The Sisimiut area was deglaciated in the early Holocene, c. 11cal ka BP. At that time the lowlands were inundated by the sea, but the isostatic rebound surpassed the global sea-level rise, and the lowlands emerged from the sea. The pioneer vegetation in the area consisted of mosses and herbaceous plants. The oldest remains of woody plants (Empetrum nigrum) are dated to c. 10.3cal ka BP, and remains of Salix herbacea and Harrimanella hypnoides are found in slightly younger sediments. The maximum occurrence of statoblasts of the bryozoan Plumatella repens from c.10 to 4.5cal ka BP probably reflects the Holocene thermal maximum, which is also indicated in geochemical proxies of the lake sediments. A maximum in organic matter accumulation in one of the three studied lakes c. 3cal ka BP can probably be ascribed to a late Holocene short-duration temperature maximum or a period of increased aridity. Cenococcum geophilum sclerotia are common in the late Holocene, implying increased soil erosion during the Neoglaciation. A comparison with sediment and macrofossil records from inland shows similar Holocene trends and a similar immigration history. It also reveals that there has been a significant gradient throughout the Holocene, from an oceanic and stable climate at the outer coast to a more continental and unstable climate with warmer summers and drier conditions close to the margin of the Greenland ice sheet, where the buffer capacity of the sea is lower.
- Programområde 5: Natur og klima