Late Glacial and Holocene glacier fluctuations at high Northern latitude

Abstract:

Over the last decade numerous glaciers and glacier forelands connected to distal glacier-fed lakes have been mapped and sampled in Scandinavia and in the Arctic with the purpose to obtain high resolution records of past glacier fluctuations. Direct dating of moraines combined with multi proxy analyses of lake sediments is shown to be a powerful tool for robust glacier reconstructions. We have emphasised comparing different sediment parameters by means of statistical methods as well as integrating chronological uncertainties along with uncertainties of reconstructed glacier activity. Here we will present several new and un- published studies showing the potential to use distal glacier-fed lakes to resolve the puzzle of past climate. For the Late-Glacial and early Holocene we present and discuss new data along the Arctic coast of Norway that with its high precision shows that the late glacial culmination occurred around 14.1 followed by rapid retreat of land based glaciers throughout the Late Glacial except from glacier advances during the Intra Allerød Cold period and at the very end of the Younger Dryas time period. For the Neoglacial we will present new data from Lyngen in Arctic Norway towards Svalbard discussing the onset and type of variability as recorded in lake sediment along the coast. For the late Holocene we will present a new high resolution spatiotemporal reconstruction from the small plateau glacier Northern Folgefonna in western Norway covering the last 1200yrs. Reliably proxy reconstructions reflecting seasonal changes in past atmospheric circulation are sparse. However, it is shown that winter accumulation on glaciers in western Norway is highly sensitive to changes in the strength of wintertime westerly winds, which makes them valuable recorders of past atmospheric circulation. Our spatiotemporal reconstruction is based on an integrated study of terrestrial moraine sequences, sub-glacial topography, and multi-proxy records from two distal glacier-fed lakes located at the opposite sides of the glacier in an east-west transect indicating that the” Little Ice Age” was caused by a strengthening of the westerlies.