Small Glaciers Research Articles

Latest Pleistocene glacier advances and post-Younger Dryas rock glacier stabilization in the Mt. Kriváň group, High Tatra Mountains, Slovakia

The timing of glacier disappearance and rock glacier stabilization in the highest massifs of the Carpathians is still poorly documented. In this paper, we establish the extent and chronology of the final stages of glaciation and timing of stabilization of the uppermost rock glaciers in the Tatra Mountains, which are the highest (2654 m a.s.l.), northernmost (N 49°12′), and coldest range in the Carpathians. On the base of morphostratigraphic principles, Schmidt Hammer tests and glacier equilibrium line altitude (ELA) estimation, we assigned moraines and rock glaciers in the Mt. Kriváň massif (SW part of High Tatras) to a threefold stratigraphic sequence with glacial stages/advances from older to younger: Popradské pleso (Pp), Suchá važecká I (Sv I) and Suchá važecká II (Sv II). Landforms attributed to two younger advances, Sv I and Sv II, were sampled for the purpose of cosmogenic 10Be surface exposure dating. Our data show that Pp and Sv I glacial advances occurred during the Oldest Dryas climatic downturn. The younger advance (Sv I) occurred just before the Bølling-Allerød (B/A) warming at 14.9 ± 0.4 ka, at this time small glaciers occupied lower glacial cirques in the study area. The youngest Sv II advance was characterized by rock glaciers and small debris-covered glaciers confined to the highest cirques. The mean exposure age of four relict rock glaciers of this stage is 11.1 ± 0.9 ka but individual rock glacier mean ages spanned between 11.8 and 10.4 ka. Our research results show that the youngest moraines and rock glaciers in the Tatra Mountains were formed during the Younger Dryas (YD), but the final permafrost melting and rock glacier stabilization period was delayed until the early Holocene, but no later than 10.4 ka. In high elevation cirque bottoms (up to 2120 m a.s.l.), the YD glaciers and rock glaciers readvanced across land which was ice-free as early as 14.8–14.2 ka. Thus, it is likely that during the B/A interphase, glaciers completely disappeared in the Tatra Mountains. The YD was the last period of glacial/periglacial activity in the massif. As we investigated one of the highest-situated rock glaciers in the Tatras (up to 2220 m a.s.l.), we conclude that all rock glaciers in this massif are relict landforms which developed in response to severe Lateglacial climate conditions. The Lateglacial climate of the Tatra Mountains is discussed herein on the basis of glacier equilibrium line altitude (ELA) estimation and the vertical distribution of rock glacier belts. We argue that paleoclimate significance of the presented geomorphological record may match paleobotanical proxy reconstructions and the results of climate simulations, but only if the impact of enhanced temperature seasonality on glacier mass balance and rock glacier activity is taken into account.

Glaciers, rock avalanches and the ‘buzzsaw’ in cirque development: Why mountain cirques are of mainly glacial origin

AbstractIt has been proposed that most cirques are source‐area depressions of large, deep‐seated rock‐slope failures. Yet the close relation between cirques and climate is convincing evidence of the dominance of glacial erosion, rather than rock‐slope failure, in mountain cirque development and distribution. Cirque floor altitudes have a lower limit that varies with snowfall by 1000 m or more between windward and leeward sides of mountain systems. Glaciation levels and equilibrium line altitudes implied by cirques vary in parallel with those for modern glaciers. Cirques are often found mainly on the poleward or leeward slopes of individual mountain ranges, as are modern small glaciers (because of solar radiation and wind effects on ablation and accumulation).Most rock‐slope failures (RSFs: rock slides, rock avalanches and gravitational deformations) do not involve the deep‐seated rotational movement that would produce a cirque form. Although some deep‐seated RSFs with arcuate head scars may be confused with cirques, identification as a glacial cirque is more confident as the floor is longer, wider and more gently sloping. Some scars from major RSFs may resemble poor or moderately developed cirques, but tend to have steeper floors, to be more scattered and closely related to geology, whereas glacial cirques develop on all rock types. Deep‐seated RSFs high on slopes can be associated with seismic shaking, but cirques develop without relation to seismicity. Degree of cirque development can be related to duration of exposure to glaciation. Often RSFs are found adjacent to cirques, or in glacial transfluences; only a proportion are well situated to develop into glacial cirques. Valley‐head cirques are continued down‐valley by glacial troughs. The ‘overdeepening’ (rock basins with reversed slopes) found in a large minority of cirques is not due to rock avalanching, fluvial or periglacial erosion.The RSF proposal should therefore be rejected in favour of the traditional glacial explanation, without any nivation stage being necessary. Rock‐slope failure is one of several possible ways of initiating hollows for glacier accumulation, as well as an ancillary process of cirque extension or widening through collapse of glacially oversteepened slopes.Headward extension of adjacent cirques on a ridge leads to displacement of the divide, sometimes by 2 km or more, lowering ridge and summit altitudes and producing the ‘glacial buzzsaw’ effect. Where a relatively lower snowline has led to cirque erosion on all sides of a mountain, cirque intersection lowers summits further. The buzzsaw hypothesis is not applicable, however, where remnants of a preglacial summit surface survive. © 2020 John Wiley & Sons, Ltd.

Spatial and temporal changes in ablation, distribution and evolution of glacial zones on Irenebreen, a small glacier of the High Arctic, Svalbard

The purpose of this work was to provide a detailed description of the temporal and spatial variability of ablation on Irenebreen – with a focus on the spatial distribution and evolution of glacial zones in the summer season of 2017. Irenebreen is a small Arctic glacier on the Kaffiøyra plain of north-western Spitsbergen. Direct field studies did not cover the whole period of ablation, and ablation zones were therefore also identified based on satellite data for a period extending beyond the research timeframe. The distribution and evolution of glacial zones on Irenebreen, the snow persisting on its surface and its phase transitions all result from the intensity and variability of ablation in the summer season, and thus may affect the total magnitude of ablation. The mean value of ablation in summer was 87.7 cm w.e. for the whole glacier. The application of satellite imaging in the near infrared channel enabled efficient classification of glacial zones based on the reflection coefficient. Glacial zones are an essential element in the assessment of the temporal and spatial variability of ablation. Their evolution is determined by ablation processes. It is therefore important to study the melting simultaneously with the temporal and spatial observations of the glacial zones. Classifying them is becoming more important as the melt season on Svalbard glaciers is significantly increasing.

СОКРАЩЕНИЕ ЛЕДНИКОВ СЕВЕРНОЙ ЧАСТИ СРЕДИННОГО ХРЕБТА НА КАМЧАТКЕ В ПЕРИОД С 1950 ПО 2016-2017 ГГ

The Northern part of the Sredinny (Middle) Range is the largest glaciation area in Kamchatka in terms of the numbers and areas of glaciers. As of 2016–2017, there were 465 glaciers in this area with a total area of about 255±17 km2. Amongst the morphological types, the cirque (corrie), slope, and corrie-valley glaciers predominate (64%), but more than half of the total area (54%) is covered by the corrie-valley and transaction glaciers. The average area of glaciers over this region is 0.55 km2, while for the transection ones it is 8.3 km2. The main part (77.4%) of the glaciers in the region is located in the altitude range of 1200–1800 m. The firn line on both slopes of the Central Range lies within the altitude range of 880–1910 m. Analysis of changes in the size of the recent glaciation in comparison with the data of the mid-twentieth century indicates that the trend towards its reduction, established in the second half of the twentieth century, remains at the present time. The loss of the area of glaciers in the region registered in the USSR Glacier Inventory (1950), by 2016–2017 amounts to almost 125 km2 (35.6%). Note, that losses for the first 15 years of the twenty-first century turn out to be approximately equal to the total sum of losses for second half of the twentieth century. It means that at the beginning of the twenty-first century the rate of reduction of glaciers is 4.3 times greater, i.e. about 1.45% of the area per year. The glaciers of the South-Eastern (62.9%) and Southern (43.6%) exposures reduced the most (significantly more than others). Loss of the total area was the greatest in small glaciers with sizes smaller 0.1 km2 (> 70%) and the smallest in large glaciers exceeding 5 km2 (< 11%). The process of disintegration of large glaciers into smaller ones did also accelerate, that increased total number of glaciers. The increase in the rate of glaciers area reduction in the region at the beginning of the twenty-first century was mainly caused by the rise in summer air temperatures, that also intensified in these years. Similar values of the relative reduction of glacier areas are observed in the North Chui Range (Altay), in the Bernese and Pennine Alps, in the Polar Ural, in the Nordenskjold Land (Svalbard), etc.

Timing of Little Ice Age maxima and subsequent glacier retreat in northern Troms and western Finnmark, northern Norway

ABSTRACT Glaciers are important indicators of climate change, and recent observations worldwide document increasing rates of mountain glacier recession. Here we present approximately 200 years of change in mountain glacier extent in northern Troms and western Finnmark, northern Norway. This was achieved through (1) mapping and lichenometric dating of major moraine systems within a subset of the main study area (the Rotsund Valley) and (2) mapping recent (post-1980s) changes in ice extent from remotely sensed data. Lichenometric dating reveals that the Little Ice Age (LIA) maximum occurred approximately 1814 (±41 years), which is before the early twentieth-century LIA maximum proposed on the nearby Lyngen Peninsula but younger than LIA maximum limits in southern and central Norway (mid-eighteenth century). Between LIA maximum and 1989, a small sample of measured glaciers (n = 15) shrank a total of 3.9 km2 (39 percent), and those that shrank by more than 50 percent are fronted by proglacial lakes. Between 1989 and 2018, the total area of glaciers within the study area (n = 219 in 1989) shrank by approximately 35 km2. Very small glaciers (<0.5 km2) show the highest relative rates of shrinkage, and 90 percent of mapped glaciers within the study area were less than 0.5 km2 in 2018.

Multiproxy reconstruction of Holocene glaciers in Sierra Nevada (south Spain)

Pleistocene glaciers shaped the highest lands of the National Park of Sierra Nevada, South Spain. Alpine glaciers filled the western valleys of the massif with hundreds of meters of ice. Surface exposure dating shows evidence of glacial expansion during the Younger Dryas and the subsequent disappearance of glaciers of the massif during the Early Holocene. Since then, glacial records and lake sediments reveal that the massif has been ice-free for the most part of the Holocene, with the development of small glaciers during the coldest phases inside the highest northern cirques. This occurred at 2.8–2.7, 1.4–1.2 cal. ka BP and during the Little Ice Age (1300–1850 CE), when documentary sources confirm also the existence of some glaciers at the foot of the highest summits. This historical period was probably the coldest and wettest phase of the Holocene in the massif and recorded the largest glaciers of the current interglacial. Those glaciers finally melted away during the mid-20th century.

Identifying and mapping very small (&lt;0.5 km2) mountain glaciers on coarse to high-resolution imagery

AbstractSmall mountain glaciers are an important part of the cryosphere and tend to respond rapidly to climate warming. Historically, mapping very small glaciers (generally considered to be &lt;0.5 km2) using satellite imagery has often been subjective due to the difficulty in differentiating them from perennial snowpatches. For this reason, most scientists implement minimum size-thresholds (typically 0.01–0.05 km2). Here, we compare the ability of different remote-sensing approaches to identify and map very small glaciers on imagery of varying spatial resolutions (30–0.25 m) and investigate how operator subjectivity influences the results. Based on this analysis, we support the use of a minimum size-threshold of 0.01 km2for imagery with coarse to medium spatial resolution (30–10 m). However, when mapping on high-resolution imagery (&lt;1 m) with minimal seasonal snow cover, glaciers &lt;0.05 km2and even &lt;0.01 km2are readily identifiable and using a minimum threshold may be inappropriate. For these cases, we develop a set of criteria to enable the identification of very small glaciers and classify them ascertain,probableorpossible.This should facilitate a more consistent approach to identifying and mapping very small glaciers on high-resolution imagery, helping to produce more comprehensive and accurate glacier inventories.

Glacier anomalies and relevant disaster risks on the Tibetan Plateau and surroundings

The Tibetan Plateau and its surroundings contain the largest number of glaciers outside the polar regions. In the past 100 years, the glaciers on the Tibetan Plateau and its surrounding areas have been retreating slowly. Since the 1990s, however, the state of glaciers has undergone abnormal changes. Compared with the data derived from the First Chinese Glacier Inventory (CGI) (1960s−1980s), the glacier volume in China decreased by approximately 20% and the glacier area was reduced by approximately 17.7%, based on the data derived from the Second CGI. In particular, the glacier mass loss of the small glaciers was characterized by an area less than 1 km2 and was more intensive than that of lager glaciers. Abnormal changes in the glaciers on the Tibetan Plateau and the surrounding areas are mainly reflected by the spatial pattern. Through the systematic analysis of the data on glacier area, terminal position, and mass balance changes, it was found that the glacier changes in the region experienced obvious spatial heterogeneity from 1990 to 2010. The “Karakoram glacier anomaly” in the eastern Pamir, Karakoram, and western Kunlun regions has exhibited slight mass stability or even glacier advance. However, the glaciers on the southeastern Tibetan Plateau experienced the most intensive and accelerated shrinkage. On the evaluated timescale, the state of glaciers on the Tibetan Plateau and its surroundings has undergone abnormal changes regarding the loss rate of glacier volume. In the past 50 years, most of the glaciers have had a negative mass balance. Moreover, the mass loss process has intensified, especially since the 1990s. It is estimated that the loss rate of glacier volume from the Tibetan Plateau was as large as −15.6 ± 10.1 Gt/a between 2003 and 2009. In addition to the abnormal changes in spatial patterns and temporal changes, the glaciers exhibited an abnormal change within the glacial system. The most significant variability within the glacier system was the abnormal change in the structure of glacier ice. Another abnormal change within the glacier system was that the glaciers showed a sustained slowdown concomitant with ice thinning. Abnormal warming at high altitudes is an important driver of abnormal changes in glaciers on the Tibetan Plateau and its surroundings. Moreover, these contrasting glacier behaviors on the Tibetan Plateau and surroundings are related to atmospheric circulation processes, especially interactions between the westerlies and the Indian Summer Monsoon. In addition, changes in glaciers on the Tibetan Plateau and its surroundings are closely related to the enhancement of human activities. The South Asian region on the southern slope of the Himalayas acts as a main source of severe anthropogenic aerosol emissions, especially that of black carbon. The black carbon transported from South Asia to the glaciers reduces the glacier’s albedo and thus accelerates glacier melting. As global warming intensifies, the abnormal glacier status will likely lead to more hazards, such as ice collapse and glacial lake outburst floods. To reduce the potential glacial risks on the Tibetan Plateau and surroundings, it is necessary to further strengthen the abilities of glacier monitoring and disaster prevention.

Impact of parent material, vegetation cover, and site wetness on variability of soil properties in proglacial areas of small glaciers along the northeastern coast of Sørkappland (SE Spitsbergen)

Climate warming that began after the Little Ice Age (LIA) and glacier recession due to this warming are responsible for exposure of new areas, which previously had been covered with an ice mass in many parts of the world. Areas newly abandoned by glaciers are sites where primary plant succession and development of soil cover occur. The main aim of this study was to determine impact of parent material, vegetation cover, and site wetness on spatial variability of physical and chemical properties of surface soil layers in the oldest parts of proglacial areas of small and rapidly retreating glaciers such as Kambreen, Bevanbreen, and Coryellbreen, which are located along the northeastern coast of Sørkappland (SE Spitsbergen). Surface soil samples (up to a depth of 10 cm) were collected from sites, which differed in terms of the parent material of the soil (glaciofluvial deposits, glacial till), vegetation cover (bare soils, initial tundra vegetation, moss tundra vegetation), and site wetness (dry, moist, wet). Physical and chemical soil properties such as content of sand, silt, clay, TOC, TN, Si, Al, Ca, Mg, K, Na, P as well as soil pH and soil EC were determined. The obtained research results indicate that the studied surface soil layers are characterized by very high spatial variability of physical and chemical properties. The different parent material of soil (glacial till and glaciofluvial deposits) in the studied proglacial areas affects particle-size distribution, soil pH, soil EC, and content of TN, Ca, and Na. The surface layer of soils developed from glacial till has a finer texture, lower mean soil pH and EC, lower mean content of Ca and Na as well as higher mean content of TN relative to the surface layer of soils formed from glaciofluvial deposits. Vegetation cover, which is very sparse in the study area, has a very low impact on the variability of the properties of the studied surface soil layers. A comparison of bare soils with soils covered with initial and moss tundra vegetation communities indicates that only the more dense and best developed moss tundra vegetation community affects the higher mean content of TOC and TN in the soil. Site wetness is the most important among the studied three soil-forming factors affecting the spatial variability of the physical properties (particle-size distribution) and chemical properties (soil EC, content of TOC, TN, Si, Al, Mg, K, P) of the surface layer of the studied soils. Soils occurring at dry and moist sites are characterized by very similar physical and chemical properties, while soils occurring at wet sites exhibit significantly higher mean soil EC and higher mean content of the sand and Si as well as significantly lower mean content of TOC, TN, silt, clay, Al, Mg, K, and P.

The dynamics of mountain erosion: Cirque growth slows as landscapes age

AbstractGlacial cirques are widely used palaeoenvironmental indicators, and are key to understanding the role of glaciers in shaping mountain topography. However, notable uncertainty persists regarding the rate and timing of cirque erosion. In order to address this uncertainty, we analyse the dimensions of 2208 cirques in Britain and Ireland and model ice accumulation to investigate the degree of coupling between glacier occupation times and cirque growth. Results indicate that during the last ~120 ka, cirques were glacier‐free for an average of 52.0 ± 21.2 ka (43 ± 18%); occupied by small (largely cirque‐confined) glaciers for 16.2 ± 9.9 ka (14 ± 8%); and occupied by large glaciers, including ice sheets, for 51.8 ± 18.6 ka (43 ± 16%). Over the entire Quaternary (i.e. 2.6 Ma), we estimate that cirques were glacier‐free for 1.1 ± 0.5 Ma; occupied by small glaciers for 0.3 ± 0.2 Ma; and occupied by large glaciers for 1.1 ± 0.4 Ma. Comparing occupation times to cirque depths, and calculating required erosion rates, reveals that continuous cirque growth during glacier occupation is unlikely. Instead, we propose that cirques attained much of their size during the first occupation of a non‐glacially sculpted landscape (perhaps during the timeframe of a single glacial cycle). During subsequent glacier occupations, cirque growth may have slowed considerably, with the highest rates of subglacial erosion focused during periods of marginal (small glacier) glaciation. We propose comparatively slow rates of growth following initial cirque development because a ‘least resistance’ shape is formed, and as cirques deepen, sediment becomes trapped subglacially, partly protecting the bedrock from subsequent erosion. In support of the idea of rapid cirque growth, we present evidence from northern British Columbia, where cirques of comparable size to those in Britain and Ireland developed in less than 140 ka. © 2019 John Wiley &amp; Sons, Ltd. © 2019 John Wiley &amp; Sons, Ltd.

Volume Changes of Elbrus Glaciers From 1997 to 2017

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 meter 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 4000 m a.s.l. where the average ice thickness was 44.6±7.3 m, 18% of the volume lies within 4000-4500 m a.s.l. (thickness of 41.2±7.3 m), and just 14% lies above 4500 m a.s.l. (thickness of 29.7±6.65 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 4000 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.

Heterogeneous Influence of Glacier Morphology on the Mass Balance Variability in High Mountain Asia

We investigate the control of the morphological variables on the 2000–2016 glacier‐wide mass balances of 6,470 individual glaciers of High Mountain Asia. We separate the data set into 12 regions assumed to be climatically homogeneous. We find that the slope of the glacier tongue, mean glacier elevation, percentage of supraglacial debris cover, and avalanche contributing area all together explain a maximum of 48% and a minimum of 8% of the glacier‐wide mass balance variability, within a given region. The best predictors of the glacier‐wide mass balance are the slope of the glacier tongue and the mean glacier elevation for most regions, with the notable exception of the inner Tibetan Plateau. Glacier‐wide mass balances do not differ significantly between debris‐free and debris‐covered glaciers in 7 of the 12 regions analyzed. Lake‐terminating glaciers have more negative mass balances than the regional averages, the influence of lakes being stronger on small glaciers than on large glaciers.

Area changes of glaciers on active volcanoes in Latin America between 1986 and 2015 observed from multi-temporal satellite imagery

ABSTRACTGlaciers on active volcanoes are subject to changes in both climate fluctuations and volcanic activity. Whereas many studies analysed changes on individual volcanoes, this study presents for the first time a comparison of glacier changes on active volcanoes on a continental scale. Glacier areas were mapped for 59 volcanoes across Latin America around 1986, 1999 and 2015 using a semi-automated band ratio method combined with manual editing using satellite images from Landsat 4/5/7/8 and Sentinel-2. Area changes were compared with the Smithsonian volcano database to analyse possible glacier–volcano interactions. Over the full period, the mapped area changed from 1399.3 ± 80 km2to 1016.1 ± 34 km2(−383.2 km2) or −27.4% (−0.92% a−1) in relative terms. Small glaciers, especially in tropical regions lost more of their area compared to large and extra–tropical glaciers. Interestingly, 46 out of 59 analysed glaciers (78%) showed a decelerating shrinkage rate in the second period (−1.20% a−1before 1999 and −0.70% a−1after 1999). We found a slightly higher (but statistically not significant) area loss rate (−1.03% a−1) for glaciers on volcanoes with eruptions than without (−0.86% a−1).

Avalanches and micrometeorology driving mass and energy balance of the lowest perennial ice field of the Alps: a case study

Abstract. The mass balance of very small glaciers is often governed by anomalous snow accumulation, winter precipitation being multiplied by snow redistribution processes (gravitationally or wind driven), or suppressed snow ablation driven by micrometeorological effects lowering net radiation and/or turbulent heat exchange. In this case study, we analysed the relative contribution of snow accumulation and ablation processes governing the long- and short-term mass balance of the lowest perennial ice field of the Alps, the Ice Chapel, located at 870 m a.s.l. in the Berchtesgaden National Park (Germany). This study emphasizes the importance of the local topographic setting for the survival of a perennial ice field located far below the climatic snow line. Although long-term mass balance measurements of the ice field surface showed a dramatic mass loss between 1973 and 2014, the ice field mass balance was rather stable between 2014 and 2017 and even showed a strong mass gain in 2017/2018 with an increase in surface height by 50 %–100 % relative to the ice field thickness. Measurements suggest that the winter mass balance clearly dominated the annual mass balance. At the Ice Chapel surface, 92 % of snow accumulation was gained by snow avalanching, thus clearly governing the 2017/2018 winter mass balance of the ice field with mean snow depths of 32 m at the end of the accumulation period. Avalanche deposition was amplified by preferential deposition of snowfall in the wind-sheltered rock face surrounding the ice field. Detailed micrometeorological measurements combined with a numerical analysis of the small-scale near-surface atmospheric flow field identified the micrometeorological processes driving the energy balance of the ice field. Measurements revealed a katabatic flow system draining down the ice field throughout the day, showing strong temporal and spatial dynamics. The spatial origin of the thermal flow system was shown to be of particular importance for the ice field surface energy balance. Numerical simulation indicates that deep katabatic flows, which developed at higher-elevation shaded areas of the rock face and drained down the ice field, enhance sensible heat exchange towards the ice field surface by enhancing turbulence close to the ice surface. Conversely, the shallow katabatic flow developing at the ice field surface appeared to laterally decouple the local near-surface atmosphere from the warmer adjacent air suppressing heat exchange. Numerical results thus suggest that shallow katabatic flows driven by the cooling effect of the ice field surface are especially efficient in lowering the climatic sensitivity of the ice field to the surrounding rising air temperatures. Such micrometeorological phenomena must be taken into account when calculating mass and energy balances of very small glaciers or perennial ice fields at elevations far below the climatic snow line.

Study of the glacial flow of rivers in the Grønfjord bay basin (Western Svalbard)

The melting of glaciers in the Arctic archipelagoes provides glacier runoff, which must be considered when assessing river flow. Glacial runoff, as a component of the total river flow, directly affects the thermal and ice conditions of the bays, the productivity and species composition of the marine biota. Also, this process is broadly related to the livelihoods of the Arctic villages. Furthermore, it acts as the important factor for the development of transport and tourism. Melted water of Svalbard glaciers is a significant contribution in total runoff of the local rivers. The issue of this study is to assess this contribution. Grønfjord Bay was selected for assessment because of the fact of regular measurements of water discharge in the river estuaries from June to October. Among 7 rivers flowing into the bay, 6 have glacial runoff. Despite the fact that only small mountain glaciers are common in this area, its melting largely determines the water regime of the rivers. The value of the glacier runoff in Grønfjord Bay was calculated based on an estimation of the glaciers melting by average summer air temperature in 2017 and 2018. Comparison of the amount of glacial and total flow was carried out on the rivers flowing into the Grønfjord Bay.The comparative analysis of the glacial and total river flows size along the 6 rivers of the Grønfjord Bay: Grøndalselva, Grønfjorddalselva, Bretjørna, Aldegonda, Brydebekken, Vasstakelva showed significant differences in the glacier runoff content depending on the area of glaciation in the catchment of rivers. The content of glacial runoff in the total freshwater discharge by rivers into the bay in 2017 and 2018 vary from 20 to 90 %. The largest glacier runoff is observed on the Bretjørna river — 90 %, the Grøndalselva, Brydebekken and Vasstakelva have the smallest glacier runoff — 20 %. The average total glacial runoff of the rivers varied from 41 to 53 % of the total discharge of the rivers of the gulf.

Reserve of ice in glaciers on the Nordenskiöld Land, Spitsbergen, and their changes over the last decades

Data on thickness and area of 16 glaciers on the Nordenskiöld Land (Svalbard) were obtained in 1999 and 2010–2013. These data were used to determine volume of the glaciers and to establish statistical local relationship between the volume V and the area A (V–A scaling) in the form of the power function V = cAγ, and then to calculate the total ice volume of all 202 glaciers in this area and its changes during the period since 1936 to 2002–2008. The total area of 16 glaciers was 129.9±0.35 km2, 14 of which had areas from 0.2 to 8.1 km2. The two largest ones, the Fridtjof and the West Grenfjord, had the areas 17.5 and 47.3 km2, respectively, and thus occupied about 50% (64.8 km2) of the total area of 16 glaciers. These two glaciers account for 67% of the total measured volume (10,034 km3) of the 16 glaciers. A nonlinear least-squares method was used to estimate ice reserves in all 202 glaciers from data on the volume and area of 16 glaciers. The relation between volume V and area A of the glaciers (V–A scaling) was obtained as the ratio V = 0.03637A1,283 with 95%‑th confidence intervals of the coefficients с and γ, (0.02303–0,4971) and (1.184–1.381), respectively. This made possible to calculate total volume of 202 glaciers as of 2002-2008 state using data from RGI v.6.0, and that prove to be equal to 32.89 (16.75–56.63) km3. To verify this estimation, we applied the bootstrapping method for chosen 43 glaciers and calculated the volume by means of sequential use of data for large and smaller glaciers. According to this estimate, the total volume of 202 glaciers amounted to 30.34 km3 with a 95% confidence interval of 15.42–44.27 km3, that turned out to be slightly smaller than the volume calculated by nonlinear least squares method basing on measurements on 16 glaciers. Despite the large error (on the average, from −49% to +84%) in estimating the total volume of 202 glaciers in the Nordenskiöld Land, the data obtained were used for assessment of relative changes in the total volume of glaciers in this area over different time intervals. During the period from 1936 to1990 (54 years), the total area of all glaciers reduced from 738.1 to 546.7 km2, and the total volume decreased from 49,205 to 34,857 km3. Similar results for the period 1990–2002–2008 (~15 years) are the total area changes from 546.7 to 507.9 km2 and their total volume - from 34.857 to 32.890 km3. The rate of decrease of the volume for the period 1936–1990 was equal to −0.266 km3/year, for the period 1990–2002–2008 – minus 0.131 km3/year, and as a whole for the studied period (since 1936 to 2002–2008) – minus 0.236 km3/year. The average mass balance in the first period was equal to −0.372 m w.e./year, in the second one −0.224 m w.e./year, and for the whole time −0.342 m w.e./year.

Glacier dynamics in the southern part of East Siberia (Russia) from the final part of the LGM to the present based on from biogeochemical proxies from bottom sediments of proglacial lakes

In the present study, we have reconstructed glacier dynamics based on the high (1–0.5 mm) resolution X-ray fluorescence spectrometry scanning, the Fourier-transform infrared technique and 14C-dating used in the analyses of the lake bottom sediments, fluvioglacial deposits and a peat bog situated on East Siberian Mountains (East Sayan, Baikal, Barguzin and Kodar Ridges) between 51.723°N, 100.601°E and 56.885°N, 117.580°E. We have found what the largest glacier deposits on the Baikal shoreline, so-called Tompuda end moraine, formed in two stages. The first stage occurred until ca. 12 cal ka BP; then, there was a short pause. The second stage ended by 9.5 cal ka BP. Azarova glacier (Kodar Ridge) retreated upwards the Kodar Ridge by ca. 11 cal ka BP. It may indicate that the Bølling-Allerød warming was very evident, and it was a trigger for these deglacial events in East Siberia. It is most likely that “remains” of the Late Pleistocene glaciers were cardinally shrunk or fully disappeared during the Holocene Thermal Optimum in the southern part of East Siberia. Climate conditions were suitable for glacier formation after 3 cal ka BP. However, if there were new glaciers in the Middle Holocene, their sizes were likely to be less than 1 km2. For this reason, these glaciers should have completely melted during the Roman and Medieval Warm Periods. It is most likely, small glaciers observed at present in the south of East Siberia were mainly formed during the Little Ice Age.

Recent geodetic mass balance and extent changes of very small glaciers in the Hulugou Basin, Central Qilian Mountains, China

Very small glaciers (\({<}0.5\,\hbox {km}^{2})\) 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 \(0.024~\hbox {km}^{2}\) \(\hbox {a}^{-1}\) and the geodetic mass balance was \(-0.68\pm 0.11~\hbox {m}\) water equivalent (m w.e.) \(\hbox {a}^{-1}\) 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 \(0.005~\hbox {km}^{2}\) \(\hbox {a}^{-1}\) and the geodetic mass balance was \(-0.53\pm 0.11~\hbox {m}\) w.e. \(\hbox {a}^{-1}\) 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.

A multi-proxy approach to Late Holocene fluctuations of Tungnahryggsjökull glaciers in the Tröllaskagi peninsula (northern Iceland)

The Tröllaskagi Peninsula in northern Iceland hosts more than a hundred small glaciers that have left a rich terrestrial record of Holocene climatic fluctuations in their forelands. Traditionally, it has been assumed that most of the Tröllaskagi glaciers reached their Late Holocene maximum extent during the Little Ice Age (LIA). However, there is evidence of slightly more advanced pre-LIA positions. LIA moraines from Iceland have been primary dated mostly through lichenometric dating, but the limitations of this technique do not allow dating of glacial advances prior to the 18th or 19th centuries. The application of 36Cl Cosmic-Ray Exposure (CRE) dating to Tungnahryggsjökull moraine sequences in Vesturdalur and Austurdalur (central Tröllaskagi) has revealed a number of pre-LIA glacial advances at ~400 and ~700 CE, and a number of LIA advances in the 15th and 17th centuries, the earliest LIA advances dated so far in Tröllaskagi. This technique hence shows that the LIA chronology in Tröllaskagi agrees with that of other European areas such as the Alps or the Mediterranean mountains. The combined use of lichenometric dating, aerial photographs, satellite images and fieldwork shows that the regional colonization lag of the commonly used lichen species Rhizocarpon geographicum is longer than previously assumed. For exploratory purposes, an alternative lichen species (Porpidia soredizodes) has been tested for lichenometric dating, estimating a tentative growth rate of 0.737 mm yr−1.

Transcriptome-Wide Patterns of the Genetic and Expression Variations in Two Sympatric Schizothoracine Fishes in a Tibetan Plateau Glacier Lake.

Sympatric speciation remains a central focus of evolutionary biology. Although some evidence shows speciation occurring in this way, little is known about the gene expression evolution and the characteristics of population genetics as species diverge. Two closely related Gymnocypris fish (Gymnocypris chui and Gymnocypris scleracanthus), which come from a small glacier lake in the Tibetan Plateau, Lake Langcuo, exist a possible incipient sympatric adaptive ecological speciation. We generated large amounts of RNA-Seq data from multiple individuals and tissues from each of the two species and compared gene expression patterns and genetic polymorphisms between them. Ordination analysis separated samples by organ rather than by species. The degree of expression difference between organs within and between species was different. Phylogenetic analyses indicated that the two closely related taxa formed a monophyletic complex. Population structure analysis displayed two distinctly divergent clusters of G. chui and G. scleracanthus populations. By contrast, G. scleracanthus population genetic diversity is higher than that of G. chui. Considerable sites of the two populations were differentiated with a coefficient of FST = 0.25–0.50, implying that a small proportion of loci nevertheless exhibited deep divergence in two comparisons. Concomitantly, putatively selected genes during speciation revealed functional categories are enriched in bone morphogenesis, cell growth, neurogenetics, enzyme activity, and binding activity in G. chui population. In contrast, nutrition and localization were highlighted in G. scleracanthus. Collectively, morphological traits and dietary preference combine with genetic variation and expression variation, probably contributed to the incipient speciation of two sympatric populations.