Small Glaciers Research Articles

A national glacier inventory and variations in glacier extent in Iceland from the Little Ice Age maximum to 2019

Abstract — A national glacier outline inventory for several different times since the end of the Little Ice Age (LIA) in Iceland has been created with input from several research groups and institutions, and submitted to the GLIMS (Global Land Ice Measurements from Space, nsidc.org/glims) database, where it is openly available. The glacier outlines have been revised and updated for consistency and the most representative outline chosen. The maximum glacier extent during the LIA was not reached simultaneously in Iceland, but many glaciers started retreating from their outermost LIA moraines around 1890. The total area of glaciers in Iceland in 2019 was approximately 10,400 km2, and has decreased by more than 2200 km2 since the end of the 19th century (corresponding to an 18% loss in area) and by approximately 750 km2 since ~2000. The larger ice caps have lost 10–30% of their maximum LIA area, whereas intermediate-size glaciers have been reduced by up to 80%. During the first two decades of the 21st century, the decrease rate has on average been approximately 40 km2 a-1. During this period, some tens of small glaciers have disappeared entirely. Temporal glacier inventories are important for climate change studies, for calibration of glacier models, for studies of glacier surges and glacier dynamics, and they are essential for better understanding of the state of glaciers. Although surges, volcanic eruptions and jökulhlaups influence the position of some glacier termini, glacier variations have been rather synchronous in Iceland, largely following climatic variations since the end of the 19th century.

Very Small Glaciers as Geoheritage: Combining a Spatio-Temporal Visualisation of Their Development and Related Effects of Climate Change

Outside the main mountain ranges and high North and South regions, individual isolated very small glaciers are the only glacier remnants and exceptional high-mountain active geomorphosites, which can be used to represent climate change consequences first hand to the local general public. The isolated, very small Triglav glacier in Slovenia was used to represent 3D glacier area changes for the period 1829–2016, together with long-term meteorological changes. Spatio-temporal changes of the glacier were derived mainly from old images and postcards with the help of interactive orientation (monoplotting), which enables the acquisition of a 3D glacier boundary from a single image by using a modern detailed digital elevation model. Very intuitive 3D visualisation was prepared, which shows the spatio-temporal changes of the glacier area, together with changes in average annual temperature and maximum annual snow depth. The last two are presented by colour palettes, where red colours represent stages when temperatures or maximum snow depths deviate from long-term averages in a negative way, meaning accelerating the glacier area reduction. Blue colours are used for stages when these parameters deviate from long-term averages in a positive way, meaning preserving the glacier area. From this 3D visualisation, one can easily recognise which meteorological parameter is the most important for the Triglav glacier preservation; this is the maximum annual snow depth. Such kind of 3D visualisation has a great potential for promotion of other active or evolving passive geomorphosites too.

Climate sensitivity and geomorphological response of cirque glaciers from the late glacial to the Holocene, Sierra Nevada, Spain

Through a detailed geomorphological study, including thourough mapping of the geomorphic features as well as 10Be Cosmic-Ray Exposure (CRE) dating, the geomorphological evolution of the Mulhacén cirque since the maximum ice extent of the last glacial cycle until nowadays was determined. This glacial cirque is shaped on the northern face of the Mulhacén peak (3479 m a.s.l. 37°03′12″N/3°18′41″W), Sierra Nevada, southern Spain. It includes several depositional and erosional glacial landforms that allowed reconstructing its environmental evolution since the last glacial cycle. Furthermore, the sequence of glacial oscillations from this site was compared to that of other cirques of the massif, evidencing that: (i) new glaciers formed in these cirques during the Younger Dryas (YD), and (ii) disappeared at 11.7 ± 1.0 ka. Depending on the altitude, orientation and height of the cirque walls, the final deglaciation of the cirques generated a diversity of landscapes, including a wide range of glacial and periglacial landforms, such as polished surfaces, sequences of moraines, proto-rock glaciers or large rock glacier systems. No glaciers existed in the Sierra Nevada during the Middle Holocene. Only the cirques whose summits exceed 3300 m, are north-exposed and whose walls exceed 300 m high (i.e. Mulhacén and Veleta) hosted glaciers during Neoglacial phases, including the Little Ice Age (LIA) (approx. 1300–1850 CE). During these periods, climate oscillations favoured the formation of small glaciers in these cirques, which generated large moraine systems with either one polygenic ridge or a sequence of spaced frontal arcs. The existence of glaciers impeded the formation of permafrost-related landforms, such as rock glaciers and protalus lobes until the end of the LIA, when they started to form. These results are compared with the deglacial evolution in 55 cirques from Iberian mountains as well as from glacial cirques from other mid-latitude mountains and subpolar regions. The chronology of their deglaciation as well as the landforms generated during glacial retreat followed similar patterns, with no significant differences at regional scale. For each mountain range, the geomorphological diversity existing in each cirque depends on the local topographic characteristics although they formed during the same climatic phases.

Lateglacial and Holocene environmental history of the central Kola region, northwestern Russia revealed by a sediment succession from Lake Imandra

Bolshaya Imandra, the northern sub‐basin of Lake Imandra, was investigated by a hydro‐acoustic survey followed by sediment coring down to the acoustic basement. The sediment record was analysed by a combined physical, biogeochemical, sedimentological, granulometrical and micropalaeontological approach to reconstruct the regional climatic and environmental history. Chronological control was obtained by 14C dating, 137Cs, and Hg markers as well as pollen stratigraphy and revealed that the sediment succession offers the first continuous record spanning the Lateglacial and Holocene for this lake. Following the deglaciation prior to c. 13 200 cal. a BP, the lake's sub‐basin initially was occupied by a glacifluvial river system, before a proglacial lake with glaciolacustrine sedimentation established. Rather mild climate, a sparse vegetation cover and successive retreat of the Scandinavian Ice Sheet (SIS) from the lake catchment characterized the Bølling/Allerød interstadial, lasting until 12 710 cal. a BP. During the subsequent Younger Dryas chronozone, until 11 550 cal. a BP, climate cooling led to a decrease in vegetation cover and a re‐advance of the SIS. The SIS disappeared from the catchment at the Holocene transition, but small glaciers persisted in the mountains at the eastern lake shore. During the Early Holocene, until 8400 cal. a BP, sedimentation changed from glaciolacustrine to lacustrine and rising temperatures caused the spread of thermophilous vegetation. The Middle Holocene, until 3700 cal. a BP, comprises the regional Holocene Thermal Maximum (8000–4600 cal. a BP) with relatively stable temperatures, denser vegetation cover and absence of mountain glaciers. Reoccurrence of mountain glaciers during the Late Holocene, until 30 cal. a BP, presumably results from a slight cooling and increased humidity. Since c. 30 cal. a BP Lake Imandra has been strongly influenced by human impact, originating in industrial and mining activities. Our results are in overall agreement with vegetation and climate reconstructions in the Kola region.

Minor Imbalance of the Lowermost Italian Glacier from 2006 to 2019

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.

Glacier shrinkage in the Alps continues unabated as revealed by a new glacier inventory from Sentinel-2

Abstract. The ongoing glacier shrinkage in the Alps requires frequent updates of glacier outlines to provide an accurate database for monitoring, modelling purposes (e.g. determination of run-off, mass balance, or future glacier extent), and other applications. With the launch of the first Sentinel-2 (S2) satellite in 2015, it became possible to create a consistent, Alpine-wide glacier inventory with an unprecedented spatial resolution of 10 m. The first S2 images from August 2015 already provided excellent mapping conditions for most glacierized regions in the Alps and were used as a base for the compilation of a new Alpine-wide glacier inventory in a collaborative team effort. In all countries, glacier outlines from the latest national inventories have been used as a guide to compile an update consistent with the respective previous interpretation. The automated mapping of clean glacier ice was straightforward using the band ratio method, but the numerous debris-covered glaciers required intense manual editing. Cloud cover over many glaciers in Italy required also including S2 scenes from 2016. The outline uncertainty was determined with digitizing of 14 glaciers several times by all participants. Topographic information for all glaciers was obtained from the ALOS AW3D30 digital elevation model (DEM). Overall, we derived a total glacier area of 1806±60 km2 when considering 4395 glaciers >0.01 km2. This is 14 % (−1.2 % a−1) less than the 2100 km2 derived from Landsat in 2003 and indicates an unabated continuation of glacier shrinkage in the Alps since the mid-1980s. It is a lower-bound estimate, as due to the higher spatial resolution of S2 many small glaciers were additionally mapped or increased in size compared to 2003. Median elevations peak around 3000 m a.s.l., with a high variability that depends on location and aspect. The uncertainty assessment revealed locally strong differences in interpretation of debris-covered glaciers, resulting in limitations for change assessment when using glacier extents digitized by different analysts. The inventory is available at https://doi.org/10.1594/PANGAEA.909133 (Paul et al., 2019).

Assessment of Changes in Mass Balance of the Tuyuksu Group of Glaciers, Northern Tien Shan, Between 1958 and 2016 Using Ground-Based Observations and Pléiades Satellite Imagery

Continuous measurements of glaciological mass balance have been conducted at the Central Tuyuksu glacier, Tuyuksu group of glaciers, Ile Alatau, northern Tien Shan since 1957 showing that cumulative mass balance was negative since the 1970s. Geodetic mass balance was calculated for the 1958-1998 and 1998-2016 periods using multi-temporal digital elevation models derived from the historic photogrammetric surveys from 1958 and 1998, and the high-resolution Pleiades satellite stereo imagery from 2016. Geodetic measurements revealed a mean surface lowering of 23.2±2.2 m (0.40 ± 0.04 m a-1) and reduction in volume of (67.7±6.7)x106 m3 in 1958-2016 at the Central Tuyuksu glacier yielding a geodetic mass balance of -21.8±2.6 m w.e. Similar trends were observed at other glaciers of the Tuyuksu group which lost in total 83.4x106 m3 of ice. Annual rates of mass balance have not changed significantly from 1958-1998 (-0.39±0.05 m w.e.) to 1998-2016 (-0.35±0.18 m w.e.) at the Central Tuyuksu and at other glaciers of the Tuyuksu group whose maximum elevations exceed 4000 m a.s.l. While glacier thinning intensified in the ablation zone and affected larger area in 1998-2016 extending to 3600-3700 m a.s.l., accumulation increased at higher elevations in 1998-2016. Geodetic mass balance was more negative in 1998-2016 than in 1958-1998 at the smaller glaciers with lower maximum elevations. At the Central Tuyuksu, geodetic mass balance was in close agreement with glaciological mass balance particularly in 1958-1998 when the difference between the geodetic and cumulative glaciological mass balance values did not exceed 5 %. During 1998-2016, this difference increased to 14 % with glaciological method producing more negative mass balance. This discrepancy was attributed to a systematic bias introduced by the lack of stakes in the accumulation zone of Central Tuyuksu whose contribution to uncertainty increased in 1998-2016 in line with an increase in accumulation. Negative mass balance of the Tuyuksu group of glaciers was attributed to continuing increase in summer temperatures and low accumulation observed in the 1970s-1980s and at the turn of the century.

Multi-frequency and multi-attribute GPR data fusion based on 2-D wavelet transform

High frequency GPR signals offer high resolution while low frequency GPR signals offer greater depth of penetration. Effective fusion of multiple frequencies can combine the advantages of both. In addition, GPR attribute analysis can improve subsurface imaging, but a single attribute can only partly highlight details of different physical and geometrical properties of subsurface potential targets. In order to overcome these challenges, we implement an advanced multi-frequency and multi-attribute GPR data fusion approach based on 2-D wavelet transform utilizing a dynamic fusion weight scheme derived from edge detection algorithm, which is tested on data from a small glacier in the north-eastern Alps by 250 & 500 MHz central frequency antennas. Besides, information entropy and spatial frequency are developed as quantitative evaluation parameters to analyze the fusion outcomes. The results demonstrate that the proposed approach can enhance the efficiency and scope of GPR data interpretation in an automatic and objective way.

Rain-On-Snow (ROS) events and their relations to snowpack and ice layer changes on small glaciers in Svalbard, the high Arctic

The research consisted in a detailed analysis of Rain-On-Snow (ROS) events in the winter season (November–April) in the area of Waldemarbreen and Irenebreen – two glaciers subject to long-term monitoring on Kaffiøyra, NW Spitsbergen. The intensity and frequency of ROS events were evaluated along with their long-term variability in the years 1976–2018. An attempt was made to identify the relationship between ROS events and the properties of the snow cover of Waldemarbreen and Irenebreen – mainly changes in the number and thickness of ice layers and snow density, which have a major influence on the winter snowpack and on the time the snow begins to melt. These are some of the first studies of this type concerning not only glacier forefields but also changes occurring on glaciers. It was found that as the temperature of air has been rising in recent years, the melting of snow has been beginning earlier on glaciers and in their forefields. Also, the frequency and size of ROS events has increased. In recent years the number of days with heavy ROS events – mainly over 15 mm, but also under 15 mm – have been on the increase. The ROS events affect the number of ice layers, whereas heavy ROS events contribute to the formation of ice layers of greater thickness. The increase in ROS events is accompanied by a decrease in snow density on glaciers. As with the number of ROS events within a given year, there is also a clear increase in the number of ice layers and their thickness on the snow cover, in particular on small glaciers in the High Arctic.

Spatial Changes in Glaciers Between 1965 and 2018 in Tirungkhad Watershed, Upper Sutlej Basin, Himachal Pradesh

This paper is an attempt to estimate spatial changes (area and length in the frontal area) in glaciers of Tirungkhad watershed in Upper Sutlej Basin. It also investigates the influence of topography on the changes in glaciers. High-resolution (spatial) Corona KH4A (1965), Landsat TM (1990) and Sentinel 2B (2018) imageries and Aster GDEM elevation data have been used in this study to estimate changes of the glaciers between 1965 and 2018. Total 41 glaciers with an area of 58.73 km2 were mapped from Sentinel 2B imagery (2018). Due to cloud cover, 20 glaciers were selected for change calculation. During the period, 1965–2018, the glaciers have lost 1.95 ± 1.06 km2 or 5.58 ± 3.16% (0.11 ± 0.06%/year) of its total area. Average area loss rate was 0.037 ± 0.020 km2/year during 1965–2018. The glacier area change showed almost uniform rate throughout the period 1965–2018 (– 0.038 ± 0.053 km2/year during 1990–2018, and – 0.035 ± 0.057 km2/year during 1965–1990). Average retreat rate of glaciers was 6.76 ± 1.91 m/year during 1965–2018 (6.95 ± 2.08 m/year during 1965–1990 and 6.60 ± 1.74 m/year during 1990–2018). The topographic analysis showed that smaller glaciers had lost a higher percentage of area as compared to the larger glaciers.

Late Holocene Moisture Changes in the Core Area of Arid Central Asia Reflected by Rock Magnetic Records of Glacier Lake Kalakuli Sediments in the Westernmost Tibetan Plateau and their Influences on the Evolution of Ancient Silk Road

AbstractThe evolution of Ancient Silk Road (ASR) was deeply influenced by late Holocene moisture changes in Arid Central Asia (ACA). Nevertheless, controversies in Holocene moisture change pattern of ACA and poorly–constrained age models of related studies have made the discussion about late Holocene moisture changes in ACA and their influences on the evolution of ASR difficult. Recently, a high–resolution age model during the late Holocene was established for Kalakuli Lake, a small glacier lake located in the core area of ACA. A thorough rock magnetic investigation was carried out on Kalakuli Lake sediments based on this age model. The magnetic mineral assemblage of Kalakuli Lake sediments is still dominated by primary magnetite despite minor diagenetic effects. Comparisons of rock magnetic records to parameters previously used as indicator of glacier fluctuations suggest that clastic input to Kalakuli Lake was high (low) and magnetic grain size is relatively larger (smaller), when glaciers on Muztagh Ata advanced (retreated). The ARM/SIRM ratio, a magnetic grain size proxy, is directly related to lake hydrodynamics, which are ultimately controlled by glacier fluctuations on Muztagh Ata as the result of regional moisture changes. Late Holocene moisture changes indicated by the ARM/SIRM ratio are consistent with cool/wet and warm/dry oscillations indicated by the unweighted average of biomarker hydrogen isotopic data of the C26 and C28 n–alkanoic acids in a previous study about Kalakuli Lake, most moisture change records of the core area of ACA and winter insolation of the Northern Hemisphere, but opposite to Asian monsoon evolution. Given Asian monsoon and the westerlies are mutually inhibited, we propose that late Holocene moisture changes in the core area of ACA were controlled by the intensity of Asian monsoon versus the westerlies under the governance of solar insolation. Generally increased moisture since the late Holocene indicated by the ARM/SIRM ratio favored cultural exchange and integration between the western and the eastern Eurasia, which paved the way for the formation of ASR. Coincidence between significant increase in moisture at ~200 BC suggested by the ARM/SIRM ratio and the formation of ASR indicates moisture as an important factor that facilitated the formation of ASR. The onsets of three prosperity periods of ASR in the history generally correspond to periods when moisture was relatively high, nevertheless, stagnant periods of ASR do not coincide with periods when moisture was relatively low in the core area of ACA. Disorganized correlations between stagnant periods of ASR and moisture changes in the core area of ACA suggest that moisture is not the decisive factor influencing the evolution of ASR.

Discovery of a significant cave entrance in stripe karst, Horsethief Creek Group, Wells Gray Provincial Park, British Columbia, Canada

In April 2018, a significant cave entrance was recognized during an aerial survey in Wells Gray Provincial Park, British Columbia. A September 2018 assessment of the site confirmed one of the largest known, and previously undocumented, cave entrances in Canada. The feature is a large vertically walled sink swallowing a small river, likely leading to a spring 2.16 km horizontally from, and 460 m below, the sink. The entrance shaft was partially descended, surveyed, and found to have a volume of over 450 000 m3. Formed in a carbonate unit of the upper Proterozoic Horsethief Creek Group, the cave entrance occurs in stripe karst extending well beyond the known cave drainage. The disappearing river drains an area of 6.3 km2 in a valley containing two small glaciers. The river has a low flow (September) rate estimated at 0.3–0.5 m3/s, comparable with some of the largest sinks in Canada. Historic aerial photographs of the area show the entrance was hidden by perennial snowfields until regional climatic warming caused the snow plug to collapse sometime within the past decade.

The influence of water percolation through crevasses on the thermal regime of a Himalayan mountain glacier

Abstract. In cold and arid climates, small glaciers with cold accumulation zones are often thought to be entirely cold based. However, scattering in ground-penetrating radar (GPR) measurements on the Rikha Samba Glacier in the Nepal Himalayas suggests a large amount of temperate ice that seems to be influenced by the presence of crevassed areas. We used a coupled thermo-mechanical model forced by a firn model accounting for firn heating to interpret the observed thermal regime. Using a simple energy conservation approach, we show that the addition of water percolation and refreezing in crevassed areas explains these observations. Model experiments show that both steady and transient thermal regimes are significantly affected by latent heat release in crevassed areas. This makes half of the glacier base temperate, resulting in an ice dynamic mainly controlled by basal friction instead of ice deformation. The timescale of thermal regime change, in response to atmospheric warming, is also greatly diminished, with a potential switch from cold to temperate basal ice in 50–60 years in the upper part of the glacier instead of the 100–150 years that it would take without the effect of the crevasses. This study highlights the crucial role of water percolation through the crevasses on the thermal regime of glaciers and validates a simple method to account for it in glacier thermo-mechanical models.

Comparison of turbulent structures and energy fluxes over exposed and debris-covered glacier ice

AbstractWe present the first direct comparison of turbulence conditions measured simultaneously over exposed ice and a 0.08 m thick supraglacial debris cover on Suldenferner, a small glacier in the Italian Alps. Surface roughness, sensible heat fluxes (~20–50 W m−2), latent heat fluxes (~2–10 W m−2), topology and scale of turbulence are similar over both glacier surface types during katabatic and synoptically disturbed conditions. Exceptions are sunny days when buoyant convection becomes significant over debris-covered ice (sensible heat flux ~ −100 W m−2; latent heat flux ~ −30 W m−2) and prevailing katabatic conditions are rapidly broken down even over this thin debris cover. The similarity in turbulent properties implies that both surface types can be treated the same in terms of boundary layer similarity theory. The differences in turbulence between the two surface types on this glacier are dominated by the radiative and thermal contrasts, thus during sunny days debris cover alters both the local surface turbulent energy fluxes and the glacier component of valley circulation. These variations under different flow conditions should be accounted for when distributing temperature fields for modeling applications over partially debris-covered glaciers.

Constraints on the timing of debris-covered and rock glaciers: An exploratory case study in the Hólar area, northern Iceland

Eighteen samples for 36Cl Cosmic-Ray Exposure (CRE) dating were taken from glacially polished bedrocks, moraine boulders, fossil/active rock glaciers and debris-covered glaciers in Fremri-Grjótárdalur and Hóladalur cirques in the Víðinesdalur, Hofsdalur and Héðinsdalur valleys, close to Hólar village, in the Tröllaskagi peninsula, northern Iceland. Boulder sampling was preceded by a study of the boulder stability with the twofold aim of: ensuring that the surfaces to be sampled were stable enough for the reliable application of CRE dating, and to better understand the relation between the glacier dynamics and exposition history. The results show that the glaciers which occupy the valleys in Tröllaskagi began their retreat around 16 ka. Later, the glaciers advanced again around 11 ka within the cirques, and small moraines were formed. Thereafter, these small glaciers retreated and evolved into rock glaciers as debris from paraglacial processes accumulated on the glacier surface. The fronts of these rock glaciers stabilized definitively shortly after their formation and became eventually fossil after the melting of their internal ice. New rock glaciers and debris-covered glaciers formed afterwards, which still have internal ice at present, although their current dynamics are mostly related to subsidence. The stabilization of these rock glaciers and debris-covered glaciers is dated to the period between 7 and 3 ka, although they may have been reactivated during cold neoglacial periods. This research demonstrates the potential interest in applying CRE dating methods to debris-covered glaciers and rock glaciers to determine their origin, evolution and phase of cessation of internal movement until they finally lost their internal ice and became fossil.

Deformation Time Series and Driving-Force Analysis of Glaciers in the Eastern Tienshan Mountains Using the SBAS InSAR Method.

Glacier melting is one of the important causes of glacier morphology change and can provide basic parameters for calculating glacier volume change and glacier mass balance, which, in turn, is important for evaluating water resources. However, it is difficult to obtain large-scale time series of glacier changes due to the cloudy and foggy conditions which are typical of mountain areas. Gravity-measuring satellites and laser altimetry satellites can monitor changes in glacier volume over a wide area, while synthetic-aperture radar satellites can monitoring glacier morphology with a high spatial and temporal resolution. In this article, an interferometric method using a short temporal baseline and a short spatial baseline, called the Small Baseline Subsets (SBAS) Interferometric Synthetic-Aperture Radar (InSAR) method, was used to study the average rate of glacier deformation on Karlik Mountain, in the Eastern Tienshan Mountains, China, by using 19 Sentinel-1A images from November 2017 to December 2018. Thus, a time series analysis of glacier deformation was conducted. It was found that the average glacier deformation in the study region was −11.77 ± 9.73 mm/year, with the observation sites generally moving away from the satellite along the Line of Sight (LOS). Taking the ridge line as the dividing line, it was found that the melting rate of southern slopes was higher than that of northern slopes. According to the perpendicular of the mountain direction, the mountain was divided into an area in the northwest with large glaciers (Area I) and an area in the southeast with small glaciers (Area II). It was found that the melting rate in the southeast area was larger than that in the northwest area. Additionally, through the analysis of temperature and precipitation data, it was found that precipitation played a leading role in glacier deformation in the study region. Through the statistical analysis of the deformation, it was concluded that the absolute value of deformation is large at elevations below 4200 m while the absolute value of the deformation is very small at elevations above 4500 m; the direction of deformation is always away from the satellite along the LOS and the absolute value of glacier deformation decreases with increasing elevation.

Turkish glacier inventory and classification from high-resolution satellite data

In view of the rapid and accelerating glacier retreat observed worldwide, the creation of an updated glacier inventory is fundamental to understand the glacier changes. Here we present the Turkish glacier inventory based on recent high-resolution satellite images (Pleiades, Google Earth™ and SPOT images). Outlines are manually digitized in ArcMap software. We identified 51 glaciers covering 12.29 km2: more than 60% of the Turkish glacierized area is located on Mount Ararat where the ice cap and four small outlet glaciers cover 7.37 km2. Turkish glaciation is characterized by small glaciers or glacierets partly debris-covered: only three glaciers (Erinç, Izbırak and Ararat glaciers) are larger than 0.5 km2. To assess the evolution of glaciers, we have focused on Mount Ararat where we digitized outlines for 1990, 1994, 2000 and 2016: in 26 years considered the glacier shows a retreat of 2.99 km2, − 29% of the initial value, showing a reduction rate dramatically higher than the main glacierized mountain ranges of the world.

Chemical weathering in Antarctica: an example of igneous rock particles in Big Lachman Lake sediments, James Ross Island

Lacustrine sediments of the Big Lachman Lake (James Ross Island, Antarctica) are dominated by clay- and silt-sized particles of varied petrographic composition. These are of volcanic origin and are derived predominantly from the Mendel Formation. The intensity of chemical weathering of volcanic rock particles in the sediments was expressed by the Chemical Index of Alteration (CIA), which reflects alteration of feldspars and formation of clay minerals. The observed mineral assemblage of montmorillonite, illite, and kaolinite probably originated from alteration of volcanic glass and from alteration of feldspars to clay minerals. CIA weathering rates from the lacustrine sediments are similar to those of Early Jurrasic high-Ti volcanic rocks of the Mount Poster Formation and Middle Jurrasic high-Ti volcanic rocks of the Mapple Formation from the Antarctic Peninsula. However, the sediments show a good fit in OIB-normalized incompatible trace-element patterns only with the high-Ti volcanic rocks from the Middle Jurassic rhyolites of the Mapple Formation, while the fit with Cenozoic basalts of the James Ross Island Volcanic Group is poorer. Rocks from the Antarctic Peninsula were probably transported through the Prince Gustav channel by small glaciers during the Neogene and Quaternary.

The glacial history of Greece: a comprehensive review

This paper reviews the glacial history of the mountains of Greece at the southernmost tip of the Balkans, providing a new synthesis of our current understanding of glaciations. The ice cover during the largest Middle Pleistocene glaciations (MIS 12/MIS 6) was more extensive than previously thought. Latest evidence from Mt Chelmos suggests that valley glaciers radiated from a central plateau ice field, whereas the findings of other glacial studies in western Balkans further indicate that extensive ice field/ice caps formed on mountains throughout this region during the Middle Pleistocene glaciations. Ice extent was considerably smaller during the Tymphian Stage (MIS 5d–MIS 2) and this has been confirmed by cosmogenic exposure ages in recent studies on Mt Olympus and Mt Chelmos. During the Holocene, only very small glaciers formed in some deep cirques where they survived because of strong local topoclimatic controls. A comparative analysis with the findings of other glacial and palaeoclimatic studies in the Balkans is also presented to highlight correlations between them. Moisture supply seems to have been the most critical factor for the formation of glaciers in the mountains of Greece. The comparison of Late Pleistocene Equilibrium Line Altitudes (ELAs) across the Balkans indicates a wetter climate in southern Greece that can be attributed to different palaeoatmospheric circulation mechanisms and precipitation regime in central Mediterranean. Conclusively, whilst important information has been added in the last 2 decades, this paper highlights the need for further research in Greece and the wider Balkans to establish the timing and extent of glaciations.

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.