Cryosphere Forum 2021: Status of research on changing permafrost and associated impacts in the Hindu Kush Himalaya

Kaytan Kelkar, Louise Farquharson, Dmitry Nicolsky

Geophysical Institute Permafrost Laboratory (GIPL), University of Alaska, Fairbanks, AK 99775

Abstract

Slope instability in periglacial terrain is a natural phenomenon rapidly driven by climate change and resultant air temperature warming. The subsequent loss of slope support caused by accelerated permafrost degradation is on the rise. This projected increase in thaw-vulnerable slope instability poses a threat to human lives and vital infrastructure. We aim to determine mechanisms of permafrost thaw induced slope destabilization and map thaw-vulnerable slopes. Our interdisciplinary approach will include: 1) conduct field surveys at predisposed unstable slopes; 2) use a range of remote sensing techniques to map the location of mass movements across sites in the discontinuous permafrost region of Alaska; 3) establish a permafrost monitoring network across a suite of representative sites; and 4) integrate terrain parameters to construct a GIPL mountain permafrost model.

The Hindu Kush Himalaya (HKH) region presents an opportunity to advance permafrost
research because our knowledge of permafrost extent and its vulnerability to thaw in the HKH is far from complete. A lack of ground truthing of permafrost occurrence compounded with sparse in-situ monitoring of permafrost slopes are a drawback. We hope to expand our research endeavors in the HKH region by building collaborations and partnerships with local government agencies and universities with shared research interests. There is scope to establish a robust longterm periglacial slope monitoring network. Each site will provide real time continuous ground temperature that documents rapid permafrost thaw and will enhance our understanding of future permafrost dynamics and its potential implications for slope failure events. This international effort will foster collaboration between Alaskan researchers and local experts, facilitating the exchange of data and encourage the sharing of research ideologies that will ultimately improve our understanding of permafrost affected slope failures across the HKH region and Alaska. Furthermore, this research pursuit will foster outreach to promote best land-use practices and educate local mountain communities of the dangers of living in a dynamic landscape. This proposed multidisciplinary approach will serve as a valuable resource to support a common global response to constrain the timing and location of thaw vulnerable mass-movements.

M. Younis Khan¹, Sher Muhammad<sup>2

1</sup>National Centre of Excellence in Geology, University of Peshawar, Peshawar, Pakistan
²The International Centre for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal

Abstract

Mountain permafrost is sensitive to climate change with expected degradation in the near future in response to global warming. Geophysical methods have been successfully applied to study the permafrost dynamics and degradation in other parts of the world but no such studies exist in Pakistan. Our proposed research will include state-of-the-art geophysical technologies to evaluate the permafrost landscape in northern Pakistan. This would help us focus on the most vulnerable areas with a direct threat from permafrost to land use, key infrastructure such as Karakoram Highway (KKH) which is a part of the China Pakistan Economic Corridor (CPEC), water channels, and trigger land degradation in the areas that are hot spots for tourism. To address the permafrost degradation and associated impacts, non-destructive high resolution geophysical methods (ERT and GPR) will be employed to characterize selected permafrost sites in detail using existing permafrost maps. In second phase, results obtained from geophysical imaging could be integrated with permafrost surface temperature, shallow-subsurface boreholes and drilling/core data sets. The data products obtained from advanced high-tech methods for measuring properties of frozen soil and for inferring or predicting permafrost characteristics will be useable for stakeholders and policymakers to reduce the risks related to permafrost degradation in a multi-sectorial context. Such field-based investigations will produce preliminary insight of permafrost dynamics and observable impacts on society at different levels. The pilot projects are expected to initiate the permafrost related research, and contribute to the capacity building of early-career researchers in Pakistan.

William Brian Whalley

University of Sheffield

Abstract

There has been much recent interest in the preservation of ice in rock glaciers and associated hydrological implications, especially with respect to continental mountain areas in a heating climate. This is also linked to the diminution of glacier volumes and associated glacier discharge and the need for modelling. Correspondingly, there has been an interest in mapping rock glaciers, producing inventories and the development of machine learning algorithms for identifying rock glaciers and distinguishing them from glaciers and debris-covered glaciers. The importance of ‘reservoir ice’ contained in rock glaciers has been noted in the ‘Dry Andes’ and extends to the Himalaya-Karakorum-Hindu Kush. Most recent literature on this topic has assumed that rock glaciers indicate the presence of discontinuous permafrost and that they can be used for permafrost mapping. This assumption, that rock glaciers (a term used to describe ‘a creeping mass of ice-rich debris on mountain slopes’) are zonal landforms and follow ‘morphoclimatic’ ideas linking landforms to climate. This is the ‘permafrost (or ‘cryogenic’) model of rock glacier formation and the exclusive landform-climate relationship followed by recent rock glacier mapping in the Hindu Kush. However, there is a long-standing view that rock glaciers are the result of an interplay between glacier ice and weathered debris loads from mountain slopes that accumulates on the glacier surface and protects it from melting. The ‘glacigenic’ (azonal) model of rock glaciers is denied by the permafrost model. This paper re-examines some terrestrial observations of glaciers and rock glaciers in the Bashgal Valley, eastern Afghanistan (Nuristan) in 1976. Gradual transitions between glaciers, debris-covered glaciers and rock glaciers are clearly seen on the ground. The steep snouts of some rock glaciers were advancing over previously deposited moraines or grassy meadows. These observations are compared to recent satellite imagery (Google Earth, Mapcarta) where surface lowering and snout recession are seen on debris-free glaciers. Meltwater pools are forming on some rock glaciers and are associated with similar melt features on debris-covered glaciers. Such features have been associated with glacier ice core melting on rock glaciers in the Alps and Andes. These observations indicate that rock glaciers may contain more ‘reservoir ice’ than if they were cryogenic features but that they cannot be used to map permafrost extent. Further, development of meltwater pools and ice-dammed lakes draining sub-glacially in rock glaciers may enhance the likelihood of sudden drainage (glacier lake outburst floods) and debris flow production.

Dagmar Brombierstäudl, Susanne Schmidt, Marcus Nüsser

Heidelberg University

Abstract

In the semi-arid high mountains of the Upper Indus Basin (UIB), meltwater supply from the cryosphere is vital for irrigated agriculture and hydropower generation. One mostly overlooked cryosphere component is aufeis, which appears as a sheet-like formation of ice layers, created by successive and laminated freezing of flowing water. Although a common hydrological phenomenon across the permafrost areas of the northern hemisphere, it has so far been neglected in cryosphere studies in the UIB despite its potential hydrological importance for regional water supply.

This study aims to redress this knowledge gap by generating an inventory of aufeis occurrence together with an analysis of their spatial distribution and the role of topographical parameters. The analysis is based on a Landsat time-series using imagery from 2010 to 2020, supported and validated by several field campaigns carried out between 2014 and 2020. In total, 8274 images covering 22 Landsat tiles over the whole UIB were used and processed with the Google Earth Engine platform.

More than 3700 aufeis fields were detected in the whole Upper Indus Basin, covering an area of about 298 ± 38 km². The spatial distribution of their occurrence indicates a distinct elevation range between 4000 and 5500 m a.s.l. and is marked by a pronounced longitudinal increase to the east. In contrast to the western part of the UIB (Gilgit-Baltistan), where only some few and small aufeis fields can be detected, 65% of the aufeis covered areas (195 ± 23 km²) exist on the Tibetan Plateau. Our database fills an important research gap and will help in further cryosphere and permafrost studies in the UIB and beyond.

Cai Jiaxin

Southwest Jiaotong University

Abstract

Identifying active rock glaciers (ARGs) has mainly relied on the visual interpretation of their geomorphic characteristics based on aerial optical images, while inventorying ARGs from their kinematic features has also been proposed in recent years. The geomorphic- and kinematic-based approaches both have their pros and cons. However, a thorough comparative analysis of these two methods has not been carried out. In this study, using the Sentinel-1 SAR images acquired between 2015 and 2019, we employed a small baseline subset InSAR (SBAS-InSAR) method to derive the mean annual surface displacement velocity over the Daxue Shan, Southeast Tibet Plateau. We then compiled a rock glac ier inventory by synthetically using the derived surface velocity and geomorphic features based on Google Earth satellite images. This kinematic-based inventory (KBI) was then compared with a preexisting rock glacier dataset in Daxue Shan from the geomorphic-based inventory (GBI). The results show that our SBAS-InSAR derived inventory consists of 344 rock glaciers, 36% (i.e., 125) more than that derived from the geomorphic-based method (i.e., 251). Only 32 ARGs are identified by the GBI but are not included in the KBI. Among the 219 ARGs detected by both approaches, the ARGs having area differences of more than 20% account for 20% (i.e., 70) of the total number of KBI. The mean velocity of ARGs calculated from SBAS-InSAR mainly ranges between 10–35 mm∙a^–1. The comparative analyses show that ARGs mapping from the kinematic-based approach is more efficient and accurate than the geomorphic-based approach. However, the completeness of KBI is affected by SAR data acquisition time, signal decorrelation, geometric distortion of SAR images, and the sensitivity of InSAR measurement to ground deformation. We highlight that selection of inventory approach has a great influence on the ARGs -based studies such as the mountain permafrost distribution simulation and water storage estimation.

Yan Hu^1,2,3, Stephan Harrison², Lin Liu^1,3, Joanne Laura Wood²

¹Earth System Science Programme, Faculty of Science, The Chinese University of Hong Kong, Hong Kong SAR, China

²College of Life and Environmental Sciences, University of Exeter, Penryn, Cornwall, TR10 9EZ, UK

³Institute of Environment, Energy and Sustainability, The Chinese University of Hong Kong, The Chinese University of Hong Kong, Hong Kong SAR, China

Abstract

Rock glaciers contain significant amounts of ground ice and serve as important freshwater resources as mountain glaciers melt in response to climate warming. However, current knowledge about ice content in rock glaciers has been acquired mainly from in situ investigations in limited study areas. This hinders a comprehensive understanding of ice storage in rock glaciers situated in remote mountains over local to regional scales. In this study, we develop an empirical rheological model to infer ice content of rock glaciers using readily available input data including rock glacier planar shape, surface slope angle, active layer thickness, and surface creep rate. The model is calibrated and validated using observational data from the Chilean Andes and Swiss Alps. We apply the model to infer the ice content of five rock glaciers in Khumbu and Lhotse Valleys, north-eastern Nepal. The velocity constraints applied to the model are derived from Interferometric Synthetic Aperture Radar (InSAR) measurements. The inferred volumetric ice fraction in Khumbu and Lhotse Valleys ranges from 71% to 75.3% and water volume equivalents lie between 1.40 to 5.92 million m³ for individual landforms. Considering previous mapping results and extrapolating from our findings to the entire Nepalese Himalaya, the total amount of water stored in rock glaciers could be in the magnitude of 10 billion m³, equivalent to a ratio of 1:17 between rock glacier and glacier reservoirs. Due to the accessibility of the input parameters of the model developed in this study, it is possible to apply this approach to permafrost regions where previous information about ice content of rock glaciers is lacking, and ultimately to estimate the water storage potential of the remotely located rock glaciers.

Élise Devoie^1,2, Jeffrey McKenzie¹, Stephan Gruber²

¹Earth and Planetary Sciences, McGill University, Montréal, QC, H3A 0C6

²Geography and Environmental Studies, Carleton University, Ottawa, ON, K1S 5B6

Objective: A compilation of existing measured soil freezing characteristic curves is presented for future applications in permafrost thaw modelling.

Key Findings

1. Warming climate results in widespread permafrost thaw, making the need for SFCCs more apparent
2. An open-source compilation of SFCCs is presented
3. Uncertainty in existing SFCCs is compared based on measurement technique, water content, and soil disturbance

Abstract

As climate warms, much of the earth’s permafrost warms and approaches the freeze/thaw temperature. Accurately modelling active layer dynamics and permafrost evolution is dependent on soil freezing characteristic curves (SFCC). These relate the unfrozen water content in a soil to its temperature. The SFCC is a soil-specific mathematical construct and can be measured or estimated. SFCCs depend on many factors including soil properties, soil pore water pressure, dissolved salts, (hysteresis in) freezing/thawing point depression, and degree of saturation, all of which can be site-specific and time varying. This has led to the development of many diverse SFCCs for applications in different study sites, fields of study and for differing research purposes. Each numerical model incorporating freeze/thaw makes an implicit assumption when assigning an SFCC, and this choice introduces uncertainty into the modelling results.

Many SFCCs are empirically based and rely on collection of freezing and thawing data for the soil in question. Short of this, SFCCs based on theory alone are highly dependent on soil properties. In many regions, these detailed data are not available, and yet permafrost models are still necessary and depend on soil freeze/thaw processes. To address this, a synthesis of measured SFCC data from literature is organized into an open-source compilation for the available range of studied soils. Data digitized from previous (historic) lab and field measurements from 1943 to present is gathered, and data collection methods are compared. Uncertainty bounds are estimated for each measurement technique based on the aggregate data. Future work understanding the propagation of this uncertainty in permafrost modelling is outlined.

Kyung “Robin” Kim¹, Prakrut Kansara¹, Ryan Haagenson², Harihar Rajaram², Venkataraman Lakshmi¹_­

¹The Department of Engineering Systems and Environment, University of Virginia, Charlottesville, VA, USA

²The Department of Environmental Health and Engineering, Johns Hopkins University, Baltimore, MD, USA

Abstract

The projected thawing of alpine permafrost in the 21st century will trigger major challenges related to slope instability, carbon emissions, public health, and water resource management in mountain communities and their downstream neighbors. Thus, accurate estimates of permafrost coverage at high resolution are desirable, especially in data sparse regions like High Mountain Asia, where highly rugged terrain renders in-situ data collection difficult. By simple definition, a Mean Annual Ground Temperature (MAGT) of or below 0 °C for at least two consecutive years determines permafrost presence in a given area. However, the Mean Annual Air Temperature (MAAT) and increasingly, the Mean Annual Land Surface Temperature (MALST) are used as proxy variables in lieu of direct MAGT measurements due to the accessibility and potential of remotely sensed observations. This study leverages the sampling frequency and spatial coverage of daily LST products from Terra and Aqua MODIS (Moderate Resolution Imaging Spectroradiometer) to map a first-order Permafrost Zonation Index (PZI) in HMA based on MALST from monthly averages and a cumulative normal distribution function used by Gruber (2012). Mean monthly snow depths for the HMA region provided by Liu et al (2021) are incorporated into a modified equation based on weighted freezing/thawing degree day indices originally derived by Smith and Riseborough (2002) to account for the insulating effect of snow cover on the MAGT. Total permafrost areas are calculated for the following sub-regions in HMA: the Tien Shan (95,800 km²), Pamirs (63,400 km²), Hindu Kush (17,100 km²), Karakoram (64,600 km²), Himalayas (101,000 km²), Hengduan (50,600 km²), and Qinghai-Tibetan Plateau (717,000 km²). The issue of whether MALST based on non-gap filled monthly averages of daily MODIS LST estimates captures the annual thermal flux between ground and surface remains an outstanding question.

Ying Li¹, Kerry Leith^1,2, Matthew Perras³, Rui Wu¹, Paul Selvadurai¹, Simon Loew¹

¹ Department of Earth Sciences, ETH Zurich, Zurich, Switzerland

² Surface Geosciences, GNS Science, Lower Hutt, New Zealand

³Department of Civil Engineering, York University, 4700 Keele St, Toronto, Canada

Abstract

Permafrost has been noted as sensitive to changes in atmospheric temperature, and it is predicted that rising temperatures, widely expected throughout the next century, may lead to increased slope instability in high mountainous areas, as evidenced by increase in rock fall event frequency since 1940 from permafrost areas and paraglacial slopes. The physics of warming-associated failure in natural permafrost settings (e.g. alpine and Himalaya rock slopes), however, it is difficult to study as the processes can last from days to centuries, the driving factors can be complex and coupled, and the internal damage is not visible. Laboratory investigations can be performed under reasonable time scales and have the advantage of controlling and isolating a single driving factor. Here, we present results from a single edge notch bending (SENB) test undertaken on a 400 × 90 × 90 mm prisms of Herrnholz granite subjected to alternating phases of freezing below 0° C, followed by thawing, under a constant load of 10.2 kN (70% of the predetermined peak strength). This test was undertaken in the Rock Physics and Mechanics Lab at ETH Zurich, and provides initial insights into the effect of warming on stability of a frozen, critically stressed fracture.

Initial determination of the short-term peak strength of the Herrnholz granite was determined on two samples by loading to failure under load-point displacement (piston) control at a rate of 1 μm/s in the SENB configuration under ambient conditions. Results indicated an average strength of 15 kN, and fracture toughness of 1.82 MPa m^1/2. To produce a geometrically well-defined and reproducibly sharp crack (avoiding crack tip blunting), we performed five load/hold/unload cycles to extend a fatigue crack from the initial notch. The load rose from 1 to 11 kN (75% of the predetermined peak strength) at a rate of 0.02 kN/s, and was held constant until crack mouth opening displacement (CMOD) was observed reached 5% of the accumulated opening during the loading phase, or hold period exceeded 10 min, before lowering again to 1 kN. The precracked sample under natural saturation degree was then allowed to creep with a constant load of 10.2 kN under 3 days of constant air temperature at -7 °C, 4 days of warming at a constant rate of 0.3°C/h, and approximately a half-day at a constant air temperature of 23°C.

Progressive failure characteristics during both the freezing and thawing phases were observed through the combination of CMOD and digital image correlation-based surface strains. The CMOD and strain rate reduced to around 1% of the rate at the initiation of the constant load period (1.4 × 10^-3 mm/h and 2.1 × 10⁻⁵ h⁻¹) within the first day of the freezing period, delimiting the secondary creep phase. This phase lasted for about 2 days until the air temperature reached 0°C, when the CMOD and strain rates both increased gradually for about 3 hours, reaching a maximum of 2 × 10^-3 mm/h, and 5.6 × 10⁻⁵ h⁻¹, respectively, before progressing to failure in within 4 days.

Follow-up tests on similar specimens are planned and expected to provide more data to constrain the response of critically stressed frozen fractures to changes in the thermal conditions. This unique dataset will provide initial insight into the long-term behaviour of natural permafrost settings upon climate warming.

Tara Tripura Mantha¹, Santonu Goswami²

¹Completed post-graduation at University of Hyderabad, India²Earth and Climate Science Area, NRSC, ISRO, India

Abstract

Permafrost related hazards through degradation are observed to increase due to climatechange. However, scarce studies have been carried out for alpine permafrost, especially in theIndian Himalayan region due to lack of accessibility. Given the dependency of humansettlement in such areas, better understanding of this region is a major environmentalconcern. In this study, we use SAR remote sensing technique to identify seasonal groundsubsidence at Tso Kar area through interferometric analysis. Quantification of seasonalsubsidence is further analysed with the major climate change parameters such as land surfacetemperature and precipitation. This novel approach can provide some new insights intopermafrost degradation using ground subsidence as the indicator.

Alessandro Cicoira¹, Xingyue Li¹, Lars Blatny¹, Bertil Trottet¹, and Johan Gaume^1,2

¹ Snow and Avalanche Simulation Laboratory (SLAB), Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland

² WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland

Abstract:

Numerical modelling is an essential tool for the analysis and management of mountain risks: it allows quantitative description of the run-out distance and impact pressure of rapid mass movements and may contribute to better understand the fundamental processes controlling their magnitude, frequency, and dynamics. Yet, a unified model able to simulate multi-phase cascading events, including their initiation, propagation, entrainment and finally deposition is still missing. Hence, more detailed and physically-based models are still required to advance our understanding of gravitational mass movements and process chains and ultimately to contribute improving hazard assessment and risk management.

Here, we present a three dimensional numerical modelling approach based on a hybrid Eulerian-Lagrangian Material Point Method (MPM), finite strain elasto-plasticity and critical state soil mechanics to simulate in a unified manner the mechanical processes leading to failure and instabilities of heterogeneous materials, the dynamic behaviour of the consequent mass movements, including phase transitions and interactions, as well as processes of entrainment and deposition. In order to demonstrate the potential of our approach, we investigate four real-scale cases: the 1963 Vajont rock-slide and lake outburst flood (IT), the 2017 Piz Cengalo rock-avalanche (CH), the 2018 Wisshorn rock- and snow avalanche (CH), and the 2020 collapse of the Whymper hanging glacier (IT). Results show a good agreement with available data. Finally, we discuss the relevance and limitations of our approach and suggest improvement strategies for future developments.

Javed Hassan^{1, 3}, Xiaoqing CHEN^{1, 2, 3}, Sher Muhammad⁴, Nazir Ahmed Bazai^{1, 3}

¹Key Laboratory of Mountain Hazards and Earth Surface Process, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
²CAS Centre for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China
³University of Chinese Academy of Sciences, Beijing 100049, China
⁴International Center for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal

Abstract

The destabilization of rock glaciers and permafrost variations is of great importance to the safety of the population and infrastructure in the Karakoram region because of their effects on land stability and river obstructions. In this study, we compiled the first complete rock glacier inventory for the Hunza Basin, western Karakoram, of 616 rock glaciers with an area of 194 km2 between 2800 and 5700 m a.s.l. We categorized the rock glaciers as intact or relict, and their distributions and destabilization were further analyzed and used along with in situ climate and elevation dataset to model the permafrost probability distribution. The modeled areas where the permafrost zonation index (PZI) is 0.5-1.00 indicate that permafrost occurs over 85% of the catchment area and lies above 3525 m a.s.l., which closely matches the zero-degree isotherm of 3800 m a.s.l. Based on the sensitivity analysis of the independent variables, elevation is the most sensitive variable, followed by net radiation, for predicting the probabilities of the presence and absence of permafrost. The model distributions are quite precise, with median posterior areas under the curve of 0.98 and 0.96 for model training and testing, respectively. We analyzed the rock glacier destabilization for 68 rock glaciers that interacted with river channels, of which 50 blocked or diverted river channels. Destabilized rock glaciers can be closely linked to the 0℃ isotherm between 3400 and 4600 m a.s.l. The significant damage caused by periodic floods from the subsequent blockage of river channels by landslides can be attributed to variations in permafrost which demolished infrastructure, including a hydropower plant, suspension bridge and water supply system in Hassan-abad catchment. Quantification of rock glacier dynamics and permafrost in the region can further improve policies related to the reduction in disaster risk and mitigation of associated hazards.

Prashant Baral^1,2, Mohd. Anul Haq³

¹Geographic Information Systems, NIIT University, Rajasthan, India

²International Centre for Integrated Mountain Development, Nepal

³Computer Science and Information Technology College, Majmaah University, Al Majmaah, Kingdom of Saudi Arabia

Abstract

Permafrost investigations through field-based research in the Hindu Kush Himalayan (HKH) region are logistically difficult and economically challenging. As a result, several recent studies have relied upon the use of remote sensing techniques for understanding permafrost distribution in this region. In addition to the remote sensing methods, application of multiple machine learning algorithms to generate permafrost probability models is found to be efficient for the data scarce Himalayan region. Permafrost probability maps produced from these models are able to provide a reasonable estimate of the probability of permafrost occurrence for different locations within the HKH region. The models are capable of predicting the probability based on information from historical global climate data and remotely sensed topographic and topoclimatic attributes. These probability estimates are essential to anticipate changes in areal distribution of permafrost and to analyse the resulting implications of thawing permafrost due to rising temperatures in the region.

Chunlin Song^1,2, Genxu Wang^1,2

¹State Key Laboratory of Hydraulics and Mountain River Engineering, College of Water Resource and Hydropower, Sichuan University, Chengdu, China

²Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China

Abstract

Permafrost carbon pool destabilization causes hydrological export of active layer and permafrost layer carbon, yet the export patterns and magnitudes are not well understood. Here we investigated the radiocarbon (¹⁴C) in dissolved organic and inorganic carbon (DOC and DIC, respectively) exported from a mid-sized permafrost river in the Qinghai-Tibet Plateau (QTP). We took advantage of radiocarbon dating and a statistical model and partitioned the riverine carbon from different age categories. DOC and DIC showed bomb-depleted ¹⁴C signatures corresponding to millennial ages, which were positively correlated to the permafrost top temperature and affected by active layer dynamics. Further, 83±34.4% of DOC was derived from active layer and permafrost layer pre-aged carbon. DIC export was comprised of a smaller portion of pre-aged carbon (38.5±2.5%) but a much larger flux of pre-aged carbon due to higher annual DIC export. Interestingly, approximately 58% of annual pre-aged DOC and DIC were exported in summer. The monsoon climate-induced high discharge and maximum active layer thaw depth in summer enhanced the remarkably rapid fluvial export of millennial-aged carbon. These results suggest a unique old carbon loss pattern in QTP permafrost region compared to higher latitude permafrost regions with a non-monsoonal climate. As climate warms, more old carbon export is expected and may alter the permafrost carbon-climate feedback and affect the river ecosystem health.

Sher Muhammad

The International Centre for Integrated Mountain Development (ICIMOD), Kathmandu, Nepal

Abstract

Permafrost is the least explored cryosphere component in the Hindukush-Karakoram-Himalaya (HKH) region. Also, existing permafrost distribution maps in the HKH are coarse with negligible field validation. In the warming world, it is important to study permafrost and its associated impacts on society as climate change directly affects permafrost by thawing it. The most commons impacts of climate warming on permafrost are 1) permafrost is thawing, causing to leave water and soil behind – northern villages, roads, and other infrastructure built on the permafrost may be destroyed. 2) Permafrost melt causes organic carbon in the soil to decompose and release CO2 and CH4. 3) Also, unfrozen bacteria and viruses could make human and animals unhealthy/ cause sickness. To monitor the impacts of climate change on the permafrost, mapping of its spatial distribution is required. Permafrost is mostly represented on maps using permafrost zones or permafrost extent. This study map permafrost zones in the Upper Indus Basin using multiple datasets. We use a criterion of mean annual air temperature (MAAT), slope, elevation, and glacier cover was used to determine the permafrost extent. The final output and extent of the permafrost were categorized into three classes as high, medium, and low probability. The results were compared with the global permafrost extent data. We propose to use this map for further improvement, using geological expertise of identifying permafrost landforms within high and moderate probability zones and update the map. In this step, we will be using high-resolution data as google earth. After revising/improvement based on google earth data and geological parameters, field validation may be performed to validate the results. For field validation, specific locations will be identified.

Arnab Singh, Darwin Rana, Sangya Mishra, Dibas Shrestha

Central Department of Hydrology and Meteorology, Tribhuvan University

Abstract

Rock glaciers are an important indicator of the existence of permafrost. Study of permafrost variation isnecessary to understand the stability, its nature in regards to global warming and hydrology. In thisstudy, we made an inventory (n = 106) of rock glacier in the Solukhumbu region, Nepal, and dividedthem into Talus or Relict, with assumption that former contains permafrost while the latter does notand are controlled by predictor values (Mean Air Temperature, Slope, Aspect and Potential IncomingSolar Radiation). The distribution is done through three statistical models: Logistic regression, RandomForest and Support Vector Machines with varying degree of performance. Three different versions ofsame models are run over a range of pseudorandom numbers and Support Vector Machine with 5-foldrepeated cross-validation performed best (Accuracy = 0.81, Kappa = 0.6), default Logistic regression(Accuracy = 0.8, Kappa = 0.59), and Random Forest with 10-Fold Variation (Accuracy = 0.68, Kappa =0.36).

Aayushi Pandey, Bankim Chandra Yadav, John Mohd Wani, A.P. Dimri

School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India

Abstract

The Himalayan cold-arid areas contain substantial permafrost. It experiences cycle of thawing and freezing depending on the adjacent surface fluxes and climate change as well. Understanding of permafrost is important from trapping of water and methane; and from planning and policy perspective as well. In geocryological studies, dynamics of permafrost coupled with land surface processes needs attention. A study by Rastogi and Nawani (1976) stated permafrost in the Tso Kar basin (Ladakh region). Therefore, in the present work a novel model, which assess the permafrost distribution using remote sensing, is attempted. Due to non-availability of permafrost information, a hypothetical permafrost model is developed based on thresholds provided by Baral and Haq (2020) and Kalinicheva et al. (2019, 2021). Remote sensing inputs viz., land surface temperature (LST), emissivity (both derived from Landsat 8), and topographic factors viz., elevation (from SRTM digital elevation model), wetness index and potential incoming solar radiation, are used. All these data are at horizontal spatial resolution of 30 meters. Using Geographic Information System (GIS) and machine learning techniques, a novel model is developed for ‘no-permafrost’, ‘probable permafrost’ and ‘permafrost’ over the Tso Kar Basin. The 70% (training) of available data is used for model development and remaining 30% (validation) of available data is used for test. The first order model estimate show that the 24.10% area in the basin is found to be ‘no-permafrost’, 70.11 % is found to be ‘probable permafrost’ and 5.77% is found to be ‘permafrost’ (without masking the lake area).

References

Baral P and Haq MA, (2020) Spatial prediction of permafrost occurrence in Sikkim Himalayas using logistic regression, random forests, support vector machines and neural network. Geomorphology. https://doi.org/10.1016/j.geomorph.2020.107331

Kalinicheva SV, Fedorov AN, Zhelezniak MN (2019) Mapping Mountain permafrost landscapes in Siberia using Landsat thermal imagery. Geosciences 9(1): 4. https://doi.org/10.3390/geosciences9010004

Kalinicheva SV, Shestakova AA (2021) Using thermal remote sensing in the classification of mountain permafrost landscapes. Journal of Mountain Science 18(3). https://doi.org/10.1007/s11629-020-6475-7

Rastogi SP, Nawani PC. (1976) Permafrost areas in TsoKar Basin. In Symposium on the Contribution of Earth Sciences Towards the Research and Development Activities in the N.R. Vol 3, Article 7: 1–7.

Lea Hartl, Austrian Academy of Sciences

Active and relict rock glaciers are abundant in the Austrian Alps. This presentation gives a general overview of fieldwork-based monitoring efforts and the data basis available in the region, highlighting longterm measurements of rock glacier surface displacement going back to the 1950s, as well as recent monitoring projects focused on hydrogeological parameters of rock glacier runoff. Surface displacement at Hochebenkar, the longterm monitoring site, has increased significantly in the last decades and recently reached a new maximum annual velocity. As the rock glacier advances, an access road situated below is increasingly threatened by rock fall. Preliminary results from the hydrogeological measurements conducted at different rock glacier sites indicate shifting runoff regimes associated with reduced ice content. Under ongoing climate change conditions, it is likely that the rapid changes we are seeing today will continue, possibly at further increased rates. To conclude the presentation and with the intention of gathering input from the community, some points of discussion are raised regarding future monitoring strategies of rock glacier processes and how ongoing changes of glacial and peri-glacial landforms can best be represented in inventories.

John Mohd Wani, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India-110067

Abstract

Permafrost is defined as the ground (soil or rock and included ice and organic material) that remains at or below 0 °C for at least two consecutive years. Permafrost is invisible and usually lies beneath the ground surface. The permafrost is a common phenomenon across the cold regions at high latitudes (Arctic, Antarctica) and high elevation mountain areas like the Alps, Andes, and the Himalayas. Himalaya is known for its glaciers and snow cover from time immemorial, and most of the focus during the past remained on these two cryospheric components. However, the frozen ground, more specifically the permafrost in the higher elevation regions of the Himalaya largely remained unknown till date. The practical relevance of permafrost research in the Indian Himalayan region is given by its role in local/regional water availability, construction and maintenance of infrastructure as well as disasters such as landslides. Secondly, it is believed to have a lesser impact on the mountain ecosystem in comparison to other cryospheric components such as snow and glaciers. Across the Hindu Kush Himalayan region, permafrost research in the Qinghai-Tibetan Plateau is very well developed and globally recognised. However, permafrost extent and its characteristics from the Indian Himalayan Region is known sparingly except a few localised studies. Therefore, we aim to infer permafrost and its characteristics from a representative catchment in the trans-Himalayan region of Ladakh for the first time. Field data (near-surface ground temperature and meteorological) acquisition and computer modelling were used to achieve this objective. The results strongly indicate the existence of significant permafrost areas across the high elevations of the cold-arid regions of study catchment. Therefore, it is expected that this will encourage similar studies at other locations in the region, which would greatly improve the understanding of the permafrost in the region.

Kotaro FUKUI¹, Koji FUJITA², Phuntsho Tshering³, Takanobu SAWAGAKI⁴, and Shun TSUTAKI^5
1Tatecal Museum, Japan
²Nagoya University, Japan
³Department of Geology and Mines, Bhutan
⁴Hosei University, Japan
⁵National Institute of Polar Research, Japan

Abstract

We carried out a permafrost research expedition in the Bhutan Himalayas from 23 Sep to 24 Oct 2014. An aim of our expedition is to make a rock glaciers inventory and identify the lower limit of mountain permafrost. We identified a total of 81 rock glaciers along the Snowman trek route. Since active rock glaciers appeared above 4500-4600 m, the lower limit of mountain permafrost in the Bhutan Himalayas was estimated to be 4500-4600 m. Thus, the lower limit of mountain permafrost in Bhutan Himalayas is slightly lower than the eastern Nepal Himalayas. Mean annual ground surface temperature (MAGST) at 4890 and 5170 m asl are 0.5 and -2.9 degrees C, respectively. MAGST around the lower limit of mountain permafrost may be positive in this region.

Jeannette Noetzli^1,2
1 WSL Institute for Snow and Avalanche Research SLF
² Swiss Permafrost Monitoring Network PERMOS
Abstract
In this talk I will present the monitoring strategy for long-term climate-related observation of mountain permafrost in the Swiss Alps as implemented by the Swiss Permafrost Monitoring Network PERMOS together with the key results and major challenges after more than two decades of operation. Temperature measurements at the ground surface and in boreholes up to 100 m depth, observed changes in ice content based on repeated geophysical surveys at fixed installed profiles, and rock glacier velocities derived from annual terrestrial geodetic surveys show a congruent picture of warming and degrading permafrost in the Swiss Alps. Guidelines and standards related to field installation, maintenance as well as data management and quality control are crucial to obtain long-term, consistent, and comparable data to document and assess the state and changes mountain permafrost.

Juditha Schmidt
Doctoral Research Fellow, Section of Physical Geography and Hydrology, University of Oslo

Abstract

The thermal regime of permafrost is governed by a complex interplay of different processes such as conductive heat transfer, vertical and lateral movement of water and the surface energy balance. Including these energy and water fluxes into model studies can improve simulations of permafrost ground temperatures including permafrost evolution, future projections and subsequent climate-triggered feedbacks.

In this workshop, we present the thermal model CryoGrid, which is designed to simulate ground temperatures, water fluxes and the energy transfer from the atmosphere to the ground. With this, it provides a flexible platform to explore new parametrizations for a range of permafrost processes.

In the first part of the workshop, we will introduce the concept of CryoGrid as a community model with several groups of researchers working on the development and improvement of the code. We will present different model applications ranging from permafrost mapping to excess ice processes and explain the physical background of the model.

The second part will focus on the usage of CryoGrid, aiming at an audience without practical experience with the model. We will give information where the code can be downloaded and explain step by step how to set up model runs. Furthermore, we will discuss examples on the influence of snow and topography on ground temperatures.

Gopal Penny, University of Notre Dame, United States

Abstract

Streamflow regimes are rapidly changing in many regions of the world. The ability to attribute these changes to specific hydrological processes and their underlying climatic and anthropogenic drivers is essential to formulate effective water policy. In this talk, I present an approach to hydrological attribution that leverages the method of multiple hypotheses, which I use to generate a holistic understanding of watershed-scale processes. I apply the approach to understand changes in the Upper Jhelum River, an important tributary headwater of the Indus basin, where streamflow has declined considerably since 2000 and has yet to be adequately attributed to its corresponding drivers. Using remote sensing and secondary data collected from the watershed, I explore changes in land use, climate, surface water, and groundwater. The evidence reveals that climate, rather than land use, had a considerably stronger influence on reductions in streamflow, both through reduced precipitation and increased evapotranspiration.

L.C.P. Martin, F. Brun, S. Westermann, J. Fiddes, Y. Lei, P. Kraaijenbrink, T. Mathys and W.W. Immerzeel

Abstract

Ground thermal regime of high mountain catchments impacts the partition between infiltration and runoff, latent and sensible heat fluxes, frozen and liquid subsurface water and the presence (or absence) of permafrost. In the context of global warming, hydrological modifications associated to ground thermal changes are of critical importance for extensive headwater regions such as the Qinghai-Tibet Plateau (QTP) and the Himalayas, which are major water towers of the world. Improving our ability to quantify these changes is therefore a key scientific challenge both regarding basic science and continentalscale water resource management. Many watersheds of the QTP have seen their hydrologic budget modified over the last decades as evidenced by strong lake level variations observed in endorheic basins. Yet, the role of ground thermal changes in these variations has not been assessed. Lake Paiku (central Himalayas, southern TP) has exhibited important level decreases since the 70s and thus offers the possibility to test the potential role of ground thermal changes and permafrost thaw on these hydrologic changes. We present distributed ground thermo-hydric simulations covering the watershed over the last four decades. We use the Cryogrid model to simulate the surface energy balance and the ground thermo-hydric regime while accounting for the phase changes and the soil water budget. Because the surface radiative, sensible and latent heat fluxes in alpine environments are strongly dependent on the physiography, the model is forced with distributed downscaled forcing data produced with the TOPOSCALE model. Forcing data and simulated surface conditions are evaluated against meteorological data acquired within the basin, ground surface temperature loggers and remotely sensed surface temperatures. The simulations show that, contrary to large scale estimates of permafrost occurrence probability, a significant proportion of the basin is underlaid by permafrost. This proportion decreased from 52 to 39% between 1980 and 2019. We also show that over the 1980-2020 period, ground temperatures warmed at a rate neighboring 1.7°C per centuries. The permafrost elevation limit rose from 4728 to 4838 m asl (300 m per century). Unfrozen surface conditions increased at a rate of 23 days per century and evaporation increased at a rate of 180 mm per century (32% increase over the period). These first results highlight the potential of catchment-scale thermo-hydric simulations to better quantify hydrological changes to come in the QTP.

Tamara Mathys¹, Christin Hilbich¹, Eric Pohl¹, Christian Hauck¹, Martin Hoelzle^1
1Department of Geosciences, University of Fribourg, Chemin du Musée 4, CH-1700 Fribourg

Abstract

With ongoing climate change, there is a pressing need to better understand how much water is stored as near surface ground ice in regions with extensive permafrost occurrences. This is especially important in arid regions, such as Central Asia (CA), where water security is threatened as a result of rapid glacier recession (Barandun et al., 2020). The Central Asian region contains one of the largest areas of mountain permafrost in the world (Marchenko et al., 2007). Nevertheless, very little is known about the permafrost distribution, current thermal ground conditions, and ground ice contents in CA. This is mostly due to the lack of (in-situ) geothermal and geophysical baseline datasets in the region, which would be important tools to improve water management strategies, as well as aiding the development of sound model estimates that quantify future changes on CA’s permafrost under climate change.

To contribute to reducing the data scarcity regarding permafrost distribution and ground ice content in Central Asia, we conducted extensive ERT (Electrical Resistivity Tomography) surveys in the Tien Shan and Pamir Alay of Kyrgyzstan. The field sites of the ERT surveys carried out in summer 2021 comprise a variety of landforms including amongst others rock glaciers, talus slopes, moraines, and vegetated planes. Our results indicate widespread permafrost occurrences at all study sites and point to potentially substantial ground ice volumes that are not limited to rock glaciers alone. This clearly reveals the importance of permafrost research in the region, particularly with regard to its hydrological significance.

These measurements represent the first surveys in the framework of a planned Central Asian permafrost monitoring network in Kyrgyzstan, Tajikistan, and Kazakhstan that will include (i) the annual repetition of selected ERT profiles to detect potential resistivity changes with climate change that can indicate changes in the content of ground ice and liquid water (ii) distributed ground surface temperature (GST) measurements, and (iii) drilling of new boreholes to monitor the thermal state of permafrost in Central Asia.

References:

Barandun, M., Fiddes, J., Scherler, M., Mathys, T., Saks, T., Petrakov, D., & Hoelzle, M. 2020: The state and future of the cryosphere in Central Asia. Water Security, 11, 100072.
Marchenko, S. S., Gorbunov, A. P., & Romanovsky, V. E. 2007: Permafrost warming in the Tien Shan Mountains, Central Asia. Global and Planetary Change, 56(3–4), 311–327.

Wilfried Haeberli
Geography Department, University of Zurich, Switzerland

Abstract

The striking flow features usually called “rock glaciers” in non-consolidated talus and debris of cold mountains are not only fascinating but also of increasing scientific interest. The International Permafrost Association (IPA) coordinates inventories of these landforms at regional to global levels. Modern geodetic methods enable high-precision determination of flow fields and their evolution over time. Interdisciplinary research on mountain permafrost and related phenomena of viscous flow is far advanced and comprehensive. Numerous drillings, borehole measurements, geophysical soundings, thermal monitoring, laboratory creep tests, absolute age dating and numerical models, etc. provide detailed information about the materials, physical conditions and processes involved.

Viscous flow is enabled by long-term subsurface freezing processes under conditions of negative temperatures throughout the year (= permafrost). Ice segregation in the frost susceptible silt to fine-sand fraction thereby builds up average ice contents, which are highly variable within a characteristic range of about 40 – 90% by volume and clearly in excess of the original pore space of the material (typically about 30% by volume). This formation of subsurface ice induces cohesion in the originally cohesion-free material by connecting rock particles with each other but at the same time also lowers internal friction by reducing particle-to-particle contacts. Such ice-rich perennially frozen material undergoes “secondary creep” or “steady-state creep” with unlimited deformation. The resulting cumulative deformation over characteristic time scales of millennia then leads to the striking, lava stream-like landforms usually called “rock glaciers”. Longitudinal surface structures result from extending flow, often in the upper parts where flow starts, while transverse furrows and ridges mark zones of compressing flow, often in less inclined lower parts towards oversteepened fronts of the advancing mass with freshly exposed debris.

In strong contrast to the rapid melting and vanishing of glaciers as surface ice, the subsurface ice of perennially frozen ground and rock glaciers degrades and thaws very slowly through effects of heat diffusion combined with latent heat exchange. Permafrost is therefore likely to continue existing in mountain slopes when nearby glaciers may already long have disappeared. Creep rates in ice-rich perennially frozen materials depend on temperature. Globally rising atmospheric temperatures tend to warm up and soften ice-rich permafrost on slopes. As a consequence of this – and again in strong contrast to the rapidly retreating, decaying and slowing down of glaciers – viscous creep and advance of rockglacier permafrost presently accelerates at many sites.

References:

Arenson, L., Colgan, W., Marshall, H.P. (2021): Physical, thermal and mechanical properties of snow, ice, and permafrost. In: Haeberli, W., Whiteman, C. (Eds.), Snow and IceRelated Hazards, Risks, and Disasters. Elsevier, pp. 35–71.
Cicoira, A., Marcer, M., Gärtner-Roer, I., Bodin, X., Arenson, L.U. and Vieli, A. (2020): A general theory of rock glacier creep based on in-situ and remote sensing observations, Permafrost and Periglacial Processes 32, 139–153. doi:10.1002/ppp.2090.

Haeberli, W., Hallet, B., Arenson, L., Elconin, R., Humlum, O., Kääb, A., Kaufmann, V., Ladanyi, B., Matsuoka, N., Springman, S. and Vonder Mühll, D. (2006): Permafrost creep and rock glacier dynamics. Permafrost and Periglacial Processes 17/3, 189-214. doi: 10.1002/ppp, 2006.

Annett Bartsch^1
1b.geos GmbH, Industriestrasse 1, 2100 Korneuburg

Abstract

The objective of Permafrost_CCI is to develop and deliver permafrost maps as ECV (Essential Climate Variable) products primarily derived from satellite measurements. The required associated parameters by GCOS for the ECV Permafrost are “Depth of active layer (m)” and “Permafrost temperature (K)”. Algorithms have been identified which can provide these parameters ingesting a set of global satellite data products (Land Surface Temperature (LST), Snow Water Equivalent (SWE), and landcover) in a permafrost model scheme that computes the ground thermal regime.

Permafrost_CCI builds on the legacy of ESA DUE GlobPermafrost project (2016-2019, www.globpermafrost.info). A Permafrost Information System (PerSys) based on satellite data has been setup as part of GlobPermafrost. This includes a data catalogue as well as a WebGIS hosted by the Alfred-Wegener-Institute for Polar and Marine Research, both linked to the Pangaea repository for easy data access.

Extended permafrost modelling (time series) is implemented in the new ESA CCI+ Permafrost project (2018-2021, http://cci.esa.int/Permafrost), which will provide the key for our understanding of the changes of surface features over time. Additional focus is on documentation of kinematics from rock glaciers in several mountain regions across the world supporting the IPA action group ‘kinematics as an essential climate variable’. We will present the Permafrost Information System including the time series for the northern hemisphere, and with focus on the Hindu Kush Himalaya (1997-2018).

KONG Sen^a,b, WEN Zhi^a,c*, WU Qing-bai^a, ZHANG Ming-li^a,d
a. State Key Laboratory of Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, 730000, China
^b. China Electric Power Research Institute, Beijing 100192, China
^c. School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou Gansu 730100, China
^d. Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou University of Technology, Lanzhou, Gansu 730050, China

Abstract

Due to the impact of climate warming and thermal disturbance induced by engineering construction, permafrost on the Qinghai-Tibet Plateau has been degraded significantly that threatens the proposed Qinghai-Tibet expressway greatly. Past experiences indicated that thermosyphon is one of the potential solutions for this problem. This study quantified the economic impacts of climate warming on the Qinghai-Tibet expressway and predicted the role of thermosyphons on mitigating embankment settlement, and meanwhile quantitatively evaluated the adaptation benefits of thermosyphons on the Qinghai-Tibet expressway from an economic perspective. The results show that the construction of expressway can improve the current status of the regional economy greatly, the economic benefit can be achieved ¥31 billion. And the employment of thermosyphon technology can offset the impact of climate warming on the stability of embankments in permafrost regions, prolong the service life of the expressway and enhance its service value. The thermosyphon with spacing of 4m, 3m and 2m can extend 1 year, 3 years and 7 years respectively. The results can provide a scientific basis for design, operation and maintenance of expressway engineering in permafrost regions from an economic perspective.

Kristoffer Aalstad¹, Joel Fiddes², Leo Martin³, Esteban Alonso-González⁴, Yeliz A. Yılmaz¹, Norbert Pirk¹, Sebastian Westermann¹

¹Department of Geosciences, University of Oslo, Oslo, Norway
²WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland
³Faculty of Geosciences, Utrecht University, Utrecht, The Netherlands
⁴Centre d’Etudes Spatiales de la Biosphère, Toulouse, France

Abstract

Meteorological forcing data is a crucial ingredient when modeling the past, present, and future state of the cryosphere. At the same time, cold regions (i.e. the high elevations and/or latitudes of our planet) where most of the cryosphere is found are typically remote with a very low density of in-situ observations. The few meteorological stations that do exist are typically quite unrepresentative due to the often extreme surface heterogeneity and complex terrain in these regions. This makes empirical-statistical and geostatistical downscaling techniques that rely heavily on station data somewhat impractical for cryospheric applications. On the other side of the scale, we have dynamical downscaling techniques that rely on using sophisticated regional climate models to downscale historical global reanalysis data or projections from global climate models. Although these are not as dependent on local observations in that they are able to mechanistically model the state of the atmosphere, they are prohibitively expensive to run at the decadal timescales and hillslope (1 km – 100 m) spatial scale that is often sought in cryospheric applications.

In this workshop, we will provide an overview of various downscaling techniques and introduce the topography-based downscaling routine TopoSCALE as well as its many applications and downstream methods listed below. TopoSCALE was developed to provide a computationally feasible technique for generating hourly hillslope scale atmospheric forcing for cryospheric modeling from global reanalysis data or other atmospheric model outputs, without the need for in-situ data. It relies heavily on topographic parameters derived from digital elevation models to be able to scale the input atmospheric forcing to the local topography. It has been tested quite extensively in a variety of environments, including: the Swiss Alps, Svalbard, the California Sierra Nevada, and High Mountain Asia. TopoSCALE is also being used as part of ongoing permafrost reanalysis efforts in the ESA Permafrost_CCI project. The scheme can be coupled to a clustering framework (TopoSUB) which can speed up distributed simulations by orders of magnitude compared to the more traditional gridded approach to land surface modeling. TopoSCALE can also be used together with bias-correction techniques to help downscale future regional climate projections to the hillslope scale with applications to cryospheric climate impact studies. Recent and ongoing applications of TopoSCALE together with snow data assimilation have been particularly fruitful in being able to handle biases in solid precipitation, which has been one of the most challenging problems for downscaling in cryospheric applications. Importantly, TopoSCALE lets modellers shift limited computational resources away from the downscaling exercise to probing uncertainties through ensemble simulations and constraining these with Earth observations.

Stephan Gruber, Carleton University

Abstract

Marco Marcer^1,2, Xavier Bodin³, Philippe Schoeneich^2
1 Technical University of Denmark, BYG Arctic DTU, Sisimiut, Greenland
² University of Grenoble-Alpes, PACTE, Grenoble, France
³ University Savoie-Mont-Blanc, EDYTEM, Chambéry, France

Abstract

The awareness on periglacial hazards started to rise among the French community in the early 2000s after the Bérard rock glacier collapse and the Drus pillar rockslide. Successive studies highlighted how this type of events correlated to climate warming and how their frequency could increase in the future. This triggered joint efforts from the Universities of Grenoble-Alpes and Savoie-Mont-Blanc, the National Service of Mountain Risks and several concerned municipalities, achieving during the past 15 years a comprehensive hazard assessment on permafrost degradation processes in the region affecting rockwalls, infrastructures and rock glaciers. This presentation will focus on the rock glacier hazard assessment, which was based on creating a regional scale inventory. The inventory was the basis for highlighting areas at observable and potential risk using modeling and remote sensing approaches. Areas presenting observable risk became key study sites, highlighted the degradation processes involved and creating the basis for operational in-situ risk assessment.

Tokuta Yokohata, National Institute for Environmental Studies, Japan

Abstract

Permafrost covers a wide area of the Northern Hemisphere, including high-altitude mountainous areas even at mid-low latitudes. There is concern that the thawing of mountain permafrost can cause slope instability and substantially impact alpine ecosystems. However, permafrost in mountainous areas is difficult to observe, and detailed analyses have not been performed on its current distribution and future changes. Here, we show that the surface air temperature required to sustain Japan’s mountain permafrost is estimated to decrease rapidly at present; most mountain permafrost in Japan is projected to disappear by the second half of the 21st century regardless of climate scenarios. Our projections indicate that climate change has a considerable impact on mountain environments and that even if climate stabilization is achieved, Japan’s mountain permafrost may almost disappear. It is important to consider measures to adapt to the changing mountain environment

Dongfeng Li
Department of Geography, National University of Singapore

Abstract

Approximately 40% of the Tibetan Plateau is underlain by continuous permafrost, yet its impact on fluvial water and sediment dynamics remains poorly investigated. Here we show that water and sediment dynamics in the permafrost-dominated Tuotuohe basin on the Tibetan Plateau are driven by air temperature and permafrost thaw, based on 33-year daily in situ observations (1985–2017). Air temperature regulates the seasonal patterns of discharge and suspended sediment concentration (SSC) by controlling the changes in active contributing drainage area (ACDA, the erodible landscape that contributes hydrogeomorphic processes within a catchment) and governing multiple thermal processes such as glacier-snow melt and permafrost thaw. Rainstorms determine the short-lived fluvial extreme events by intensifying slope processes and channel erosion and likely also by enhancing thaw slumps. Furthermore, the SSCs at equal levels of discharges are lower in autumn (September–October) than in spring (May–June) and summer (July–August). This reduced sediment availability in autumn can possibly be attributed to the increased supra-permafrost groundwater runoff and the reduced surface runoff and erosion. Due to rapid climate warming, the erodible landscapes are expanding and fluvial water and sediment fluxes are increasing. In a warmer and wetter future for the TP, the fluvial sediment fluxes of similar permafrost-underlain basins will continue to increase with expanding erodible landscapes and intensifying thermal and pluvial-driven geomorphic processes. Thus, permafrost thaw should be considered as an important driver of past and future water and sediment changes for the Tibetan Plateau.

Overall, this work has provided the sedimentary evidence of modern climate change through robust observational sediment flux data over multiple decades. It demonstrates that sediment fluxes in pristine cold environments are more sensitive to air temperature and thermal-driven geomorphic processes than to precipitation and pluvial-driven processes. Such findings may also have implications for other cold environments such as the Arctic, Antarctic, and other high mountainous basins.

Zhu Dan^1
1Chengdu Institute of Biology, Chinese Academy of Sciences No.9 Section 4, Renmin Road South, Chengdu 610041, China

Abstract

A large number of studies in northern peatlands have shown that the freeze-thaw process occurs more frequently under the warming climate and has induced more methane emissions particular during freeze-thaw periods. The Tibetan Plateau, which embodies the largest area of frozen ground in mid- to low latitude of the world, has been experienced a rapid permafrost degradation and seasonal freeze-thaw change during the past decades. However, the response and potential feedback of the methane flux from peatlands on the Tibetan Plateau to seasonal freeze-thaw remains unknown. In this study, we sampled peat soil from the largest peatland complex on the Tibetan Plateau to examine the methane emissions under simulated freeze-thaw cycles in a diurnal basis. In an incubation experiment of 15 days, the intensity of the freeze-thaw were set as two levels, i.e. mild (-5℃~4℃) and intense (-15℃~4℃), water content of peat samples were set as two levels as well, i.e. 100% and 80 % of maximum water holding capacity (MWHC). The results showed that the peak of methane emission from the peat soil occurred during the first freeze-thaw cycle, with the highest reaching a value of 0.103 mg·kg-1·h-1. The cumulative methane emissions showed a sequence as: mild+100%MWHC > intense +100%MWHC > mild+80%MWHC > intense+80%MWHC. Methane emission rate was significantly correlated to the activities of dissolved organic carbon (DOC), β-D-cellobiosidase and phenol oxidase in various freeze-thaw conditions (P<0.05). This study has highlighted the importance of freeze-thaw cycles in controlling methane emission from alpine peatlands and implied that methane emissions from alpine peatlands would increase under the degradation of seasonal frozen ground.

Raju Chauhan
Department of Environmental Science, Patan Multiple Campus, Tribhuvan University, Lalitpur, Nepal

Abstract

Permafrost is a key component of the terrestrial ecosystem as well as the major influencer of the alpine ecosystem. As permafrost are highly sensitive to the changing climatic pattern, they can have greater influences on these ecosystems. Vast areas of the Hindu Kush Himalaya (HKH) Region are underlain by a perennially frozen layer of soil. Yet, research on permafrost and ecosystem, and their nexus is an underdeveloped field in this region as relatively few studies have been conducted. Studies are concentrated on understanding ecological responses to permafrost degradation, ecosystem services of permafrost region, the influence of climate and anthropogenic activities on permafrost ecosystem, permafrost thaw and its influence on biogeochemical cycles and greenhouse gas emission, and application of terrestrial ecosystem models for simulating permafrost. The spatial and temporal coverage of permafrost and ecosystem research in the HKH region is very confined as most studies are concentrated on China- Tibet region. Permafrost ecosystem structure, community types, biodiversity and biological productivity, the habitat conditions including soil environment, incorporating thaw distribution and mechanisms into models for forecasting carbon exchange with the atmosphere, permafrost- rangeland relationship, and their implication on mountain livelihood and regional change would be some of the key areas of importance for the future research activities in HKH region. There is a need of understanding permafrost- ecosystem nexus of the HKH region and adopting effective measures to protect permafrost for maintaining the stability of permafrost and ecological balance.