{"NOAAStudyId":"12887","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":"2012-03-30","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-12887.xml","doi":null,"earliestYearBP":3950,"earliestYearCE":-2000,"entryId":"noaa-icecore-12887","funding":[],"investigators":"Kobashi, T.; Kawamura, K.; Severinghaus, J.; Barnola, J.M.; Nakaegawa, T.; Vinther, B.M.; Johnsen, S.J.; Box, J.E.","mostRecentYearBP":-43,"mostRecentYearCE":1993,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/12887","originalSource":null,"publication":[{"abstract":"Greenland recently incurred record high temperatures and ice loss \r\nby melting, adding to concerns that anthropogenic warming is \r\nimpacting the Greenland ice sheet and in turn accelerating global \r\nsea-level rise.  Yet, it remains imprecisely known for Greenland \r\nhow much warming is caused by increasing atmospheric greenhouse \r\ngases versus natural variability. To address this need, we reconstruct \r\nGreenland surface snow temperature variability over the past 4000 \r\nyears at the GISP2 site (near the Summit of the Greenland ice sheet; \r\nhereafter referred to as Greenland temperature) with a new method \r\nthat utilises argon and nitrogen isotopic ratios from occluded air \r\nbubbles. The estimated average Greenland snow temperature over \r\nthe past 4000 years was -30.7°C with a standard deviation of 1.0°C \r\nand exhibited a long-term decrease of roughly 1.5°C, which is \r\nconsistent with earlier studies. The current decadal average \r\nsurface temperature (2001–2010) at the GISP2 site is -29.9°C. \r\nThe record indicates that warmer temperatures were the norm \r\nin the earlier part of the past 4000 years, including century-long\r\nintervals nearly 1°C warmer than the present decade (2001-2010). \r\nTherefore, we conclude that the current decadal mean temperature \r\nin Greenland has not exceeded the envelope of natural variability \r\nover the past 4000 years, a period that seems to include part of \r\nthe Holocene Thermal Maximum.  Notwithstanding this conclusion, \r\nclimate models project that if anthropogenic greenhouse gas \r\nemissions continue, the Greenland temperature would exceed \r\nthe natural variability of the past 4000 years sometime \r\nbefore the year 2100.\r\n","author":null,"citation":"Kobashi, T., K. Kawamura, J.P. Severinghaus, J.-M. Barnola, \r\nT. Nakaegawa, B.M. Vinther, S.J. Johnsen, and J.E. Box. 2011. \r\nHigh variability of Greenland surface temperature over the\r\npast 4000 years estimated from trapped air in an ice core.\r\nGeophys. Res. Lett., 38, L21501, doi:10.1029/2011GL049444.","edition":null,"identifier":{"id":"10.1029/2011GL049444","type":"doi","url":"http://dx.doi.org/10.1029/2011GL049444"},"issue":null,"journal":"Geophysical Research Letters","pages":null,"pubRank":"1","pubYear":2011,"reportNumber":null,"title":"High variability of Greenland surface temperature over the past 4000 years estimated from trapped air in an ice core","type":"publication","volume":null}],"reconstruction":"Y","scienceKeywords":["Air Temperature Reconstruction","Arctic","temperature"],"site":[{"NOAASiteId":"19978","geo":{"geoType":"Feature","geometry":{"coordinates":["72.6","-38.5"],"type":"POINT"},"properties":{"easternmostLongitude":"-38.5","maxElevationMeters":"3200","minElevationMeters":"3200","northernmostLatitude":"72.6","southernmostLatitude":"72.6","westernmostLongitude":"-38.5"}},"locationName":"Continent>North America>Greenland","mappable":"Y","paleoData":[{"NOAADataTableId":"21223","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>ice core>reconstruction","earth science>paleoclimate>ice core>nitrogen isotopes"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/isotopes/gisp2-temperature2011.txt","linkText":"gisp2-temperature2011.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS|ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"year Common Era","cvWhat":"age variable>age"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS|ICE CORES","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>isotope ratio>delta 15N excess","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature>surface temperature"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS|ICE CORES","cvDetail":null,"cvError":"one standard deviation","cvFormat":"Numeric","cvMaterial":"reconstruction material>isotope ratio>delta 15N excess","cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature>surface temperature"}]},{"NOAAKeywords":["earth science>paleoclimate>ice core>nitrogen isotopes","earth science>paleoclimate>ice core>reconstruction"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/icecore/greenland/summit/gisp2/isotopes/gisp2-temperature2011.xls","linkText":"gisp2-temperature2011.xls","urlDescription":"Data","variables":[]}],"dataTableName":"d15Nd40Ar2011","dataTableNotes":null,"earliestYear":-2000,"earliestYearBP":3950,"earliestYearCE":-2000,"mostRecentYear":1993,"mostRecentYearBP":-43,"mostRecentYearCE":1993,"species":[],"timeUnit":"AD"}],"siteName":"GISP2"}],"studyCode":null,"studyName":"GISP2 Ice Core 4000 Year Ar-N Isotope Temperature Reconstruction ","studyNotes":"Greenland summit surface snow temperature for the past 4000 years \nreconstructed by a new method that utilises argon and nitrogen \nisotopic ratios from occluded air bubbles. Simultaneous, \nhigh-precision analyses of d15N and d40Ar in trapped air from \nthe GISP2 ice core (Kobashi et al. 2008a) was used for this study. \nThe method for the temperature reconstruction relies on the fact \nthat gases in firn (unconsolidated snow) layers fractionate \naccording to the depth and temperature gradient (DT) at the top \nand bottom of the layer (Severinghaus et al., 1998). Information \nabout past depths and DTs at the time of air bubble trapping \nin the ice sheet can be retrieved by measuring d15N and d40Ar \nin the occluded air in ice cores.  Then, the surface temperature \nhistory can be reconstructed by integrating the DTs over time \n(Kobashi et al., 2008b, 2010) with a firn densification/heat \ndiffusion model (Goujon et al., 2003). \n","version":"1.0","xmlId":"10950"}