Kurupa Lake, Alaska 5,700 Year Inferred Chlorophyll and Summer Temperature Reconstruction Boldt, B.R.; Kaufman, D.S.; McKay, N.P.; Briner, J.P. Boldt, B.R. Kaufman, D.S. McKay, N.P. Briner, J.P. Air Temperature Reconstruction earth science/paleoclimate/climate reconstructions|paleolimnology (non-freezing days,null,one standard deviation upper bound,count,Jun-Sep,climate reconstructions|paleolimnology,averaged,null,N,3-year mean; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/paleolimnology (age,null,95% confidence interval upper bound,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,one standard deviation lower bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,null,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged,null,N,100-year-mean; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (non-freezing days,null,one standard deviation lower bound,count,Jun-Sep,climate reconstructions|paleolimnology,averaged,null,N,3-year mean; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (non-freezing days,null,two standard deviations lower bound,count,Jun-Sep,climate reconstructions|paleolimnology,averaged,null,N,3-year mean; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,one standard deviation lower bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,one standard deviation upper bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations lower bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations upper bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,null,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged,null,N,100-year-mean; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/paleolimnology (depth,null,null,centimeter,null,paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleolimnology (age,null,null,calendar year before present,null,climate reconstructions|paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations lower bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations lower bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged,null,N,100-year-mean; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations upper bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged,null,N,100-year-mean; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (non-freezing days,null,two standard deviations upper bound,count,Jun-Sep,climate reconstructions|paleolimnology,averaged,null,N,3-year mean; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/paleolimnology (reflectance,sediment,null,dimensionless,null,paleolimnology,null,spectrophotometry,N,ratio between the reflectance minimum (absorption maximum) and the reflectance value for 660-670nm) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,null,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations upper bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations lower bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged,null,N,100-year-mean; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (non-freezing days,null,null,count,Jun-Sep,climate reconstructions|paleolimnology,averaged,null,N,3-year mean; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,one standard deviation upper bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,two standard deviations upper bound,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged,null,N,100-year-mean; anomalies relative to 1961-1990; calibrated to 20th Century Reanalysis; based on sediment chlorophyll) earth science/paleoclimate/paleolimnology (age,null,95% confidence interval lower bound,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/climate reconstructions|paleolimnology (temperature,null,null,degree Celsius,Jun-Sep,climate reconstructions|paleolimnology,anomalized|averaged|smoothed,null,N,3-year-mean smoothed; anomalies relative to 1961-1990; calibrated to GISTEMP reanalysis; based on sediment chlorophyll) earth science/paleoclimate/paleolimnology (age,null,null,calendar year before present,null,paleolimnology,null,null,N,null) earth science/paleoclimate/paleolimnology earth science/paleoclimate/paleolimnology (Kurupa Lake>LATITUDE 68.3637>LONGITUDE -154.6496) Quantitative records of pre-industrial temperature changes are fundamental for understanding long-term natural climate variability. We used visible reflectance spectroscopy to measure chlorophyll content (and its derivatives) in a sediment core from Kurupa Lake, north-central Brooks Range, Alaska, to reconstruct summer temperature and the number of annual non-freezing days over the past 5.7 ka. A calibration-in-time approach was used to convert downcore changes in chlorophyll content to the climate variables, and an ensemble approach was used to integrate age and calibration uncertainties. The strongest correlation (r median = 0.69, p median = 0.02, RMSEP = 1.9C) is for summer (June through September) temperature using the 20th Century Reanalysis Project dataset. The chlorophyll-inferred 3-year-mean summer temperature shows that the warmest century (3.0-2.9 ka BP) was about 3.0C (90% range of the ensemble members = 2.3-4.0C) higher and that the coldest century (1.4-1.3 ka BP) was about 5.5C lower (90% range = -7.6C to -5.0C) than during the reference period (AD 1961-1990). Century-to-century temperature changes over the past 5.7 ka at Kurupa Lake have been large (90% range = -2.8C to 3.1C shifts in centennial mean), including the shift between the 19th and 20th centuries, which was above the 90th percentile of temperature changes across all representations of the reconstruction. In contrast to most Northern Hemisphere temperature reconstructions, Kurupa Lake shows no overall millennial-scale cooling trend. We suggest that increased summer duration (by 4.3 days during the last 6 ka) along with no long-term increase in sea-ice cover over the adjacent Chukchi Sea counter-balanced the influence of decreased insolation intensity on the aquatic productivity in Kurupa Lake. STUDY NOTES: Inferred sediment chlorophyll content and summer (June-September) temperature reconstruction from Kurupa Lake, Brooks Range, Alaska, for the past 5.7 ka. Data are spectrally inferred (RABD) chlorophyll concentration, geochronology (14C and 210Pb), and summer temperature reconstructions (3-yr and 100-yr). NCDC-Paleoclimatology https://www.ncdc.noaa.gov/data-access/paleoclimatology-data - Bauer Bruce Investigator : Boldt, B.R. Investigator : Kaufman, D.S. Investigator : McKay, N.P. Investigator : Briner, J.P. 2015-07-09 ONLINE Files online, ASCII https://www.ncdc.noaa.gov/paleo/study/18995 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrrean.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrgis.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrnfd.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp100yr.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015rabd.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrrean.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrgis.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrnfd.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp100yr.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015rabd.txt English https://www.ncdc.noaa.gov/paleo/study/18995 https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrrean.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrgis.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp3yrnfd.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015temp100yr.txt https://www1.ncdc.noaa.gov/pub/data/paleo/paleolimnology/northamerica/usa/alaska/kurupa2015rabd.txt Brandon R. Boldt, Darrell S. Kaufman, Nicholas P. McKay, and Jason P. Briner 2015Holocene summer temperature reconstruction from sedimentary chlorophyll content, with treatment of age uncertainties, Kurupa Lake, Arctic Alaska The Holocene254641-65010.1177/0959683614565929http://hol.sagepub.com/content/25/4/641.abstract START YEAR: 5698 cal yr BP * END YEAR: -60 cal yr BP -154.6496 68.3637 -154.6496 68.3637