Rapid Holocene glacier fluctuations in arctic Norway in concert with the strength and spatial pattern of the westerlies

Alpine glaciers are often located in remote regions of the world, areas that only rarely are covered by instrumental records or biological proxy data. Reconstructions of glaciers have therefore proven useful for understanding past climate dynamics on both shorter and longer time-scales. Because of selective preservation of moraine ridges, such records do not exclude the possibility of multiple Holocene glacier advances. This problem is true regardless whether cosmogenic isotopes or lichenometry have been used to date the moraines, or based on radiocarbon dating of mega-fossils buried in till or underneath the moraines themselves. To overcome this problem Karlén (1976) initially suggested that glacial erosion and the associated production of rock-flour deposited in downstream distal glacier-fed lakes could provide continuous records of glacial fluctuations, hence overcoming the problem of selective moraine preservation. In recent years, new collaborative research efforts have developed the methods used to reconstruct past glacier activity based on sediments deposited in distal glacier-fed lakes. Records of glacier fluctuations as preserved in lake sediments now includes the application of various methods such as measuring the amount of minerogenic versus biologic matter (typically inferred from Loss-on-ignition (LOI)), grain size analysis (GSA), magnetic properties (MP), geochemical elements (GE), Rare-Earth Elements (REE), Bulk Sediment Density (BSD), but also other techniques such as XRF analyses. Several glaciers along the coast of Arctic Norway have been reconstructed based on multi-proxy approaches. Here we present data on Holocene glacier fluctuations from three geographical areas; the ice cap Folgefonna, the Okstindan glacier massif and from a small alpine glacier in Lyngen. In Scandinavia, the overall pattern of glacier growth and the onset of the Neoglacial previously have been attributed to the gradual weakening of summer insolation at high northern latitudes during the Holocene. Superimposed on the gradual increase in glacier-covered areas, the four largest glacier advances are bracketed between 7400-7000, 1400-1200, 900-700 and 300-150 years before AD 2000. In contrast to most reconstructed glaciers in Scandinavia, we found that the largest glacier advance at Okstindan was not associated with the "Little Ice Age", but rather to an earlier period centered about AD 700. Periods with glacier advances are all associated with periods of increased winter precipitation along the coast of Norway and hence a stronger effect of the westerlies, where differences in the distribution of precipitation are assumed to reflect changes in the position of the westerlies.