Palaeohydrological changes and human-impact history over the last millennium recorded at Lake Joux in the Jura Mountains, Switzerland

Abstract

On the basis of sediment and pollen analyses of a radiocarbon-dated sediment sequence from Lake Joux in the Swiss Jura Mountains (west-central Europe), this paper presents a high-resolution record of lake-level and vegetation changes for the last millennium. The lake-level record makes it possible to determine that low-stands of the water-table dominated at c. AD 1200—1400, and from 1720 onward, with interruptions by short-lived rise events at c. AD 1340 and 1840. Highstands prevailed at c. AD 1100, and around AD 1450, 1550 and 1700. The comparison of the Joux lake-level record with a solar irradiance record based on cosmogenic nucleides supports the hypothesis of a major solar forcing of climate variations in west-central Europe over the last millennium. In agreement with other palaeohydrological records established in Western Europe and in the central North Atlantic Ocean, the Joux lake-level record suggests that, on a multicentennial scale, the period of the `Little Ice Age' coincided in the European mid-latitudes with wetter climatic conditions, and probably with an increase in summer precipitation. Variations in the hydrological cycle appear to have been associated with changes in the general atmospheric circulation pattern, probably coupled with variations in oceanic circulation and solar activity. The Joux record also points to changes in water resources expected to result from ongoing global warming. Finally, despite the severe climatic conditions which prevail in the Joux Valley, the human impact history at Lake Joux over the last millennium seems to reflect political choices and economic context more than climatic changes.

A multi-proxy perspective on millennium-long climate variability in the Southern Pyrenees

“…Nieto- . A similar hydrological response was detected in other areas of the W Mediterranean, like the French Jura (Magny et al, 2008) or Morocco (Détriché et al, 2009). However, Capdella tree ring sequence display a more complex variability, characterized by relative rainfall minima centred at ca.…”

“…This environmental response disagrees with proposed patterns for the Western Mediterranean (Fletcher and Zielhofer, in press), but it is consistent with results obtained in Central European lakes (e.g. Magny et al, 2008Magny et al, , 2011a, likely indicating a high influence of local conditions and other as yet undetermined climate mechanisms.…”

“…Nieto- Moreno et al, 2011), (iii) increased Westerlies in the W Mediterranean , (iv) increased storm activity in the nearby French Mediterranean Coast (Dezileau et al, 2011) and (v) more frequent floods in the Tagus headwaters Benito et al, 2003). Accordingly, increased water availability has been reconstructed in other areas of the W Mediterranean, such as Morocco (Détriché et al, 2009;Esper et al, 2007) and in the Alps (Magny et al, 2008(Magny et al, , 2010.…”

Evidence of NAO control on subsurface ice accumulation in a 1200 yr old cave-ice sequence, St. Livres ice cave, Switzerland

“…According to these data, the period between 1520 and 1545 was marked by a positive winter NAO index (Cook et al, 2002) in general and warm and dry winter climate anomalies in Switzerland in particular (Pfister, 1999), which could have let to abundant cave-ice ablation over almost three decades and produce the "AD 1415-1531" accumulation gap underlined by the organic deposits of layer S17. Considering the area is likely to have experienced more abundant summer precipitation during the same period (e.g., Casty et al, 2005;Magny et al, 2008), we argue that this organic rich detrital layer in St. Livres ice cave may clearly reflect a climatic signal.…”

A 2500-year multi-proxy reconstruction of climate change and human activities in northern Spain: The Lake Arreo record

“…Decreasing lake salinity and forest recovery after AD 1300 ( , the Alps (Magny et al, 2008) and southern Spain (Martín -Puertas et al, 2009), and with the higher flood frequency that occurred in Spain between AD 1430-1685 (Thorndycraft and Benito, 2006). The Lake Arreo record also supports a complex paleohydrological structure for the LIA as evidenced in other areas in the IP and the Alps (Magny et al, 2008).…”