Recent Increases in Winter Snowfall Provide Resilience to Very Small Glaciers in the Julian Alps, Europe

Abstract

: Very small glaciers (<0.5 km2) account for more than 80% of the total number of glaciers and more than 15% of the total glacier area in the European Alps. This study seeks to better understand the impact of extreme snowfall events on the resilience of very small glaciers and ice patches in the southeastern European Alps, an area with the highest mean annual precipitation in the entire Alpine chain. Mean annual precipitation here is up to 3300 mm water equivalent, and the winter snow accumulation is approximately 6.80 m at 1800 m asl averaged over the period 1979–2018. As a consequence, very small glaciers and ice/firn patches are still present in this area at rather low altitudes (1830–2340 m). We performed repeated geodetic mass balance measurements on 14 ice bodies during the period 2006–2018 and the results show an increase greater than 10% increase in ice volume over this period. This is in accordance with several extreme winter snow accumulations in the 2000s, promoting a positive mass balance in the following years. The long-term evolution of these very small glaciers and ice bodies matches well with changes in mean temperature of the ablation season linked to variability of Atlantic Multidecadal Oscillation. Nevertheless, the recent behaviour of such residual ice masses in this area where orographic precipitation represents an important component of weather amplification is somehow different to most of the Alps. We analysed synoptic meteorological conditions leading to the exceptional snowy winters in the 2000s, which appear to be related to the influence and modification of atmospheric planetary waves and Arctic Amplification, with further positive feedbacks due to change in local sea surface temperature and its interactions with low level flows and the orography. Although further summer warming is expected in the next decades, we conclude that modification of storm tracks and more frequent occurrence of extreme snowfall events during winter are crucial in ensuring the resilience of small glacial remnants in maritime alpine sectors.

Diverging snowfall trends across months and elevation in the northeastern Italian Alps

“…The general picture is therefore that at low elevations and mid‐latitudes there are decreasing trends in snowfall and particularly in the snowfall/precipitation ratio (Safeeq et al ., 2016), while at high elevations or in cold/polar regions the decreasing trends are less evident. On the contrary, even some increasing trends are detected during the core of the winter season, when an increase in precipitation is found (Wang and He, 2013; Bjorkman et al ., 2015; Colucci et al ., 2021). The attribution analysis in our study highlights that decreasing HN trends at low altitudes are mainly explained by positive temperature trends, while increasing HN trends at higher elevations, found especially in the core winter months, are connected to positive trends in precipitation.…”

Response of Very Small Glaciers to Climate Variations and Change: Examples from the Pirin Mountains, Bulgaria

“…This process will probably last for longer than in other regions of the Mediterranean, but forecasting is complicated due to the strong dependence of small firnice bodies on topography and accidental factors such as heavy snowfalls and avalanche events. For example, the glacierets and ice patches in the Julian Alps have been stagnating since the beginning of the 21st century despite the rising temperatures, due to an increase in winter precipitation [55,59,66]. However, for Southern Europe, most forecasts propose a gradual decrease in precipitation over the following decades [67], which will doom Pirin glacierets to a progressive decline.…”

Long-term mass-balance monitoring and evolution of ice in caves through structure from motion–multi-view stereo and ground-penetrating radar techniques

“…Kanin) massif at 2162 m a.s.l. The area close to the cave entrance hosts several small glaciers, glacierets and ice patches representing some of the lowest evidence of glaciation in the European Alps (Colucci and Zebre, 2016; Colucci et al, 2021). The presence of steep rock walls and a deep karstic gorge opening to the north favour wind drifted snow accumulation right next to the large entrance of the cave (15 x 4 m approximately).…”