A high-resolution 1200-year lacustrine record of glacier and climate fluctuations in Lofoten, northern Norway

Abstract

Here we present the first high-resolution late-Holocene glacier record from the Lofoten archipelago in northern Norway. The study is based on analyses of lacustrine sediments from the distal glacier-fed lake Kveitvikvatnet (30.1 m a.s.l.), as well as glacial-geomorphological mapping of the ~4.2-km2 surrounding catchment. The lake sediment cores have been examined for input of glacial-derived sediments by using physical, geochemical and magnetic sediment properties, including x-ray fluorescence (XRF), magnetic susceptibility (MS), grain size analyses, dry bulk density (DBD) and loss-on-ignition (LOI). Former glacier extent has been reconstructed using aerial photography and glacial-geomorphological mapping. Lichenometric dating has been used to construct a moraine chronology covering the recent fluctuations of the largest glacier (back to AD ~1740). AMS radiocarbon dating reveals that the lake sediment record covers the last 1200 years, thereby including both the ‘Little Ice Age’ (LIA) and the ‘Medieval Climate Anomaly’ (MCA). By linking continuously deposited lake sediment proxies of glacier fluctuation to known glacier frontal positions and an independent temperature reconstruction, former fluctuations in the equilibrium-line altitude (ELA) and winter precipitation have been reconstructed. Reconstructed winter precipitation estimates have also been correlated to instrumental data from the region back to AD 1895 and show a remarkable correlation, which further strengthens our approach. We found that both MCA and LIA were periods of substantial glacier variations with respect to the present, with a maximum lowering of the ELA of ~75 and ~85 m, respectively. Increased precipitation during these intervals, associated with more frequent and/or intense winter storms, is suggested to be the major driving force of glacier fluctuations in Lofoten.

An inverse approach to the course of the ‘Little Ice Age’ glacier advance and the following deglaciation at Austerdalsisen, eastern Svartisen, northern Norway

“…This is illustrated by the uncertainty intervals for calibrated radiocarbon dates in Figure 8a. Still, the fluctuations observed prior to the LIA glacier maximum correspond well to observed fluctuations of a maritime cirque glacier at Langstrandtindan in Lofoten (Figure 8d) about 200 km north of Austerdalsisen (Nielsen et al, 2016).…”

“…(c) Reconstructed front position of the Great Aletsch glacier in the Swiss Alps (Holzhauser et al, 2005). (d) Reconstructed ELA from a cirque glacier in Langstrandtindan, Lofoten, northern Norway (Nielsen et al, 2016).…”

“…The time span for the LIA glacierization at Austerdalsisen is comparable to Great Aletch Glacier in the European Alps between ca. AD 1300 and 1950 (Holzhauser, 1997; Matthews and Briffa, 2005; Figure 8) and to variations of cirque glaciers at Langstrandtindan in Lofoten (Nielsen et al, 2016). The LIA glacier maximum at Austerdalsisen about AD 1750 (1749) fits with the historical maximum at Nigardsbreen in AD 1748 (Foss, 1750), but is much older than the suggested LIA glacier maximum at Great Aletsch glacier ca.…”

Palaeoclimatic and regional implications of Older Dryas and Younger Dryas local glacier activity in the low‐Arctic valley Finnkongdalen, Andøya, northern Norway

“…The relative importance of wind‐blown snow is reduced with the increasing magnitude of small cirque/valley glaciers, as shown by Nielsen et al . (2016a) for a cirque glacier in Lofoten.…”

“…The regionally representative winter precipitation at sea level is found by correcting the contribution of snow at the ELA for the effect of leeward accumulation of windtransported snow, using a D/A ratio of 3.83. The D/A ratio is an easy way of estimating the potential for leeward accumulation of snow by wind, including snowavalanches, on cirque or small valley glaciers (Dahl et al 1997;Nielsen et al 2016a). The ratio is based on the total drainage area (D) above the ELA (the potential surface where snow can be deposited) and the reconstructed accumulation area of the glacier (A).…”