Taylor Dome Late Quaternary Ice Core CO2 Data: Readme file ----------------------------------------------------------------------- World Data Center A- Paleoclimatology ----------------------------------------------------------------------- NOTE: PLEASE CITE ORIGINAL REFERENCE WHEN USING THIS DATA!!!!! NAME OF DATA SET: Taylor Dome Late Quaternary Ice Core CO2 Data CONTRIBUTORS: H.J. Smith, H. Fischer, M. Wahlen, D. Mastroianni, B. Deck, Scripps Institution of Oceanography. IGBP PAGES/WDCA CONTRIBUTION SERIES NUMBER: 2000-002 SUGGESTED DATA CITATION: Smith, H.J., et al, 2000, Taylor Dome Late Quaternary Ice Core CO2 Holocene Data. IGBP PAGES/World Data Center-A for Paleoclimatology Data Contribution Series # 2000-002. NOAA/NGDC Paleoclimatology Program, Boulder CO, USA. ORIGINAL REFERENCES: 1) For CO2 concentration and d13CO2 data from ages between 27 kyBP and 11 kyBP: Smith, H. J., Fischer, H., Mastroianni, D., Deck, B. and Wahlen, M., 1999, Dual modes of the carbon cycle since the Last Glacial Maximum. Nature 400, 248-250. 2) For CO2 concentration and d13CO2 data from ages between 10.6 kyBP and 1.3 kyBP: Indermühle A., T.F. Stocker, F. Joos, H. Fischer, H.J. Smith, M. Wahlen, B. Deck, D. Mastroianni, J. Tschumi, T. Blunier, R. Meyer, B. Stauffer, 1999, Holocene carbon-cycle dynamics based on CO2 trapped in ice at Taylor Dome, Antarctica. Nature 398, 121-126. ADDITIONAL REFERENCES: Craig, H., Horibe, Y. & Sowers, T. Gravitational separation of gases and isotopes in polar ice caps. Science, 242, 1675-1678 (1988). Leuenberger, M. and Siegenthaler, U. (1988) Ice-age atmospheric concentration of nitrous oxide from an Antarctic ice core. Nature 360, 449-451. Schwander, J. The Environmental Record in Glaciers and Ice Sheets, eds. H. Oeschger and C. C. Langway, Jr., pp.53-67. John Wiley and Sons Limited (1989). Smith, H. J., Wahlen, M., Mastroianni, D. & Taylor, K. C. (1997) The CO2 concentration of air trapped in GISP2 ice from the LGM-Holocene transition. Geophys. Res. Lett. 24(1), 1-4. Sowers, T. & Bender, M. Elemental and isotopic composition of occluded O2 and N2 in polar ice. J. Geophys. Res. 94, 5137-5150 (1989). Steig, E. J. et al. (1998) Synchronous climate changes in Antarctica and the North Atlantic. Science 282(5386), 92-95. Sucher, C. (1997) Trapped Gases in the Taylor Dome Ice Core: Implications for East Antarctic Climate Change. Master's Thesis, U. Rhode Island. Wahlen, M., Allen, D. and Deck, B. (1991) Initial measurements of CO2 concentrations (1530 to 1940 AD) in air occluded in the GISP 2 ice core from central Greenland. Geophys. Res. Lett. 18(8), 1457-1460. LAST UPDATE: 01/2000 (Original Receipt by WDCA Paleo) GEOGRAPHIC REGION: Global PERIOD OF RECORD: 27 - 0.4 KYr BP LIST OF FILES: readme.taylor.lateQ.CO2.txt(this file), taylor.lateQ.CO2.data.xls (Microsoft Excel format), taylor.lateQ.CO2.data.txt (tab-delimited text format), taylor.lateQ.CO2.data.notes.txt. DESCRIPTION: The carbon-isotopic composition of atmospheric CO2 since the Last Glacial. Project Description: The main purpose of this work was to measure the concentration and carbon-isotopic composition (d13CO2) of atmospheric CO2 from air trapped in ice over the interval between 27 and 1.3 thousand years before the present from Taylor Dome, Antarctica, in order to investigate the causes of the CO2 concentration increase which occurred during the transition between the last glacial maximum (LGM) and the Holocene. The d13CO2 data were collected between 09 February 1998 and 25 May 1998. The CO2 concentration data were collected between 07 January 1998 and 29 July 1998. All measurements were made in the laboratory of Martin Wahlen, at Scripps Institution of Oceanography, University of California, San Diego, in La Jolla, California. Data Set Descriptions: All samples were taken from the ice cores of Taylor Dome, Antarctica (77 48'S,158 43'E, elevation 2374 m), drilled in 1993/94. The methods used for determining the CO2 concentration of air trapped in ice and the measurement of it's C-isotopic composition are described in detail in Wahlen et al. (1991) and Smith et al.(1997). Briefly, these techniques involve the dry extraction of trapped gas by crushing ice samples at low temperature in order to avoid exposing the gas to liquid water, in which CO2 is soluble. CO2 concentration measurements have an internal precision of ± 3 ppmv (2-sigma) and are calculated by comparison to 3 standards of precisely known compositions which are run with every sample. The Craig-corrected carbon-isotopic measurements, performed on a VG Prism II isotope ratio mass spectrometer, have a 1-sigma precision of ±0.075, based on numerous analyses of the CO2 separated from an atmospheric air standard exposed to uncrushed ice, in order to simulate the conditions of a sample run and to check for fractionation during extraction. d13CO2 is reported in normal delta notation as the per mil difference between the isotopic composition of the sample and standard VPDB carbon, [(13C/12C)sample/(13C/12C)VPDB-1] * (1000). The d13CO2 values reported here have been corrected for the gravitational separation of gases of different masses in the firn, and for the presence of N2O (which results in isobaric interferences with CO2 during mass spectrometry). Gravitational separation in the firn (Craig et al., 1988; Schwander, 1989) was determined by using the values of d15N2 of air trapped in Taylor Dome ice from Sucher (1997), following the approach of Sowers and Bender (1989). The gravitational correction for d13CO2 is approximately 0.005 per meter. C-isotopic data are corrected for the presence of N2O on the basis of calibrations performed in our laboratory on CO2-N2O mixtures. The N2O concentrations of atmospheric air used for this correction, adapted from Leuenberger and Siegenthaler (1988), are linear interpolations of the following concentrations and dates: 275 ppb (0-9.25 yBP), 200 ppb (16.1-27.2 kyBP). The N2O correction is approximately 0.001 per ppb of N2O. The total 1-sigma uncertainty in the reported d13CO2 of a single sample, including uncertainties in the gravitational and N2O corrections, is 0.085. Duplicate analyses of samples with air ages of 2.19 and 17.2 kyBP have a 1-sigma uncertainty of 0.060 and a triplicate analysis of the sample with an air age of 27.4 kyBP has a 1-sigma uncertainty of 0.049. The depth-age scale and air age-ice age differences were calculated using a combination of flow modeling, correlating variations in the d18O of the ice with the well-dated GISP2, and matching atmospheric CH4 concentrations and d18O of O2 with variations seen in GISP2 (Steig et al., 1998).