Secret Lake, NW Greenland Holocene Chironomid d18O and Inferred Temperature Lasher, G.E.; Axford, Y.; McFarlin, J.M.; Kelly, M.A.; Osterberg, E.; Berkelhammer, M.B. Lasher, G.E. Axford, Y. McFarlin, J.M. Kelly, M.A. Osterberg, E. Berkelhammer, M.B. earth science/paleoclimate/paleolimnology (delta 18O,midge,null,per mil VSMOW,null,paleolimnology,null,isotope ratio mass spectrometry,N,null) earth science/paleoclimate/paleolimnology (delta 18O,lake water,null,per mil VSMOW,null,paleolimnology,averaged,null,N,3 point moving average of sample_inferred_lw_d18O values) earth science/paleoclimate/paleolimnology (delta 18O,lake water,null,per mil VSMOW,null,paleolimnology,differenced,null,N,sample_d18O_chiron - 22.4 per mil (methods outlined in Lasher et al. 2017) earth science/paleoclimate/climate reconstructions|paleolimnology (maximum temperature,delta 18O,null,degree Celsius,annual,climate reconstructions|paleolimnology,anomalized,regression analysis,N,Thule annual temp-d18O: reconstruction_d18O relative to depth 0 (age -64 cal yr BP) / 0.44) earth science/paleoclimate/climate reconstructions|paleolimnology (age,null,null,calendar year before present,null,climate reconstructions|paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,3 point moving average of sample_age values) earth science/paleoclimate/paleolimnology (delta 18O,midge,null,per mil VSMOW,null,paleolimnology,averaged,null,N,3 point moving average of sample_d18O_chiron values) earth science/paleoclimate/climate reconstructions|paleolimnology (depth,null,null,centimeter,null,climate reconstructions|paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,delta 18O,null,degree Celsius,annual,climate reconstructions|paleolimnology,anomalized,regression analysis,N,Global temp-d18O: reconstruction_d18O relative to depth 0 (age -64 cal yr BP) / 0.67) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,delta 18O,null,degree Celsius,Jun-Aug,climate reconstructions|paleolimnology,anomalized,regression analysis,N,Thule summer temp-d18O: reconstruction_d18O relative to depth 0 (age -64 cal yr BP) / 0.59) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Secret Lake>LATITUDE 76.58021>LONGITUDE -68.65907) Reconstructions of Holocene lake water isotopic composition based upon subfossil aquatic organic material offer new insights into Arctic climate. We present quantitative estimates of warmth during the Holocene Thermal Maximum in northwest Greenland, inferred from oxygen isotopes of chironomid head capsules and aquatic moss preserved in lake sediments. d18O values of chironomids from surface sediments of multiple Greenland lakes indicate that these subfossil remains record the d18O values of the lake water in which they grow. Our lake water d18O reconstruction is supported by downcore agreement with d18O values in aquatic moss and chironomid remains. d18O of both organic materials from Secret Lake decrease after 4 ka (ka = thousands of years ago) by 3 permil into the Neoglacial. We argue that lake water at Secret Lake primarily reflects precipitation d18O values, which is strongly correlated with air temperature in NW Greenland, and that this signal is biased towards summer and early autumn conditions. Other factors may have influenced Secret Lake d18O values through the Holocene, including evaporation of lake water and changing seasonality and source of precipitation. The maximum early Holocene summer and early autumn-biased temperature anomaly at Secret Lake is 2.5-4C warmer than present from 7.7 (the beginning of our record) to ~6 ka. The maximum late Holocene cold anomaly (which includes the Little Ice Age) is 1.5-3C colder than present. These ranges of possible temperature anomalies reflect uncertainty in the d18O - temperature relationship for precipitation at the study site through the Holocene. STUDY NOTES: Oxygen isotope record measured on chironomid head capsule macrofossils, with inferred temperatures NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Lasher, G.E. Investigator : Axford, Y. Investigator : McFarlin, J.M. Investigator : Kelly, M.A. Investigator : Osterberg, E. Investigator : Berkelhammer, M.B. 2018-10-01 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/25311 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greenland/secret2017.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greenland/secret2017.txt English https://www.ncdc.noaa.gov/paleo/study/25311 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/greenland/secret2017.txt G. Everett Lasher, Yarrow Axford, Jamie M. McFarlin, Meredith A. Kelly, Erich C.Osterberg, Max B. Berkelhammer2017Holocene temperatures and isotopes of precipitation in Northwest Greenland recorded in lacustrine organic materialsQuaternary Science Reviews17044-5510.1016/j.quascirev.2017.06.016ttps://www.sciencedirect.com/science/article/pii/S0277379116305650 START YEAR: 7730 cal yr BP * END YEAR: -64 cal yr BP -68.65907 76.58021 -68.65907 76.58021