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Abstract The Barents Sea Ice Sheet was a marine-based ice sheet, i.e., it rested on the Barents Sea floor during the Last Glacial Maximum (21 ky BP). The Bjørnøyrenna Ice Stream was the largest ice stream draining the Barents Sea Ice Sheet and is regarded as an analogue for contemporary ice streams in West Antarctica. Here, the retreat of the Bjørnøyrenna Ice Stream is simulated by means of two numerical ice sheet models and results assessed against geological data. We investigate the sensitivity of the ice stream to changes in ocean temperature and the impact of grounding-line physics on ice stream retreat. Our results suggest that the role played by sub-shelf melting depends on how the grounding-line physics is represented in the models. When an analytic constraint on the ice flux across the grounding line is applied, the retreat of Bjørnøyrenna Ice Stream is primarily driven by internal ice dynamics rather than by oceanic forcing. This suggests that implementations of grounding-line physics need to be carefully assessed when evaluating and predicting the response of contemporary marine-based ice sheets and individual ice streams to ongoing and future ocean warming.

Abstract We document the occurrence in December 2015 of unprecedented high monthly mean temperatures in the observational record of mountain sites in the eastern Alps. For the first time in the last 150 years mean December temperature exceeded 0 °C at elevations between 2100 and 2500 m, with December mean anomalies exceeding 6.5 °C with respect to the 1971–2000 mean. Along with the absence of snow cover, such temperatures might have lead to unprecedented winter ablation of glaciers in this elevation range. Smaller temperature anomalies occurred in surrounding low elevation sites, highlighting the key role of topography in this event. Specifically, strong inversions associated with the very stable synoptic conditions during the month amplified the anomalies at the high elevations of the mountain glacier sites. We analyze the processes underlying this exceptional event and place this anomaly within the context of future warming scenarios over the region.

Very small glaciers (2) 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.

Three very small Alpine glaciers in the Julian Alps are presented: the Eastern and the Western Canin glaciers in Italy and the Triglav glacier in Slovenia. The history of measurements using a measuring tape and via geodetic means on Canin glaciers is presented in brief; the majority of the paper deals with the acquisition of glacier boundaries from archive non-metrical images. The acquisition is based on interactive orientation method (mono-plotting) using lidar DTM. Seven archive non-metrical images of Mount Canin from 1893 to the mid-1970s and two aero-photogrametric images from periodic aerial photogrammetric surveys of Slovenia from 2000 and 2011 were used to determine the glaciers’ areas. In addition, a map of Canin glaciers from 1908 was geo-referenced. Five archive non-metrical images of Triglav glacier from 1897 to 1962 were used to determine the glacier area. Problems with obstructed areas are presented, and possible solutions are also given for deriving areas behind the obstructions. The usefulness of archival imagery for long-time monitoring of glaciers is presented, and the importance of old mountaineering publications as a source of such images is emphasized.

The behaviour of mountain glaciers on decadal time scales is a useful indicator for assessing climate change. Although less monitored and studied than the ice sheet, local glaciers and ice caps along the coast of Greenland are substantial contributors to meltwater runoff and sea level rise. This study analyses the cumulative area, ice mass and Equilibrium Line Altitude (ELA) change that occurred on 4100 glaciers and ice caps in West Greenland from 1985 to approximately 2020, using remotely sensed data and including glaciers smaller than 1 km2 in the calculations. The glaciers involved in the study decreased in area by 1774 ± 229 km2 which corresponds to almost −15%. Their surface elevation decreased on average by 20.6 ± 3.9 m, corresponding to a rate of −0.5 ± 0.1 m w.e. a−1. The ELA shows a median regional rise of 150 m with marked local variability and higher median rise in the northern part of the study area. Strong regional gradients in ELA of individual glaciers are found, both towards the ice sheet and in areas where local orography affects precipitation. The observed high spatial variability of changes suggests that more monitoring on sub-regional level is needed.