Quantitative analysis of an accelerated glacial decline in the Gran Paradiso Group since the Little Ice Age (Western Italian Alps)

Alpine glaciers are very sensitive to climate variations that modify their shape and size in response to changes in their mass balance. Here we present new data on recent glacier changes in the Gran Paradiso Group and we provide quantitative data documenting a glacial decline since the Little Ice Age accelerated during the last three decades. Through detailed geomorphological and glacial geological field surveys and photointerpretation, we reconstructed the Little Ice Age glacial limits; glacier limits were outlined from multitemporal aerial photographs. The collected dataset was organized in a dynamic glaciological database organized in GIS environment. Based on annual glaciological surveys (conducted since the beginning of the 20th century by the Italian Glaciological Committee) we reconstructed time-distance curves since the end of the 19th centuries. The curves were validated also on the basis of multitemporal aerial photographs. The results, useful to understand the loss of water resources stored in the Italian glaciers and to create model of their future behaviour, underlined the strong imbalance of the glaciers in the study area and highlighted the rapid increase in their reduction rate during the last years. These changes are leading to impressive change in glacier shapes and dimensions and lead to an increase of the geomorphological hazard, due to the creation of new ice-free area.