Glacier and lake-level variations in west-central Europe over the last 3500 years

On the basis of glacier and lake-level records, this paper attempts, for the first time, a comparison between high-resolution palaeohydrological and palaeoglaciological data in west-central Europe over the past 3500 years. A data set of tree-ring width, radiocarbon and archaeological data, in addition to historical sources, were used to reconstruct fluctuations of the Great Aletsch, the Gorner and the Lower Grindelwald glaciers in the Swiss Alps. The three ice-streams experienced nearly synchronous advances at c. 1000-600 BC and AD 500-600, 800-900, 1100-1200 and 1300-1860. These glacier fluctuations show strong correspondence with lake-level variations reconstructed in eastern France (Jura mountains and Pre-Alps) and on the Swiss Plateau. This supports the hypothesis of climatically driven fluctuations. Historical data available for the period since AD 1550 reveal, in detail, various meteorological conditions behind the successive glacier advances. However, in agreement with the general trend shown by the historical data, the synchroneity between glacier advances and periods of higher lake level suggests the impact of general winter cooling and an increase in summer moisture as responsible for reinforced feeding of both glaciers and lakes in west-central Europe over the past 3500 years. Finally, a comparison between the Great Aletsch glacier and the residual 14 C records supports the hypothesis that variations in solar activity were a major forcing factor of climatic oscillations in west-central Europe during the late Holocene.