A multiproxy evaluation of Holocene environmental change from Lake Igaliku, South Greenland

Abstract

This is the first integrated multiproxy study to investigate climate, catchment evolution and lake ecology in South Greenland. A 4-m-long sedimentary sequence from Lake Igaliku (61o 00′ N, 45o 26′ W, 15 m asl) documents major environmental and climatic changes in south Greenland during the last 10 ka. The chronology is based on a 210Pb and 137Cs profile and 28 radiocarbon dates. The paleoenvironmental history is interpreted on the basis of magnetic susceptibility, grain size, total organic carbon, total nitrogen and sulphur, sedimentation rates, pollen, and diatom assemblages. The basal radiocarbon date at ca. 10 cal ka BP provides a minimum age for the deglaciation of the basin, which is followed by ~500 years of high sedimentation rates in a glacio-marine environment. After the glacio-isostatic emergence of the basin ca. 9.5 cal ka BP, limnological and terrestrial proxies suggests early warmth, which may have been interrupted by a cold, dry and windy period between 8.6 and 8.1 cal ka BP. A dry and windy event ~5.3–4.8 cal ka BP preceded the Neoglacial transition at Lake Igaliku, which is characterized by a shift toward moister and perhaps cooler conditions ~4.8 cal ka BP, causing major changes in terrestrial and aquatic ecological conditions. Significant cooling is documented after ~3 cal ka BP. Since ~1 cal ka BP the climatic-driven changes were overprinted by the human influence of Norse and recent agriculture.