ABSTRACT
Very small glaciers (area <0.1 km2) have received increased scientific attention during recent years, both for their rapid responses to the climate forcing and because they are characterized ...by microclimatic conditions, often marginal to glacier formation. They are particularly sensitive to climate changes and characterized by a great mass turnover, particularly evident in maritime areas with high precipitation. Here we consider the evolution from 1920 of the ‘Canin Eastern Glacier’ (Italian Southeastern Alps) in order to correlate its evolution to the precipitation–temperature trends. We reconstructed a precipitation–temperature record at the altitude of the glacier, filling a lack of knowledge in this alpine sector. We observed a decrease in the mean annual precipitation of 10% in 90 years and a warming trend of 0.1°C decade−1 since 1851, and of 0.7°C decade−1 in the last 20 years. An inverse correlation between precipitation and mean air temperature during summer and ablation periods was also observed. Glacier dynamics revealed a phase of stability between 1945 and 1985 that seems to be a peculiar characteristic of this area. Moreover, through a general regression model the glacial terminus variations seem to be statistically influenced only by winter precipitation. This fact opens interesting perspectives for the possible future evolution of this small glacier and, more in general, to other small glaciers in maritime areas in regard to climate change scenarios.
Pyrenean glaciers are the largest in southern Europe. Their survival is threatened by climate change, highlighting the significance of their study. This research presents an assessment of changes in ...the glacierized area and thickness of Pyrenean glaciers from 2011 to 2020, using high‐resolution optical satellite, airborne lidar and UAV images. The total glacierized area has shrunk by 23.2% and thickness has decreased on average by 6.3 m. These two variables show no correlation for individual glaciers. Although climatic conditions do not vary much among glaciers, their evolution was heterogeneous during the study period. The smaller glaciers (<10 ha) show a higher variability in their area decrease and thickness loss whereas the four largest glaciers (>10 ha) have a more homogeneous response. This can be attributed to the generally larger influence of local topography on the response of the smaller Pyrenean glaciers. There is no sign of slowdown in glacier shrinkage respect to previous decades.
Plain Language Summary
Pyrenean glaciers are the largest in southern Europe. Their survival is threatened by climate change, highlighting the significance and relevance of their study. This study presents an assessment of changes in the glacierized area and thickness of Pyrenean glaciers during 2011–2020 based on UAV, optical satellite imagery and lidar observations. In this period, their total area shrank by 23.2% and thickness decreased by 6.3 m on average. Although climatic conditions do not vary much among glaciers, their evolution was heterogeneous during the observed period. The smaller Pyrenean glaciers (area <10 ha) are highly controlled by local topography, whereas the largest glaciers are predominantly influenced by regional climate forcing. There is no sign of slowdown in shrinkage of Pyrenean glaciers respect to previous decades. This indicates the continuous decline of Pyrenean glaciers toward an ice‐free mountain range in the coming decades.
Key Points
The glacierized area shrank by 23.2% and thickness decreased on average by 6.3 m during the 2011–2020 period
There is no sign of slowdown in glacier shrinkage respect to previous decades
The smaller Pyrenean glaciers are influenced by local topography as they show highly contrasted evolution under the same climatic conditions
Very small glaciers (<0.5 km2) account for more than 80% of the total number of glaciers in mid- to low-latitude mountain ranges. Although their total area and volume is small compared to larger ...glaciers, they are a relevant component of the cryosphere, contributing to landscape formation, local hydrology and sea-level rise. Worldwide glacier monitoring mostly focuses on medium-sized to large glaciers leaving us with a limited understanding of the response of dwarf glaciers to climate change. In this study, we present a comprehensive modeling framework to assess past and future changes of very small glaciers at the mountain-range scale. Among other processes our model accounts for snow redistribution, changes in glacier geometry and the time-varying effect of supraglacial debris. It computes the mass balance distribution, the englacial temperature regime and proglacial runoff. The evolution of 1,133 individual glaciers in the Swiss Alps is modeled in detail until 2060 based on new distributed data sets. Our results indicate that 52% of all very small glaciers in Switzerland will completely disappear within the next 25 years. However, a few avalanche-fed glaciers at low elevation might be able to survive even substantial atmospheric warming. We find highly variable sensitivities of very small glaciers to air temperature change, with gently-sloping, low-elevation, and debris-covered glaciers being most sensitive.
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•100 years of mass balance and climatic analysis for the lowermost Italian glacier.•Lower degree of imbalance compared to other European glaciers.•Glacier behavior progressively ...decoupled from atmospheric warming due to debris cover.
Small, debris-covered and avalanche-fed glaciers are widespread in high-relief areas of the world. However, their climatic response is poorly known because they cannot be investigated with ‘traditional’ techniques, like the glaciological mass-balance method, and long-term observations series are very rare. This work documents changes in elevation, mass balance rate and surface cover in the last century (from 1920 to 2020) for the small, debris-covered and avalanche-fed Montasio Glacier, where recent investigations show unusual response to climatic changes, but it is unclear whether this response is a short- or a long-term characteristic. Glacier response is analysed primarily through Digital Elevation Models reconstructed from different types of data sources (maps, terrestrial and aerial images, point clouds). Glacier changes are analysed jointly with trends in the most relevant climatic variables. The glacier experienced phases of rapid mass loss between 1920 and 1948 (−0.49 m w.e. y-1) and between 1982 and 2006 (−0.36 m w.e. y-1). Smaller imbalance occurred between 1948 and 1982 (−0.14 m w.e. y-1) and, remarkably, between 2006 and 2020 (−0.03 m w.e. y-1). Whereas the 1948–1982 was a favourable time-window for most glaciers in the Alps, the last fifteen years were characterized by rapid warming and show a clear divergence between the behaviour of the Montasio Glacier and of the rest of Alpine glaciers. A century-long increase in debris cover, now 2–3 m thick in the lower half of the glacier, explains largely this divergence. Snow-rich winters in recent years also played a role, because the glacier reacts sensitively to changes in solid precipitation. Even in the case of possible decreased snowfalls and increased melt associated with warming temperatures during the next decades, the glacier is not expected to vanish soon, because it will likely survive under a thick layer of debris and shadowed by the north walls of the Mount Jôf di Montasio. On the other hand, the results of this study, paired with the current distribution of permafrost in the study area, suggest that the Montasio Glacier will unlikely evolve into a rock glacier or a glacial-permafrost composite landform.
The response of very small glaciers to climate changes is highly scattered and little known in comparison with larger ice bodies. In particular, small avalanche-fed and debris-covered glaciers lack ...mass balance series of sufficient length. In this paper we present 13 years of high-resolution observations over the Occidentale del Montasio Glacier, collected using Airborne Laser Scanning, Terrestrial Laser Scanning, and Structure from Motion Multi-View Stereo techniques for monitoring its geodetic mass balance and surface dynamics. The results have been analyzed jointly with meteorological variables, and compared to a sample of “reference” glaciers for the European Alps. From 2006 to 2019 the mass balance showed high interannual variability and an average rate much closer to zero than the average of the Alpine reference glaciers (−0.09 vs. −1.42 m water equivalent per year, respectively). This behavior can be explained by the high correlation between annual balance and solid precipitation, which displayed recent peaks. The air temperature is not significantly correlated with the mass balance, which is main controlled by avalanche activity, shadowing and debris cover. However, its rapid increase is progressively reducing the fraction of solid precipitation, and increasing the length of the ablation season.
Very small glaciers (
<
0.5
km
2
)
account for more than 70% of the total number of glaciers in the Qilian Mountains. Despite their total area and volume being small, they are important water ...resources in the Hexi Corridor. While glacier monitoring mostly focuses on medium-sized and large valley glaciers (e.g., Qiyi Glacier and Laohugou Glacier No. 12) in the Qilian Mountains, little is known about very small glacier mass balance in this region. This study presents a geodetic mass balance of six very small glaciers in the Hulugou Basin by comparing Shuttle Radar Topography Mission (SRTM) C-band (2000) and airborne laser scanning (2012) digital elevation models (DEMs). The total glaciers’ area decreased by 23.6% at a rate of
0.024
km
2
a
-
1
and the geodetic mass balance was
-
0.68
±
0.11
m
water equivalent (m w.e.)
a
-
1
from 2000 to 2012. Shiyi Glacier, as the monitored glacier in the Basin, had lost 10.9% of the surface area at a rate of
0.005
km
2
a
-
1
and the geodetic mass balance was
-
0.53
±
0.11
m
w.e.
a
-
1
for the period. Climatic variations over the last decade showed a pronounced increase in summer temperatures. The warmer conditions probably explain the glaciers mass loss observed in the Hulugou Basin.
Los glaciares fueron comunes en las montañas mediterráneas durante la Pequeña Edad del Hielo. En partes de Turquía, algunos glaciares fueron varios kilómetros más largos de lo que son ahora, mientras ...en los Pirineos fueron varios cientos de metros más largos. En las montañas mediterráneas más húmedas, como los Alpes Dináricos, se desarrollaron muchos pequeños glaciares y neveros. Incluso en las montañas meridionales más secas, como el Alto Atlas, pequeños glaciares y campos de nieve permanentes estuvieron presentes. Este trabajo examina la evidencia a partir de dos regiones contrastadas (los Balcanes occidentales y meridionales y el Alto Atlas) y la significación climática de los glaciares en estas regiones durante la Pequeña Edad del Hielo. Se pone especial énfasis en los controles climatológicos del balance de masa glaciar bajo distintas condiciones climáticas. Los glaciares en climas fríos y secos muestran diferente sensibilidad al cambio climático regional en comparación con los glaciares en climas fríos y húmedos. Además, los factores que controlan la ablación de los glaciares en diferentes regímenes climáticos pueden variar considerablemente, especialmente por lo que respecta a las contribuciones relativas de la fusión y la sublimación. Todos los glaciares de las montañas mediterráneas estuvieron fuertemente controlados por factores topoclimáticos locales. Los glaciares alimentados por avalanchas han sido los más resilientes al cambio climático, de manera que el incremento que representa la acumulación de nieve por avalanchas explica la supervivencia de glaciares en los Alpes Dináricos y los semi-permanentes campos de nieve del Alto Atlas. Además, la geología y la morfología heredada desde las glaciaciones del Pleistoceno desempeñan un papel importante para explicar los patrones de distribución de los glaciares de la Pequeña Edad del Hielo y en especial los patrones de retroceso y supervivencia de esos glaciares. La resiliencia de algunos de los últimos glaciares mediterráneos, de cara al cambio climático, presenta contradicciones, y la comparación entre los glaciares que han desaparecido y los que permanecen arroja luz sobre el futuro de glaciares similares.
We propose an integrated methodology to image the internal structure, evaluate the volume and estimate the densities of different units within ice bodies, useful for more precise mass estimation of ...very small glaciers. The procedure encompasses light detection and ranging (LiDAR) and ground penetrating radar (GPR) common offset data. The case study is the Canin Eastern Glacieret (CEG), a very small and maritime glacier in the Eastern Alps, and one of the lowermost glaciers of the European Alps. We calculate both volumetric and mass variations of the analysed ice body by integrating GPR measurements with LiDAR surveys acquired in different years (2006 and 2011). Between 2006 and 2011, the area of the glacieret increased from 8,510 to 17,530 m
2
with a gain of 9,016 m
2
. The observed volume increase has been estimated in 96,350 m
3
(+97 %), which corresponds to a positive mass balance of 3.89 m w.e.. This quite unusual finding in the present global warming behaviour is mainly due to the above-average winter accumulation (c
w
) in the considered period. Moreover, the winter season 2008–2009 represented an exceptional event with a c
w
equal to 13.38 m, the highest of the available record. Thanks to density estimation, we infer the total mass of the CEG at the time of the geophysical surveys, comparing such results with the ones obtained with available empirical equations, observing an important mass gain in the 5 years considered.
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