{"NOAAStudyId":"15309","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":"2012-01-02","dataPublisher":"NOAA","dataType":"PALEOLIMNOLOGY","dataTypeInformation":"https://www.ncdc.noaa.gov/data-access/paleoclimatology-data/datasets/lake","difMetadataLink":"http://www1.ncdc.noaa.gov/pub/data/metadata/published/paleo/dif/xml/noaa-lake-15309.xml","doi":null,"earliestYearBP":12190,"earliestYearCE":-10240,"entryId":"noaa-lake-15309","funding":[],"investigators":"Larsen, D.J.; Miller, G.H.; Geirsdóttir, A.; Olafsdottir, S.","mostRecentYearBP":-56,"mostRecentYearCE":2006,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/15309","originalSource":null,"publication":[{"abstract":"Iceland is well situated to monitor North Atlantic Holocene climate variability. Terrestrial sites there offer the potential for well-dated, high-resolution, continuous records of environmental change and/or glacier activity. Laminated sediments from the proglacial lake Hvítárvatn provide a continuous record of environmental change and the development of the adjacent Langjökull ice cap for the past 10.2 ka. Replicate lake sediment cores, collected from multiple locations in the basin, are placed in a secure geochronology by splicing a varve chronology for the past 3 ka with a tephra-constrained, paleomagnetic secular variation derived chronology for older sediments. Multiple proxies, including sedimentation rate, bulk density, ice-rafted debris, sediment organic matter, biogenic silica, and diatom abundance, allow annual to multi-decadal resolution and reveal a dynamic Holocene terrestrial climate. Following regional deglaciation of the main Iceland Ice Sheet, summer temperatures were high enough that mountain ice caps had already melted, or were contributing insignificant sediment to the lake. Pronounced increases in sedimentation rate, sediment density, and the influx of terrestrial organic matter, between 8.7 and 7.9 ka suggest early Holocene warmth was interrupted by two distinct pulses of cold summers leading to widespread landscape destabilization and possibly glacier growth. The Holocene thermal maximum (HTM; 7.9 to 5.5 ka) was characterized by high within-lake productivity and ice-free conditions in the watershed. Neoglaciation is recorded as a non-linear transition toward cooler summers, landscape destabilization, and the inception and expansion of Langjökull beginning ca 5.5 ka, with notable increases in ice cap size and landscape instability at 4.2 and 3.0 ka. The past two millennia are characterized by the abrupt onset of sustained cold periods at ca 550 and 1250 AD, separated by an interval of relative warmth from ca 950 to 1150 AD. The greatest Holocene extent of Langjökull occurred in the nineteenth century and is coincident with peak landscape instability, followed by ice recession throughout the twentieth century.","author":{"name":"Larsen, D.J., Miller, G.H., Geirsdottir, A., Olafsdottir, S."},"citation":"Larsen, D.J., Miller, G.H., Geirsdottir, A., Olafsdottir, S. 2012. Non-linear Holocene climate evolution in the North Atlantic: a high resolution, multi-proxy record of glacier activity and environmental change from Hvitarvatn, central Iceland. Quaternary Science Reviews, 39, 14 - 25. ","edition":null,"identifier":null,"issue":null,"journal":"Quaternary Science Reviews","pages":"14 - 25","pubRank":"1","pubYear":2012,"reportNumber":null,"title":"Non-linear Holocene climate evolution in the North Atlantic: a high resolution, multi-proxy record of glacier activity and environmental change from Hvitarvatn, central Iceland.","type":"publication","volume":"39"}],"reconstruction":"N","scienceKeywords":["Arctic","Medieval Warm Period","Little Ice Age (LIA)","Glacial"],"site":[{"NOAASiteId":"55169","geo":{"geoType":"Feature","geometry":{"coordinates":["64.64172","-19.83995"],"type":"POINT"},"properties":{"easternmostLongitude":"-19.83995","maxElevationMeters":"422","minElevationMeters":"422","northernmostLatitude":"64.64172","southernmostLatitude":"64.64172","westernmostLongitude":"-19.83995"}},"locationName":"Continent>Europe>Northern Europe>Iceland","mappable":"Y","paleoData":[{"NOAADataTableId":"25277","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth 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sites: HVT03-1 and HVT03-2.","earliestYear":10250,"earliestYearBP":10250,"earliestYearCE":-8300,"mostRecentYear":-50,"mostRecentYearBP":-50,"mostRecentYearCE":2000,"species":[],"timeUnit":"cal yr BP"},{"NOAADataTableId":"25278","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>magnetic susceptibility"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvitarvatn2012-density-ms.txt","linkText":"hvitarvatn2012-density-ms.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"calendar year before present","cvWhat":"age variable>age"},{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological 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size","dataTableNotes":null,"earliestYear":10156,"earliestYearBP":10156,"earliestYearCE":-8206,"mostRecentYear":-41,"mostRecentYearBP":-41,"mostRecentYearCE":1991,"species":[],"timeUnit":"cal yr BP"},{"NOAADataTableId":"25282","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>physical properties"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/europe/iceland/hvitarvatn2012-ird.txt","linkText":"hvitarvatn2012-ird.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":null,"cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"calendar year before present","cvWhat":"age variable>age"},{"cvAdditionalInfo":"size fraction > 2mm","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":"geological material>bulk geological 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