HOLOCENE CLIMATE VARIABILITY IN NORTHERN FINNMARK

Palaeoenvironmental records along a west to east transect of lake sites across the northernmost peninsulas of Finnmark, north Norway, have been investigated for evidence of Holocene climate variations. All the sites investigated lie outside (north of) the Scandinavian Younger Dryas ice limit. The hypothesis we seek to test is that Holocene climatic variability seen in these records is related to variations in the strength, and northward and eastward penetration, of the Norwegian current, a distal arm of the Gulf Stream which brings warm water into the Barents Sea.

Over Gunnarsfjorden (71° 02' 18" N, 28° 10' 6.6" E; 78m above sea level), is a small lake on the east coast of Nordkinnhalvoya which was core in late winter 2000. High temporal resolution (100yr) palynological analyses of the 2.3m of organic sediments recovered from this lake show evidence of post-glacial environmental variations since at least 12,500 calibrated years BP (10,580 14C BP). A second site 2km west of Over Gunnarsfjorden, Ned Trollhetta (71° 02' 28" N, 28° 06' 56" E), lies at 167m asl; a basal AMS radiocarbon date from this lake indicates that sediment accumulation started earlier - about 15,000 calibrated years BP (12,665 14C BP); outline pollen analyses indicate significant development of early late-glacial vegetation.

Detailed analyses of the Holocene record at Over Gunnarsfjorden suggest that there have been episodes of more and less temperate climates throughout this interval. Similar environmental variations are also seen in the Holocene pollen records from two further sites which were cored in late winter 2001, Liten Èap'pesjav'ri on Mageroya to the west and Over Kobbkrokvatnet on Varanger to the east.

These field sites lie to the north of the “Risvik” and “Outer Porsanger” moraine complexes of Finnmark. Prior to this study the ages of these moraines has not been known, despite their potential for constraining the deglacial history of the Barents Sea and Fennoscandanavian Ice Sheets. The new AMS chronology proposed here supports a model of early (ca 15,000 calibrated years BP) deglaciation of the Finnmark peninsulas. This is in broad agreement with rapid deglaciation of the Barents Sea Ice Sheet suggested by recently collected marine sedimentary records.