Holocene century-scale temperature variability from West Greenland lake records

Synchronous changes in high-resolution loss on ignition profiles from widely separated shallow Arctic lakes in West Greenland suggest that sedimentary records of lake productivity provide a sensitive century-scale time series of variability in surface-air temperatures throughout the Holocene. Ice cover greatly reduces biological activity in arctic lakes, and the common productivity response among lakes is attributed to air-temperature--controlled variations in the length of the ice-cover period. Comparison with the Greenland oxygen isotope records from Summit ice cores demonstrates that the inferred temperature fluctuations in the lakes closely follow the century-scale fluctuations in the Greenland Ice Core Project delta (super 18) O record but correlate less well with the Greenland Ice Sheet Project 2 record. Low-altitude continental lake records thus not only confirm features of Holocene atmospheric temperature variability otherwise seen only in high-altitude ice cores from central Greenland, but also highlight discrepancies between the ice-core time series. The combined lake and ice-core data provide corroborative evidence for an intrinsically unstable Holocene climate in Greenland, including the 8200 yr B.P. event that is currently recognized as the most pronounced Holocene climatic cooling with possible global significance. Our finding of a link between paleoproductivity and surface-air temperature has important implications for reconstructing natural climate variability in areas where such information is still rare. The results illustrate the large potential of paleolimnological studies in the Arctic.