Changes in area and geodetic mass balance of small glaciers, Polar Urals, Russia, 1950 - 2008

Funded by:

National Geographic logoThe National Geographic Fund for Research and Exploration

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Institute of Geography, Russian Academy of Sciences, Moscow, Russia

Background

Glaciers in most parts of the world are currently receding in response to the climatic warming. The loss of glacier mass leads to changes in the local and regional water balances and to global sea level rise. Modelling studies suggest that very small glaciers (e.g. <0.5 km2) will respond most strongly to the projected climatic warming. However, the strong links between behaviour of very small glaciers and local topographic and climatic factors make their response to climatic warming less certain and it is important to investigate their behaviour in regions with various climatic and topographic conditions.

Location map. Black rectangles show location of the Polar Urals on the inset map and glaciated study area on the main map.The Ural Mountains, a range dividing geographical Europe and Asia, is a region where very small glaciers are widespread north of 64oN in the regions of Polar (66-68oN) and sub-Polar (64-66oN) Urals . Research into the Urals glaciers dates back to the early 1930s when selected glaciers of the sub-Polar Urals were first mapped. Extensive aerial surveys were conducted in the 1950s and 1960s. A regular glacier monitoring programme continued in the region between 1957 and 1981 and mass balance observations of two reference glaciers, IGAN and Obruchev, were reported to the World Glacier Monitoring Service. Although by the 1980s glacier wastage had already been observed in the region, regular glaciological monitoring was discontinued. This resulted in a lack of data about the behaviour of the Urals glaciers at a time when intensified retreat of small glaciers was reported worldwide.

In 2008-10, the University of Reading and Institute of Geography, Russian Academy of Sciences conducted a comprehensive survey of small glaciers in the Polar Ural, the first since termination of the regional glacier monitoring programme in 1981. The objectives of the were to: (i) quantify changes in the area of 30 glaciers between 1953 (the years of the previous large-scale glacier inventories) and the early 21st century; (ii) quantify changes in surface elevation and volume and calculate geodetic mass balances for two formerly reference glaciers (Obruchev and IGAN) between 1963 and 2008; (iii) relate the observed glacier changes to changes in regional air temperature and precipitation. Glaciological mass balance records for the IGAN and Obruchev glaciers, dating back to the 1958-1980 period, are among the earliest mass balance records in Russia and the estimated geodetic mass balance data supplement the earlier glaciological data (despite the differences in their instrumental and physical biases) and help to validate mass balance records reconstructed from proxy data.

Data and Methods

In this work, we used a combination of remote sensing and field survey methods. We used both historical field data and surveys several glaciers in the field to obtain comprehensive and high-accuracy data on glacier surface elevation. An assessment of changes in surface area of 30 glaciers was conducted using aerial photographs acquired in 1953 and/or 1960 and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and panchromatic Landsat Enhanced Thematic Mapper (ETM+) imagery from 2000. Smaller-scale aerial and terrestrial photogrammetric surveys of selected glaciers were conducted by the Institute of Geography, Russian Academy of Science (IGRAS) in the Polar Urals in 1973 and 1981 and their data were used to assess glacier changes at higher temporal resolution. Terrestrial theodolite surveys of IGAN and Obruchev glaciers were conducted by IGRAS on 10 and 28 August 1963 respectively. In July-August 2008, we conducted Digital Global Positioning System (DGPS) surveys of the IGAN, Obruchev, Chernov, MGU, and Dolgushin glaciers to calculate changes in the elevations of glacier surfaces and calculate their mass balance relative to 1963.

Results

In total, area of 30 surveyed glaciers declined by 22.3 ± 3.9% in the 1953/1960-2000 period. The areas of individual glaciers decreased by 4% to 46% and these differences are explained by the strong influence of topographic and local meteorological conditions on the behaviour of small glaciers.

Examples of glacier retreat

The observed glacier shrinkage intensified in the 1981-2000 in comparison with the 1953-1981 period.

Repeated photography, featuring formation of a proglacial lake, illustrates acceleration of MGU glacier recession in the 1974-1991 period relative to the 1958-1974 period.Repeated photography, featuring formation of a proglacial lake, illustrates acceleration of MGU glacier recession in the 1974-1991 period relative to the 1958-1974 period.

MGU glacier in 2008. The inset image shows the extent of the lake in 2008 relative to the glacier size in 1953. Circled is the area where separation between the glacier tongue and the accumulation zone is likely to occur.The proglacial lake, formed in the 1980s, occupied 28% of the 1953 MGU glacier area in 2008.

We calculated that surfaces of the Obruchev and IGAN glaciers lowered by 22.5 ± 1.7 m and 14.9 ± 2.1 m. Obruchev glacier, positioned at lower elevations, experienced stronger downwasting at an average rate of 0.5 m a-1 between 1963 and 2008. As expected, the largest changes occurred on the glacier tongue where surface lowering exceeded 40-50 m. Over 45 years, geodetic mass balances of the Obruchev and IGAN glaciers were -20.66 ± 2.91 and -13.54 ± 2.57 m w.e. respectively.

Data for five glaciers only, the ones we surveyed in the field in 2008, were available to assess changes in glacier shrinkage rates in the first decade of the 21st century when climatic warming intensified. These data suggest that a combination of increasing cold-season precipitation and changes in glacier morphology resulting in greater shading effects slowed down glacier shrinkage in 2000-2008 in comparison with 1981(1973) -2000 but did not fully compensate for effects summer warming.

Publications

Results of this project have been published in the Journal of Glaciology:

Shahgedanova, M., G. Nosenko, I. Bushueva, M. Ivanov (2012) Changes in area and geodetic mass balance of small glaciers, Polar Urals, Russia, 1950 - 2008. Journal of Glaciology, 58 (211), 953-964, doi: 10.3189/2012JoG11J233.

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