Glacial Retreat Research Articles

Spatiotemporal Changes in Land Use and Ecosystem Service Values Under the Influence of Glacier Retreat in a High-Andean Environment

Glaciers supply multiple ecosystem services that are threatened by climate change. The retreat and disappearance of tropical glaciers is an important dynamic that affects ecosystems and local communities. The knowledge of the impacts of this land-change dynamics on the supply of ecosystem services is lacking. In that sense, the assessment developed can provide evidence about the costs and benefits of promoting conservation and human well-being at the same time. Then, the main objective of this research is to determine the spatial–temporal changes and their effects on the economic value of ecosystem services in a glacial retreat environment. We selected the Marangani district as a study area. It comprises the La Raya Mountain range in the Andes. The assessments were carried out across two scales of observation: the municipality and the watershed level. Here, we process spectral information from Landsat Sensor using the Random Forest algorithm in the Google Earth Engine platform to classify 10 biomes. It was carried out over more than 30 years (from 1986 to 2019). After that, ecosystem services provided by the biomes were valued using the transfer method. This research shows that at the municipality level, almost all the LULCs faced variations over time, and the glaciers had the highest change, accumulating a ratio of –85.51%, whereas at the watershed level, a higher tendency of land changes is observed in the areas without glaciers, and those with glacier areas count on permanent larger bofedales. At the municipality level, the economic value of ecosystems shows that bofedales and water surfaces are the LULCs that supply the highest ecosystem services (∼33,000 USD ha−1 yr−1 each). In addition, without the inflation adjustment, the total ESV is on a trajectory of losing ESV (–$9.67 × 106). In the watersheds with glacier retreat, significant quantity of bofedales and natural grasslands controls the fluctuations of ESV. These high-mountain watersheds play an essential role in providing benefits and value to local communities. In general, the municipality level indicates the trajectory of changes in the district, whereas the watershed scale shows the urgency for implementing spatial conservation actions.

Initiation mechanisms and dynamics of a debris flow originated from debris-ice mixture slope failure in southeast Tibet, China

Glacial debris flows are a common catastrophic hazard in alpine regions due to glacier recession and permafrost thawing. They are frequently triggered by heavy rainfall and outburst floods. To date, studies on debris flows originated from debris-ice mixture slope failures triggered by glacier melting in low-intensity rainfall conditions are still limited. In this study, a typical glacial debris flow that occurred in September 2020 on the west side of Namcha Barwa in southeast Tibet, China, is taken as a benchmark to reveal the initiation mechanisms and dynamics of debris-ice landslide-debris flow hazard chains. The flow discharge, erosion, entrainment, deposition, and dynamic process of the debris flow are evidenced by both field investigations and numerical simulations with a single-phase cell-based simulation program, Erosion–Deposition Debris Flow Analysis (EDDA) (Chen and Zhang, 2015) and a multi-phase flow model r.avaflow (Pudasaini and Mergili, 2019). This hazard chain was originated from a debris-ice mixture slope failure with a volume of 1.14× 106 m3 in a temperate area under little rainfall. The mobile mixture entrained saturated moraines and water in the ravine channel and rapidly transformed into a viscous debris flow, traveling about 9.78 km and entraining 50% more materials along the path. The peak discharge and frontal flow velocity at the outlet of the ravine reached 4700 m3/s and 11.4 m/s, respectively. About 3.75× 105 m3 of debris deposited on the riverbed and partially blocked the Yarlung Tsangpo, causing severe damage to local infrastructures. This study provides a scientific basis for understanding the evolution process of a debris-ice landslide-debris flow hazard chain and for minimizing its adverse impact on key infrastructures in the region.

Kinematic Analysis of the 2020 Elliot Creek Landslide, British Columbia, Using Remote Sensing Data

The 2020 Elliot Creek landslide-tsunami-flood cascade originated from an 18.3 Mm3 rock slope failure in quartz diorite bedrock in a valley undergoing rapid glacial retreat. We used airborne LiDAR and optical imagery to characterize the slope and its surroundings. Using the LiDAR, we determined that two rockslides (2020 and an older undated one) occurred on this slope and shared a common basal rupture surface. We mapped two main sets of lineaments that represent structures that controlled the orientation of the lateral and rear release surfaces. Analysis of the topographic profile indicates a wedge-shaped failure block and a stepped rupture surface. Further topographic profile analysis indicates the possibility of a structurally controlled geomorphic step in the valley that corresponds with a change in the orientation of the valley. The rapid retreat of the West Grenville Glacier and the positions of the rupture surfaces suggest glacial retreat played a role in the landslides.

Geologic, Geomorphologic, and Climatic Preparatory Conditions for the Evolution of the Dangkhar Landslide, Himachal Pradesh, India

Abstract With an estimated volume of approximately 15 to 20 km3, the Dangkhar landslide located in the Spiti valley, Himachal Pradesh, India, is one of the largest landslides on earth. Its initiation is geochronologically constrained to have occurred during the late Pleistocene and may be related to glacial retreat following local last glacial maximum, which, depending on the source, occurred around 80 to 30 ka years ago. There is significant value in understanding the causative factors contributing to such an enormous and rare event. On the basis of comprehensive field studies and laboratory investigations, it is concluded that erosional, structural, and depositional features within and surroundings of the Dangkhar landslide are critical for understanding landslide initiation and its long-term behavior. The landslide developed as a block slide along a synformal flexure, and through-cutting lateral valleys fulfill the kinematic conditions for creating a massive removable block of earth. Deposits of weakly cemented and crudely bedded carbonate breccias in the landslide’s toe region represent depositional activity during recession of the main valley glacier, and cross-cutting structural relationships involving ground ruptures (lineaments) and rock glaciers in the head region record long-term, ongoing landslide deformations subsequent to its initiation. Stable isotope signatures of samples indicate presence of freshwater associated with the formation of breccia deposits. While many details concerning the timing and development of the Dangkhar landslide remain unknown, recent studies illuminate some very important aspects. The glacial history of the Spiti valley combined with structural kinematics are clearly important factors concerning landslide development. Also important are constraints concerning the minimum age of landslide initiation after recession of a valley glacier, and structural evidence documenting long-term ongoing slope deformations.

St. Lawrence Ice Stream overflow on the northern edge of the middle Estuary during the Bølling-Allerød and response of the Laurentide Ice Sheet margin to the Intra-Allerød Cold Period in southern Québec, Canada

The middle and upper Estuary regions of the St. Lawrence River include the Laurentian highlands to the north and the Appalachian piedmont and uplands to the south. From a synthesis of the literature, the glacial dynamics of these regions are the result of: 1) the changing position of an ice dispersion centre in the Québec-Labrador Dome; 2) the upstream retreat of a calving bay from the Gulf of St. Lawrence to the middle Estuary at the origin of the rapid inland extension of the St. Lawrence Ice Stream (StLIS) of the Laurentide Ice Sheet (LIS); 3) the progressive separation of Appalachian ices from the LIS; and 4) an increasing topographic control on ice flows. The LIS ice flowed southeastward over the area independently of structural topography during the Glacial Maximum or closely thereafter. From published and original data, the StLIS eventually reached the lower part of the middle estuary as a moving-inland head of ice flow convergence. The ice diversion accelerated the regional-scale ablation on both sides of the estuary likely under the warmer Bølling climate. A generalized thinning in the middle estuary is inferred to cause the northward ice-flow reversal of the Appalachian ice divide to expand into the studied region, consequently initiating the Northward Ice Overflow (NIO) on the Laurentian margin, up to elevations of 750 to 950 m in the Beaupré Basin. This likely took place between the end of the Bølling and the early Allerød. Based on this study, the northern part of the region records a detailed Late Glacial sequence of ice flows and retreat events. After the initiation of the NIO, the overflow ice in the Beaupré Basin thinned by at least 100 m during part of the Allerød. The Beaupré Group of Moraines and the Savane Moraine in the Laurentians provide evidence of a significant subsequent slowdown in the glacial retreat. These moraines are attributed to the Intra-Allerød Cold Period (IACP) between approximately 13.250 and 13.050 cal ka BP, based on their older age position relative to: 1) the Saint-Narcisse Moraine of early Younger Dryas; 2) the deglaciation of a lake basin whose basal sediments are dated at 12.750 cal ka BP; and 3) the local marine invasion (Goldthwait Sea) prior to 13-12.9 ± 0.1 cal ka BP. Laterally to these moraines, the glacial megalineations of the Montmorency massif and Gouffre Valley represent a major glacial flow toward the SSE from the Québec-Labrador Dome which did not override the Beaupré Basin. This LIS flow is closely followed by a reactivated StLIS which flowed into small valleys and lowlands of the north shore of the middle and upper estuary from the Québec City region to the Malbaie Valley (glacial striations and the Escarpment and South-Éboulements moraines). The LIS flow episode toward the SSE probably began at the start of the IACP. At least two moraine belts (Cherry River–Mégantic and Mount Ham) are tentatively associated with the IACP in southern Québec and thus would have a climatic origin. These new findings confirm a much shorter duration for the sequence of late glacial events in the region than was proposed in previous models as well as continuity between the early StLIS in the Gulf (the Laurentian Channel Ice Stream) and the late StLIS of the middle estuary. The IACP slowdown of the glacial retreat opens the possibility of correlation at the scale of the southeastern margin of the LIS.

Aspects of Human Adaptation to Life in Mesopotamia in the Light of Pottery Scenes and Pictographic Writing

One of the most important turning points that resulted in the achievements of man and human civilization in history, is first, the great climate change that occurred when the last glacial retreat began about 18,000 years ago, with the Middle Stone Age approximately. Secondly, the stage of man’s transition from gathering food to producing food, which is one of the most important steps that man has taken on his way to stability in the lifestyle thousands of years ago, and because of its importance, researchers called it the Neolithic Revolution. After the great change in the climate in the Near East region, human's confrontation with their new environment and trying to adapt to it constituted one of the most important challenges that man had to face, to ensure survival. And then this challenge led to the most important human discoveries, which are attempts to domesticate and agriculture: they began with attempts to grow grain, then succeeded little by little and became stable agriculture and led to the emergence of agricultural settlements, and this is mainly the content of adaptation. Because of the importance of that stage of human life in which writing was still non-existent and unknown, it was addressed by researchers from several aspects, and in light of archaeological evidence in terms of architectural styles, the development of stone tools, and pottery products (in terms of the accuracy of industry and techniques used), as well as Important studies were conducted on plant and animal remains, and other studies on the human lifestyle in the period following the discovery of agriculture. Despite the aforementioned studies on the archaeological remains, which revealed the many facades of life in Mesopotamia during that stage, the visual picture of the manifestations of adaptation to life and the extent of human harmony with natural phenomena in light of stability in that period, remains an important part to complement what His image is research and studies. Fortunately, the images and scenes painted on pottery from the late Neolithic and Metallic Age serve us, which by studying and analyzing them we aim to see the reflection of the reality of man's interaction and adaptation with his natural environment. Thus, our models come from pottery scenes from the region of Mesopotamia (Iraq and Syria) in the time frame that starts from the period of Hassuna, Samarra, Halaf and Ubaid, and finally some models from the era of Warka and Jemda-Nasr, and these are the models that carry the elements that serve the objectives of the research. One of the objectives of the research is also to track the developments that occurred in these inscriptions, which later became elements of the first and oldest models of writing in history, cuneiform writing, from its pictorial stage, and this confirms more that the elements and symbols of writing are rooted in pottery inscriptions from preceding eras. We use some scenes on pottery models from present-day Iran and Turkey for the purpose of comparison.

Understanding the role of anthropogenic emissions in glaciers retreat in the central Andes of Chile

Glaciers in Chilean Central Andes have significatively retreated, at least, in the last 60 years. From 2004 to 2014, the largest retreat in the area (−0.15 km2 yr−1) was observed at Olivares Alpha Glacier (OAG). Previous glacier fluctuation studies proposed that two open-pit mines distant 7 km from the glacier could be the cause of its enhanced retreat. However, this had not been yet tested due to the lack of measured data. Here, we investigated the impact that major air pollutants emitted by local mining activities could have on the differences observed in OAG glacial retreat compared with a glacier of similar size and altitude with no nearby anthropogenic sources: Bello Glacier (BG), which has a reported lower retreat (−0.02 km2 yr−1). Results revealed a link between anthropogenic air pollutants and glacial retreat rates, meaning that glacial retreat is decoupled from climatic and glaciological factors. Considering that both glaciers are located in the same climatic setting, the anthropogenic air pollutants deposited onto the OAG surface appear to be forcing positive feedback in which the pollutants deposition best explain the differences in the glacier retreat. With the results of this study, it has been calculated that the impact of mining in OAG could be responsible for 82% of its total retreat since between 2004 and 2014, and only the remaining 18% would correspond to the impact of climate change.

Methane dynamics in the Hailuogou Glacier forefield, Southwest China

Soils in glacier forefields have a significant capacity for atmospheric CH4 uptake, but this pattern could be changed by high soil water content (SWC). The Hailuogou Glacier in SW China is a typical temperate monsoon glacier on siliceous bedrock, where a forefield soil chronosequence has developed with progressive glacier recession. To understand CH4 dynamics and their potential regulatory factors, we measured the concentrations and stable carbon (C) isotope compositions of CH4 and CO2, soil physicochemical properties, and perfromed a high-throughput sequencing. Among nine sampling sites, soil CH4 concentrations of six sites were below atmospheric levels and δ13C–CH4 values were similar to atmospheric levels. The average value was approximately −48.6‰ and without obvious fractionation. The soil CH4 concentrations exceeded atmospheric levels for the remaining three sites, and the δ13C–CH4 values were more enriched with increasing soil CH4 concentration. We calculated the soil-atmosphere CH4 flux (Jatm) using the concentration gradient method based on the soil CH4 concentration, sampling depth, and soil porosity. Jatm ranges from −0.08 to −0.52 mg m−2 d−1, acting as an atmospheric CH4 sink. It also shows that the correlation with soil exposure age or vegetation succession was insignificant. But the CH4 emission shows a larger variation changing from 0.05 to 1.8 mg m−2 d−1, which could result from local CH4 production differences catalyzed by aceticlastic methanogens. The results showed that not all sites acted as a net CH4 sink. SWC may have an important influence on CH4 dynamics in the Hailuogou Glacier forefield (HGF).

A Responsible Tourism System at Glacier Tourism Sites: Reducing the Impacts of Tourism Activities on Glaciers

The anthropogenic heat release from tourism activities has a cumulative effect on glacial retreat when coupled with climate change. Mitigating the impacts of glacial tourism activities on glaciers and promoting the sustainable development of glacial tourism have become urgent issues. Taking Yulong and Hailuogou glacier tourism destinations as examples, we collected survey questionnaires related to glacial tourists (n=1113) and tourism companies (n=329) by systematic field surveys during 2016–2017, and we obtained data on energy consumption from catering, accommodation, transportation, sightseeing, shopping, entertainment, and waste disposal. This study builds a responsible tourism system and discusses the strategies and measures used to engage stakeholders (mainly tourism companies, tourists, local governments, tourism associations, and the central government) in responsible tourism in order to reduce the impacts of tourism activities on glaciers. These strategies mainly include: improving the energy efficiency of the supply of tourism products and services, promoting the consumption of low-energy tourism products and services, strengthening the supervision and management of low-energy consumption tourism development, creating an environment for energy savings and consumption reduction, and establishing a long-term operational mechanism for responsible tourism management. A rewsponsible tourism system allows stakeholders to properly address this dilemma, internalize sustainable development goals to find their intrinsic self-discipline, and work together to fulfill the public responsibility of realizing the sustainable development of glacial tourism.

Mapping of the Subglacial Topography of Folgefonna Ice Cap in Western Norway—Consequences for Ice Retreat Patterns and Hydrological Changes

Folgefonna consists of three ice caps which are rapidly retreating in response to warmer temperatures. The melting of Folgefonna has implications for meltwater drainage and hydropower production, as well as the potential for geohazards and impacts to tourism, the communities and infrastructures surrounding the glacier. To support future adaptation strategies, we need to know the subglacial topography of the ice caps to identify water divides and possible areas for geohazards. Therefore, we mapped the subglacial topography at Sørfonna, the largest of the Folgefonna ice caps, using an ice-penetrating radar (2.5 MHz antennas; 1,000 × 500 m grid). The results show a highly irregular subglacial landscape, with deep valleys and high mountain peaks. The maximum ice thickness is 570 m and the mean ice thickness is 190 m. We examined the retreat pattern of Sørfonna using the subglacial topography map in combination with a simple ice flow model and simulated the ice retreat 150 years into the future. We used two climate scenarios (one with a 1.5°C warming and a 3% increase in precipitation, and a second with a 3.5°C warming together with 15% increase in precipitation) and focused on how the glacial retreat will cause hydrological changes in the catchments surrounding the glacier. The main drainage pattern shifts during glacial retreat, with a larger proportion of southward drainage compared to the present day. The ice flow modelling also reveals that the southern part of Sørfonna is more durable during climate change whereas the thinner part of the ice cap, in the north, melts faster. We suggest that increased winter precipitation in a future warmer climate makes the southern part of Sørfonna more resilient than many other glaciers in southern Norway. The subglacial topography map and the retreat pattern also reveal areas that may accumulate water and could potentially generate a future glacial outburst flood. Sediments from distal glacier-fed lakes around Sørfonna have been used to constrain the thresholds identified on the subglacial topography map. Combining sedimentological evidence from distal glacier-fed lakes with the new subglacial topography map confirms that the retreat of specific outlet glaciers, such as Bondhusbreen, Buerbreen, and Møsevassbreen, will have a large impact on meltwater routing, as they are situated behind bedrock thresholds in the upper part of the glacier’s catchment area.

Trends in Temperature, Precipitation, Potential Evapotranspiration, and Water Availability across the Teesta River Basin under 1.5 and 2 °C Temperature Rise Scenarios of CMIP6

Considering the linkages between climate change and water management, a lack of effort has been observed in analyzing the imprints of climate change over the transboundary Teesta river basin, where the changing climatic conditions can trigger substantial changes in eco-hydrological and socio-politico-economic setups. Therefore, to stimulate effective basin management, we investigated the trends in temperature, precipitation, potential evapotranspiration, and water availability under 1.5 and 2 °C warming levels across the transboundary Teesta river basin. The ensemble median of five bias-corrected model outputs from the Coupled Model Intercomparison Project Phase 6 (CMIP6) was used for this purpose. The results indicate that the temperature is expected to significantly increase (decrease) in the near (far) future, along with an overall significant increasing trend in monsoon precipitation. The evaporation paradox is found in the near future, and the water availability is likely to increase, with some exceptions for the pre-monsoon season. The perpetuation of such changes might result in environmental degradation through snow melting, glacial recession, and floods. Anticipating the changing climatic scenarios and their possible impacts, in this study, we recommend a variety of short- and long-term strategies for the concerned stakeholders to implement the Sustainable Development Goal 13, i.e., “Climate Action”, over the Teesta river basin.

Landscape connectivity among coastal giant salamander (Dicamptodon tenebrosus) populations shows no association with land use, fire frequency, or river drainage but exhibits genetic signatures of potential conservation concern.

Determining the genetic consequences of both historical and contemporary events can clarify the effects of the environment on population connectivity and inform conservation decisions. Historical events (like glaciations) and contemporary factors (like logging) can disrupt gene flow between populations. This is especially true among species with specialized ecological requirements and low dispersal ability, like amphibians. We test for the genetic consequences of historical and contemporary disturbances in the coastal giant salamander (Dicamptodon tenebrosus) in the Pacific Northwest of the United States. We consider predictions based on the contemporary landscape (habitat connectivity, logging, forest fires, and topography), in addition to relatively ancient post-Pleistocene range expansion (following the last glacial retreat). To assess local versus larger-scale effects, we sampled 318 individuals across 23 sites, which were clustered in five sampling regions. Genetic variation was assessed using five microsatellite markers. We found evidence of (i) historical regional isolation, with decreased genetic diversity among more recently colonized northern sites, as well as (ii) high levels of inbreeding and loss of heterozygosity at local scales, despite relatively low overall population differentiation (FST) or strong evidence for population bottlenecks. Genetic diversity was not associated with contemporary disturbances (logging or fire), and there were no detectable effects on the genetic connectivity of populations based on intervening landscape features (habitat fragmentation and topography). However, lower genetic diversity in more northern regions indicates a lag in recovery of genetic diversity following post-Pleistocene expansion. Additionally, some populations had evidence of having undergone a recent genetic bottleneck or had high inbreeding (FIS) values. Lower genetic diversity in more northern sites means populations may be more vulnerable to future environmental changes, and managing for connectivity alone may not be sufficient given low mobility. Recent apparent reductions in some populations were not clearly linked to anthropogenic disturbances we examined. This suggests the type of disturbances this species is sensitive to may not be well understood.

Remotely sensed time series of rapid terrace formation: Laguna del Viedma valley (Patagonia)

The Patagonian Andes were affected by a range of geophysical drivers of landscape incision during the Last Glacial Interglacial Transition and Early Holocene. Deciphering drivers of river system response during this period is complex, and magnitudes and timescales of landscape change are poorly constrained. Herein, a remotely sensed time series of modern terrace formation is investigated from the Laguna del Viedma valley as a modern analogue of Late Quaternary landscape evolution in Patagonia. The aim of the research was to constrain the timing of terrace formation following lake level fall of the Laguna del Viedma over a 35 year period from 1985-2019. The objectives were to: 1) use satellite imagery from 1985-2019 to document glacier and lake changes in the study area; 2) map landforms of the Laguna del Viedma valley; and 3) analyse terrace elevations. In total seven terrace surfaces were distinguished, with the oldest four pre-dating the ALOS PALSAR DEM (February 2000) used. Landform evidence shows the highest, and vegetated, T1 terrace surface (+40-75 m) grades to the highest lake level and was likely the elevation of the valley floor during Holocene neoglacials. Viedma glacier recession then led to a phase of lake regressions/transgressions with an overall trend of lake level fall. The DEM shows ~20 m incision from the 1985 floodplain level (T3) to the T4 level floodplain by 2000. This constrains a minimum rate of incision of 1.33 m/yr, however, the satellite time series demonstrates rapid T3 terrace formation, with evidence for mass movements contributing to lateral terrace erosion by 1986. The implications of the data are discussed within the context of the Late Quaternary palaeohydrology of Patagonia where lake level falls of 10s to 100s of metres occurred within many large river systems of the Patagonian Andes from 42-52⁰ S. The data herein demonstrate that base level falls from sudden lake drainage events were likely a major driver of rapid landscape change in Patagonia during deglaciation.

The Class Conflict Rises When You Turn up the Heat: An Interdisciplinary Examination of the Relationship between Climate Change and Left-Wing Terrorist Recruitment

ABSTRACT The increasing impacts of climate change have created a global humanitarian crisis. Growing populations, unstable political structures, and competition over scarce resources are generating unprecedented levels of insecurity. Capitalising on these complex situations, terrorist organisations are using the environment as a weapon of war, exploiting the strains and grievances exacerbated by climate change to increase support, aid recruitment, and incite violence. Often neglected within contemporary analyses is the potential impact of anthropogenic climate change on left-wing terrorist organisations. Consequently, the research presented in this paper takes an interdisciplinary approach, combining terrorism studies with disaster management to examine a specific type of security crisis that exists in this overlapping relationship between climate change and left-wing conflict. Three regional case studies of terrorist groups and activity are examined in detail—the Revolutionary Armed Forces of Colombia, the Shining Path in Peru, and Naxalites in India. The article reveals the complex issues that underlie climate disasters, focusing on the impact hazards such as deforestation, rising sea levels, extreme weather, glacial retreat, drought, famine, water scarcity, and migration have on left-wing terrorist recruitment and activity.

Novel plant communities after glacial retreat in Colombia: (many) losses and (few) gains

Early plant primary succession in recently deglacierized terrains is a good indicator of the species losses and gains that affect novel alpine plant communities migrating under the pressure of climate warming. In the tropical alpine -páramo- region of the northern Andes, home to the world's greatest alpine phyto-diversity, forced primary succession will condition the conservation of many species. Using a post-glacial chronosequence between the little ice age and present below the Conejeras glacier (Colombia) as a space-for-time substitution approach, we sought to determine how time since deglacierization affects the composition, the biogeographic origin and the growth form distribution of novel tropical alpine plant communities. Using an array of multivariate techniques and the Dirichlet model, we assessed relationships among plant communities and with environmental factors. Communities established in less than 169 years lacked a number of characteristic and endemic species usually found in the national park Los Nevados, such as Calamagrostis effusa, Senecio isabelis and Espeletia hartwegiana. Moreover, these communities have been colonized by non-native species, e.g., Rumex acetosella. Upright shrubs and large tussock grasses, characteristic of the alpine tropics, established slowly because they required highly organic, slow-developing soils. Taxa of tropical biogeographic origin were under-represented early after deglacierization in comparison with temperate taxa. These results suggest the existence of a strong climatic debt for some native species, tropical growth forms and taxa of tropical origin, which may translate into significant taxonomic and functional losses whereas the few observed gains concern the establishment of non-native species.

Hydrogeological Model of the Forefield Drainage System of Werenskioldbreen, Svalbard

The significant recession of Arctic glaciers caused by climate warming is expanding their proglacial zones. Thus, their importance for the hydrology of glacierised basins is growing. In contrast to the surface waters in such areas, the role of groundwater in the hydrological balance of Svalbard catchments is poorly known. This paper presents the hydrogeological conditions and groundwater flow within the permafrost active layer in the forefield of the Werenskioldbreen glacier basin (44.1 km2), 61% of which is glacierised. Based on field studies of groundwater in the 2017 ablation season and laboratory analyses of the hydrogeological properties of proglacial sediments, a three-dimensional groundwater flow model (FEFLOW) for part of the glacier forefield (4.8 km2) was developed. The main results show the components and characteristics of the groundwater balance and indicate the preferential groundwater flow paths. The volume of water retained in the sediments of the marginal zone is 1.0073 mln m3. The maximum potential free pore space that could be filled by water is 2.0689 mln m3. The calculated groundwater discharge for average conditions is 6076.9 m3 d−1, which is about 2% of the total seasonal catchment runoff from the main glacial river. The results of the spatial analysis for the groundwater depth and the groundwater flow directions are also presented. There need to be further detailed studies of hydrogeological processes in glacial basins in Svalbard in order to develop existing knowledge.

River Response to Melting Cryosphere Since Late Quaternary in the Pir Panjal Range of NW Himalaya

Rambiara River basin, a sub-basin of the Upper Indus, is dotted with fluvial and glacial geomorphic landforms. The presence of large number of glacial landforms like moraines, cirques, aretes, U-shaped valleys, etc. reflects the enormous erosive power of the past glaciers. During the Last Glacial Maximum (LGM), glaciers on average were 200 m thick and extended more than 10 km from the present-day cirque marks. Rock glaciers outnumber the clean glaciers that cover an area of 0.22 and 1.25 km2, respectively, in the basin. Glacial lakes are the prominent features in the higher reaches of the basin and occupy an area ranging from 0.01 to 0.70 km2. Downstream, the river is characterized by large channel width, anomalous sinuosity, braided pattern, and the presence of unpaired fluvial terraces. The large channel width depicts the enormous discharge from the glacial- and snow-melt during the Late Pleistocene when glaciers covered most of the Pir Panjal. After LGM, the glacier cover and the river discharge significantly decreased as highlighted by a large number of braided bars and the narrow stream to which the river is reduced. The warming trends observed across the Himalayas encompassing the Pir Panjal Range since the last century has further contributed significantly to the glacier recession in the basin.

Holocene ice-free strait followed by dynamic Neoglacial fluctuations: Hornsund, Svalbard

The recession of the Hornbreen-Hambergbreen glaciers (Hornsund, Svalbard) will lead to the formation of a strait between the Greenland and Barents Seas within a few decades. We provide evidence for the earlier existence of this strait, in the Early–Middle Holocene and presumably since 1.3 ka cal. BP until glacier advance 0.7 ± 0.3 ka or earlier. Radiocarbon dating of mollusc shells from the ground moraines in the Hornbreen forefield indicate the existence of the marine environment at the contemporary glacierized head of Hornsund since 10.9 ka cal. BP or earlier due to glacier retreat. The gap in the radiocarbon dates between 3.9 and 1.3 ka cal. BP and the published results of 10Be exposure dating on Treskelen suggest the strait’s closure after glacier advance in the Neoglacial. Subsequent re-opening occurred around 1.3 ka cal. BP, but according to 10Be dates from Treskelen, the strait has again been closed since ca. 0.7 ± 0.3 ka or earlier. The oldest known surge of Hornbreen occurred around 1900. Analysis of Landsat satellite images, morphometric indicators characterizing the glacier frontal zones and previous studies indicate one surge of Hambergbreen (1957–1968) and five re-advances of Hornbreen in the 20th century (after 1936, between 1958 and 1962, in 1986–1990, 1998–1999, 2011). While the warmer Holocene intervals might be a benchmark for the effects of future climate change, glacier dynamics in post-Little Ice Age climate warming seems to be an analogue of glacier retreats and re-advances in the earlier periods of the Holocene.

SEM-EDS and water chemistry characteristics at the early stages of glacier recession reveal biogeochemical coupling between proglacial sediments and meltwater

Most glaciers worldwide are undergoing climate-forced recession, but the impact of glacier changes on biogeochemical cycles is unclear. This study examines the influence of proglacial sediment weathering on meltwater chemistry at the early stages of glacier recession in the High Arctic of Svalbard. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) in combination with a wide range of geochemical analyses were used in this study. The SEM-EDS analyses of sediments collected in front of Werenskioldbreen show general degradation of pyrite and carbonate grains with age. The outer parts of pyrite grains have a gradual decrease in sulphur and gradual increase in iron oxides due to pyrite oxidation. This process was less advanced in the proglacial zone younger than 100 years compared to older sites such as the terminal moraine from the Little Ice Age. In both the proglacial zone and the terminal moraine, physical weathering of mineral grains, including formation of microcracks and microfractures, clearly enhanced pyrite oxidation. A consequence of proglacial sediment weathering is that the river chemistry is strongly affected by carbonate dissolution driven by sulphuric acid from sulphide oxidation. Also, reactive iron oxides, a product of sulphide oxidation, are mobilized in the proglacial zone. The results of this study show that proglacial weathering in the High Arctic of Svalbard is strongly coupled to river geochemistry, especially during the early stages of proglacial exposure after glacier recession.

Assessing Sources and Distribution of Heavy Metals in Environmental Media of the Tibetan Plateau: A Critical Review

With a unique multi-sphere environmental system, the Tibetan Plateau (TP) plays an essential role in the ecological sheltering function for China and other parts of Asia. However, black carbon, persistent organic pollutants, and heavy metals (HMs) have been increased dramatically since the 1950s, reflecting rising emissions in Asia. In this context, the sources and distribution of HMs were summarized in the environment media of the TP. The results showed that 1) HMs in the TP may be generated from geogenic/pedogenic associations (Cu, Cr, Ni, As, and Co) and anthropogenic activities of local or long-distance atmospheric transmission (Cd, Pb, Zn, and Hg). 2) The atmospheric transport emission sources of HMs are mainly from the surrounding heavily-polluted regions by the Indian and East Asian monsoons and the southern branch of westerly winds. 3) Soil, water, snow, glacier, sediment, and vegetation act as vital sinks of atmospheric deposits of HMs; 4) Significant bioaccumulation of arsenic (As), lead (Pb), and methylmercury (MeHg) have been found in terrestrial and aquatic biota chains in the TP; 5) The enhancement of anthropogenic activities, climate change, glacial retreat and permafrost degradation had potential impacts on the behaviors and fates of HMs in the TP. Therefore, the ecological risk of HMs is of particular concern, and feasible and effective environmental safety strategies are required to reduce the adverse effects of inorganic pollutants in the TP. Our review will provide a reference for researchers to further study regional HMs pollution around the TP.