Swiss stone pine (Pinus cembra L.) tree-ring data as a proxy for extending glacier mass-balance series in the Italian Rhaetian Alps

The ongoing climate changes and global warming affect high elevation areas more than other environments. As a consequence, the glaciers as sensitive sentinels of climate changes, promptly modify their shape and extension to manage with the new climatic conditions. Thus, glacier mass-balance reconstruction represents a powerful proxy for documenting past climate changes at high elevation environments. The longer the extension of records back in time, the most significant are the information on glaciers’ behavior, necessary to model their dynamics and to predict expected changes in the near future. However, series of annual mass-balance measurements longer than 60 years are very rare. The sensitivity of the Swiss stone pine (Pinus cembra L.) to May–September mean temperature perfectly overlaps with the ablation season of the glaciers in the European Alps. The latewood density data (MXD) of this species was therefore used for the first time to reconstruct the summer mass balance of an Alpine glacier, back to the glaciological year 1811/12. Since the net mass-balance of a glacier is not only related to the ablation season temperature, but also to the snow accumulation that occurs during the winter, we used a synthetic gridded precipitation series interpolated at the study site as an independent proxy to infer the winter mass balance. The reconstructed MXD/precipitation-based net mass balance agrees well with field data of both Careser Glacier and other Alpine glaciers, elongating the existing series of about 150 years. Mass-balance reconstruction underlines periods of lowered and enhanced ablation during the last two centuries, which match also with geomorphological evidences and documentary knowledge. Our results highlight the possibility to use Swiss stone pine MXD data for dendroglaciological purposes, because it represents a power full tool to extend deeply in the past the data on summer and annual mass balance of the Alpine glaciers. Moreover, new promising dendrochronological findings aimed at reconstructing precipitation in the Alpine region promote the Swiss stone pine as a reliable and temporally stable proxy to perform accurate glaciological reconstructions.