Lake V57, Nunavut 2,000 Year Midge Inferred Temperatures Porinchu, D.F.; MacDonald, G.M.; Rolland, N. Porinchu, D.F. MacDonald, G.M. Rolland, N. Air Temperature Reconstruction PAGES 2k Network PAGES Arctic 2k earth science/paleoclimate/climate reconstructions|insect|paleolimnology (surface air temperature,midge assemblage,null,degree Celsius,Jul,climate reconstructions|insect|paleolimnology,null,regression analysis,N,calibration data set: Central Canadian Arctic Porinchu et al. 2009; weighted-averaging partial least-squares regression) earth science/paleoclimate/climate reconstructions|insect|paleolimnology (lake surface temperature,midge assemblage,null,degree Celsius,summer,climate reconstructions|insect|paleolimnology,null,regression analysis,N,weighted-averaging partial least-squares regression) earth science/paleoclimate/climate reconstructions|insect|paleolimnology (depth,null,null,centimeter,null,climate reconstructions|insect|paleolimnology,null,null,N,null) earth science/paleoclimate/insect|paleolimnology (detrended correspondence analysis axis,null,null,dimensionless,null,insect|paleolimnology,null,null,N,DCA axis 1 of chironomid assemblage) earth science/paleoclimate/climate reconstructions|insect|paleolimnology (age,null,null,year Common Era,null,climate reconstructions|insect|paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (organic matter,sediment,null,weight percent,null,paleolimnology,null,loss on ignition,N,loss on ignition 550 degrees C for two hours) earth science/paleoclimate/paleolimnology (Lake V57>LATITUDE 68.657>LONGITUDE -105.357) A lake sediment core recovered from Lake V57 on Victoria Island, Nunavut, Canada, spanning the last 2000 years, was analyzed for sub-fossil midge remains and organic-matter content estimated by loss-on-ignition (LOI)). Significant changes in midge community composition occurred during the last 2000 years, with a distinct midge community appearing after 1600 AD. The chironomid community between 0 and 1600 AD was dominated by Heterotrissocladius, Tanytarsus, Abiskomyia, and Paracladius. At approximately 1600 AD, Heterotrissocladius decreased in relative abundance and taxa such as Corynocera ambigua, C. oliveri, Psectrocladius sordidellus type, and Pentanneurini increased in relative abundance. Previously published midge-based inference models for average July air temperature (AJAT) and summer surface-water temperature (SSWT) were applied to the subfossil midge stratigraphy. The AJAT reconstruction indicates relatively cool conditions existed between 1100 and 1600 AD, with exceptional warming occurring after 1600 AD, as lake productivity inferred from organic-matter content increased concomitantly with midge-inferred AJAT and SSWT. The cooler conditions between 1200 and 1600 AD, and the pattern of warming over recent centuries inferred from Lake V57 is broadly consistent with temperature-sensitive biogenic silica records from other sites in the central Canadian Arctic and the treeline zone to the south suggesting a regionally synchronous response to climate forcing. STUDY NOTES: Midge-inferred Average July Air Temperature (AJAT) and Summer Surface Water Temperature (SSWT) for the last 2,000 years for Lake V57, Nunavut, Canada NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Porinchu, D.F. Investigator : MacDonald, G.M. Investigator : Rolland, N. 2008-11-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/6201 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/nu/v57midge2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/nu/v57midge2008.xls https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/nu/v57midge2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/nu/v57midge2008.xls English https://www.ncdc.noaa.gov/paleo/study/6201 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/nu/v57midge2008.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/canada/nu/v57midge2008.xls Porinchu, D.F., G.M. MacDonald, and N. Rolland2009A 2000 year midge-based paleotemperature reconstruction from the Canadian Arctic ArchipelagoJournal of Paleolimnology411177-18810.1007/s10933-008-9263-x START YEAR: 1918 cal yr BP * END YEAR: -49 cal yr BP -105.357 68.657 -105.357 68.657