Description
The authors analyzed a 3.5-m-long sediment core, which was extracted in September of 1994 from a lake (Raffels So) located at 70°35.7'N, 21°32.1'W on an island (Raffles O) situated just off Liverpool Land on the east coast of Greenland, for a number of properties related to the past presence of seabirds there, obtaining a 10,000-year record that tells us much about the region's climatic history. Key to the study were biogeochemical data that, in the words of the authors, reflect "variations in seabird breeding colonies in the catchment which influence nutrient and cadmium supply to the lake." This work revealed sharp increases in the values of the parameters they measured between about 1100 and 700 years before present, indicative of the summer presence of significant numbers of seabirds during what they described as a "medieval warm period," which had been preceded by a several-hundred-year period of little to no (inferred) bird presence. Thereafter, their data pointed to another absence of birds during "a subsequent Little Ice Age," which they say was "the coldest period since the early Holocene in East Greenland." There were also signs of a "resettlement of seabirds during the last 100 years, indicated by an increase of organic matter in the lake sediment and confirmed by bird observations." However, the values of the most recent biogeochemical measurements were not as great as those from the earlier Medieval Warm Period. Hence, we conclude that much of the period from approximately AD 900-1300 was warmer than it was over the course of the 20th century to at least September 1994, when the sediment core was obtained.