil d13CH4 drop is likely to be a combination of increased CH4 emissions from Arctic lake ecosystems and an increase in the ratio of C3/C4 plants in wetlands where CH4 is emitted. The C3/C4 ratio increase is the result of increasing CO2 values throughout the Holocene combined with the activation of high NH ecosystems that are predominantly C3 type. The dDCH4 record over the early-mid Holocene shows a slightly decreasing trend that would be predicted by increased CH4 emissions from Arctic lakes. Between 4 ka and 1 ka, dDCH4 values increase ~20 per mil while d13CH4 values remain effectively constant. There are at least two plausible explanations for this 20 per mil dDCH4 shift. First, a dramatic shift in CH4 emissions from higher latitudes to the tropics could account for the observed shift though the lack of a corresponding d13CH4 shift is difficult to reconcile. Secondly, a gradual release of marine clathrates with enriched dDCH4 values explains both the dDCH4 and d13CH4 records over this period. ADDITIONAL REFERENCES: Meese, D.A., A.J. Gow, R.B. Alley, P.M. Grootes, M. Ram, K.C. Taylor, G.A. Zielinski, J.F. Bolzan, P.A. Mayewski, and E.D. Waddington. 1997. The GISP2 depth-age scale: Method and results. Journal of Geophysical Research, 102(C12): 26,411-26,424. Sowers, T. 2006. Late Quaternary atmospheric CH4 isotope record suggests marine clathrates are stable. Science 311: 838-841. Sowers, T., S. Bernard, O. Aballain, J. Chappellaz, J.-M. Barnola, and T. Marik (2005). Records of the d13C of atmospheric CH4 over the last two centuries as recorded in Antarctic snow and ice. Global Biogeochemical Cycles 19(GB2002). GEOGRAPHIC REGION: Greenland PERIOD OF RECORD: 11 KYrBP - present FUNDING SOURCES: US National Science Foundation (NSF) grants OPP-0520470, 0440759, and 0538538. DESCRIPTION: d13C and dD of atmospheric methane from the GISP II ice core covering the last 11,000 years at a resolution of approximately 300 years. Wet extraction methodology used for both. GISP II Ice Core: 72°36'N, 38°30'W, 3203m asl. DATA: GISP2 ice core Holocene CH4 isotope data Column 1: Gas Age (kyr BP) Column 2: d13C (permil PDB) Column 3: dD (permil SMOW) GasAge d13C dD 0.10 -49.9 -113.8 0.10 -50.0 -107 0.10 -49.9 -116.9 0.10 -49.6 -104.3 0.10 -49.3 -116.4 0.10 -48.8 0.10 -49.3 -109.1 0.20 -49.1 0.20 -49.2 -116.5 0.20 -49.4 -99.7 0.40 -47.7 -90.3 0.60 -48.0 -105.3 0.80 -49.1 -94.5 1.00 -48.5 -99.4 1.20 -48.2 -98.2 1.40 -48.2 -87.2 1.60 -48.3 -85.5 1.80 -48.2 -92 2.00 -48.3 2.20 -48.2 -98.3 2.40 -48.7 -112.9 2.60 -48.7 -103.7 2.80 -48.0 -95.6 3.00 -47.3 -102.6 3.20 -47.6 -104.5 3.40 -48.3 -109.6 3.60 -48.5 -111.2 3.80 -47.8 -102.7 4.00 -48.7 4.20 -48.2 -119.5 4.40 -48.3 -117.7 4.60 -47.8 -107.8 4.80 -48.3 -113.1 5.00 -47.5 -114.8 5.20 -47.4 -88.1 5.40 -47.8 -121 5.60 -47.9 -107.7 5.80 -47.3 -97.5 6.00 -48.1 6.20 -47.6 -99.9 6.40 -47.9 -115 6.60 -47.0 -112.8 6.80 -47.0 -100.5 7.00 -47.8 7.20 -46.6 -112.8 7.40 -47.6 -103.5 7.60 -47.2 -125.6 7.80 -47.2 -112.6 8.00 -47.3 8.10 -47.3 -106.9 8.10 -47.0 -111 8.10 -46.9 -99 8.20 -47.2 -113.9 8.20 -48.0 -114.2 8.20 -47.4 -108.1 8.20 -46.2 -101.9 8.30 -46.8 8.30 -47.5 -108.9 8.40 -47.0 -109 8.60 -46.7 -112.7 8.80 -46.5 -102.8 9.00 -47.2 -125 9.20 -47.0 -117.7 9.40 -46.2 -98.7 9.60 -47.2 -107.9 9.80 -46.5 -109.8 10.00 -46.0 -109.7 10.20 -46.8 -112.6 10.40 -46.6 -108 10.60 -46.6 -109.7 10.80 -46.1 11.00 -46.2 -88.2 11.20 -45.6 -98.1 11.30 -46.4 -108