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• Scientific literature since 1920 is analysed quantitatively and qualitatively. • All cryospheric elements (glacier, snow, (perma) frost) are considered. • Almost half (46.2 %) of the papers focus on soil formation after glacier retreat. • Half of the papers study primarily direct interactions between cryosphere and soil. • Literature that covers geomorphodynamical changes is represented the least. A review of the status of research on high mountain soils and their alterations caused by changes in the cryosphere in the European Alps is given. Soils of high mountain environments are not only exposed to atmospheric warming, rising CO 2 levels, and changing precipitation patterns but also to climate-driven changes in the cryosphere. The massive reduction of glacier coverage as well as snow cover and (perma) frost extent can affect soils in various ways. We performed a comprehensive literature analysis and considered both the direct impacts (changes in surface coverage or ground thermal conditions) and indirect impacts (changing hydrosphere, lithosphere/geomorphodynamics, or biosphere) of cryosphere changes on soil. All considered studies had a multidisciplinary character: around 34 % of the articles covered two spheres (cryosphere, pedosphere), 40 % covered three spheres (cryosphere, pedosphere, and an additional sphere), and 26 % covered more than three spheres. Most studies focused on initial soil formation in glacier forefields. The impact of changing geomorphodynamics on soils is underrepresented in literature, even though it is one of the major consequences of changes in the cryosphere. We therefore finally discuss possible consequences of changing geomorphodynamics due to changes in the cryosphere for high mountain soils. [ABSTRACT FROM AUTHOR]

Abstract During the Quaternary several glaciations occurred in the mountain regions around the Mediterranean and, in recent years, new ages have better constrained their timing. However, this is not the case for the Apuan Alps, a high-rainfall mountain chain adjacent to the Mediterranean Sea. Here, in spite of the widespread evidence for glaciers, the complete lack of geochronological information hinders our understanding of glaciation history. In this paper, we utilize speleothem ages to better constrain the timing of these glacial features. We re-examine 293 uranium‑thorium ages from 19 speleothems collected in five caves at different elevations. After a period of very low growth between 160 and 132 ka, the analysed speleothems grew almost continuously to ~75 ka, this period was followed by intermittent growth with lower deposition rate and presence of hiatuses until ~12.5/12 ka. This is consistent with an ice coverage persisting over the Apuan Alps, inhibiting or interrupting the growth of speleothems via the limited availability of groundwater and the scarcity/absence of soils. This interval is much greater than the time interval that has previously been attributed to the existence of glaciers on the Apuan Alps, which has been assumed to be restricted to Marine Isotope Stage (MIS) 2. Instead, ice cover probably also appeared in the Apuan Alps during MIS 4. The phase of restarting of growth, which may implies the definitive or substantial glacier melts seem to predate the Holocene. Highlights • Speleothem growth curves used to better constrain the timing of glacial features. • 293 U\Th ages from 19 speleothems collected in five caves at different elevations. • Glacial expansion in the Apuan Alps was not only limited to the MIS2. [ABSTRACT FROM AUTHOR]

Abstract The Ny-Alesund region is characterised by diversified surface processes which carve the landscape and so exhibits variable and complex landforms. Extensive work has been carried out on climate change using various proxies however no much attention has been paid in understanding the climate events using geomorphological and sedimentological parameters. In the present paper sediment characteristics, AMS 14C dates and geomorphic features have been used for the reconstruction of palaeoclimate. On the basis of distribution of landforms, and sediments, this region has been classified into five morphological zones such as glacial (moraines GL), proglacial (lacustrine deposits LD), outwash plain (sandur deposits OWP), fluvial deposits (FD) and coastal cliff (CC). The geomorphic analysis and sedimentary parameters revealed that GL consists of unconsolidated, unstratified, massive, devoid of any sedimentary structures, coarse grained, matrix supported boulders, whereas OWP, LD, FD and CC are semi-consolidated, stratified, fine grained, layers of sand, silt, and clay with gravels and faint sedimentary structures. The sediments of CC and LD are very poorly sorted, very positively skewed, very leptokurtic, medium to fine sand, silt and clay. The sediment characteristics coded in the geomorphic features of various morphological zones explains that this region was carved and dominated by glaciers under cold climate at ice stages during 47.5, 38, 23, 18, 8.8, 6.l, 1 ka BP and paraglacial processes under warm climate at interglacial stages during 44, 27, 12, 10.5 ka BP. The poorly sorted sediments for all the morphological zones explain the fluctuating energy of the depositional environment and so the prevailing climate was not consistent and persistent for long period of time. [ABSTRACT FROM AUTHOR]

Abstract: This paper describes a multi-temporal grid method for quantifying changes in glacier coverage. A multi-temporal grid synthesizes spatial, attribute and process components of glacier information by sequentially combining spatial data from satellite images or maps. It enables us to identify glacier retreat and advance areas in individual grid cells for three or more periods of data sets. Discrepancies among the sequential data sets were detected graphically and numerically, including noise from geo-location error, misclassification, or different interpretation results in various pixel resolutions. Noise was detected and corrected to a large extent by visualization of the synthetic grid. The paper compares the results with that from a common method based on individual data sets, focusing on the Mt. Naimona’Nyi and Mt. Qomolangma regions at the northern slopes of the Himalayas. Results show that the identified noise (e.g. by 2.5km2 in the Mt. Naimona’Nyi region) is much larger than measurement uncertainty calculated by sensor resolution and co-registration error (e.g. by 0.015km2 in the Mt. Naimona’Nyi region). After noise removal, we notice that glacier recession clearly accelerates. The multi-temporal grid method results in a better quantification of glacier variation. It shows that glaciers in the Himalayas have both retreated and advanced during the last several decades, with retreat dominating and accelerating. Glaciers on the northern slope of Mt. Qomolangma in the middle Himalayas retreat more extensively and faster than those in the Mt. Naimona’Nyi region in the western Himalayas. [Copyright &y& Elsevier]

In recent years, increasing moisture over the Arctic and subarctic regions shows that the Arctic is experiencing wetting conditions, and poleward atmospheric moisture transport (PAMT) plays a vital role in the atmosphere-ice/snow interactions in the Arctic. To identify the effect of PAMT on the surface energy balance (SEB) for the Arctic glacier, meteorological data from an automatic weather station (AWS) at 377 m a.s.l. on the Austre Lovénbreen glacier, as well as the ERA5 reanalysis data from 30 April 2014 to 30 April 2015, were analyzed in this paper. Our results show that the net shortwave radiation (S net) (18 W m−2, 55%), turbulent sensible (H) (14 W m−2, 43%) and subsurface heat flux (G) (1 W m−2, 2%) act as the energy sources, while the net longwave radiation (L net) (−19 W m−2, 56%), melt energy (Q m) (−12 W m−2, 35%) and turbulent latent heat flux (LE) (−3 W m−2, 9%) represent the heat sink. The development process of Atmospheric River (AR), primary form of PAMT, near the Svalbard in February 2015 was revealed according to the total column water vapor, 850 hPa winds and geopotential height fields. Compared to summer, the glacier SEB was more affected in winter by PAMT, leading to a frequent overcast and thus increasing air temperature, moisture, and wind speed, all of which are variables governing the SEB by decreasing H, LE and G less than increasing the L net. Our findings obtained here can help to better understand the diverse SEB change on the high Arctic glacier from the perspective of PAMT and large-scale atmospheric circulations anomalies. [ABSTRACT FROM AUTHOR]

Supraglacial debris complicates the melting state of debris-covered glaciers, and whether debris increases or decreases the rate of glacier melt is ambiguous according to different observations. In this paper, we aim to determine the potential factors that influence changes in thickness of debris-covered glaciers. First, we present the thickness changes of a large debris-covered glacier in the Tienshan Mountain using high-resolution Digital Elevation Model (DEM) data from three periods in 2000, 2009 and 2013. It is shown that the thickness changes differ greatly over the debris-covered portions of the glacier. These debris-covered regions can be divided into three parts along the glacier axis according to the rate of thickness change. Specifically, these parts include the zone of minimal change, the zone of heavy thinning, and the zone of slight thinning. Detailed information on the closely related factors, including the debris thickness, which was measured across the whole glacier during our field work, and the presence of ice cliffs and supraglacial lakes detected on high-resolution satellite images, are combined to determine the reasons for the differences in melting state among the three zones. The results show that the thickness changes of the debris-covered glacier are jointly influenced by debris thickness and the presence of ice cliffs and supraglacial lakes; moreover, the dominant factor differs among the different zones. The critical debris thickness, which mostly appears in the minimal change zone and accelerates glacier melting, as confirmed through field observations, is not associated with glacier thinning because its location is close to the accumulation zone. The regions where the rates of thinning are greatest coincide with the regions where the ice cliffs are densest. Where the debris is thicker than 1 m on average, the glacier is still thinning slightly due to the presence of ice cliffs and lakes. It is proven that the quantity and area of the ice cliffs and supraglacial lakes is the key to understanding the melting rate of debris covered glacier. [ABSTRACT FROM AUTHOR]

This paper presents a Glacier Termini Tracking (GTT) toolbox for the two-dimensional analysis of glacier-terminus position changes. The input consists of a vector layer with several termini lines relating to the same glacier at different times. The output layers allow analyses to be conducted of glacier-terminus retreats, changes in retreats over time and along the ice face, and glacier-terminus fluctuations over time. The application of three tools from the toolbox is demonstrated via the analysis of eight glacier-terminus retreats and fluctuations at the Hornsund fjord in south Svalbard. It is proposed that this toolbox may also be useful in the study of other line features that change over time, like coastlines and rivers. The toolbox has been coded in Python and runs via ArcGIS. [ABSTRACT FROM AUTHOR]

We review the scientific efforts over the last decades to reconstruct erosion from continuous alpine lake sediment records. We focused both on methodological issues, showing the growing importance of non-destructive high resolution approaches (XRF core-scanner) as well as progresses in the understanding of processes leading to the creation of an “erosion signal” in lakes. We distinguish “continuous records” from “event-records”. Both provide complementary information but need to be studied with different approaches. Continuous regionally-relevant records proved to be particularly pertinent to document regional erosion patterns throughout the Holocene, in particular applying the source to sink approach. Event-based approaches demonstrated and took advantage of the strong non-linearity of sediment transport in high altitude catchment areas. This led to flood frequency and intensity reconstructions, highlighting the influence of climate change upon flood dynamics in the mountain. The combination of different record types, both in terms of location (high vs. low elevation), sedimentology (high vs. low terrigenous contribution) and significance (local vs. regional) is one of the main outputs of this paper. It allows the establishment of comprehensive histories of NW French Alps erosion, but also and consequently, soil dynamics and hydrological patterns throughout the Holocene. We also discuss the influence of glacier dynamics, one of the major agents of erosion in the Alps. A major feature is the growing human influence upon erosion at a local scale since at least the middle of the Bronze Age (3500 cal. BP). However and according to the regional record from Lake Bourget, only few periods of rising erosion at local scales generated a regional record that can be discriminated from wetter climatic periods. Among them, the period between 200 BCE and 400 AD appeared to be marked by a generalised rise in human-triggered erosion at local scales in the northern French Alps. This review highlights the importance of modern high-resolution and interdisciplinary studies of lake sediments, in order to better understand the complex relationships between humans, climate and the Earth system in general. We strongly argue that regional integration of data is now required to move a step further. Such an integration is easier with cost- and time-effective methods as well as after a better definition of approaches and their limits. This should lead to a stronger collaboration between paleo-data producers and modellers in the near future. [ABSTRACT FROM AUTHOR]

The cryosphere consists of frozen water and includes lakes/rivers/sea ice, glaciers, ice caps/sheets, snow cover, and permafrost. Because highly reflective snow and ice are the main components of the cryosphere, it plays an important role in the global energy balance. Thus, any qualitative or quantitative change in the physical properties and extents of the cryosphere affects global air circulation, ocean and air temperatures, sea level, and ocean current patterns. Due to the hardships involved in collecting ground control points and field data for high alpine glaciers or vast polar ice sheets, several researchers are currently using remote sensing. Satellites provide an effective space-borne platform for remotely sensing frozen areas at the global and regional scales. However, satellite remote sensing has several constraints, such as limited spatial and temporal resolutions and expensive data acquisition. Therefore, aerial and terrestrial remote sensing platforms and sensors are needed to cover temporal and spatial gaps for comprehensive cryospheric research. Light Detection and Ranging (LiDAR) antennas form a group of active remote sensors that can easily be deployed on all three platforms, i.e., satellite, aerial, and terrestrial. The generation of elevation data for glacial and snow-covered terrain from photogrammetry requires high contrast amongst various reflective surfaces (ice, snow, firn, and slush). Conventional passive optical remote sensors do not provide the necessary accuracy, especially due to the unavailability of reliable ground control points. However, active LiDAR sensors can fill this research gap and provide high-resolution and accurate Digital Elevation Models (DEMs). Due to the obvious advantages of LiDAR over conventional passive remote sensors, the number of LiDAR-based cryospheric studies has increased in recent years. In this review, we highlight studies that have utilised LiDAR sensors for the cryospheric research of various features, such as snow cover, polar ice sheets and their atmospheres, alpine glaciers, and permafrost. Because this technology shows immense promise for applications in future cryospheric research, we also emphasise the prospects of utilising LiDAR sensors. In this paper, a large compilation of relevant references is presented to allow readers to explore particular topics of interest. [ABSTRACT FROM AUTHOR]

Glaciers are an important climate indicator due to their sensitive dependence upon local and regional climate variables, which makes them worthwhile research subjects. A comprehensive description of the glaciers' interaction with the environment and their dynamical behavior requires complex physical models and the measurement of relevant parameters. In-situ data acquisitions are costly and often spatially sparse due to the large extent of glaciers; however, satellite-based sensors offer timely data with complete ground coverage, making them a good choice for continuous monitoring of glaciers. Synthetic aperture radar (SAR) allows a nearly weather-independent monitoring of glacier motion, which is beneficial for often cloudy regions like Alaska or Patagonia. This paper presents a new workflow for the automatic extraction of glacier surfaces from SAR intensity images and the determination of their velocities involving a fluid mechanics model. An initial motion estimation is obtained from intensity tracking on SAR image pairs and subsequently corrected by a physics-based spatial regularization. The surface velocity is approximated by the two-dimensional Navier–Stokes equation for incompressible fluids. The regularization is formulated as a data assimilation problem in which the final solution is a proper solution of the Navier–Stokes equation and simultaneously fitted to the observed velocity. This partial differential equation (PDE) constrained optimization is solved with adjoint models using finite element methods. The proposed method is evaluated on the Taku Glacier, AK, an outlet glacier of the Juneau Icefield. Our presented approach is independent from the type of sensor as long as initial velocity estimates can be obtained. The final results can be used as input to methods estimating ice volume and thickness. [ABSTRACT FROM AUTHOR]

Although glacial landsystems produced under warm/wet based conditions are very common on Earth, even here, observations of subglacial landforms such as eskers emerging from extant glaciers are rare. This paper describes a system of sinuous ridges emerging from the in situ but now degraded piedmont terminus of a Late Amazonian-aged (∼150 Ma) glacier-like form in the southern Phlegra Montes region of Mars. We believe this to be the first identification of martian eskers that can be directly linked to their parent glacier. Together with their contextual landform assemblage, the eskers are indicative of significant glacial meltwater production and subglacial routing. However, although the eskers are evidence of a wet-based regime, the confinement of the glacial system to a well-defined, regionally significant graben, and the absence of eskers elsewhere in the region, is interpreted as evidence of sub-glacial melting as a response to locally enhanced geothermal heat flux rather than climate-induced warming. These observations offer important new insights to the forcing of glacial dynamic and melting behaviour on Mars by factors other than climate. [ABSTRACT FROM AUTHOR]

Cirques are glacially eroded, bowl-shaped depressions, characterised by steep headwalls and flat or overdeepened floors. Given their association with past glaciers, cirques are sometimes used as proxies for palaeoclimate. However, cirques are shaped over multiple glacial cycles, and their usefulness as palaeoclimate indicators therefore remains open to question. In this paper, we map 3984 glacier-free cirques across the Scandinavian Peninsula and analyse variations in cirque floor altitude (CFA). We explore the relationships between CFAs and cirque aspect, latitude, longitude, and distance to the coast. We test the validity of using CFAs as indicators of palaeoclimate through comparison with the equilibrium-line altitudes (ELAs) of 513 modern cirque glaciers. Results indicate that both CFAs and modern cirque-glacier ELAs decrease with latitude and vary with aspect, being generally lowest on east-facing slopes. However, the clearest and strongest trend in both CFAs and modern cirque glacier ELAs is an increase in elevation with distance from the modern coast (i.e., distance 'inland'). This likely indicates that similar climatic gradients, particularly an inland reduction in precipitation, acted to regulate former sites of glacier initiation (reflected by CFAs) and modern glacier ELAs. This would imply that CFAs are a useful proxy for palaeoclimate. However, we note that both CFAs and modern ELAs reflect the general topography of this region (with increasing elevations moving inland), and the glacial history of the area (indirectly linked to palaeoclimate) may have played a role in regulating where cirques have formed. For these reasons, we suggest that palaeoclimatic interpretations derived from CFAs should be treated with caution. • We analyse cirque floor altitudes as a proxy for palaeo ELAs across the Scandinavian Peninsula. • Results indicate that precipitation and temperature play a key role in regulating past and present ELAs. • The dominant trend in cirque floor altitudes shows increasing values with distance inland from the coast. [ABSTRACT FROM AUTHOR]

The Cordillera Blanca, located in the central zone of the Andes Mountains in Peru, has shown a retreat in its glaciers. This paper presents a trend analysis of the glacier area over the groups of Nevados Caullaraju-Pastoruri from 1975 to 2010 using Landsat-5 Thematic Mapper (TM) imagery. In the case of the Nevados Pastoruri/Tuco, the study period was extended back to 1957 by using an aerial photograph taken that year. The extent of clean glacier ice was estimated using Normalized Difference Snow Index (NDSI) thresholds. Moreover, the estimation of debris-covered glacier ice was retrieved by means of a decision tree classification method using NDSI, Normalized Difference Vegetation Index (NDVI) and Land Surface Temperature (LST). Area estimations derived from Landsat imagery were compared to the glacier ground-truth data in 1975 and 2010. Results show a statistically significant (p < 0.05) decreasing trend over the whole study area. Total glacier area decreased at a rate of 4.5 km 2 per decade from 1975 to 2010, with a total loss of 22.5 km 2 (58%). Lower decreasing rates were found for the period 1987–2010: 3.5 km 2 per decade with a total loss of 7.7 km 2 (32.5%). In the case of the Nevados Pastoruri/Tuco, decreasing rates of clean ice extent were constant for the periods 1957–2010, 1975–2010 and 1987–2010, with values close to 1.4 km 2 per decade and a total loss between 1957 and 2010 estimated at about 5 km 2 (54%). This work shows an evident area decrease in the Caullaraju-Pastoruri tropical glaciers, which needs to be included in a future hydrological scenario of local adaptability and water management. [ABSTRACT FROM AUTHOR]

Contaminants in the Canadian Arctic have been studied over the last twenty years under the guidance of the Northern Contaminants Program. This paper provides the current state of knowledge on mercury (Hg) in the Canadian Arctic terrestrial environment. Snow, ice, and soils on land are key reservoirs for atmospheric deposition and can become sources of Hg through the melting of terrestrial ice and snow and via soil erosion. In the Canadian Arctic, new data have been collected for snow and ice that provide more information on the net accumulation and storage of Hg in the cryosphere. Concentrations of total Hg (THg) in terrestrial snow are highly variable but on average, relatively low (< 5 ng L - 1 ), and methylmercury (MeHg) levels in terrestrial snow are also generally low (< 0.1 ng L - 1 ). On average, THg concentrations in snow on Canadian Arctic glaciers are much lower than those reported on terrestrial lowlands or sea ice. Hg in snow may be affected by photochemical exchanges with the atmosphere mediated by marine aerosols and halogens, and by post-depositional redistribution within the snow pack. Regional accumulation rates of THg in Canadian Arctic glaciers varied little during the past century but show evidence of an increasing north-to-south gradient. Temporal trends of THg in glacier cores indicate an abrupt increase in the early 1990s, possibly due to volcanic emissions, followed by more stable, but relatively elevated levels. Little information is available on Hg concentrations and processes in Arctic soils. Terrestrial Arctic wildlife typically have low levels of THg (< 5 μg g - 1 dry weight) in their tissues, although caribou ( Rangifer tarandus ) can have higher Hg because they consume large amounts of lichen. THg concentrations in the Yukon’s Porcupine caribou herd vary among years but there has been no significant increase or decrease over the last two decades. [ABSTRACT FROM AUTHOR]

The study of Pleistocene glaciations in the Dinaric Alps began at the end of the 19th century. Since then, the interpretation of glaciation in this area has not seen much study until the beginning of the 21st century, when a few modern geomorphological studies with numerical dating and equilibrium line altitude (ELA) reconstructions were carried out in the SE part of the Dinaric Alps (where Mount Lovćen is situated). The morphology of Mount Lovćen consists of a karst landscape modified by glacial processes. This paper presents geomorphological evidence of glaciations on Mount Lovćen, along with a reconstruction of paleoglacier dimensions and estimations of the paleo-equilibrium line altitude. Mapping of glacial landforms on Mount Lovćen revealed at least two different glacial events. Only limited patches of older glacial deposits were identified, and therefore the reconstruction of glacier dimensions and ELA were only performed for the younger glaciation. This glacier extended over an area of at least 39.9 km 2 and reached a maximum thickness of about 290 m. The regional ELA for the Mount Lovćen glaciers was calculated as 1259 m. [ABSTRACT FROM AUTHOR]

TanDEM-X SAR mission was launched in June, 2010 with an aim to generate high resolution global DEMs of HRTI-3 specification. Considering this, it is very important to evaluate the accuracy of the DEM generated using TanDEM-X InSAR data over the rugged terrains of Indian Himalayas. This paper presents the results of an evaluation study of the DEMs generated through interferometric technique using TanDEM-X data over two Indian Himalayan glaciers viz. Hamtah and Gangotri. The two generated DEMs have been compared with the corresponding accurate Differential Global Positioning System (DGPS) values. On the basis of comparison of the elevation values between TanDEM-X DEM and DGPS data, it is observed that the Hamtah and Gangotri glacier DEMs show RMSE values 7.0 m and 8.2 m respectively. To evaluate the performance between TanDEM-X DEM and SRTM DEM, the SRTM DEM of the Hamtah glacier has also been compared with the DPGS points of Hamtah glacier and found to have a RMSE of 13.5m. Overall, the obtained results indicate that the generated TanDEM-X DEMs are of superior quality. [ABSTRACT FROM AUTHOR]

Summary Glacier and snow cover changes with related impacts on melt runoff can seriously affect human societies which are depending on fresh water from cryospheric sources. Observed trends and projected future evolutions of climatic and cryospheric variables clearly show the need to adapt to these changes. Accordingly, the topics addressed herein have been put on the agendas of many larger funding agencies. This article provides a brief overview on major ongoing activities on glacier, snow and related runoff research in order to then analyze data gaps and research needs from a climate change adaptation perspective. Major data needs are identified with respect to the spatial and temporal coverage of local-scale data and related needs for (data) services that distribute and maintain these data sets. Moreover, clear research needs are also recognized at the local scale where process knowledge needs to be improved (e.g., the influence of albedo on snow and ice or debris cover on glaciers) in order to derive plausible climate change impacts assessments. The paper then discusses directions on how to move forward to better serve the practical needs for climate change adaptation planning. In the future, substantial support by large funding agencies might be key for capacity building in target regions of climate change adaptation programs, for longer-term and more sustainable commitments, and for the development of approaches, which aim at assessing the transferability of data, techniques, and tools. [ABSTRACT FROM AUTHOR]

Abstract: During the last two decades surface elevation data haven been gathered over the Greenland Ice Sheet (GrIS) from a variety of sensor, ranging from laser altimetry to stereoscopic DEMs derived from imaging sensors. The spatio-temporal resolution, the accuracy and the spatial coverage among the data differ widely. For example, ICESat, a spaceborne laser profiler, has a high temporal resolution but sparse spatial coverage which places the nearest ground track to the calving front of the Kangerlussuaq Glacier in East Greenland, our study site, 30km up stream. On the other hand, stereoscopic DEMs provide almost continuous spatial coverage, but at a lower accuracy. This is a typical scenario for many rapidly changing outlet glaciers in Greenland where a fusion of the disparate data sets is highly desirable to construct detailed spatio-temporal histories of elevation change. We present in this paper how our recently developed SERAC method (Surface Elevation Reconstruction And Change detection) is well suited to cope with this fusion problem. More specifically, we describe a novel approach to adjust stereoscopic DEMs to the laser altimetry point cloud, based on height corrections determined from the time-series of elevation changes calculated by SERAC. These corrections are then used in a height adjustment of the DEMs. [Copyright &y& Elsevier]

Abstract: Debris cover is widely present in the ablation areas of mountain glaciers. Such debris plays an important role in glacier mass balance, but it complicates the glacier boundary and area estimation when using remotely sensed images. Automatic recognition of the debris is much more difficult than recognizing bare ice on optical remotely sensed images because the debris has almost the same spectral characteristics of the surrounding terrain. In this paper, the scattering characteristics of the debris on the C- and L-band polarimetric SAR images are presented and analyzed to study the possibility of recognizing debris thickness and extent. The Koxkar glacier, in the central Tianshan Mountain Range, was selected as the study area. It was found that debris is distinct from bare ice in cross polarization (HV) of both the L- and C-bands. The L-band volume scattering component, acquired from target decomposition, increases with debris thickness when the debris is less than 25cm deep, but the volume scattering does not increases if the debris is thicker than 25cm. In contrast, the C-band SAR data does not appear to be sensitive to debris thickness. This difference may be caused by different radar penetration depth of the debris. On the basis of the polarimetric property analysis, two methods were developed to determine the extent of the debris. In the first method, the simple threshold to distinguish debris from non-debris areas is presented. Using this threshold, approximately 90% of the debris can be recognized. In the second method, by combining more polarimetric features and support vector machines, recognition of debris reaches an accuracy greater than 95%. [Copyright &y& Elsevier]

In this paper we used ground-based thermal infrared imaging to investigate the spatial variability of surface temperatures on a mountain glacier at high spatial resolution and to estimate the supraglacial debris thickness distribution. The surveyed area is the eastern tongue of Gran Zebrù glacier, a small mountain glacier of the Ortles-Cevedale group (Italy). A FLIR E85 Thermal Camera was used to obtain a panoramic thermal image of the glacier surface on 30 September 2019 that was calibrated and georeferenced in order to obtain surface temperatures. Based on field data, debris thickness and debris surface temperature were correlated by using an exponential equation. The equation was used to estimate debris thickness on the glacier from the temperature data. The results show a spatial variability of surface temperatures, with the lowest temperatures found on snow and ice surfaces, and the highest on supraglacial debris. The estimated debris thicknesses show an inhomogeneous distribution, with a calculated mean debris thickness of 0.09 m in the areas of continous debris coverage. We found a good correspondence between measured and estimated debris thickness at 30 validation points (RMSE = 0.04 m and r = of 0.92). We demonstrated that ground-based thermal imaging can provide very high resolution maps of glacier surface temperatures and of debris thickness that can be used for the estimation of glacier ablation, with a spatial resolution more suitable than that offered by satellite data, especially for glaciers with a small area and with a heterogeneous surface. • Thermography is a valid tool to map debris thickness. • There is a good relation between debris thickness and surface temperature until 0.5 m of thickness. • Debris thickness spatial variability is relevant for the ablation of a glacier. • There is a good relation between estimated and measured debris thickness with the thermography. [ABSTRACT FROM AUTHOR]

Mt. Everest (Qomolangma or Sagarmatha), the highest mount on Earth and located in the central Himalayas between China and Nepal, is characterized by highly concentrated glaciers and diverse landscapes, and is considered to be one of the most sensitive area to climate change. In this paper, we comprehensively synthesized the climate and environmental changes in the Mt. Everest region, including changes in air temperature, precipitation, glaciers and glacial lakes, atmospheric environment, river and lake water quality, and vegetation phenology. Historical temperature reconstruction from ice cores and tree rings revealed the distinct features of 20th century warming in the Mt. Everest region. Meteorological observations further proved that the Mt. Everest region has been experiencing significant warming (approximately 0.33 °C/decade) but relatively stable precipitation during 1961−2018 AD. Projected results (during 2006−2099 AD) under different representative concentration pathway scenarios showed a general warming trend in the region, with larger warming occurring in winter than in summer. Meanwhile, the precipitation projections varied spatially with no significant trends over the region. Intensive glacier shrinkage was characterized by decreasing glacier areas, while glacier-fed river runoff increased. Glacial lakes expanded with increasing glacial lake areas and numbers. These findings indicated a clear regional hydrological response to climate warming. Owing to the remote location of Mt. Everest, the present atmospheric environment remained relatively clean; however, long-range transport of atmospheric pollutants from South Asia and West Asia may have substantially influenced the Mt. Everest region, resulting in increasing concentrations of pollutants since the Industrial Revolution. Anthropogenic activities have been shown to influence river and lake water quality in this remote region, especially in the downstream. The end of the vegetation growing season advanced in the northern slope and did not change in southern slope region of the Mt. Everest, and there was no significant change in start date of the growing season in the region. This review will enhance our understanding of climate and environmental changes in the Mt. Everest region under global warming. • Climate and environmental changes were synthesized in the Mt. Everest region. • Glaciers have retreated significantly, posing impacts to river runoff and glacial lakes. • Transboundary transport of atmospheric pollutants influenced the region. • TThere was no significant change in start date of the growing season. [ABSTRACT FROM AUTHOR]

Abstract: This paper provides an overview of a 100 year history of hydropower in Nepal. The importance of hydropower in Nepal is highlighted and major issues that the country has to consider for the development of hydropower have been analysed in detail. It is the only resource available to generate electricity, both for large export projects and small village mini grid projects in almost any part of the country. The challenges of demand and supply fluctuations, mainly due to the seasonal fluctuation of river discharges, are also described. An analysis of river flow trends shows that the impact of river flow has to be analysed river by river, as the trends are not consistent throughout the country. The social and organisational issues and their relationship with the political stability in the country have also been discussed. [Copyright &y& Elsevier]

Abstract: Since 2000, 18 High Asia glaciers have been surveyed for black carbon (BC) deposition 22 times, and numerous snow samples and ice cores have been collected by researchers. However, most of the results were interpreted individually in papers. Here, we assemble the data and discuss the distribution of BC deposition and its impacts on the melting of the glaciers through radiative forcing. We find that BC distribution on the surfaces of High Asia glaciers primarily depends upon their elevations (i.e., higher sites have lower concentrations) and then upon regional BC emissions and surface melting conditions. BC concentrations in High Asia glaciers are similar to the Arctic and western American mountains but are significantly less than heavy industrialized areas such as northern China. Although Himalayan glaciers, which are important due to their water resources, are directly facing the strong emissions from South Asia, their mean BC is the lowest due to high elevations. A new finding indicated by ice core records suggested that great valleys in the eastern Himalayan section are effective pathways for BC entering the Tibetan Plateau and make increasing BC trends in the local glaciers. On average, BC deposition causes a mean forcing of ∼6 Wm−2 (roughly estimated 5% of the total forcing) in High Asia glaciers and therefore may not be a major factor impacting the melting of most glaciers. [Copyright &y& Elsevier]

Abstract: Glaciers flow velocity is an important parameter for the study of glacier dynamics, mass balance and climate change, and can provide precursory warning of glacier melting induced flooding, debris flowing, etc. The Tuomuer-Khan Tengri Mountain Range is one of the largest glaciated areas in Tian Shan Mountain. However, the knowledge of glacier motion in this area is still rather limited. Using the method of robust Offset-tracking and four pairs of PALSAR images covering the Tuomuer-Khan Tengri Mountain Range, this paper estimates the displacement fields of the mountain glaciers in this area for each pair. The displacement fields are then mapped into daily glacier flow velocities by dividing the acquiring intervals of each pair. Using a series of checkpoints selected in stationary areas where the displacements can be assumed to be zero, we evaluate the estimation error of the displacement fields and find that most of them are less than 2.17cm/day. The displacement fields are analyzed in detail with regards to glacier bed terrain and glacial temperature and thickness. We find that they are in excellent accordance with the flow characteristic of typical mountain glaciers. The velocity changes among the observation years have been carefully examined. This along with the associated runoff measurements makes us conclude that the glaciers in the Tuomuer-Khan Tengri Range are assumedly in dynamic equilibrium between intensified melting and increased precipitation and glaciation, and their velocity will maintain stable in the near future. We also find that the altitudes of the velocity peaks are close to the recorded snowline, which indicates that detecting the changes of velocity peaks'' position might provide a reference for monitoring the changes of the snowlines. [Copyright &y& Elsevier]

Summary: In this paper we proposed: (1) an algorithm of glacier melt, sublimation/evaporation, accumulation, mass balance and retreat; (2) a dynamic Hydrological Response Unit approach for incorporating the algorithm into the Soil and Water Assessment Tool (SWAT) model; and (3) simulated the transient glacier retreat and its impacts on streamflow at basin scale. Application of the enhanced SWAT model in the Manas River Basin (MRB) in the Tianshan Mountains in northwest China, shows that the approach is viable as evidenced by a Nash–Sutcliff efficiency of 0.65 and a percent bias of −3.7% for daily streamflow and water balance, respectively. The results indicate that the glacier area decreased by 11% during the simulation period from 1961 to 1999, which is within the range of records from other glaciers. On average, glacier melt contributed 25% to streamflow, although glacier area accounts for only 14% of the catchment drainage area in the MRB. Glacier melt was positively correlated to temperature change (R 2 =0.70, statistical significance P <0.001) and negatively correlated to precipitation (R 2 =0.20, statistical significance P <0.005). The results indicate that glacier melt was more sensitive to temperature change than to precipitation change, implying that modeling the effects of climate change with increasing temperatures and decreasing precipitation should be further studied. [ABSTRACT FROM AUTHOR]

Abstract: Arctic glaciers are reliable indicators of global climate changes. However, monitoring snow and ice dynamics in Arctic regions is challenging: some fast but key events can be missed since they are short in time but significant in the hydrological budget. In the context of long term monitoring with high temporal and spatial resolutions of the snow cover dynamics, automated digital cameras were installed around the Austre Lovénbreen glacier basin (Spitsbergen, Norway, 79°N). Despite data losses due to rough weather conditions and control electronics failure, a dataset of 2411 pictures (out of an expected 3294) was gathered over a 1year hydrological period to assess the snow coverage of the glacier as a function of time with daily resolution. 73% of the total number of expected images was thus recorded, with gaps associated with temporary electronics or data storage failure. The six camera stations oriented so as to observe the glacier itself provide a surface coverage of 96%. Furthermore, geometric corrections of the pictures, using reference ground control points located on the glacier through GPS receivers, yield a quantitative information from initially qualitative images. Projecting the resulting mosaic of the images gathered from six cameras on a GIS allows for the precise monitoring of ice-related processes, and especially the snow coverage evolution over time. This paper summarizes our current understanding of such dynamics, based on the analysis of daily mosaics of images allowing for the observation of both long term evolution on the seasonal scale and the short term events on a weekly scale. Such results demonstrated over one typical full hydrological season (April–October 2009) that snow coverage evolves following discrete steps, either due to water precipitation or warm events, with a snow coverage ranging from 100% (april) to 37% (September). [Copyright &y& Elsevier]

Abstract: Moraine-dammed glacial lakes are becoming increasingly common in the Himalaya as a result of glacier mass loss, causing concern about glacier lake outburst flood risk. In addition to extant lakes, the potential exists for many more to form, as more glaciers ablate down to the level of potential moraine dams. In this paper, we document the recent rapid growth of, a moraine-dammed lake on Ngozumpa Glacier, Nepal. Using a combination of ground-based mapping and sonar surveys, aerial photographs (<1m resolution), and ASTER imagery (15m resolution), processes and rates of lake expansion have been determined. The lake first formed between 1984 and 1992 when collapse of an englacial conduit allowed water to accumulate at the level of a gap in the lateral moraine, ~km from the glacier terminus. Lake growth was initially slow, but since 2001 it has undergone exponential growth at an average rate of 10%y−1. In 2009, the lake area was 300,000m2, and its volume was at least 2.2million m3. Calving, subaqueous melting, and melting of subaerial ice faces all contribute to the expansion of the lake; but large-scale, full-height slab calving is now the dominant contributor to growth. Comparison with other lakes in the region indicate that lake growth will likely continue unchecked whilst the spillway remains at its current level and may attain a volume of hundreds of millions of cubic metres within the next few decades. [Copyright &y& Elsevier]

Abstract: A sensor web is a collection of heterogeneous sensors which autonomously reacts to the observed environment. The SouthEast Alaska MOnitoring Network for Science, Technology, Education, and Research (SEAMONSTER) project has implemented a sensor web in partially glaciated watersheds near Juneau, Alaska, on the edge of the Juneau Icefield. By coupling the SEAMONSTER sensor web with digital earth technologies the scientific utility, education and public outreach efforts, and sensor web management of the project all greatly benefit. This paper describes the scientific motivation for a sensor web, the technology developed to implement the sensor web, the software developed to couple the sensor web with digital earth technologies, and demonstrates the SEAMONSTER sensor web in a digital earth framework. [ABSTRACT FROM AUTHOR]

Abstract: Glaciated mountains are among the most sensitive environments to climatic changes, and recent work has shown that large-scale glacial melting, including at the end of the Pleistocene, caused a significant increase in the incidence of large volcanic sector collapse and debris flows on then-active volcanoes. With current accelerated rates of glacial melting, glaciated active volcanoes are at an increasing risk of sector collapse, debris flow and landslide. These catastrophic events are Earth''s most damaging erosion phenomenon, causing extensive property damage and loss of life. This paper illustrates these effects in well-studied settings, focusing on the end-Pleistocene to Holocene glaciovolcanic growth and destruction of the cone of the active volcano Planchon–Peteroa in the Andean Southern Volcanic Zone at latitude 35° 15′ S, along the border between Chile and Argentina. The development of the volcano over the last 14,000years illustrates how glacial melting and magmatic activity can trigger landslides and sector collapses. Planchon had a large sector collapse that produced a highly mobile and erosive debris avalanche 11,000years BP, and other slope instabilities during the end-Pleistocene/early Holocene deglaciation. The summit amphitheater left after the sector collapse was subject to alternating periods of glaciation and melting-induced lake formation. Breaching of the moraine dams then formed lahars and landslides originating at the western edge of the summit amphitheater, and the deposits are preserved along the western flank of the volcano. Deep incision of moraine deposits further down the western slope of the volcano indicates that the lahars and landslides were water-rich and had high erosive power. As illustrated by Planchon–Peteroa, the interplay among glacial growth and melting, magmatic activity, and slope stability is complex, but must be accounted for in volcanic hazard assessment. Planchon–Peteroa currently has the southernmost temperate zone mountain glacier in the Andes. Accelerated glacial melting at present rates of climate change could lead to a recurrence of many of these post-Pleistocene events. A framework for augmenting hazard assessments and countermeasures is also proposed based on the types of hazards presented by accelerated glacial melting. Glacial melting may lead to volcanic hazards in areas not previously considered at risk, and hence there may be a low level of preparedness. Compared to the end-Pleistocene accelerated glacial melting and sector collapses, present-day glacial melting in volcanic terrain has the potential to affect large human populations. Human settlements, hydropower production, forestry, mining and wilderness tourism are all concentrated near some glaciated volcanic areas. For example, the area covered by the debris avalanche from Volcan Planchon currently supports a rich agricultural economy in Chile. Effective risk management is needed to address the issues of changing patterns in vulnerability, the nature and redistribution of hazards, and the potential socioeconomic consequences of glaciovolcanic events. Since these events are infrequent, local communities frequently do not have a memory of past occurrences, and therefore have a low awareness of the potential effects. Systematic and structured impact assessment allows objective risk analysis, uncertainty analysis, and a framework for balancing countermeasures and contingency measures with public need and acceptance. An impact assessment approach similar to that used in land use planning is presented here, with the following major elements: (i) hazard characterization; (ii) consequence characterization; (iii) risk assessment; (iv) risk control and countermeasures; and (v) risk communication. The emphasis is on effective risk communication, supported by facts, in order to address the increased hazards posed by accelerated glacial melting on volcanic cone stability. Decision makers must then weigh societal acceptance of the risk control and countermeasures against their costs and consequences. [Copyright &y& Elsevier]

Abstract: Proglacial meltwater streams draining out of the Himalayan glaciers carry considerable amounts of suspended sediment, with a variety of particle sizes, because of the supraglacial, englacial, and subglacial debris, as well as formation of sediments from erosion by the movement of the ice. This paper examines particle size transported in the proglacial meltwater stream of Gangotri Glacier for seven consecutive melt seasons (May–October, 2000–2006) in order to provide information on (i) temporal variations in the particle size distribution, (ii) texture and mineralogy of the sediments, and (iii) origin and evacuation pattern of the sediments. Our results indicate dominance of silt size (0.002–0.06mm) particles (71%) followed by sand size (0.06–0.6mm) particles (24%) and clay size (<0.002mm) particles (5%) during the melt season, with increased variation as melt season progresses. The sediment contains quartz, feldspar, mica, illite, and kaolinite minerals, which represent a poor to poorly sorted fraction with a coarse to fine skewed textural distribution. Overall, this study indicates a subglacial evacuation pattern of the suspended sediment based on (i) size classification, (ii) higher percentage of coarser particles toward the end of the melting season, (iii) symmetrical to positively skewed with a kurtosis of mesokurtic to platykurtic texture, and (iv) a less-rounded shape of particle size. Our result on the evolution of meltwater pathways indicates a progressively better interconnected drainage system with advancing melt season. The evolution of meltwater pathways also demonstrates complex behavior of the glacial system and the need for a better understanding of sediment availability and contribution. [ABSTRACT FROM AUTHOR]

Abstract: Recent advances in geochronology provide opportunities to identify the glacial and periglacial sequences in mountain area. In this paper, we focus on the Upper Durance catchment (Southern French Alps), in the Clarée valley, where no absolute chronological benchmark was defined. Glacial remnants and periglacial features were investigated, integrated within a chronological scenario thanks to relative (weathering rind thickness) and absolute (CRE technique) dates. We find evidence of the existence of a Late-Glacial valley glacier, that has never been reported before. Then the upper valleys became ice-free during a period corresponding to the Early-Holocene Climate Optimum, whereas two sequences of cirque glaciation are identified during the second half of the Holocene. We also show evidence of three main generations of rockglaciers, which also mainly developed during the second half of the Holocene, probably at the end of the Subboreal period. The location and the altitudes of rockglaciers are strongly dependent on the geomorphic setting (especially the location of the sediment sources), hence complicating their palaeo-climatic interpretations. [Copyright &y& Elsevier]

Abstract: Detailed studies of glacier flow and deformation of ice require high-resolution numerical modeling. The model presented in this paper, icetools, solves the Stokes equation including all components of the stress tensor, termed full Stokes, with the finite element method to enable such detailed studies. Icetools is capable of running in parallel on computational clusters providing the computing power for large-scale simulations. Two different numerical tests were performed to demonstrate the capability of the model; (1) a comparison with the analytical solution for gravity driven plane flow down an inclined plane, and (2) flow over a Gaussian-shaped bed disturbance in comparison with the analytical transfer functions for this case. The second test involves time evolution of the surface geometry from an initially uniformly sloping surface. A linear rheology medium with a viscosity of and a non-linear medium with Glen rheology exponent and rate factor of were studied. Both correlate well with the analytical solution and reach steady state, defined as when the maximum vertical movement drops below times the mean ice thickness per year, after 282 years for the linear case and 135 years for the non-linear case, respectively. [Copyright &y& Elsevier]

Abstract: This paper provides an overview of the current status of the cryosphere in China and its changes. Up-to-date statistics of the cryosphere in China are summarized based on the latest available data. There are 46,377 glaciers in China, covering an area of 59,425 km2. The glacier ice reserve is estimated to be about 5600 km3 and the annual glacier runoff is about 61.6×109 m3. The continuous snow cover extent (>60 days) in China is about 3.4×106 km2 and the maximum water equivalent is 95.9×109 m3 yr−1. The permafrost area in China is about 1.72×106 km2. The total ground ice reserve on the Qinghai–Tibetan Plateau is estimated to be about 10,923 km3. Recent investigations indicated that glacier areas in China have shrunk about 2–10% over the past 45 yr. Total glacier area has receded by about 5.5%. Snow mass has increased slightly. Permafrost is clearly degrading, as indicated by shrinking areas of permafrost, increasing depth of the active layer, rising of lower limit of permafrost, and thinning of the seasonal frost depth. Some models predict that glacier area shrinkage could be as high as 26.7% in 2050, with glacier runoff increasing until its maximum in about 2030. Although snow mass shows an increasing trend in western China, in eastern China the trend is toward decreasing snow mass, with increasing interannual fluctuations. Permafrost degradation is likely to continue, with one-third to one-half of the permafrost on the Qinghai–Tibetan Plateau anticipated to degrade by 2100. Most of the high-temperature permafrost will disappear by then. The permafrost in northeastern China will retreat further northward. [Copyright &y& Elsevier]

Abstract: Few detailed studies of thermal dynamics exist for alpine river systems despite their high climatic sensitivity. This paper examines water column temperatures (15min resolution) for snowmelt/glacier-fed streams and groundwater tributaries in the French Pyrénées. Streambed temperatures were monitored at: (1) the Taillon Glacier stream, (2) the Tourettes groundwater-fed tributary, and (3) the Taillon glacier stream downstream of the confluence with (2). Stream temperatures were analysed with reference to hydrological (snowline altitude, glacial ice exposure and river discharge) and climatological (air temperature, incident short-wave radiation and precipitation) data to infer key processes driving thermal variability. Mean water column temperature increased by 7°C in 2002, and 8.6°C in 2003, over a distance of 1km from the Taillon Glacier snout. Groundwater springs punctuated longitudinal glacial stream thermal patterns by decreasing (karstic) and increasing (hillslope) temperatures. Bed temperatures at all depths were coldest (warmest) and most (least) variable for the Taillon (Tourettes) stream. Stream temperatures varied at sub-seasonal time-scales. In particular, extreme precipitation events decreased temperatures in the Taillon Glacier stream by up to 10°C in the water column and 0.05m depth, 7.5°C at 0.20m depth and 5°C at 0.40m depth. Key drivers of thermal variability were: (1) dynamic water source contributions (i.e. snowmelt, ice-melt and groundwater), (2) proximity to source, and (3) prevailing hydroclimatological conditions. The variability of water column and streambed temperatures indicates alpine river basins to be highly thermally heterogeneous. [Copyright &y& Elsevier]

Accelerated glacier and ice sheet retreat and thinning in recent decades has profound consequences for catchment sediment supply with attendant repercussions for nutrient cycling, carbon fluxes and natural resource management. This paper evaluates the impacts of deglaciation on sediment yields from glaciated, deglaciating and recently-deglaciated catchments. It summarises the key characteristics of sediment yields from glaciated catchments to be that they span five orders of magnitude, vary with latitude and are greatest in high-relief and tectonically-active regions. We review the available quantitative data on sediment yields from glaciated catchments and we comment extensively on spatio-temporal variability to understand global to local and inter- and intra-catchment controls. Significant gaps in the available sediment yield data and also in our knowledge of sediment sources, pathways and sinks are identified. We constrain a set of novel approaches by which these gaps could be addressed. In particular, we suggest that the opportunities presented by emerging datasets and analytical methods enabling landcover changes, Digital Elevation Model (DEM) change detection, analyses of connectivity and analyses of sediment plumes are exciting and these approaches should become practical tools for understanding intra- and inter-catchment sediment yields from deglaciating landscapes. We showcase preliminary studies utilising these datasets and they are used to formulate hypotheses designed to stimulate further research. • Explanation of importance of understanding sediment yields from deglaciating catchments. • Concise summary of the key characteristics of sediment yields from glaciated catchments. • Review of spatio-temporal trends in global data compilation. • Identification of gaps in the available data and therefore our knowledge. • Suggestions for capitalising on emerging datasets and methods to address these gaps. [ABSTRACT FROM AUTHOR]

Glacier recession in response to climate warming has resulted in an increase in the size and number of glacial lakes. Glacial lakes are an important focus for research as they impact water resources, glacier mass balance, and some produce catastrophic glacial lake outburst floods (GLOFs). Glaciers in Peru have retreated and thinned in recent decades, prompting the need for monitoring of ice- and water-bodies across the cordilleras. These monitoring efforts have been greatly facilitated by the availability of satellite imagery. However, knowledge gaps remain, particularly in relation to the formation, temporal evolution, and catastrophic drainage of glacial lakes. In this paper we address this gap by producing the most current and detailed glacial lake inventory in Peru and provide a set of reproducible methods that can be applied consistently for different time periods, and for other mountainous regions. The new lake inventory presented includes a total of 4557 glacial lakes covering a total area of 328.85 km2. In addition to detailing lake distribution and extent, the inventory includes other metrics, such as dam type and volume, which are important for GLOF hazard assessments. Analysis of these metrics showed that the majority of glacial lakes are detached from current glaciers (97%) and are classified as either embedded (i.e. bedrock dammed; ~64% of all lakes) or (moraine) dammed (~28% of all lakes) lakes. We also found that lake size varies with dam type; with dammed lakes tending to have larger areas than embedded lakes. The inventory presented provides an unparalleled view of the current state of glacial lakes in Peru and represents an important first step towards (1) improved understanding of glacial lakes and their topographic and morphological characteristics and (2) assessing risk associated with GLOFs. • We present a new contemporary and comprehensive lake inventory for the Peruvian Cordilleras • We provide a set of inventorying methods to facilitate replicability in other locations, globally • We record and analyse a number of important lake metrics for understanding GLOF hazards • We estimate lake volume in all glaciated cordilleras and compare these with other studies [ABSTRACT FROM AUTHOR]

Varves – annual sediment layers, common in glacial lakes – are an important source of paleoclimate information. Manually recording their occurrence, typically by visual inspection, can be both time-consuming and prone to error, leading to several attempts in recent years to at least partially computerize the process. However, existing computerized methods of varve detection still require moderate to large amounts of user interaction — they are semi-automated, rather than fully automated. In light of that, this paper is a step towards fully automatic detection of varves. The presented program, DeepVarveNet - a glacial varve detector built on a convolutional neural network, is designed to automatically delineate annual layers in such lacustrine sediment in digital images of photographed sediment cores. To the best of the authors' knowledge, this is the first approach that applies a convolutional neural network to this task. The performance of DeepVarveNet was assessed on a data set comprising images from seven sediment coring sites, of varying sedimentological properties. They represent three northeast U.S. glacial paleolakes, and glacial paleolake Ojibway. Our testing set contained 1415 identified varves, on which DeepVarveNet demonstrated sensitivity at a level of 0.986 and precision equal to 0.834, exceeding that of BMPix and ANFIS, the existing semi-automated varve identifiers. • A varve detector is proposed to delineate annual layers in lacustrine deposit. • The method is dedicated to images of photographed sediment cores. • The core of the method is a convolutional neural network. • Tests on a dataset of 1415 varves from seven sediment cores were performed. • The method demonstrated sensitivity of 0.986 and precision equal to 0.834. [ABSTRACT FROM AUTHOR]