EVOLUTION OF THE ELBRUS GLACIATION SINCE THE MID XIX CENTURY UNDER CHANGING CLIMATE. KEY FINDINGS OF THE GLACIO-CARTOGRAPHICAL MONITORING
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Changes in the area and volume that have been occurring from the middle of the XIX century within the largest in Europe Elbrus glaciation were studied using lichenometry and digital cartography methods. There were cyclical, approximately 55 years long, frontal fluctuations of glaciers Bolshoi Azau (the largest Elbrus glacier) and Dzhankuat (which is representative of all Central Caucasus glaciation). Quantitative data on changes in the area and volume of the Elbrus glaciation indicated that the greatest rates of its retreat coincided with the 1850–1887 period. Beginning in 1887, the area reduction was occurring practically evenly through time while the decrease in its volume has even slowed down. These facts suggest that global climate warming, which alternated with short-term cooling periods, began in the middle of the XIX century after the end of the Little Ice Age. The warming was most likely due to natural rather than anthropogenic causes.Keywords:
Little ice age
Ice caps
Latest satellite images have been utilized to update the inventories of glaciers and glacial lakes in the Pumqu river basin, Xizang (Tibet), in the study. Compared to the inventories in 1970s, the areas of glaciers are reduced by 19.05% while the areas of glacial lakes are increased by 26.76%. The magnitudes of glacier retreat rate and glacial lake increase rate during the period of 2001–2013 are more significant than those for the period of the 1970s–2001. The accelerated changes in areas of the glaciers and glacial lakes, as well as the increasing temperature and rising variability of precipitation, have resulted in an increased risk of glacial lake outburst floods (GLOFs) in the Pumqu river basin. Integrated criteria were established to identify potentially dangerous glacial lakes based on a bibliometric analysis method. It is found, in total, 19 glacial lakes were identified as dangerous. Such finding suggests that there is an immediate need to conduct field surveys not only to validate the findings, but also to acquire information for further use in order to assure the welfare of the humans.
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第四紀後期の日本海堆積物は,センチメートルからメートルスケールでリズミカルに繰り返す明暗の縞で特徴づけられる.日本海中南部ODP797地点より採取された堆積コアについて高解像度解析を行った結果,これら明暗縞は日本海全域にわたって数百年から数千年間隔で繰り返し起こった海洋環境変動を反映し,近年グリーンランド氷床記録より見いだされたダンスガード・オシュガー・サイクルと呼ばれる突然かつ急激な気候変動に同調していることが明らかになった.日本海におけるその変動は,ダンスガード・オシュガー・サイクル温暖期に対応した東シナ海沿岸水の日本海への流入比率の増加,表層水塩分の低下による深層水循環の減衰,表層での生物生産性の増加とそれによる暗色縞の堆積および,寒冷期に対応した東シナ海沿岸水流入比率の減少,表層水塩分の上昇による深層水循環の強化,生物生産性の減少とそれによる明色縞の堆積で特徴づけられる.さらに,東シナ海沿岸水流入比率の増加は,中央アジアの湿潤化に伴う黄河あるいは揚子江流出量の増大を反映した可能性がある.
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We have analyzed one rapidly expanding glacial lake and one stagnant glacial lake located in the central Himalaya to understand the impact of local topography on the expansion and evolution of glacial lakes using remote sensing data. The slope, aspect, incoming solar radiation and compactness ratio of glaciers associated with the glacial lakes have been studied and analyzed. Glacier topography play important role in the expansion of glacial lakes as observed from the study..
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<p>In recent years, the number and size of glacial lakes in mountain regions have increased worldwide associated to the climate-induced glacier retreat and thinning. Glacial lakes can cause glacial lake outburst floods (GLOFs) which can pose a significant natural hazard in mountainous areas and can cause loss of human life as well as damage to infrastructure and property.</p><p>The glacial landscape of the Jostedalsbreen ice cap in south-western Norway is currently undergoing significant changes reflected by progressing glacier length changes of the outlet glaciers and the formation of new glacial lakes within the recently exposed glacier forefields. We present a new glacier area outline for the entire Jostedalsbreen ice cap and the first detailed inventory of glacial lakes which were formed within the newly exposed ice-free area at the Jostedalsbreen ice cap. In detail, we explore (i) the glacial lake characteristics and types and (ii) analyse their spatial distribution and hazard potential.</p><p>For the period from 1952-1985 to 2017/2018 the entire glacier area of the Jostdalsbreen ice cap experienced a loss of 79 km<sup>2</sup>. A glacier area reduction of 10 km<sup>2</sup> occurred since 1999-2006. Two percent of the recently exposed surface area (since 1952-1985) is currently covered with newly developed glacial lakes corresponding to a total number of 57 lakes. In addition, eleven lakes that already existed have enlarged in size. Four types of glacial lakes are identified including bedrock-dammed, bedrock- and moraine-dammed, moraine-dammed and ice-dammed lakes. Especially ice- or moraine-dammed glacial lakes can be the source of potentially catastrophic glacier lake outburst floods. According to the inventory of glacier-related hazardous events in Norway GLOFs represent the most common hazardous events besides ice avalanches and incidents related to glacier length changes. Around the Jostedalsbreen ice cap several historical but also recent events are documented. The majority of the events caused partly severe damage to farmland and infrastructure but fortunately no people have been harmed by today.</p><p>Due to the predicted increase in summer temperatures for western Norway until the end of this century, it is very likely that the current trend of an accelerated mass loss of Norwegian glaciers will continue. As one consequence of this development, further new lakes will emerge within the newly exposed terrain. The development of new glacial lakes has diverse regional and global socio-economic implications. Especially in mainland Norway, where glaciers and glacier-fed streams have a high importance for hydropower production, tourism and climate research it is essential to gain a better understanding of the possible impacts of glacial lakes for being prepared for risks but also advantages arising from these newly emerging landscape elements.</p>
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Owing to intense glacial retreat and melting, it is anticipated that numerous glacial lakes will be formed in the next few decades. However, their development and distribution patterns in the Tibetan Plateau and its surroundings still need to be elucidated. In this study, a published glacier ice thickness distribution dataset was employed to fully detect overdeepened glacier beds as potential glacial lakes. We selected and expanded four morphological metrics to determine the formation probability of potential glacial lakes: surface slope, break in slope, lake area, and position on the glacier. The results revealed that 15,826 potential glacial lakes with areas >0.02 km2 exist in the Tibetan Plateau and its surroundings, covering an area of 2253.95 ± 1291.29 km2 with a water volume of 60.49 ± 28.94 km3 that would contribute to an equivalent sea level rise of 0.16 ± 0.08 mm. The experimental comparison and uncertainty assessment for the overdeepening processing showed that the different extraction methods and basic digital elevation models used could lead to non-negligible errors in the results (at least ±30%), which were ignored in previous studies, contributing to major divergences between the several current inventories of potential glacial lakes in the plateau. Notably, approximately 90% of the total area of the potential glacial lakes is concentrated in the lower half of the individual glaciers in the Tibetan Plateau and its surroundings. >70% of the potential glacial lakes and contemporary glacial lakes in this region were found to be concentrated within the 4000–5800 m elevation range. Moreover, the study identified 5361 potential glacial lakes with high or very high exposure probabilities, and their distribution was mostly determined by regional glacier resources. However, the numbers and sizes of some potential glacial lakes that are found in the Karakoram region are considered to be exaggerated because of the presence of numerous surge-type glaciers, which have not been discussed in previous studies. These results can improve our understanding of future glacial lake formation and distribution in the Tibetan Plateau and its surroundings and have implications for further implementation of effective prevention, mitigation, and adaptation measures for glacial lake outburst floods and water security.
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Based on surveying data of glacial striae on roches mountonnees near the terminus of Glacier No.1 and Glacier No.7 at the head of Urumqi River, Tian Shan Mt., the statistical graduation character of glacial striae is discussed in this paper. It is shown that the statistical graduation character of glacial striae conforms to the exponent model, and the parameters (A and B) of this model can be used as indexes to describe the density of glacial striae and the glacial dynamics. The larger A and B are, the larger the density of glacial striae is. The spatial distribution of the parameters (A and B) of glacial striae is influenced by the size of glacier, location in the trough, and position on the roches mountonnee. It is shown in this area that the A and B values are larger in the larger glacier (Glacier No.1) than those in the smaller (Glacier No.7), and larger on the top side of the roches mountonnee than those on the lateral side. At the same time, the A and B values are also varied from the center to the edge in glacial troughs influenced by the micro forms in glacial valleys.
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The glaciers are retreating year after year because of the global warming. As a result, the glacial lake outburst floods (GLOF) become frequent. So that more attention should be paid on them. But the study of glacial lakes with static and isolated means has not satisfied the need to monitor the glacial lake change. The basic data in this paper includes relief maps in 1970s and aster images in 2001 and 2002. The GIS tools are used to digitizing the spatial distribution of the glaciers and glacial lakes during these two periods. Then these spatial data are analyzed. The results show that the glacier area decreases 9% and the glacial lake area increase 13%. Then 24 potential risk lakes are identified in Pumqu Basin. The results are very important to monitore the GLOF and constructing an effective pre-alarm system of the GLOF hazards.
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Abstract Glacial lake outburst floods are among the most serious natural hazards in the Himalayas. Such floods are of high scientific and political importance because they exert trans‐boundary impacts on bordering countries. The preparation of an updated inventory of glacial lakes and the analysis of their evolution are an important first step in assessment of hazards from glacial lake outbursts. Here, we report the spatiotemporal developments of the glacial lakes in the Poiqu River basin, a trans‐boundary basin in the Central Himalayas, from 1976 to 2010 based on multi‐temporal Landsat images. Studied glacial lakes are classified as glacier‐fed lakes and non‐glacier‐fed lakes according to their hydrologic connection to glacial watersheds. A total of 119 glacial lakes larger than 0.01 km 2 with an overall surface area of 20.22 km 2 (±10.8%) were mapped in 2010, with glacier‐fed lakes being predominant in both number (69, 58.0%) and area (16.22 km 2 , 80.2%). We found that lakes connected to glacial watersheds (glacier‐fed lakes) significantly expanded (122.1%) from 1976 to 2010, whereas lakes not connected to glacial watersheds (non‐glacier‐fed lakes) remained stable (+2.8%) during the same period. This contrast can be attributed to the impact of glaciers. Retreating glaciers not only supply meltwater to lakes but also leave space for them to expand. Compared with other regions of the Hindu Kush Himalayas (HKH), the lake area per glacier area in the Poiqu River basin was the highest. This observation might be attributed to the different climate regimes and glacier status along the HKH. The results presented in this study confirm the significant role of glacier retreat on the evolution of glacial lakes. Copyright © 2014 John Wiley & Sons, Ltd.
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Only a few small glaciers survive today in the Mountains of the Mediterranean. Notable examples are found in the Pyrenees, Maritime Alps, Italian Apennines, the Dinaric and Albanian Alps and the mountains of Turkey. Many glaciers disappeared during the 20th Century. Glaciers were much larger and more numerous during the Little Ice Age. Small glaciers even existed as far south as the High Atlas of Morocco and the Sierra Nevada of southern Spain. In more northerly areas, such as the western Balkans, glaciers and permanent snow fields occupied hundreds of cirques on relatively low-lying mountains. In the High Atlas and the Sierra Nevada no glaciers exist today, whilst in the Balkans only a few modern glaciers have been reported (<10). A similar situation is apparent throughout the mountains of the Mediterranean region. This paper presents new evidence for glacier change since the Little Ice Age and reviews the extent, timing and climatic significance of Little Ice Age glaciation in all the main mountain areas.
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В статье критически рассмотрены литературные данные по ледникам и приледниковым озерам, расположенным в бассейне реки Мидаграбиндон, и изменения, произошедшие на них за последние полвека. На 1977 г. на этой территории насчитыва- лось 12 ледников и 3 озера. Сейчас здесь 30 ледников, из которых – 5 каменных глетче- ров. Всего выявлено 16 приледниковых озер, часть которых истекла. Составлена кар- та ледников и каменных глетчеров бассейна реки Мидаграбиндон. Морфометрические данные этих объектов приведены в таблицах. В связи с продолжающимся потеплением климата деградация оледенения возрастает. Возможно, на этот процесс оказывает влияние и спящий вулкан Казбек. The article critically examines literary data on glaciers and glacial lakes located in the Midagrabindon river basin and changes that have occurred on them over the past half century. In 1977, there were 12 glaciers and 3 lakes in this territory. Now there are 30 glaciers, 5 active rock glaciers and 16 glacial lakes. A map of glaciers, rock glaciers and glacial lakes of the Midagrabindon River basin has been compiled. Morphometric data are given in Tables. Glaciation degradation is increasing. Due to the ongoing warming of the climate, the degradation of glaciation is increasing. Perhaps this process is influenced by the dormant volcano Kazbek.
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