{"NOAAStudyId":"6197","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":"2008-11-01","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-6197.xml","doi":null,"earliestYearBP":1508,"earliestYearCE":442,"entryId":"noaa-lake-6197","funding":[],"investigators":"Loso, M.G.","mostRecentYearBP":-48,"mostRecentYearCE":1998,"onlineResourceLink":"https://www.ncdc.noaa.gov/paleo/study/6197","originalSource":null,"publication":[{"abstract":"For the heavily glaciated mountains of southern Alaska, few high-resolution, millennial-scale proxy temperature reconstructions are available for comparison with modern temperatures or with the history of glacier fluctuations. Recent catastrophic drainage of glacier-dammed Iceberg Lake, on the northern margin of the Bagley Icefield, exposed subaerial outcrops of varved lacustrine sediments that span the period 442-1998 AD. Here, an updated chronology of varve thickness measurements is used to quantitatively reconstruct melt-season temperature anomalies. From 1958 to 1998, varve thickness has a positive and marginally significant correlation with May-June temperatures at the nearest coastal measurement stations. Varve sensitivity to temperature has changed over time, however, in response to lake level changes in 1957 and earlier. I compensate for this by log-transforming the varve thickness chronology, and also by using a 400-year-long tree-ring-based temperature proxy \r\nto reconstruct melt-season temperatures at Iceberg Lake. Regression against this longer proxy record is statistically weak, but spans the full range of occupied lake levels and varve sensitivities. Reconstructed temperature anomalies have broad confidence intervals, but nominally span 1.1C over the last 1500+ years. Maximum temperatures occurred in the late twentieth century, with a minimum in the late sixth century. The Little Ice Age is present as three cool periods between 1350 and 1850 AD with maximum cooling around 1650 AD. A Medieval Warm Period is evident from 1000 to 1100 AD, but the temperature reconstruction suggests it was less warm than recent decades - an observation supported by independent geological evidence of recent glacier retreat that is unprecedented over the period of record.\r\n","author":{"name":"Loso, M.G."},"citation":"Loso, M.G. 2009. Summer temperatures during the Medieval Warm Period and Little Ice Age inferred from varved proglacial lake sediments in southern Alaska. Journal of Paleolimnology, 41(1), 117-128. doi: 10.1007/s10933-008-9264-9 ","edition":null,"identifier":{"id":"10.1007/s10933-008-9264-9 ","type":"doi","url":"http://dx.doi.org/10.1007/s10933-008-9264-9 "},"issue":"1","journal":"Journal of Paleolimnology","pages":"117-128","pubRank":"1","pubYear":2009,"reportNumber":null,"title":"Summer temperatures during the Medieval Warm Period and Little Ice Age inferred from varved proglacial lake sediments in southern Alaska","type":"publication","volume":"41"}],"reconstruction":"Y","scienceKeywords":["PAGES 2k Network","PAGES Arctic 2k","Air Temperature Reconstruction"],"site":[{"NOAASiteId":"20672","geo":{"geoType":"Feature","geometry":{"coordinates":["60.783","-142.95"],"type":"POINT"},"properties":{"easternmostLongitude":"-142.95","maxElevationMeters":"933","minElevationMeters":"933","northernmostLatitude":"60.783","southernmostLatitude":"60.783","westernmostLongitude":"-142.95"}},"locationName":"Continent>North America>United States Of America>Alaska","mappable":"Y","paleoData":[{"NOAADataTableId":"9517","coreLengthMeters":null,"dataFile":[{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>physical properties"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/iceberg2008.txt","linkText":"iceberg2008.txt","urlDescription":"Data","variables":[{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"anomalized","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; smoothed with a 24-year low-pass filter; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"smoothed","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; smoothed with a 24-year low-pass filter; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"anomalized","cvError":null,"cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; smoothed with a 24-year low-pass filter; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"smoothed","cvError":"95% confidence interval lower bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; smoothed with a 24-year low-pass filter; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"anomalized","cvError":"95% confidence interval lower bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; smoothed with a 24-year low-pass filter; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"smoothed","cvError":"95% confidence interval upper bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":"anomalies from reconstructed mean temperatures of the last millennium; smoothed with a 24-year low-pass filter; based on varve thickness","cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":"anomalized","cvError":"95% confidence interval upper bound","cvFormat":"Numeric","cvMaterial":"reconstruction material>physical measurement>varve thickness","cvMethod":null,"cvSeasonality":"2-month period>May-Jun","cvShortName":null,"cvUnit":"degree Celsius","cvWhat":"earth system variable>temperature variable>temperature"},{"cvAdditionalInfo":null,"cvDataType":"CLIMATE RECONSTRUCTIONS|PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"year Common Era","cvWhat":"age variable>age"},{"cvAdditionalInfo":"section A","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"section B","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"section J","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"section K","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"section M","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"section N","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"simple averages of data from individual sections","cvDataType":"PALEOLIMNOLOGY","cvDetail":"composited","cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"40-year lowpass filter","cvDataType":"PALEOLIMNOLOGY","cvDetail":"smoothed","cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"},{"cvAdditionalInfo":"section I","cvDataType":"PALEOLIMNOLOGY","cvDetail":null,"cvError":null,"cvFormat":"Numeric","cvMaterial":null,"cvMethod":null,"cvSeasonality":null,"cvShortName":null,"cvUnit":"millimeter","cvWhat":"physical property>length>varve thickness"}]},{"NOAAKeywords":["earth science>paleoclimate>paleolimnology>physical properties"],"fileUrl":"https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/iceberg2008.xls","linkText":"iceberg2008.xls","urlDescription":"Data","variables":[]}],"dataTableName":"Iceberg Lake Core ICEBERG","dataTableNotes":null,"earliestYear":1508,"earliestYearBP":1508,"earliestYearCE":442,"mostRecentYear":-48,"mostRecentYearBP":-48,"mostRecentYearCE":1998,"species":[],"timeUnit":"cal yr BP"}],"siteName":"Iceberg Lake"}],"studyCode":null,"studyName":"Iceberg Lake, Alaska 1,500 Year Varve Thickness and Temperature Reconstruction","studyNotes":"Varve thickness measurements and temperature reconstruction from Iceberg Lake, Alaska","version":"1.0","xmlId":"2145"}