{"NOAAStudyId":"13398","contactInfo":{"address":"325 Broadway, E/NE31","city":"Boulder","constraints":"Please cite original publication, online resource, dataset and publication DOIs (where available), and date accessed when using downloaded data. If there is no publication information, please cite investigator, title, online resource, and date accessed. The appearance of external links associated with a dataset does not constitute endorsement by the Department of Commerce/National Oceanic and Atmospheric Administration of external Web sites or the information, products or services contained therein. For other than authorized activities, the Department of Commerce/NOAA does not exercise any editorial control over the information you may find at these locations. These links are provided consistent with the stated purpose of this Department of Commerce/NOAA Web site.","country":"USA","dataCenterUrl":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data","email":"paleo@noaa.gov","fax":"303-497-6513","longName":"National Centers for Environmental Information, NESDIS, NOAA, U.S. Department of Commerce ","phone":"303-497-6280","postalCode":"80305-3328","shortName":"DOC/NOAA/NESDIS/NCEI","state":"CO","type":"CONTACT INFORMATION"},"contributionDate":"2012-10-17","dataPublisher":"NOAA","dataType":"ICE CORES","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/ice-core","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-icecore-13398.xml","doi":null,"earliestYearBP":31924,"earliestYearCE":-29974,"entryId":"noaa-icecore-13398","funding":[{"fundingAgency":"Swiss National Science Foundation","fundingGrant":null}],"investigators":"Baumgartner, M.; Schilt, A.; Eicher, O.; Schmitt, J.; Schwander, J.; Spahni, R.; Fischer, H.; Stocker, T.F.","mostRecentYearBP":11067,"mostRecentYearCE":-9117,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/13398","originalSource":null,"publication":[{"abstract":"Reconstructions of past atmospheric methane concentrations\r\nare available from ice cores from both Greenland\r\nand Antarctica. The difference observed between the two polar\r\nmethane concentration levels represents a valuable constraint\r\non the geographical location of the methane sources.\r\nHere we present new high-resolution methane records from\r\nthe North Greenland Ice Core Project (NGRIP) and the European\r\nProject for Ice Coring in Antarctica (EPICA) Dronning\r\nMaud Land (EDML) ice cores covering Termination 1,\r\nthe Last Glacial Maximum, and parts of the last glacial back\r\nto 32 000 years before present. Due to the high resolution of\r\nthe records, the synchronisation between the ice cores from\r\nNGRIP and EDML is considerably improved, and the interpolar\r\nconcentration difference of methane is determined with\r\nunprecedented precision and temporal resolution. Relative\r\nto the mean methane concentration, we find a rather stable\r\npositive relative interpolar difference throughout the record\r\nwith its minimum value of 3.7±0.7% between 21 900–\r\n21 200 years before present, which is higher than previously\r\nestimated in this interval close to the Last Glacial Maximum.\r\nThis implies that Northern Hemisphere boreal wetland\r\nsources were never completely shut off during the peak\r\nglacial, as suggested from previous bipolar methane concentration\r\nrecords. Starting at 21 000 years before present, i.e.\r\nseveral millennia prior to the transition into the Holocene,\r\nthe relative interpolar difference becomes even more positive\r\nand stays at a fairly stable level of 6.5±0.8% during\r\nTermination 1. We thus find that the boreal and tropical\r\nmethane sources increased by approximately the same factor\r\nduring Termination 1. We hypothesise that latitudinal shifts\r\nin the Intertropical Convergence Zone (ITCZ) and the monsoon\r\nsystem contribute, either by dislocation of the methane\r\nsource regions or, in case of the ITCZ, also by changing the\r\nrelative atmospheric volumes of the Northern and Southern\r\nHemispheres, to the subtle variations in the relative interpolar\r\nconcentration difference on glacial/interglacial as well as\r\non millennial time scales.","author":null,"citation":"Baumgartner, M., A. Schilt, O. Eicher, J. Schmitt, \r\nJ. Schwander, R. Spahni, H. Fischer and T.F. Stocker. 2012. \r\nHigh-resolution interpolar difference of atmospheric methane \r\naround the Last Glacial Maximum. \r\nBiogeosciences, Vol. 9, pp. 3961-3977. \r\ndoi:10.5194/bg-9-3961-2012","edition":null,"identifier":{"id":"10.5194/bg-9-3961-2012","type":"doi","url":"http://dx.doi.org/10.5194/bg-9-3961-2012"},"issue":null,"journal":"Biogeosciences","pages":null,"pubRank":"1","pubYear":2012,"reportNumber":null,"title":"High-resolution interpolar difference of atmospheric methane around the Last Glacial Maximum","type":"publication","volume":null}],"reconstruction":"N","scienceKeywords":["Last Glacial Maximum"],"site":[{"NOAASiteId":"20568","geo":{"geoType":"Feature","geometry":{"coordinates":["-75",".07"],"type":"POINT"},"properties":{"easternmostLongitude":"0.07","maxElevationMeters":"2892","minElevationMeters":"2892","northernmostLatitude":"-75","southernmostLatitude":"-75","westernmostLongitude":"0.07"}},"locationName":"Continent>Antarctica","mappable":"Y","paleoData":[{"NOAADataTableId":"23100","coreLengthMeters":531,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>ice core>atmospheric gas"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/antarctica/maud/edml2012ch4.txt","linkText":"edml2012ch4.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":null,"cvDataType":"ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Character","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":null,"cvWhat":"sampling metadata>notes"},{"cvAdditionalInfo":null,"cvDataType":"ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"meter","cvWhat":"depth variable>depth"},{"cvAdditionalInfo":null,"cvDataType":"ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"calendar year before present","cvWhat":"age variable>age>gas age"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE FORCING|ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"atmospheric material>bulk atmosphere","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"parts per billion","cvWhat":"chemical composition>compound>organic compound>hydrocarbon>alkane>n-alkane>methane"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE FORCING|ICE CORES","cvDetail":null,"cvError":"one standard deviation","cvFormat":"Numeric","cvMaterial":"atmospheric material>bulk atmosphere","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"parts per billion","cvWhat":"chemical composition>compound>organic compound>hydrocarbon>alkane>n-alkane>methane"}]}],"dataTableName":"EDML2012CH4","dataTableNotes":null,"earliestYear":31839,"earliestYearBP":31839,"earliestYearCE":-29889,"mostRecentYear":11067,"mostRecentYearBP":11067,"mostRecentYearCE":-9117,"species":[],"timeUnit":"cal yr BP"}],"siteName":"EPICA Dronning Maud Land"},{"NOAASiteId":"31412","geo":{"geoType":"Feature","geometry":{"coordinates":["75.1","-42.33"],"type":"POINT"},"properties":{"easternmostLongitude":"-42.33","maxElevationMeters":"2917","minElevationMeters":"2917","northernmostLatitude":"75.1","southernmostLatitude":"75.1","westernmostLongitude":"-42.33"}},"locationName":"Continent>North America>Greenland","mappable":"Y","paleoData":[{"NOAADataTableId":"23101","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>ice core>atmospheric gas"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/ngrip/gases/ngrip2012ch4.txt","linkText":"ngrip2012ch4.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":null,"cvDataType":"ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Character","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":null,"cvWhat":"sampling metadata>notes"},{"cvAdditionalInfo":null,"cvDataType":"ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"meter","cvWhat":"depth variable>depth"},{"cvAdditionalInfo":null,"cvDataType":"ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"calendar year before present","cvWhat":"age variable>age>gas age"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE FORCING|ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"atmospheric material>bulk atmosphere","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"parts per billion","cvWhat":"chemical composition>compound>organic compound>hydrocarbon>alkane>n-alkane>methane"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE FORCING|ICE CORES","cvDetail":null,"cvError":"one standard deviation","cvFormat":"Numeric","cvMaterial":"atmospheric material>bulk atmosphere","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"parts per billion","cvWhat":"chemical composition>compound>organic compound>hydrocarbon>alkane>n-alkane>methane"}]}],"dataTableName":"NGRIP2012CH4","dataTableNotes":null,"earliestYear":31924,"earliestYearBP":31924,"earliestYearCE":-29974,"mostRecentYear":11067,"mostRecentYearBP":11067,"mostRecentYearCE":-9117,"species":[],"timeUnit":"cal yr BP"}],"siteName":"NGRIP"}],"studyCode":null,"studyName":"NGRIP and EDML Ice Core 32-11KYrBP Methane Data","studyNotes":"Methane (CH4) record from the EPICA Dronning Maud Land ice core, Antarctica, and the North Greenland Ice Sheet Project (NGRIP) ice core, Greenland, covering 32-11KYrBP.","version":"1.0","xmlId":"11439"}