The late Neoglacial ('Little Ice Age') glacier maximum in southern Norway : new 14C-dating evidence and climatic implications

Abstract

Critical evidence is presented for the timing and extent of Holocene glacier variations in southern Norway based on end-moraine stratigraphy and 22 new14C dates. Dates have been obtained from moss layers, other plant remains, peat and soil associated with outermost moraines delimiting the Neoglacial maximum extent of four glaciers in the Jotunheimen-Jostedalsbreen region. There is conclusive evidence for a late Neoglacial ('Little Ice Age') maximum within the last 400-600 years; maximum age estimates for outer moraines are AD 1516 (Sagabreen), 1450 (Storbreen), 1440 (Bøverbreen) and about 1424 (Haugabreen). The last three glaciers have not exceeded their 'Little Ice Age' limits since at least 3205 ± 60, 5670 ± 80 and 6470 ± 80 BP, respectively. Onset of peat growth at these times is consistent with a deteriorating climate after the 'Climatic Optimum' of the early Holocene. Subsequent deterioration is indicated by the accumulation at Bøverbreen of poorly-humified peat from 4295 ± 49 to at least 3250 ± 70 BP, and from 1740 ± 60 to at least 1300 ± 60 BP. Southern Norwegian glaciers appear to have been larger at their 'Little Ice Age' maxima than at any time since regional deglaciation about 9000 BP. It is inferred that the relatively large scale of the 'Little Ice Age' glacier expansion in southern Norway was related to the most southerly migration of oceanic and atmospheric polar fronts since the early Holocene.