A lacustrine record from a small lake, Lille Sneha Sø, in the Skallingen area indicates that the region was deglaciated in the early Holocene, prior to 8000cal. a BP. Deglaciation was probably triggered by high temperatures, but it took more than 1000 years for the lake and the catchment to stabilize. Chironomids were amongst the first invertebrates to colonize the lake. The fossil chironomid assemblage is fairly rich and comparable to other records from further south in Greenland. The pioneer vegetation in the area consisted of mosses and herbaceous plants. The oldest remains of woody plants (Salix arctica) are dated to c.7700 cal. a BP, and remains of Dryas integrifolia appear at around 6700cal. a BP; these are the only woody plants recorded. Maximum concentrations of chironomids, maximum occurrence of ephippia of the water flea Daphnia pulex, highest organic matter contents and lowest minerogenic input from c. 7700 to 4400 cal. a BP probably reflect the Holocene thermal maximum (HTM). The highest temperatures during the HTM are indicated around 7000 cal. a BP, when Salix arctica, which is considered a warmth-loving plant, had a maximum. Comparisons with Holocene records from East and North Greenland show similar immigration histories and similar trends, with the Little Ice Age as the coldest period during the Holocene, culminating about 150 years ago. Subsequent warming does not indicate environmental conditions comparable to the HTM yet at this stage. The occurrence of several warmth-demanding species particularly in the early Holocene sediments indicates redeposition and implies that temperatures in the past, most likely during an interglacial period, were significantly higher than during the HTM.
- Programområde 5: Natur og klima