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The Himalayan cryosphere comprises a large concentration of glaciers that feed numerous perennial rivers, providing food and water security to millions of people living in the downstream regions. To understand the effect of changing climate on these glaciers, an assessment of the mass loss in the glacier is crucial. In this study, the volume of 279 glaciers in the Parvati basin of the Himalaya in the year 2000 was estimated as 21.3 ± 3.8 km3 using the Laminar flow and scaling methods. The regional mass loss of the glaciers over the period 2000–2015 was calculated using the Improved Accumulation Area Ratio (IAAR) and Geodetic methods. The IAAR method's estimate was based on meteorological data, whereas the geodetic method's assessment was based on Cartosat-1 satellite data for three years (2011, 2014, 2015) and SRTM DEM for 2000. The mean elevation difference based on the aforementioned DEMs was − 4.6 ± 0.26 m, whereas the mass loss for the glaciers was 14% in the Parvati basin between 2000 and 2015. The mass balance of the glaciers in the basin is estimated as − 0.44 ± 0.23 m w.e.a−1 and − 0.30 ± 0.23 m w.e.a−1, using the IAAR and Geodetic methods, respectively. These methods provide synergetic means to analyze the basin-wide mass changes of glaciers over multiple (annual and long-term) temporal scales. The volume of ice stored in the glaciers of the Parvati basin and their mass changes are quantified at a regional scale to help understand their spatial heterogeneity over those timescales. [ABSTRACT FROM AUTHOR]

Glaciers in the Hindu Kush-Karakoram-Himalayas (HKH) are a major source of freshwater in the agriculture-dependent economy of Pakistan. In recent decades, mountain glaciers have been threatened by global warming. In this study, we estimated the Equilibrium Line Altitude (ELA) and geodetic mass balance of fifteen representative glaciers from Hunza (Karakoram), Chitral (Hindu Kush), and Astore (Himalaya) using Landsat satellite images and Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) DEMs between 2000 and 2018. The climatic trends (temperature and precipitation) in the 19 years (1995–2013) time series of the three regions were assessed using the non-parametric Mann-Kendall test and Sen's Slope. The ELA of the observed glaciers except for two Atrak (Chitral) and Gulkin (Hunza) is shifted upward, while the mass balance indicates a heterogeneous pattern ranging from −0.23 ± 0.05 to −0.01 ± 0.015 m w.e a−1, −0.13 ± 0.05 to+0.17 ± 0.11 m w.e a−1 and −0.03 ± 0.02 to+0.23 ± 0.09 m w.e a−1 in Chitral, Hunza, and Astore basin, respectively. A significant or slight increasing or decreasing trend was found in the mean annual temperature, mean total precipitation, and mean discharge of the studied basins. This study will be a good contribution to understanding snow and glacier dynamics in HKH, the factors that influence them, and their interaction with the environment. [ABSTRACT FROM AUTHOR]

ABSTRACTGlaciers in the Hindu Kush-Karakoram-Himalayas (HKH) are a major source of freshwater in the agriculture-dependent economy of Pakistan. In recent decades, mountain glaciers have been threatened by global warming. In this study, we estimated the Equilibrium Line Altitude (ELA) and geodetic mass balance of fifteen representative glaciers from Hunza (Karakoram), Chitral (Hindu Kush), and Astore (Himalaya) using Landsat satellite images and Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) DEMs between 2000 and 2018. The climatic trends (temperature and precipitation) in the 19 years (1995–2013) time series of the three regions were assessed using the non-parametric Mann-Kendall test and Sen’s Slope. The ELA of the observed glaciers except for two Atrak (Chitral) and Gulkin (Hunza) is shifted upward, while the mass balance indicates a heterogeneous pattern ranging from −0.23 ± 0.05 to −0.01 ± 0.015 m w.e a−1, −0.13 ± 0.05 to+0.17 ± 0.11 m w.e a−1 and −0.03 ± 0.02 to+0.23 ± 0.09 m w.e a−1 in Chitral, Hunza, and Astore basin, respectively. A significant or slight increasing or decreasing trend was found in the mean annual temperature, mean total precipitation, and mean discharge of the studied basins. This study will be a good contribution to understanding snow and glacier dynamics in HKH, the factors that influence them, and their interaction with the environment.

Glacier mass balance can be regarded as a major direct index of climate variations. In this paper, a geodetic method was used to evaluate the mass balance of Sawir glaciers based on topographic map DEM (Digital Elevation Model), SRTM 30 m DEM, ASTER 30 m DEM, and Sentinel-1 Synthetic Aperture Radar 10 m DEM between 1959–2021, in order to explore the response to climatic alterations. In the case of Muz Taw glacier, the first comprehensive dataset concerning mass-balance readings for the 2014–2021 period was provided based on the eight-year consecutive field measurements. The glaciological average mass balance reached –883.4 ± 130 mm a–1 during this period. The geodetic mass balance for all glaciers of the Sawir Mountain range was −0.43 ± 0.12 m w. e. a−1 between 1959 and 2000, and accelerated to −0.56 ± 0.13 m w. e. a−1 between 2000 and 2021. A comparison of field measurements and remote-sensing approaches for determining the Muz Taw glacier's mass balance between 2014–2021 proves the feasibility of the remote-sensing approach, which involves mass-balance monitoring based on DEMdata. In addition, our findings support the contention that air temperature is the dominant factor for accelerated glacier mass loss and surface elevation change. [ABSTRACT FROM AUTHOR]

The Himalayan glaciers significantly contribute to the largest river systems like the Indus, Ganga, and the Brahmaputra. The change in glacial area and mass can affect the mountain community and people living in the Indo-Gangetic plain. The present study adopted the geodetic method to estimate the elevation change and mass budget of 61 glaciers in the Alaknanda Basin, using the satellite data of Cartosat-1 (2011, 2014, 2017) and SRTM (2000). Besides, the DEM of 1962 (SOI Toposheet) and 2000 (SRTM) is used to estimate the mass budget of Satopanth (SPG) and Bhagirath Kharak glaciers (BKG). The field debris thickness of SPG (2015-2017) is compared with the elevation change (2000-2017). Further, we have compared the mass loss of the glaciers with their volume. The results suggest the sustained mass loss of 1.85 ± 0.10 Gt out of 33.9 ± 8.8 Gt for 61 glaciers in the basin from 2000-2017. The mass loss of SPG and BKG during 2000-2017 is 0.20 ± 0.02 Gt and 0.24 ± 0.03 Gt, whereas from 1962 to 2000, is 0.083 ± 0.03 Gt and 0.091 ± 0.04 Gt, respectively. The analysis facilitates a better understanding of glacier mass changes in the Alaknanda basin on a multi-decadal scale. [ABSTRACT FROM AUTHOR]

Meltwater from the cryosphere contributes a significant fraction of the freshwater resources in the countries receiving water from the Third Pole. Within the ESA-MOST Dragon 4 project, we addressed in particular changes of glaciers and proglacial lakes and their interaction. In addition, we investigated rock glaciers in permafrost environments. Here, we focus on the detailed investigations which have been performed in the Poiqu River Basin, central Himalaya. We used in particular multi-temporal stereo satellite imagery, including high-resolution 1960/70s Corona and Hexagon spy images and contemporary Pleiades data. Sentinel-2 data was applied to assess the glacier flow. The results reveal that glacier mass loss continuously increased with a mass budget of −0.42 ± 0.11 m w.e.a−1 for the period 2004–2018. The mass loss has been primarily driven by an increase in summer temperature and is further accelerated by proglacial lakes, which have become abundant. The glacial lake area more than doubled between 1964 and 2017. The termini of glaciers that flow into lakes moved on average twice as fast as glaciers terminating on land, indicating that dynamical thinning plays an important role. Rock glaciers are abundant, covering approximately 21 km2, which was more than 10% of the glacier area (approximately 190 km2) in 2015. With ongoing glacier wastage, rock glaciers can become an increasingly important water resource. [ABSTRACT FROM AUTHOR]

Glacier mass balance is a key idea in understanding the relationship between glaciers and climate. In this study, Landsat images, Shuttle Radar Topography Mission, and Advance Land Operation Satellite digital elevation models, and ground observation records for 2000–2010 and 2019–2020 were used to analyze a mass balance of the Baishui River Glacier No. 1 (BRG1) in Yulong Snow Mountain, southeastern Qinghai–Tibet Plateau. Both glaciological and geodetic methods were used to understand the spatial pattern of the mass balance. A mass balance contour line map of the glacier was created for the first time. From 2000 to 2010, the mean annual mass balance of the BRG1 was calculated to be -0.99 m w.e., -1.01 m w.e., and −1.18 m w.e. using the contour line, profile curve, and geodetic methods, respectively. In addition, the analysis revealed that strong melting of the glacier occurred from July 27 to 15 September 2019, with an averaged glacier mass balance of -1.75 m w.e. and a mean daily melting rate of 35 mm w.e. The annual mass balance was assessed to be −1.31 m w.e. during 2019/20 using the contour line method. In addition, the spatial patterns on the mass balance contour maps for 2000–2010 and the summer of 2019, and the climate change in this region were analyzed. The results indicate that the increased air temperature was the main cause of the accelerated glacial melting.

Extensive efforts for quantifying regional glacier mass balance in the Qilian Mountains have been made using the geodetic method, but these estimations were rarely extended back to the period before 2000. This study presents glacier mass budgets in the Turgen Daban Range, over the western Qilian Mountain, from 1966/75 to 2020 by means of the digital elevation models generated by the topographic maps and ASTER images. The results show that the glacier mass decreased by −18.79 ± 12.48 m w.e. during the past 50 years. The average mass loss rate is estimated to be −0.19 ± 0.08 m w.e.a−1 for the 1966/75-2006 period and −0.45 ± 0.17 m w.e.a−1 during 2006–2020, respectively, suggesting a remarkable acceleration of glacier mass loss. This may be attributable to the significant increase in air temperature and the insignificant precipitation increase which cannot offset glacier melting caused by increased temperature. Due to the melting and shrinking of glaciers, the area of glacial lakes increases by 2.83 km2 from 1987 to 2020.

Glacier mass balance can be regarded as a major direct index of climate variations. In this paper, a geodetic method was used to evaluate the mass balance of Sawir glaciers based on topographic map DEM (Digital Elevation Model), SRTM 30 m DEM, ASTER 30 m DEM, and Sentinel-1 Synthetic Aperture Radar 10 m DEM between 1959–2021, in order to explore the response to climatic alterations. In the case of Muz Taw glacier, the first comprehensive dataset concerning mass-balance readings for the 2014–2021 period was provided based on the eight-year consecutive field measurements. The glaciological average mass balance reached –883.4 ± 130 mm a–1 during this period. The geodetic mass balance for all glaciers of the Sawir Mountain range was −0.43 ± 0.12 m w. e. a−1 between 1959 and 2000, and accelerated to −0.56 ± 0.13 m w. e. a−1 between 2000 and 2021. A comparison of field measurements and remote-sensing approaches for determining the Muz Taw glacier’s mass balance between 2014–2021 proves the feasibility of the remote-sensing approach, which involves mass-balance monitoring based on DEMdata. In addition, our findings support the contention that air temperature is the dominant factor for accelerated glacier mass loss and surface elevation change.

Meltwater from the cryosphere contributes a significant fraction of the freshwater resources in the countries receiving water from the Third Pole. Within the ESA-MOST Dragon 4 project, we addressed in particular changes of glaciers and proglacial lakes and their interaction. In addition, we investigated rock glaciers in permafrost environments. Here, we focus on the detailed investigations which have been performed in the Poiqu River Basin, central Himalaya. We used in particular multi-temporal stereo satellite imagery, including high-resolution 1960/70s Corona and Hexagon spy images and contemporary Pleiades data. Sentinel-2 data was applied to assess the glacier flow. The results reveal that glacier mass loss continuously increased with a mass budget of −0.42 ± 0.11 m w.e.a−1 for the period 2004–2018. The mass loss has been primarily driven by an increase in summer temperature and is further accelerated by proglacial lakes, which have become abundant. The glacial lake area more than doubled between 1964 and 2017. The termini of glaciers that flow into lakes moved on average twice as fast as glaciers terminating on land, indicating that dynamical thinning plays an important role. Rock glaciers are abundant, covering approximately 21 km2, which was more than 10% of the glacier area (approximately 190 km2) in 2015. With ongoing glacier wastage, rock glaciers can become an increasingly important water resource.

Glacial melt water is the key source for various socio-industrial and domestic activities in the Himalayas. Several recent studies suggest that glaciers are experiencing rapid melt. The glaciers health can be best assessed by mass balance. However, the mass balance investigations using in-situ methods for a large sample of glaciers are highly difficult in the Himalaya. Hence, remote sensing methods and modelling techniques are preferred. However, there is a lack of information on uncertainties associated with these methods in assessing the regional scale mass balance. Hence, these methods are applied to evaluate the regional scale mass budget of Baspa basin, Western Himalaya between 2000 and 2011. The total mass loss estimated using geodetic method amounts to −0.49 ± 0.1 gigatons, temperature index method to −0.43 ± 0.012 gigatons and AAR method to −0.36 ± 0.1 gigatons. Furthermore, this study highlights the limitations of these methods in mass loss evaluation in data scarce Himalayan regions. [ABSTRACT FROM AUTHOR]

This study describes the analysis of changes in area and volume of the Mt.Elbrus glacier system, Central Caucasus from 1997 to 2017. It is based on helicopter-borne ice thickness measurements, comparison of high-resolution imagery and two digital elevation models (DEMs) with 10 m resolution. More than 250 km of ground-penetrating radar (GPR) profiles of ice thickness with reliable reflections were obtained. The total volume of Mt. Elbrus glaciers was 5.03 ± 0.85 km3 of ice in 2017. Our results show that 68% of the total ice volume is concentrated below 4,000 m a.s.l. where the average ice thickness was 44.6 ± 7.3 m, 18% of the volume lies within 4,000–4,500 m a.s.l. (thickness of 41.2 ± 7.3 m), and just 14% lies above 4,500 m a.s.l. (thickness of 29.7 ± 6.7 m). The glacier-covered area of Mt. Elbrus decreased from 125.76 ± 0.65 km2 in 1997 to 112.20 ± 0.58 km2 in 2017, a reduction of 10.8%. Over the same period the volume decreased by 22.8%. The mass balance of the Elbrus glaciers decreased by −0.55 ± 0.04 m w.e. a−1 from 1997 to 2017. Mass balance on west-oriented glaciers is less negative than on east-and south-oriented glaciers where mass balance is most negative. The mass balance of the east-oriented Djikiugankez glacier decreased at the fastest average rate (−0.97 ± 0.07 m w.e. a−1). This glacier contains 28% of the total Elbrus glacier system ice volume, most of which is concentrated below 4,000 m a.s.l. Only one small glacier on the western slope demonstrated mass gain. Our results match well with the long term direct mass balance measurements on the Garabashi glacier on Elbrus which lost 12.58 m w.e. and 12.92 ± 0.95 m w.e. between 1997 and 2017 estimated by glaciological and geodetic method, respectively. The rate of Elbrus glacier mass loss tripled in 1997-2017 compared with the 1957-1997 period.

Mountain glaciers are excellent indicators of climate change and have an important role in the terrestrial water cycle and food security in many parts of the world. Glaciers are the major water source of rivers and lakes in the Nyainqentanglha Mountains (NM) region, where the glacier area has the second largest extent on the Tibetan Plateau. The potential of the high spatial resolution ZiYuan-3 (ZY-3) Three-Line-Array (TLA) stereo images to retrieve glacier mass balance has not been sufficiently explored. In this study, we optimized the procedure to extract a Digital Elevation Model (DEM) from ZY-3 TLA stereo images and estimated the geodetic mass balance of representative glaciers in the two typical areas of the NM using ZY-3 DEMs and the C-band Shuttle Radar Topography Mission (SRTM) DEM in three periods, i.e., 2000−2013, 2013−2017 and 2000−2017. The results provide detailed information towards better understanding of glacier change and specifically show that: (1) with our new stereo procedure, ZY-3 TLA data can significantly increase point cloud density and decrease invalid data on the glacier surface map to generate a high resolution (5 m) glacier mass balance map; (2) the glacier mass balance in both the Western Nyainqentanglha Mountains (WNM) and Eastern Nyainqentanglha Mountains (ENM) was negative in 2000−2017, and experienced faster mass loss in recent years (2013−2017) in the WNM. Overall, the glaciers in the western and eastern NM show different change patterns since they are influenced by different climate regimes; the glacier mass balances in WNM was −0.22 ± 0.23 m w.e. a−1 and −0.43 ± 0.06 m w.e. a−1 in 2000−2013 and 2013−2017, respectively, while in 2000−2017, it was −0.30 ± 0.19 m w.e. a−1 in the WNM and −0.56 ± 0.20 m w.e. a−1 in the ENM; (3) in the WNM, the glaciers experienced mass loss in 2000−2013 and 2013−2017 in the ablation zone, while in the accumulation zone mass increased in 2000−2013 and a large mass loss occurred in 2013−2017; as regards the ENM, the glacier mass balance was negative in 2000−2017 in both zones; (4) glacier mass balance can be affected by the fractional abundance of debris and glacier slope; (5) the glacier mass balances retrieved by ZY-3 and TanDEM-X data agreed well in the ablation zone, while a large difference occurred in the accumulation zone because of the snow/firn penetration of the X-band SAR signal.

We compare two independent estimates of the rate of elevation change and geodetic mass balance of the Northern Patagonian Icefield (NPI) between 2000 (3,856 km2) and 2012 (3,740 km2) from space-borne data. The first is obtained by differencing the Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) from February 2000 and a Satellite pour l'Observation de la Terre 5 (SPOT5) DEM from March 2012. The second is deduced by fitting pixel-based linear elevation trends over 118 DEMs calculated from Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) stereo images acquired between 2000 and 2012. Both methods lead to similar and strongly negative icefield-wide mass balance rates of −1.02 ± 0.21 and −1.06 ± 0.14 m w.e. yr−1 respectively, which is in agreement with earlier studies. Contrasting glacier responses are observed, with individual glacier mass balance rates ranging from −0.15 to −2.30 m w.e. yr−1 (standard deviation = 0.49 m w.e. yr−1; N = 38). For individual glaciers, the two methods agree within error bars, except for small glaciers poorly sampled in the SPOT5 DEM due to clouds. Importantly, our study confirms the lack of penetration of the C-band SRTM radar signal into the NPI snow and firn except for a region above 2,900 m a.s.l. covering

In the context of global warming, glacier changes in the Qinghai–Tibet Plateau (QTP) and its surroundings have attracted a great amount of public attention. To date, there have been many studies of glacier mass balance across the QTP. However, given that most of the previous studies have focused on a short observation period (2000–2015), and that long-term mass change measurements are available only for some local regions, we utilized declassified KH-9 images and 1 arc-second Shuttle Radar Topography Mission (SRTM) digital elevation models (DEMs) to provide the region-wide mass balance (from the mid-1970s to 2000) for a larger scale (including 11 sample regions) across the QTP and its surroundings. The final results indicate that the glaciers in the northwest of the QTP have shown a less negative or near-zero mass balance, ranging from −0.11 ± 0.13 m w.e. a −1 to 0.02 ± 0.10 m w.e. a −1 , compared to those in the southeast part, with a mass balance range of −0.30 ± 0.12 m w.e. a −1 to −0.11 ± 0.14 m w.e. a −1 . The most serious mass loss has emerged in the central-eastern Himalaya. Integrating our results with the observations after 2000 suggests that, over the past four decades (mid-1970s to the mid-2010s), the glaciers in the Himalaya, Nyainqêntanglha, and Tanggula mountains, as a whole, have exhibited accelerated mass loss, and the most significant acceleration has occurred in the eastern Nyainqêntanglha. Moreover, the Hindu Raj glaciers have shown a stable rate of continuous mass loss, while a nearly stable or slight mass gain state in the western Kunlun region can be dated back to at least as far as the mid-1970s. [ABSTRACT FROM AUTHOR]

An earthquake with a local magnitude (ML) of 5.8 occurred on 12 September 2016 near Gyeongju, South Korea. This earthquake was the largest event on record in Korea since 1978. A relatively large (ML 5.1) foreshock preceded the main shock by about 50 min, and numerous aftershocks followed. In this study, we performed seismological and geodetic analyses to determine the possibility of the occurrence of surface deformation. Estimated surface deformation using seismological analysis was less than 1 cm, and that observed by geodetic (GNSS and InSAR) data was within the range of error. These results indicate that no surface deformation occurred due to this earthquake. This may have been due to relatively small size of the fault plane (4 km × 4 km), moderate moment magnitude (Mw 5.5) or deep focal depth (15.4 km) of the earthquake. [ABSTRACT FROM AUTHOR]

The Echaurren Norte Glacier is a reference glacier for the World Glacier Monitoring Service (WGMS) network and has the longest time series of glacier mass balance data in the Southern Hemisphere. The data has been obtained by the direct glaciological method since 1975. In this study, we calculated glacier area changes using satellite images and historical aerial photographs, as well as geodetic mass balances for different periods between 1955 and 2015 for the Echaurren Norte Glacier in the Central Andes of Chile. Over this period, this glacier lost 65% of its original area and disaggregated into two ice bodies in the late 1990s. The geodetic mass balances were calculated by differencing digital elevation models derived from several sources. The results indicated a mean cumulative glacier wide mass loss of −40.64 ± 5.19 m w.e. (−0.68 ± 0.09 m w.e. a−1). Within this overall downwasting trend, a positive mass balance of 0.54 ± 0.40 m w.e. a−1 was detected for the period 2000⁻2009. These estimates agree with the results obtained with the glaciological method during the same time span. Highly negative mass change rates were found from 2010 onwards, with −1.20 ± 0.09 m w.e. a−1 during an unprecedented drought in Central Andes of Chile. The observed area and the elevation changes indicate that the Echaurren Norte Glacier may disappear in the coming years if negative mass balance rates prevail.

Himalayan glaciers, which contribute to water security for almost 1.3 billion people in Asia, are now under threat due to climate change. Assessment of glacier mass balance changes is crucial to determine the implications of climate change, but in situ measurements are limited due to rugged terrain and harsh climate of the Himalaya. Remote sensing-based geodetic method is therefore important for studying the evolution of Himalayan glaciers at a large scale. In this study, the mass balance of glaciers located in Baspa basin (Western Himalaya) is estimated for a period of 11 years between 2000 and 2011, using geodetic method. Out of 89 glaciers in the basin, 42 glaciers (greater than 1 km2) covering an area of ~72% (215 km2) of the total glaciated area were selected for the study. A mean thinning of ~50±11 m and mean accumulation of ~35±11 m was observed during the study period, with the cumulative mass balance varying between -36.9±1.98 and 6.47±1.98 m.w.e. A mean annual mass loss of -1.09±0.32 m.w.e.a-1 was observed for the entire basin, suggesting that the glaciers in Baspa basin are losing mass at higher rate compared to the glaciers in central and eastern Himalayas. This study demonstrates the utility of geodetic method to estimate mass balance of glaciers at basin scale, which will be useful to assess future changes in glacial extent and stream run-off. [ABSTRACT FROM AUTHOR]

[Display omitted] • 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. [ABSTRACT FROM AUTHOR]

Mass loss of glaciers in the Chinese Altai was detected using geodetic methods based on topographical maps (1959), the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM) (2000), and the Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) stereo images (2008). The results indicate that a continued and accelerating shrinkage has occurred in the Chinese Altai Mountains during the last 50 years, with mass deficits of 0.43 ± 0.02 and 0.54 ± 0.13 m a water equivalent (w.e.) during the periods 1959-1999 and 1999-2008, respectively. Overall, the Chinese Altai Mountains have lost 7.06 ± 0.44 km in ice volume (equivalent to −0.43 ± 0.03 m a w.e.) from 1959-2008. The spatial heterogeneity in mass loss was potentially affected by comprehensive changes in temperature and precipitation, and had a substantial correlation with glacier size and topographic settings. Comparison shows that in the Chinese Altai Mountains glaciers have experienced a more rapid mass loss than those in the Tianshan and northwestern Tibetan Plateau (TP), and the mass balance of glaciers was slightly less negative relative to those in the Russian Altai, Himalaya, and southern TP. [ABSTRACT FROM AUTHOR]

This paper documents ongoing glacier retreat in the eastern part of the Granatspitz Mountains (Hohe Tauern Range, Austrian Alps) for the time period 2003-2009 using aerial photogrammetry. Aerial photographs of 2003, 2006, and 2009 were made available by the Hydrological Service of the Regional Government of Salzburg, the Federal Office of Metrology, Surveying and Mapping, Vienna, and the Regional Government of the Tyrol, respectively. High resolution multi-temporal digital elevation models and digital orthophotos of the area of interest were derived using digital photogrammetric methods to provide a sound basis for glaciological research. Glacier outlines of the three glacial stages were mapped interactively. Temporal change in area and surface height of the glaciers mapped clearly document glacier retreat. Glacier mass balance based on the geodetic method was calculated for Stubacher Sonnblickkees (Glacier). Mean annual specific net balance amounts to -656 mm w.e. for the time period 2003-2009, with a mass balance gradient of 324 mm w.e. (100 m)-1 and an equilibrium-line altitude of 2995 m a.s.l. Digital orthophoto maps and other thematic maps, e.g. showing surface height change, were prepared to support further data interpretation. Both the study area and its spatio-temporal change were visualized with special emphasis on the glaciers in a computer generated video film. Another film (exposure 29 August 2011) shows the lower part of Stubacher Sonnblickkees and its surroundings for reasons of comparison. [ABSTRACT FROM AUTHOR]

Nowadays volume values are used in many engineering studies, such as road projects, mining enterprises, geological works and building applications. A volume can be computed by geodetic, trapezoidal and improved methods such as Simpson-based, cubic spline, and cubic Hermite formula. These improved methods model the object surface as nonlinear profiles. As the associated technology has developed then so have the opportunities for the development of new techniques in surface modelling. Now, the generation of a three-dimensional (3D) model is generally achieved by non-contact systems based on light waves and can be completed on a computer. This is particularly useful in situations where there are risks attached to reaching the location to be modelled - the calculations can be performed from a photograph or from scanned images of the object. In this study the performance of a laser scanning method, robotic total station instrument and geodetic method of volume computation were investigated. The volume computation was carried out using these methods in an excavation area and the methods were compared in terms of accuracy, time and cost. It was concluded that all the methods can satisfactorily be used for volume computing; however, the choice of method should be made according to the location and size of area, required accuracy, budget and time frame. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Mountain glaciers are excellent indicators of climate change and have an important role in the terrestrial water cycle and food security in many parts of the world. Glaciers are the major water source of rivers and lakes in the Nyainqentanglha Mountains (NM) region, where the glacier area has the second largest extent on the Tibetan Plateau. The potential of the high spatial resolution ZiYuan-3 (ZY-3) Three-Line-Array (TLA) stereo images to retrieve glacier mass balance has not been sufficiently explored. In this study, we optimized the procedure to extract a Digital Elevation Model (DEM) from ZY-3 TLA stereo images and estimated the geodetic mass balance of representative glaciers in the two typical areas of the NM using ZY-3 DEMs and the C-band Shuttle Radar Topography Mission (SRTM) DEM in three periods, i.e., 2000–2013, 2013–2017 and 2000–2017. The results provide detailed information towards better understanding of glacier change and specifically show that: (1) with our new stereo procedure, ZY-3 TLA data can significantly increase point cloud density and decrease invalid data on the glacier surface map to generate a high resolution (5 m) glacier mass balance map; (2) the glacier mass balance in both the Western Nyainqentanglha Mountains (WNM) and Eastern Nyainqentanglha Mountains (ENM) was negative in 2000–2017, and experienced faster mass loss in recent years (2013–2017) in the WNM. Overall, the glaciers in the western and eastern NM show different change patterns since they are influenced by different climate regimes; the glacier mass balances in WNM was –0.22 ± 0.23 m w.e. a−1 and –0.43 ± 0.06 m w.e. a−1 in 2000–2013 and 2013–2017, respectively, while in 2000–2017, it was –0.30 ± 0.19 m w.e. a−1 in the WNM and –0.56 ± 0.20 m w.e. a−1 in the ENM; (3) in the WNM, the glaciers experienced mass loss in 2000–2013 and 2013–2017 in the ablation zone, while in the accumulation zone mass increased in 2000–2013 and a large mass loss occurred in 2013–2017; as regards the ENM, the glacier mass balance was negative in 2000–2017 in both zones; (4) glacier mass balance can be affected by the fractional abundance of debris and glacier slope; (5) the glacier mass balances retrieved by ZY-3 and TanDEM-X data agreed well in the ablation zone, while a large difference occurred in the accumulation zone because of the snow/firn penetration of the X-band SAR signal. [ABSTRACT FROM AUTHOR]

• Calculated the glacier mass change using multi-temporal DEMs and degree-day model. • The mean rate of change in glacier surface elevation was −0.43 ± 0.18 m/a from 1972 to 2016. • Glacier coverage in the JTLB accounted for only 1.4% of its surface area, but 4.6% of its river runoff. Glacial meltwater-fed streamflow from the Qilian Mountains provides a much-needed source of water for the northeastern margins of the Tibetan Plateau (TP) and surrounding regions. We analyzed changes in glaciers located in the Lenglongling Mountains (LLM) in the eastern Qilian Mountains in terms of glacier area and surface elevation. These analyses were accomplished using multi-temporal satellite images and studying digital elevation models (DEMs) based on topographic maps and ZY-3 data. The results showed that from 1972 to 2016, glacier coverage decreased by 41.1 km2, leaving only 62.1 km2 extant in 2016. The mean rate of change in glacier surface elevation asl was −18.7 ± 1.2 m (−0.43 ± 0.03 m a−1) over the same period. In situ measured data from Ningchan No.1 Glacier (NC01), combined with meteorological records, were also employed to develop a spatially distributed degree-day model for the LLM glaciers. These two approaches yielded similar results, allowing the reconstruction of a consistent time series that detailed annual changes in glacier mass over the past 44 years. In addition, we calculated that the mean annual glacial meltwater-fed streamflow from 1972 to 2013 in the Jiutiaoling Basin (JTLB) northeast of the LLM was equivalent to 1.4 × 107 m3, or 4.6% of the area's total annual streamflow. It is remarkable that, in years when streamflow was relatively lower, such as 1972, 1991 and 2013, glacial meltwater accounted for a higher proportion (more than 8%) of the streamflow. [ABSTRACT FROM AUTHOR]

Long-term time series of annual glacier mass balance is important for revealing a glacier's response to regional climate variations. However, for the Tibetan Plateau, time series of annual glacier mass balance with more than 10 consecutive years remains scarce due to the inaccessibility and harsh climate conditions. In this study, we established an albedo-based model to reconstruct annual glacier mass balance for 2000–20 over the Dongkemadi Glacier, based on multitemporal geodetic estimates and annual minimum glacier-wide mean surface albedos. Geodetic glacier mass-balance estimates for 2000–12, 2012–14 and 2014–18 were obtained by comparing glacier surface topographic data. Minimum surface albedos were obtained from the moderate-resolution imaging spectroradiometer daily snow albedo products for 2000–20. The estimated results are supported by the field measurements of annual glacier mass balance. During the early 2000s, we detected a relatively balanced state of glacier mass change, whereas a pronounced mass loss of more than −0.5 m w.e. was found for most years in the 2010s. By analyzing the regional climate variations with the ERA5-Land monthly averaged data, we found that the accelerated glacier mass loss can be attributed to both decreased annual snowfall and increased summer air temperature.