# Bipolar Holocene Composite Ice Core CH4, d13C, and dD Data #----------------------------------------------------------------------- # World Data Service for Paleoclimatology, Boulder # and # NOAA Paleoclimatology Program # National Centers for Environmental Information (NCEI) #----------------------------------------------------------------------- # Template Version 3.0 # Encoding: UTF-8 # NOTE: Please cite Publication, and Online_Resource and date accessed when using these data. # If there is no publication information, please cite Investigators, Title, and Online_Resource and date accessed. # # Online_Resource: https://www.ncdc.noaa.gov/paleo/study/25350 # Description: NOAA Landing Page # Online_Resource: https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/beck2018south-d13c.txt # Description: NOAA location of the template # # Original_Source_URL: # Description: # # Description/Documentation lines begin with # # Data lines have no # # # Archive: Ice Core # # Dataset DOI: # # Parameter_Keywords: atmospheric gas, carbon isotopes, hydrogen isotopes #-------------------- # Contribution_Date # Date: 2018-12-07 #-------------------- # File_Last_Modified_Date # Date: 2018-12-07 #-------------------- # Title # Study_Name: Bipolar Holocene Composite Ice Core CH4, d13C, and dD Data #-------------------- # Investigators # Investigators: Beck, J.; Bock, M.; Schmitt, J.; Seth, B.; Blunier, T.; Fischer, H. #-------------------- # Description_Notes_and_Keywords # Description: Ice core Holocene composite Northern (GISP2, GRIP, NGRIP) and Southern (EDC, EDML, TALDICE, WAIS) Hemisphere methane (CH4), # carbon isotope (d13C), and hydrogen isotope (dD) data. stable carbon isotopes of methane (d13C-CH4) data measured on the TALDICE ice core; # TALDICE age scale according to synchronised CH4 data; d13C-CH4 data are free of krypton interference during the mass spectrometric analysis # and corrected for gravitational enrichment (see Beck et al., 2018) # Provided Keywords: Holocene, methane, carbon istotpes, d13C, d13C-CH4, d13CH4, ice core, TALDICE, Antarctica #-------------------- # Publication # Authors: Jonas Beck, Michael Bock, Jochen Schmitt, Barbara Seth, Thomas Blunier, and Hubertus Fischer # Published_Date_or_Year: 2018-11-30 # Published_Title: Bipolar carbon and hydrogen isotope constraints on the Holocene methane budget # Journal_Name: Biogeosciences # Volume: 15 # Edition: # Issue: # Pages: 7155-7175 # Report_Number: # DOI: 10.5194/bg-15-7155-2018 # Online_Resource: https://www.biogeosciences.net/15/7155/2018/ # Full_Citation: # Abstract: Atmospheric methane concentration shows a well-known decrease over the first half of the Holocene following the Northern Hemisphere summer insolation before it started to increase again to preindustrial values. There is a debate about what caused this change in the methane concentration evolution, in particular, whether an early anthropogenic influence or natural emissions led to the reversal of the atmospheric CH4 concentration evolution. Here, we present new methane concentration and stable hydrogen and carbon isotope data measured on ice core samples from both Greenland and Antarctica over the Holocene. With the help of a two-box model and the full suite of CH4 parameters, the new data allow us to quantify the total methane emissions in the Northern Hemisphere and Southern Hemisphere separately as well as their stable isotopic signatures, while interpretation of isotopic records of only one hemisphere may lead to erroneous conclusions. For the first half of the Holocene our results indicate an asynchronous decrease in Northern Hemisphere and Southern Hemisphere CH4 emissions by more than 30 Tg CH4 yr-1 in total, accompanied by a drop in the northern carbon isotopic source signature of about -3 per mil. This cannot be explained by a change in the source mix alone but requires shifts in the isotopic signature of the sources themselves caused by changes in the precursor material for the methane production. In the second half of the Holocene, global CH4 emissions increased by about 30 Tg CH4 yr-1, while preindustrial isotopic emission signatures remained more or less constant. However, our results show that this early increase in methane emissions took place in the Southern Hemisphere, while Northern Hemisphere emissions started to increase only about 2000 years ago. Accordingly, natural emissions in the southern tropics appear to be the main cause of the CH4 increase starting 5000 years before present, not supporting an early anthropogenic influence on the global methane budget by East Asian land use changes. #------------------ # Publication # Authors: Michael Bock, Jochen Schmitt, Jonas Beck, Barbara Seth, Jérôme Chappellaz, and Hubertus Fischer # Published_Date_or_Year: 2017-07-18 # Published_Title: Glacial/interglacial wetland, biomass burning, and geologic methane emissions constrained by dual stable isotopic CH4 ice core records # Journal_Name: Proceedings of the National Academy of Sciences of the United States of America # Volume: 114 # Edition: # Issue: 29 # Pages: E5778-E5786 # Report_Number: # DOI: 10.1073/pnas.1613883114 # Online_Resource: http://www.pnas.org/content/114/29/E5778 # Full_Citation: # Abstract: Atmospheric methane (CH4) records reconstructed from polar ice cores represent an integrated view on processes predominantly taking place in the terrestrial biogeosphere. Here, we present dual stable isotopic methane records [d13CH4 and dD(CH4)] from four Antarctic ice cores, which provide improved constraints on past changes in natural methane sources. Our isotope data show that tropical wetlands and seasonally inundated floodplains are most likely the controlling sources of atmospheric methane variations for the current and two older interglacials and their preceding glacial maxima. The changes in these sources are steered by variations in temperature, precipitation, and the water table as modulated by insolation, (local) sea level, and monsoon intensity. Based on our dD(CH4) constraint, it seems that geologic emissions of methane may play a steady but only minor role in atmospheric CH4 changes and that the glacial budget is not dominated by these sources. Superimposed on the glacial/interglacial variations is a marked difference in both isotope records, with systematically higher values during the last 25,000 y compared with older time periods. This shift cannot be explained by climatic changes. Rather, our isotopic methane budget points to a marked increase in fire activity, possibly caused by biome changes and accumulation of fuel related to the late Pleistocene megafauna extinction, which took place in the course of the last glacial. #------------------ # Publication # Authors: J. Schmitt, B. Seth, M. Bock, and H. Fischer # Published_Date_or_Year: 2014-08-19 # Published_Title: Online technique for isotope and mixing ratios of CH4, N2O, Xe and mixing ratios of organic trace gases on a single ice core sample # Journal_Name: Atmospheric Measurement Techniques # Volume: 7 # Edition: # Issue: # Pages: 2645-2665 # Report_Number: # DOI: 10.5194/amt-7-2645-2014 # Online_Resource: https://www.atmos-meas-tech.net/7/2645/2014/ # Full_Citation: # Abstract: Firn and polar ice cores enclosing trace gas species offer a unique archive to study changes in the past atmosphere and in terrestrial/marine source regions. Here we present a new online technique for ice core and air samples to measure a suite of isotope ratios and mixing ratios of trace gas species on a single sample. Isotope ratios are determined on methane, nitrous oxide and xenon with reproducibilities for ice core samples of 0.15 permil for d13C-CH4, 0.22 permil for d15N-N2O, 0.34 permil for d18O–N2O, and 0.05 permil per mass difference for d136Xe for typical concentrations of glacial ice. Mixing ratios are determined on methane, nitrous oxide, xenon, ethane, propane, methyl chloride and dichlorodifluoromethane with reproducibilities of 7 ppb for CH4, 3 ppb for N2O, 70 ppt for C2H6, 70 ppt for C3H8, 20 ppt for CH3Cl, and 2 ppt for CCl2F2. However, the blank contribution for C2H6 and C3H8 is large in view of the measured values for Antarctic ice samples. The system consists of a vacuum extraction device, a preconcentration unit and a gas chromatograph coupled to an isotope ratio mass spectrometer. CH4 is combusted to CO2 prior to detection while we bypass the oven for all other species. The highly automated system uses only ~ 160 g of ice, equivalent to ~ 16 mL air, which is less than previous methods. The measurement of this large suite of parameters on a single ice sample is new and key to understanding phase relationships of parameters which are usually not measured together. A multi-parameter data set is also key to understand in situ production processes of organic species in the ice, a critical issue observed in many organic trace gases. Novel is the determination of xenon isotope ratios using doubly charged Xe ions. The attained precision for d136Xe is suitable to correct the isotopic ratios and mixing ratios for gravitational firn diffusion effects, with the benefit that this information is derived from the same sample. Lastly, anomalies in the Xe mixing ratio, dXe/air, can be used to detect melt layers. #------------------ # Funding_Agency # Funding_Agency_Name: European Research Council # Grant: 226172 #------------------ # Funding_Agency # Funding_Agency_Name: Swiss National Science Foundation # Grant: #------------------ # Site_Information # Site_Name: TALDICE # Location: Antarctica # Country: # Northernmost_Latitude: -72.8 # Southernmost_Latitude: -72.8 # Easternmost_Longitude: 159.18 # Westernmost_Longitude: 159.18 # Elevation: 2315 m #------------------ # Data_Collection # Collection_Name: Beck2018Southd13C # Earliest_Year: 11921 # Most_Recent_Year: 80 # Time_Unit: Cal. Year BP # Core_Length: # Notes: #------------------ # Chronology_Information # Chronology: # #---------------- # Variables # # Data variables follow are preceded by "##" in columns one and two. # Data line variables format: one per line, shortname-tab-variable components (what, material, error, units, seasonality, data type,detail, method, C or N for Character or Numeric data, free text) # ## depth_m depth, , , m, , , , ,N, ## gas_age_calBP age, gas, , calendar years before present, , , , ,N,synchronised age scales (see Beck et al. 2018 section 2.3.1) present defined as 1950 CE ## d13C_raw delta 13C, methane, , per mil VPDB, ,ice core,raw,isotope ratio mass spectrometry,N, ## d13C_corr delta 13C, methane, , per mil VPDB, ,ice core,corrected,isotope ratio mass spectrometry,N,corrected for gravitational settling ## d13C_err delta 13C, methane, one standard error, per mil VPDB, ,ice core,,,N, ## data_origin data origin,,,,,,,,C,reference to orginal publication # #---------------- # Data: # Data lines follow (have no #) # Data line format - tab-delimited text, variable short name as header # Missing Values: # depth_m gas_age_calBP d13C_raw d13C_corr d13C_err data_origin 91.31 80.8 -49.28 -49.62 0.13 TALDICE_Beck2018 101.03 188.1 -48.96 -49.31 0.13 TALDICE_Beck2018 101.42 192.7 -49.02 -49.37 0.13 TALDICE_Beck2018 132.06 598.7 -47.50 -47.85 0.13 TALDICE_Bock2017 192.03 1386.4 -47.47 -47.82 0.13 TALDICE_Bock2017 216.18 1746.4 -47.11 -47.46 0.13 TALDICE_Bock2017 216.30 1749.1 -47.21 -47.55 0.13 TALDICE_Bock2017 227.03 1884.3 -47.30 -47.64 0.13 TALDICE_Bock2017 240.42 2102.7 -47.45 -47.79 0.13 TALDICE_Bock2017 253.03 2276.5 -47.83 -48.17 0.13 TALDICE_Bock2017 264.09 2439.5 -47.65 -47.99 0.13 TALDICE_Bock2017 264.40 2452.3 -47.52 -47.86 0.13 TALDICE_Bock2017 300.03 3053.3 -47.31 -47.64 0.13 TALDICE_Bock2017 348.06 3863.9 -47.32 -47.64 0.13 TALDICE_Bock2017 348.37 3883.3 -47.41 -47.73 0.13 TALDICE_Bock2017 385.03 4613.6 -47.75 -48.06 0.13 TALDICE_Bock2017 409.03 5121.2 -47.71 -48.01 0.13 TALDICE_Bock2017 433.03 5656.1 -47.70 -47.99 0.13 TALDICE_Bock2017 456.43 6188.8 -47.24 -47.52 0.13 TALDICE_Bock2017 486.00 6725.9 -47.16 -47.44 0.13 TALDICE_Bock2017 512.00 7284.7 -47.01 -47.29 0.13 TALDICE_Bock2017 534.36 7799.5 -47.01 -47.29 0.13 TALDICE_Bock2017 534.48 7804.1 -46.90 -47.18 0.13 TALDICE_Bock2017 562.48 8465.5 -46.79 -47.07 0.13 TALDICE_Bock2017 587.48 9099.0 -46.39 -46.69 0.13 TALDICE_Bock2017 623.48 9869.4 -46.39 -46.72 0.13 TALDICE_Beck2018 646.48 10514.6 -45.99 -46.34 0.13 TALDICE_Bock2017 660.27 10807.2 -45.75 -46.13 0.13 TALDICE_Bock2017 673.64 11128.6 -45.42 -45.81 0.13 TALDICE_Bock2017 681.85 11341.3 -45.54 -45.93 0.13 TALDICE_Bock2017 697.79 11719.7 -45.86 -46.25 0.13 TALDICE_Bock2017 705.64 11921.3 -45.04 -45.43 0.13 TALDICE_Bock2017