Late Holocene climate fluctuation in South Greenland and disappearance of the Norse culture

Even minor changes in climate may have profound impact on environment and mankind in the Arctic. Greenland is located in the arctic realm and is a sensitive indicator of climate changes as the island spans 14 degrees of latitude from 600N to almost 840N. Only the narrow coastal areas in Greenland are ice-free today, and during glacial times the Greenland ice sheet reached out and covered the marine shelf. Greenland has therefore only been inhabited for the last 4500 year after retreat of the ice from the coastal areas. The first Inuits came to Greenland from Canada and were hunters, who spread in several pulses along the east and west coasts of Greenland following the climactically controlled distribution of their prey.

The Inuits were living in the northern Greenland when Norse settlers about 1000 years ago established the most northerly outpost of European Christianity and civilisation in south Greenland. The Norse settlers were descendants of Norwegian and Icelandic Vikings. In 985 one of these Vikings, Eric the Read, was exiled from Iceland and therefore set out to explore new grounds and thereby found the deep and lush fjords of SW Greenland. During favourable climatic conditions at the beginning of the Medieval Warm period he established here the Norse community called the Eastern ettlement, and he was soon followed more settlers from Iceland, who established the Western Settlement further north.

The Norse settlers survived in Greenland for almost 500 years. The Icelandic Sagas report that the Western Settlement, however, was found abandoned already around 1350 presumably due to hostile Inuit attacks from the north. Collapse of the Western Settlement coincides with the onset of the climatic deterioration that followed the Medieval Warm Period and culminated with the Little Ice Age some hundred years later. The Eastern Settlement survived another hundred years, and the Icelandic Sagas describe a wedding here in 1408. After this account there is no information on the fate of the Norse community in Greenland. Many theories for the cause of their disappearance have been suggested including problems due to climate deterioration, attacks by pirates, epidemics, starvation and inbreeding. One of the great mysteries of medieval history is why the Norse culture foundered.

In order to find possible causes for their disappearance a reconstruction of late Holocene climatic changes based on terrestrial and marine investigations have been undertaken in south Greenland coastal and fjord environments.

The preliminary results suggest that influence of Atlantic subsurface water masses prevailed in the fjords with a relatively stable stratification and low hydrodynamic energy level until around 2600 14C BP. Throughout the following late Holocene the Atlantic influence decreased, while hydrodynamic energy and mixing increased in the region of the Norse settlements. The youngest series of climate fluctuations occurred during the last 1500 14C years BP and thus correlate to the cold and warm intervals of the "Dark Ages", Medieval Warm Period and the Little Ice Age. Conditions with increased storm activity and associated deep mixing of fjord waters appear to have culminated at the transition from the Medieval Warm Period to the Little Ice Age, i.e. the time when the Norse disappeared from Greenland.