Holocene climate history of Geographical Society O, East Greenland - evidence from lake sediments

Sediment cores from two lakes in the outer coastal region of East Greenland were investigated for chronology, lithology, palynology, and biogeochemist ry. A 10 m long sequence recovered in Basaltso comprises the entire lake hi story following the last glaciation of the area, probably during the Prebor eal oscillation. This is indicated by a succession from glacial via glaciol imnic to limnic sediments. Deglaciation of the area was associated with a h igh sedimentation rate, mirrored also in the basal part of a 2.6 m long cor e from a smaller lake (B1) about 1 km south of Basaltso. Limnic sedimentati on without glacial influence commenced about 10000 cal.yr BP according to r adiocarbon-dated terrestrial plant remains. Biogeochemical and palynologica l data indicate an early Holocene climatic optimum from 9000 to 6500 cal, y r BP A climatic deterioration began at 6500 cal. yr BP with an increase in snow accumulation. documented by a change in the pollen assemblage and a co inciding change in the grain-size distribution. At least since 5000 cal. yr BP, a decrease in the biogeochemical parameters in both lake sediment succ essions indicates a temperature decline. This deterioration culminated at a bout 3000-1000 cal. vr BP, when the climate was cold and dry. A slight warm ing is indicated in the pollen assemblage between ca. 1000 and 800 cal. yr BP. Following a subsequent rise in precipitation, cooling during the Little Ice Age is mirrored in lowest dwarf shrub pollen percentages and in low co ntents of organic components. (C) 2000 Elsevier Science B.V. All rights res erved.