Strong acceleration of glacier area loss in the Greater Caucasus over the past two decades

Abstract. An updated glacier inventory is important for understanding glacier behavior given the accelerating glacier retreat observed around the world. Here, we present data from new glacier inventory at two time periods (2000, 2020) covering the entire Greater Caucasus (Georgia, Russia, and Azerbaijan). Satellite imagery (Landsat, Sentinel, SPOT) was used to conduct a remote-sensing survey of glacier change. The 30 m resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM; 17 November 2011) was used to determine aspect, slope and elevations, for all glaciers. Glacier margins were mapped manually and reveal that in 2000 the mountain range contained 2186 glaciers with a total glacier surface area of 1381.5 ± 58.2 km2. By 2020, glacier surface area had decreased to 1060.9 ± 33.6 km2. Of the 2223 glaciers, fourteen have an area > 10 km2 resulting the 221.9 km2 or 20.9 % of total glacier area in 2020. The Bezingi Glacier with an area of 39.4 ± 0.9 km2 was the largest glacier mapped in 2020 database. Our result represents a 23.2 ± 3.8 % (320.6 ± 45.9 km2) or −1.16 % yr−1 reduction in total glacier surface area over the last twenty years in the Greater Caucasus. Glaciers between 1.0 km2 and 5.0 km2 account for 478.1 km2 or 34.6 % in total area in 2000, while it account for 354.0 km2 or 33.4 % in total area in 2020. The rates of area shrinkage and mean elevation vary between the northern and southern and between the western, central, and eastern Greater Caucasus. Area shrinkage is significantly stronger in the eastern Greater Caucasus (−1.82 % yr−1), where most glaciers are very small. The observed increased summer temperatures and decreased winter precipitation along with increased Saharan dust deposition might be responsible for the predominantly negative mass balances of two glaciers with long-term measurements. Both glacier inventories are available from the Global Land Ice Measurements from Space (GLIMS) database and can be used for future studies.

Download Full-text

The Greater Caucasus Glacier Inventory (Russia, Georgia and Azerbaijan)

The Cryosphere ◽

10.5194/tc-12-81-2018 ◽

2018 ◽

Vol 12 (1) ◽

pp. 81-94 ◽

Cited By ~ 16

Author(s):

Levan G. Tielidze ◽

Roger D. Wheate

Keyword(s):

Surface Area ◽

Large Scale ◽

Thermal Emission ◽

Landsat 8 ◽

Mountain Range ◽

Height Distribution ◽

Glacier Surface ◽

Data Set ◽

Glacier Inventory ◽

Greater Caucasus

Abstract. There have been numerous studies of glaciers in the Greater Caucasus, but none that have generated a modern glacier database across the whole mountain range. Here, we present an updated and expanded glacier inventory at three time periods (1960, 1986, 2014) covering the entire Greater Caucasus. Large-scale topographic maps and satellite imagery (Corona, Landsat 5, Landsat 8 and ASTER) were used to conduct a remote-sensing survey of glacier change, and the 30 m resolution Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM; 17 November 2011) was used to determine the aspect, slope and height distribution of glaciers. Glacier margins were mapped manually and reveal that in 1960 the mountains contained 2349 glaciers with a total glacier surface area of 1674.9 ± 70.4 km2. By 1986, glacier surface area had decreased to 1482.1 ± 64.4 km2 (2209 glaciers), and by 2014 to 1193.2 ± 54.0 km2 (2020 glaciers). This represents a 28.8 ± 4.4 % (481 ± 21.2 km2) or 0.53 % yr−1 reduction in total glacier surface area between 1960 and 2014 and an increase in the rate of area loss since 1986 (0.69 % yr−1) compared to 1960–1986 (0.44 % yr−1). Glacier mean size decreased from 0.70 km2 in 1960 to 0.66 km2 in 1986 and to 0.57 km2 in 2014. This new glacier inventory has been submitted to the Global Land Ice Measurements from Space (GLIMS) database and can be used as a basis data set for future studies.

Download Full-text

The Greater Caucasus Glacier Inventory (Russia/Georgia/Azerbaijan)

10.5194/tc-2017-48 ◽

2017 ◽

Cited By ~ 1

Author(s):

Levan G. Tielidze ◽

Roger D. Wheate

Keyword(s):

Surface Area ◽

Large Scale ◽

Morphological Type ◽

Landsat 8 ◽

Glacier Change ◽

Glacier Surface ◽

Glacier Inventory ◽

Greater Caucasus ◽

Rock Structure ◽

June July

Abstract. While there are a large number of glaciers in the Greater Caucasus, the region is not fully represented in modern glacier databases with previous incomplete inventories. Here, we present an expanded glacier inventory for this region over the 1960–1986–2014 period. Large scale topographic maps and satellite imagery (Landsat 5, Landsat 8 and ASTER) were used to conduct a remote sensing survey of glacier change in the Greater Caucasus mountains. Glacier margins were mapped manually and reveal that, in 1960, the mountains contained 2349 glaciers, with a total glacier surface area of 1674.9 ± 35.2 km2. By 1986, glacier surface area had decreased to 1482.1 ± 32.2 km2 (2209 glaciers), and by 2014, to 1193.2 ± 27.0 km2 (2020 glaciers). This represents a 28.8 ± 2.2 % (481 ± 10.6 km2) reduction in total glacier surface area between 1960 and 2014 and a marked acceleration in the rate of area loss since 1986. Analysis of possible controls suggest that the general decreases in both glacier area and number for the period 1960–2014 are directly due to general increase in temperature, especially in summer (June–July–August), although the response of individual glaciers was modulated by other factors, including glacier size, elevation, rock structure, exposition, morphological type and debris cover. This new glacier inventory can be used as a basis dataset for future studies including glacier change assessment.

Download Full-text

The new Swiss Glacier Inventory SGI2016: a detailed cartographic representation of Swiss glacier extent and supraglacial debris-cover

10.5194/egusphere-egu21-5873 ◽

2021 ◽

Author(s):

Andreas Linsbauer ◽

Matthias Huss ◽

Elias Hodel ◽

Andreas Bauder ◽

Mauro Fischer ◽

...

Keyword(s):

Surface Area ◽

Swiss Alps ◽

Aerial Images ◽

Aerial Photographs ◽

Slope Aspect ◽

Relative Area ◽

Glacier Surface ◽

Glacier Inventory ◽

Digital Elevation ◽

Debris Cover

With increasing anthropogenic greenhouse gas emissions and corresponding global warming, glaciers in Switzerland are shrinking rapidly as in many mountain ranges on Earth. Repeated glacier inventories are a key task to monitor such glacier changes and provide detailed information on the extent of glaciation, and important parameters such as area, elevation range, slope, aspect etc. for a given point or a period in time. Here we present the new Swiss Glacier Inventory (SGI2016) that has been acquired based on high-resolution aerial imagery and digital elevation models in cooperation with the Federal Office of Topography (swisstopo) and Glacier Monitoring in Switzerland (GLAMOS), bringing together topological and glaciological knowhow. We define the process, workflow and required glaciological adaptations to compile a highly accurate glacier inventory based on the digital Swiss topographic landscape model (swissTLM3D).The SGI2016 provides glacier outlines (areas), supraglacial debris cover, ice divides and location points of all glaciers in Switzerland referring to the years 2013-2018, whereas most of the glacier outlines have been mapped based on aerial images acquired between 2015-2017 (75% in number and 87% in area), with the centre year 2016. The SGI2016 maps 1400 individual glacier entities with a total glacier surface area of 961 km2 (whereof 11% / 104 km2 are debris-covered) and constitutes the so far most detailed cartographic representation of glacier extent in Switzerland. Analysing the dependencies between topographic parameters and debris-cover fraction on the basis of individual glaciers reveals that short glaciers with a moderate mean slope and glaciers with a low median elevation tend to have high debris fractions. A change assessment between the SGI1973 and SGI2016 based on individual glacier entities affirms the largest relative area changes for small glaciers and for low-elevation glaciers, whereas the largest glaciers show small relative area changes, though large absolute changes. The analysis further indicates a tendency for glaciers with a high share of supraglacial debris to show larger relative area changes.Despite of an observed strong glacier volume loss between 2010 and 2016, the total glacier surface area of the SGI2016 is somewhat larger than reported in the last Swiss glacier inventory SGI2010. Even though both inventories were created based on swisstopo aerial photographs, the additional data, tools, resources and methodologies used by the professional cartographers digitizing glacier outlines in 3D for the SGI2016, are able to explain the counter-intuitive difference between SGI2010 and SGI2016. A direct comparison of these two datasets is thus not meaningful, but an experiment where a representative glacier sample of the SGI2010 was re-assessed based on the approaches of the SGI2016 led to an upscaled total glacier surface area of 1010 km2 for the Swiss Alps around 2010. This indicates an area loss of 49 km2 between the two last Swiss glacier inventories. As swisstopo data products are and will be regularly updated, the SGI2016 is the first step towards a consistent and accurate data product of repeated glacier inventories in six-year time intervals that promises a high comparability for individual glaciers and glacier samples.

Download Full-text

Assessment of multispectral glacier mapping methods and derivation of glacier area changes, 1978–2002, in the central Southern Alps, New Zealand, from ASTER satellite data, field survey and existing inventory data

Journal of Glaciology ◽

10.3189/002214311797409749 ◽

2011 ◽

Vol 57 (204) ◽

pp. 667-683 ◽

Cited By ~ 27

Author(s):

E.F. Gjermundsen ◽

R. Mathieu ◽

A. Kääb ◽

T. Chinn ◽

B. Fitzharris ◽

...

Keyword(s):

New Zealand ◽

Thermal Emission ◽

Southern Alps ◽

Aerial Photographs ◽

Glacier Area ◽

Automated Classification ◽

Classification Methods ◽

Band Ratio ◽

Glacier Inventory ◽

Normalized Difference Snow Index

AbstractWe have measured the glacier area changes in the central Southern Alps, New Zealand, between 1978 and 2002 and have compiled the 2002 glacier outlines using an image scene from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER). Three automated classification methods were tested: (1) band ratio, (2) normalized-difference snow index and (3) supervised classification. The results were compared with the glacier outlines photo-interpreted from the ASTER data, and were further validated using GPS-aided field mapping of selected test glaciers. The ASTER 3/4 band ratio provided the best results. However, all the classification methods failed to extract extensive debris-covered parts of the glaciers. Therefore, the photo-interpreted 2002 outlines were used when comparing with the existing 1978 glacier inventory derived from aerial photographs. Our results show a ∼17% reduction of glacier area, mainly driven by the retreat of the large valley glaciers. Despite the large climatic gradient from west to east, glaciers on both sides of the Main Divide lost similar percentages of area, except Franz Josef and Fox Glaciers which advanced. Smaller glaciers were found to have changed very little in the study period.

Download Full-text

Glacier surface-area changes in Sagarmatha national park, Nepal, in the second half of the 20th century, by comparison of historical maps

Journal of Glaciology ◽

10.3189/002214308786570926 ◽

2008 ◽

Vol 54 (187) ◽

pp. 738-752 ◽

Cited By ~ 49

Author(s):

Franco Salerno ◽

Elisa Buraschi ◽

Gabriele Bruccoleri ◽

Gianni Tartari ◽

Claudio Smiraglia

Keyword(s):

Surface Area ◽

20Th Century ◽

Significant Role ◽

National Park ◽

Historical Maps ◽

Glacier Area ◽

Climate Data ◽

Glacier Surface ◽

Temperature Variations ◽

Sagarmatha National Park

AbstractWe investigate variations in the surface area of glaciers in Sagarmatha national park, Nepal, during the second half of the 20th century through comparison of a map applicable to the late 1950s with the official map of Nepal in the early 1990s. The comparison reveals a slight overall decrease in glacier area (by 4.9%, from 403.9 to 384.6 km2), a result which, though potentially subject to errors arising from cartographic interpretation, is in line with the area reductions found by other studies of Asian glaciers. We find that the areas of some individual glaciers, the largest situated at higher altitudes, increased during the study period. This was most apparent for the glaciers oriented to the south, with the increase occurring mainly in the glacier accumulation zones while the fronts tended to recede. Meanwhile, the smaller glaciers, situated lower and on steep basins, experienced a reduction. For the smaller glaciers, the sections most affected by change were the accumulation zones, and these glaciers showed a tendency for the front to advance. In this region there is a lack of climate data for high altitudes. Nevertheless, observations from stations situated around the park suggest that, alongside temperature variations which are often considered the primary factor eliciting glacier response, changes in precipitation play a significant role.

Download Full-text

LO STATO ATTUALE DEI GHIACCIAI ITALIANI E LA LORO RECENTE EVOLUZIONE

Istituto Lombardo - Accademia di Scienze e Lettere - Rendiconti di Scienze ◽

10.4081/scie.2016.539 ◽

2020 ◽

Author(s):

Claudio Smiraglia ◽

Guglielmina Adele Diolaiuti

Keyword(s):

High Mountain ◽

Glacier Area ◽

Glacier Surface ◽

Mountain Glacier ◽

Glacier Inventory ◽

Mountain Glaciers ◽

Proglacial Lakes ◽

The World ◽

Mountain Landscapes ◽

Recent Project

Mountain glaciers represent an important hydrological and touristic resource, and their recent evolution provides a dramatic evidence of climate change for the general public. Glacier inventories, quantifying glacier characteristics and evolution, are an important tool to describe and manage high mountain glacier environments and Italy has developed a long tradition in this sector. Our country was the first to provide itself with a glacier inventory, compiled by Comitato Glaciologico Italiano and CNR, showing a glacier surface of 530 km2. A recent project, coordinated by Università Statale di Milano with the support of private bodies and the cooperation of Comitato EvK2CNR and Comitato Glaciologico Italiano, led to the development of the new Italian Glacier Inventory, a national atlas produced from the analysis of color orthophotos at high resolution acquired between 2005 and 2011. The New Italian Glacier Inventory lists 903 glaciers, covering an area of 370 km2. The largest part of glacier area is located in Val d’Aosta (36.15% of the total), followed by Lombardia and South Tyrol. 84% of glaciers (considering the number of glaciers) have an area lower than 0.5 km2 and jointly account for 21% of the total glacier surface. Glaciers larger than 1 Km2 make up 9.4% of the total number, but cover 67.8% of the total glacier area. The comparison between data from the New Italian Glacier Inventory and the CGI-CNR inventory (1959-1962) shows a 30% reduction in glacier area in Italy; considering instead the World Glacier Inventory or WGI, published at the end of the ‘80s, which reported 1381 glaciers and an area of 609 km2, glacier loss sums up to 478 glaciers and an area of 239 km2 (-39%). This shrinkage has led to rapid and significant changes to high mountain landscapes, notably glacier fragmentation, an increase in deglaciated areas, the formation of proglacial lakes and the development of pioneer vegetation.

Download Full-text

Impacts of Climate and Supraglacial Lakes on the Surface Velocity of Baltoro Glacier from 1992 to 2017

Remote Sensing ◽

10.3390/rs10111681 ◽

2018 ◽

Vol 10 (11) ◽

pp. 1681 ◽

Cited By ~ 6

Author(s):

Anna Wendleder ◽

Peter Friedl ◽

Christoph Mayer

Keyword(s):

Thermal Emission ◽

Standardized Precipitation Index ◽

Environmental Parameters ◽

Heavy Precipitation ◽

Surface Velocity ◽

Mountain Range ◽

Glacier Surface ◽

Hazard Management ◽

Supraglacial Lakes ◽

Velocity Variations

The Baltoro Glacier is one of the largest glaciers in the Karakoram mountain range. Long-term monitoring of glacier dynamics provides key information on glacier evolution in a changing climate, which is essential for regional water resource and natural hazard management. On large glaciers, detailed field based mass balance is not feasible. Ice dynamic variations quantify changes in mass transport and possibly the influence of environmental parameters on the evolution of the glacier. Although velocity variations of Baltoro Glacier during winter and summer are linked to seasonally enhanced basal sliding, little is known about differences in timing and magnitude of (intra-)seasonal velocity variations and their determining mechanisms. We present time series of annual, seasonal, and intra-seasonal glacier surface velocities by means of intensity offset tracking applied on multi-mission Synthetic Aperture Radar (SAR) data for a period of 25 years from 1992 to 2017. Supraglacial lakes forming on the downstream glacier surface in summer were mapped from 1991 to 2017 based on the Normalized Difference Water Index (NDWI), calculated from multi-spectral Landsat and ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) imagery. Additionally, precipitation data of the Tropical Rainfall Measurement Mission (TRMM) and temperature data of ERA-Interim were used to derive the Standardized Precipitation Index (SPI) and Standardized Temperature Index (STI) from 1998 to 2017. Linking surface velocities to the SPI confirmed a strong correlation between heavy precipitation events in winter and the magnitude and the timing of glacier acceleration in summer. Downstream extensions of summer acceleration that have been found since 2015 may be explained by additional water draining from an increased number of supraglacial lakes through crevasses that have been formed in consequence of higher initial velocities, evoked by strong winter precipitation. The warmer melt seasons observed in the years 2015 to 2017 additionally affects the formation of a supraglacial lake, so stronger summer acceleration events in recent years may be indirectly related to global warming.

Download Full-text

Spatial patterns in glacier characteristics and area changes from 1962 to 2006 in the Kanchenjunga–Sikkim area, eastern Himalaya

The Cryosphere ◽

10.5194/tc-9-505-2015 ◽

2015 ◽

Vol 9 (2) ◽

pp. 505-523 ◽

Cited By ~ 55

Author(s):

A. E. Racoviteanu ◽

Y. Arnaud ◽

M. W. Williams ◽

W. F. Manley

Keyword(s):

Spatial Patterns ◽

Thermal Emission ◽

Eastern Himalaya ◽

Slope Aspect ◽

Glacier Area ◽

Glacier Surface ◽

Area Loss ◽

Debris Cover ◽

Landsat 7 ◽

The Himalaya

Abstract. This study investigates spatial patterns in glacier characteristics and area changes at decadal scales in the eastern Himalaya – Nepal (Arun and Tamor basins), India (Teesta basin in Sikkim) and parts of China and Bhutan – based on various satellite imagery: Corona KH4 imagery, Landsat 7 Enhanced Thematic Mapper Plus (ETM+) and Advanced Spaceborne Thermal Emission Radiometer (ASTER), QuickBird (QB) and WorldView-2 (WV2). We compare and contrast glacier surface area changes over the period of 1962–2000/2006 and their dependency on glacier topography (elevation, slope, aspect, percent debris cover) and climate (solar radiation, precipitation) on the eastern side of the topographic barrier (Sikkim) versus the western side (Nepal). Glacier mapping from 2000 Landsat ASTER yielded 1463 ± 88 km2 total glacierized area, of which 569 ± 34 km2 was located in Sikkim and 488 ± 29 km2 in eastern Nepal. Supraglacial debris covered 11% of the total glacierized area, and supraglacial lakes covered about 5.8% of the debris-covered glacier area alone. Glacier area loss (1962 to 2000) was 0.50 ± 0.2% yr−1, with little difference between Nepal (0.53 ± 0.2% yr−1) and Sikkim (0.44 ± 0.2% yr−1. Glacier area change was controlled mostly by glacier area, elevation, altitudinal range and, to a smaller extent, slope and aspect. In the Kanchenjunga–Sikkim area, we estimated a glacier area loss of 0.23 ± 0.08% yr−1 from 1962 to 2006 based on high-resolution imagery. On a glacier-by-glacier basis, clean glaciers exhibit more area loss on average from 1962 to 2006 (34%) compared to debris-covered glaciers (22%). Glaciers in this region of the Himalaya are shrinking at similar rates to those reported for the last decades in other parts of the Himalaya, but individual glacier rates of change vary across the study area with respect to local topography, percent debris cover or glacier elevations.

Download Full-text