Climate and glacier fluctuations at Jostedalsbreen and Folgefonna,southwestern Norway and in the western Alps from the ‘Little Ice Age’ until the present: The influence of the North Atlantic Oscillation

Abstract

Glacier length, though an indirect and delayed signal of climate conditions, can be used to determine the relationship between climate and glacier response. This study discusses glacier length change of eight outlet glaciers of Jostedalsbreen and Folgefonna (southern Norway), from the ‘Little Ice Age’ (LIA) until the present. A climate index was calculated from meteorological data from Bergen to determine the specific frontal time lags of the individual glaciers. Short and steep outlet glaciers, such as Briksdalsbreen, react rapidly to changes in climatic conditions, whereas long and gently descending glaciers, such as Nigardsbreen, need longer time to adjust to changes in temperature and/or precipitation. The time lag of Briksdalsbreen was about twice as long during the LIA as today. The correlations between North Atlantic Oscillation (NAO) and climate conditions and glacier fluctuations in Norway and the European western Alps were analysed. As the influence of the NAO on glacier fluctuations is most pronounced during winter, only the winter NAO index was considered. Fluctuations of maritime Norwegian glaciers are highly correlated with the NAO, whereas variations of more continental glaciers in the European western Alps are only partly influenced by the NAO and tend to be anti-correlated. However, the (anti-)correlation with the NAO is not constant during the record, and significantly weaker or even inversed during some periods. A comparison of the LIA glacier fluctuations in southern Norway and the European western Alps suggests that the asynchronous LIA maxima in the two regions may partly be attributed to multidecadal trends in the NAO.