Permafrost Monthly Alerts (PMAs)

USPA LogoThe USPA is pleased to announce the availability of an updated searchable database on permafrost-related publications. The American Geosciences Institute (AGI), with support from the National Science Foundation (NSF), has migrated the previous Cold Regions Bibliography to a new platform. Included are the USPA supported PMAs dating back to 2011. The Bibliography is searchable at


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July 2022 PMA

Entries in each category are listed in chronological order starting with the most recent citation. 


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2022037994 Demidov, Vasiliy (Arctic and Antarctic Research Institute, Saint Petersburg, Russian Federation); Demidov, Nikita; Verkulich, Sergey and Wetterich, Sebastian. Distribution of pingos on Svalbard: Geomorphology, 412, Article 108326, September 2022. Based on Publisher-supplied data.

The present study explores the formation, preservation and degradation of pingos in High Arctic environments, which are controlled by the interplay of permafrost, hydrology and climate conditions. The analysis of aerial and satellite images and digital elevation model data revealed 136 pingo mounds on Svalbard Archipelago. The pingos are distributed at elevations from 0 to 201 m above sea level (asl) with a median of 42 m asl. Of those, 44 pingos are found above and 92 below the maximum level of the respective local Holocene transgressions. All pingos were found in terrain favorable for the formation of hydrologically sourced open-system pingos. Based on published geological data, at least 55 pingos locate near geological faults that presumably allocate sub-permafrost waterflow feeding the pingos. With maximum and mean heights of 40 m and 9.4 m, respectively, Svalbard pingos generally have larger diameters and reach mean heights twice those found in other Arctic regions, such as the predominately closed-system pingos of Northern Alaska and the North-east Siberian lowlands. The comparison of aerial photographs of 1936-1938 with aerial photographs of 2008-2012 of Svalbard pingos exhibit no change in the general morphology of the pingos during the last about seven decades. There are exceptions - four pingos have formed on Little-Ice-Age (LIA) moraines following the local retreat of glaciers, and one pingo - the Riverbed pingo - formed in Adventdalen after 1936. The pingo growth once initiated is dynamic with height gains of up to 1 m annually, but obviously stops within several years or decades. Today, 21 pingos continue to show activity by the outflow at perennial subpermafrost springs. Dried thermokarst craters were found on top of 19 pingos of all sizes and geomorphological positions, while 11 water-filled craters were found only on large pingos with heights exceeding 12 m. Transitional landforms (flattop pingos and platforms) were identified. These landforms may point to underground ice intrusions that do not reveal themselves as classical pingo mounds.

DOI: 10.1016/j.geomorph.2022.108326

2022040391 Han Pengfei (China University of Geosciences, School of Water Resources and Environment, Beijing, China); Huang Chuanqi; Liang Sihai; Feng Yuqing and Wan Li. Variation characteristics and quantitative study of permafrost degradation in the upper reaches of Heihe River, China: Journal of Hydrology, 610, Article no. 127942, illus. incl. 8 tables, sketch maps, 60 ref., July 2022.

To quantitatively investigate the permafrost degradation and its effects on hydrological processes in the upper reaches of Heihe River, a surface frost number model was firstly constructed to simulate the permafrost distribution and degradation from 1980 to 2015. The variation characteristics of the DDF, permafrost area, low limit of permafrost, and active layer thickness were then determined in the study area. Furthermore, the Budyko framework was applied to quantify the contribution of permafrost degradation to runoff. The results indicated that the permafrost degradation was significant in the past 36 years, with an average decreasing rate of 80.4 km2/a in the permafrost area, an average increasing rate of 13 m/a and 0.61 cm/a in the low limit elevation and in the active layer thickness, respectively. It is also found that basin characteristic parameter in the Budyko framework is closely related to permafrost degradation in cold regions, 40% of whose change is contributed by permafrost degradation. In addition, it is revealed that permafrost degradation contributed more than 20% to runoff change in study area. This investigation also indicated that the runoff response to permafrost degradation has a 3 months delayed effect. This study deepens the understanding of the impact of permafrost degradation on hydrological processes.

DOI: 10.1016/j.jhydrol.2022.127942

2022041493 Li Chuanhua (Northwest Normal University, College of Geography and Environmental Science, Lanzhou, China); Wei Yufei; Liu Yunfan; Li Liangliang; Peng Lixiao; Chen Jiahao; Liu Lihui; Dou Tianbao and Wu Xiaodong. Active layer thickness in the Northern Hemisphere; changes from 2000 to 2018 and future simulations: Journal of Geophysical Research: Atmospheres, 127(12), Article e2022JD036785, illus. incl. 2 tables, 48 ref., June 27, 2022.

Active layer dynamics are basic information for understanding permafrost degradation, but there are gaps in our knowledge of the active layer thickness (ALT) variations during the past two decades and their future changes; this is especially true for data with high spatial resolution. Here, based on permafrost monitoring data and ERA5 (the 5th generation reanalysis project from the European Centre for Medium-Range Weather Forecasts)-Land temperature data, we simulated spatial changes in ALT in the Northern Hemisphere during 2000-2018 at a spatial resolution of 1 km2 using the Stefan model. We also simulated future changes in the active layer based on the CMIP6 temperature data. The results showed that ALTs less than 50 cm were mainly distributed in northeastern Siberia in Russia, Alaska and Greenland. The areas with ALTs greater than 600 cm were mainly in southern Norway, and the Mongolian Plateau. The mean ALT of permafrost in the Northern Hemisphere from 2000 to 2018 increased from 127.19 to 145.37 cm at a linear rate of 0.65 cm year-1 (R2=0.37, p<0.05). During 2000-2018, the ALT increased in 71.17% of the total permafrost area, and only 27.23% of the permafrost area showed a decreasing trend. Under different shared socioeconomic pathways (SSP1-2.6, SSP2-4.5, SSP3-7.0, and SSP5-8.5), the ALT will increase considerably by 2,100. There is a greater increase in ALT in low- and mid-latitude permafrost areas such as the Mongolian Plateau and Qinghai-Tibet Plateau, with the ALT increasing from 50 to 500 cm. Our results present an overall picture of contemporary distribution as well as future changes of ALT in the Northern Hemisphere. Abstract Copyright (2022), . American Geophysical Union. All Rights Reserved.

DOI: 10.1029/2022JD036785

2022041496 Zhang Guofei (Lanzhou University, Laboratory of Western China's Environmental Systems, Lanzhou, China); Nan Zhuotong; Hu Na; Yin Ziyun; Zhao Lin; Cheng Guodong and Mu Cuicui. Qinghai-Tibet Plateau permafrost at risk in the late 21st century: Earth's Future, 10(6), Article e2022EF002652, illus. incl. 1 table, 65 ref., June 2022. Part of a special issue entitled CMIP6; trends, interactions, evaluation, and impacts.

Global warming has led to permafrost degradation worldwide. The Qinghai-Tibet Plateau (QTP) hosts most of the world's alpine permafrost, yet its impending changes remain largely unclear, thereby affecting regional hydrological and ecological processes and the global carbon budget. By employing a land surface model adapted to simulate frozen ground, and using state-of-the-art multi-model and multi-scenario data from the Coupled Model Intercomparison Project Phase 6, changes in permafrost distribution and its thermal regimes on the QTP are systematically predicted under various shared socioeconomic pathways (SSPs). Projections for SSP2-4.5, SSP3-7.0, and SSP5-8.5 show that most of the continuous permafrost region of the QTP will persist through 2050. Much of the permafrost is likely to degrade in the late 21st century, with projected area losses of 44±4%, 59±5%, and 71±7%, respectively, by 2100. In particular, the Three Rivers Source region in the central eastern part of the QTP is a key area of permafrost degradation, where permafrost is most vulnerable and degradation occurs earliest. The mean annual ground temperature of QTP permafrost will increase by 0.8±0.2°C, 2.0±0.3°C, and 2.6±0.3°C under SSP2-4.5, SSP3-7.0, and SSP5-8.5, respectively, and the active layer thickness will increase by 0.7±0.1 m, 1.5±0.3 m, and 3.0±1.0 m, respectively. The surviving permafrost under SSP3-7.0 and SSP5-8.5 will be thermally unstable, which is a clear warning sign of complete disappearance. The analysis of permafrost sensitivity to climate change signifies that alpine permafrost on the QTP has low resilience to climate change, in contrast to permafrost in pan-Arctic high latitudes. Abstract Copyright (2022), The Authors.

DOI: 10.1029/2022EF002652

2022036633 Hoelzle, Martin (University of Fribourg, Department of Geosciences, Fribourg, Switzerland); Hauck, Christian; Mathys, Tamara; Noetzli, Jeannette; Pellet, Cécile and Scherler, Martin. Long-term energy balance measurements at three different mountain permafrost sites in the Swiss Alps: Earth System Science Data (ESSD), 14(4), p. 1531-1547, illus. incl. 4 tables, 72 ref., 2022.

The surface energy balance is a key factor influencing the ground thermal regime. With ongoing climate change, it is crucial to understand the interactions of the individual heat fluxes at the surface and within the subsurface layers, as well as their relative impacts on the permafrost thermal regime. A unique set of high-altitude meteorological measurements was analysed to determine the energy balance at three mountain permafrost sites in the Swiss Alps (Murtèl-Corvatsch, Schilthorn and Stockhorn), where data have been collected since the late 1990s in the framework of the Swiss Permafrost Monitoring Network (PERMOS). All stations are equipped with sensors for four-component radiation, air temperature, humidity, and wind speed and direction, as well as ground temperatures and snow height. The three sites differ considerably in their surface and ground material composition, as well as their ground ice contents. The energy fluxes were calculated based on two decades of field measurements. While the determination of the radiation budget and the ground heat flux is comparatively straightforward (by the four-component radiation sensor and thermistor measurements within the boreholes), larger uncertainties exist for the determination of turbulent sensible and latent heat fluxes. Our results show that mean air temperature at Murtèl-Corvatsch (1997-2018, 2600 m a.s.l.) is -1.66°C and has increased by about 0.8°C during the measurement period. At the Schilthorn site (1999-2018, 2900 m a.s.l.) a mean air temperature of -2.60°C with a mean increase of 1.0°C was measured. The Stockhorn site (2003-2018, 3400 m a.s.l.) recorded lower air temperatures with a mean of -6.18°C and an increase of 0.5°C. Measured net radiation, as the most important energy input at the surface, shows substantial differences with mean values of 30.59 W m-2 for Murtèl-Corvatsch, 32.40 W m-2 for Schilthorn and 6.91 W m-2 for Stockhorn. The calculated turbulent fluxes show values of around 7 to 13 W m-2 using the Bowen ratio method and 3 to 15 W m-2 using the bulk method at all sites. Large differences are observed regarding the energy used for the melting of the snow cover: at Schilthorn a value of 8.46 W m-2, at Murtèl-Corvatsch 4.17 W m-2 and at Stockhorn 2.26 W m-2 are calculated, reflecting the differences in snow height at the three sites. In general, we found considerable differences in the energy fluxes at the different sites. These differences help to explain and interpret the causes of a warming atmosphere. We recognise a strong relation between the net radiation and the ground heat flux. Our results further demonstrate the importance of long-term monitoring to better understand the impacts of changes in the surface energy balance components on the permafrost thermal regime. The dataset presented can be used to improve permafrost modelling studies aiming at, for example, advancing knowledge about permafrost thaw processes. The data presented and described here are available for download at the following site: URL: (Hoelzle et al., 2021).

DOI: 10.5194/essd-14-1531-2022

2022036627 Jafarov, Elchin E. (Los Alamos National Laboratory, Earth and Environmental Sciences Division, Los Alamos, NM); Svyatsky, Daniil; Newman, Brent; Harp, Dylan; Moulton, David and Wilson, Cathy. The importance of freeze-thaw cycles for lateral tracer transport in ice-wedge polygons: The Cryosphere, 16(3), p. 851-862, illus. incl. 1 table, 35 ref., 2022.

A significant portion of the Arctic coastal plain is classified as polygonal tundra and plays a vital role in soil carbon cycling. Recent research suggests that lateral transport of dissolved carbon could exceed vertical carbon releases to the atmosphere. However, the details of lateral subsurface flow in polygonal tundra have not been well studied. We incorporated a subsurface transport process into an existing state-of-the-art hydrothermal model. The model captures the physical effects of freeze-thaw cycles on lateral flow in polygonal tundra. The new modeling capability enables non-reactive tracer movement within subsurface. We utilized this new capability to investigate the impact of freeze-thaw cycles on lateral flow in the polygonal tundra. Our study indicates the important role of freeze-thaw cycles and the freeze-up effect in lateral tracer transport, suggesting that dissolved species could be transported from the middle of the polygon to the sides within a couple of thaw seasons. Introducing lateral carbon transport into the climate models could substantially reduce the uncertainty associated with the impact of thawing permafrost.

DOI: 10.5194/tc-16-851-2022

2022036637 Ohara, Noriaki (University of Wyoming, Department of Civil and Architectural Engineering, Laramie, WY); Jones, Benjamin M.; Parsekian, Andrew D.; Hinkel, Kenneth M.; Yamatani, Katsu; Kanevskiy, Mikhail; Rangel, Rodrigo C.; Breen, Amy L. and Bergstedt, Helena. A new Stefan equation to characterize the evolution of thermokarst lake and talik geometry: The Cryosphere, 16(4), p. 1247-1264, illus. incl. 1 table, 84 ref., 2022.

Thermokarst lake dynamics, which play an essential role in carbon release due to permafrost thaw, are affected by various geomorphological processes. In this study, we derive a three-dimensional (3D) Stefan equation to characterize talik geometry under a hypothetical thermokarst lake in the continuous permafrost region. Using the Euler equation in the calculus of variations, the lower bounds of the talik were determined as an extremum of the functional describing the phase boundary area with a fixed total talik volume. We demonstrate that the semi-ellipsoid geometry of the talik is optimal for minimizing the total permafrost thaw under the lake for a given annual heat supply. The model predicting ellipsoidal talik geometry was compared to talik thickness observations using transient electromagnetic (TEM) soundings in Peatball Lake on the Arctic Coastal Plain (ACP) of northern Alaska. The depth : width ratio of the elliptical sub-lake talik can characterize the energy flux anisotropy in the permafrost, although the lake bathymetry cross section may not be elliptic due to the presence of near-surface ice-rich permafrost. This theory suggests that talik development deepens lakes and results in more uniform horizontal lake expansion around the perimeter of the lakes, while wind-induced waves and currents are likely responsible for the elongation and orientation of shallow thermokarst lakes without taliks in certain regions such as the ACP of northern Alaska.

DOI: 10.5194/tc-16-1247-2022

2022036690 Smith, Noah D. (University of Exeter, College of Engineering, Mathematics and Physical Sciences, Exeter, United Kingdom); Burke, Eleanor J.; Aas, Kjetil Schanke; Althuizen, Inge H. J.; Boike, Julia; Christiansen, Casper Tai; Etzelmuller, Bernd; Friborg, Thomas; Lee, Hanna; Rumbold, Heather; Turton, Rachael H.; Westermann, Sebastian and Chadburn, Sarah E. Explicitly modelling microtopography in permafrost landscapes in a land surface model (JULES vn5.4_microtopography): Geoscientific Model Development (GMD), 15(9), p. 3603-3639, illus. incl. 7 tables, 103 ref., 2022. Part of a special issue entitled Joint UK land environment simulator (JULES); configurations, developments and documentation, edited by GMD topical editors, coordinated by Wiltshire, A. J.

Microtopography can be a key driver of heterogeneity in the ground thermal and hydrological regime of permafrost landscapes. In turn, this heterogeneity can influence plant communities, methane fluxes, and the initiation of abrupt thaw processes. Here we have implemented a two-tile representation of microtopography in JULES (the Joint UK Land Environment Simulator), where tiles are representative of repeating patterns of elevation difference. Tiles are coupled by lateral flows of water, heat, and redistribution of snow, and a surface water store is added to represent ponding. Simulations are performed of two Siberian polygon sites, (Samoylov and Kytalyk) and two Scandinavian palsa sites (Stordalen and Iskoras). The model represents the observed differences between greater snow depth in hollows vs. raised areas well. The model also improves soil moisture for hollows vs. the non-tiled configuration ("standard JULES") though the raised tile remains drier than observed. The modelled differences in snow depths and soil moisture between tiles result in the lower tile soil temperatures being warmer for palsa sites, as in reality. However, when comparing the soil temperatures for July at 20 cm depth, the difference in temperature between tiles, or "temperature splitting", is smaller than observed (3.2 vs. 5.5°C). Polygons display small (0.2°C) to zero temperature splitting, in agreement with observations. Consequently, methane fluxes are near identical (+0% to 9%) to those for standard JULES for polygons, although they can be greater than standard JULES for palsa sites (+10% to 49%). Through a sensitivity analysis we quantify the relative importance of model processes with respect to soil moisture and temperatures, identifying which parameters result in the greatest uncertainty in modelled temperature. Varying the palsa elevation between 0.5 and 3 m has little effect on modelled soil temperatures, showing that using only two tiles can still be a valid representation of sites with a range of palsa elevations. Mire saturation is heavily dependent on landscape-scale drainage. Lateral conductive fluxes, while small, reduce the temperature splitting by ~1°C and correspond to the order of observed lateral degradation rates in peat plateau regions, indicating possible application in an area-based thaw model.

DOI: 10.5194/gmd-15-3603-2022

2022036630 Wilkenskjeld, Stiig (Max Planck Institute for Meteorology, Hamburg, Germany); Miesner, Frederieke; Overduin, Paul P.; Puglini, Matteo and Brovkin, Victor. Strong increase in thawing of subsea permafrost in the 22nd century caused by anthropogenic climate change: The Cryosphere, 16(3), p. 1057-1069, illus. incl. 2 tables, 46 ref., 2022.

Most earth system models (ESMs) neglect climate feedbacks arising from carbon release from thawing permafrost, especially from thawing of subsea permafrost (SSPF). To assess the fate of SSPF in the next 1000 years, we implemented SSPF into JSBACH, the land component of the Max Planck Institute Earth System Model (MPI-ESM). This is the first implementation of SSPF processes in an ESM component. We investigate three extended scenarios from the 6th phase of the Coupled Model Intercomparison Project (CMIP6). In the 21st century only small differences are found among the scenarios, but in the upper-end emission scenario SSP5-8.5 (shared socio-economic pathway), especially in the 22nd century, SSPF ice melting is more than 15 times faster than in the pre-industrial period. In this scenario about 35% of total SSPF volume and 34% of SSPF area are lost by the year 3000 due to climatic changes. In the more moderate scenarios, the melting rate maximally exceeds that of pre-industrial times by a factor of 4, and the climate change induced SSPF loss (volume and area) by the year 3000 does not exceed 14%. Our results suggest that the rate of melting of SSPF ice is related to the length of the local open-water season and thus that the easily observable sea ice concentration may be used as a proxy for the change in SSPF.

DOI: 10.5194/tc-16-1057-2022

2022036626 Zhao Yi (Nanjing Normal University, Key Laboratory of Ministry of Education on Virtual Geographic Environment, Nanjing, China); Nan Zhuotong; Ji Hailong and Zhao Lin. Convective heat transfer of spring meltwater accelerates active layer phase change in Tibet permafrost areas: The Cryosphere, 16(3), p. 825-849, illus. incl. 3 tables, 100 ref., 2022.

Convective heat transfer (CHT) is one of the important processes that control the near-ground surface heat transfer in permafrost areas. However, this process has often not been considered in most permafrost studies, and its influence on freezing-thawing processes in the active layer lacks quantitative investigation. The Simultaneous Heat and Water (SHAW) model, one of the few land surface models in which the CHT process is well incorporated into the soil heat-mass transport processes, was applied in this study to investigate the impacts of CHT on the thermal dynamics of the active layer at the Tanggula station, a typical permafrost site on the eastern Qinghai-Tibet Plateau with abundant meteorological and soil temperature and soil moisture observation data. A control experiment was carried out to quantify the changes in active layer temperature affected by vertical advection of liquid water. Three experimental setups were used: (1) the original SHAW model with full consideration of CHT, (2) a modified SHAW model that ignores CHT due to infiltration from the surface, and (3) a modified SHAW model that completely ignores CHT processes in the system. The results show that the CHT events occurred mainly during thaw periods in melted shallow (0-0.2 m) and intermediate (0.4-1.3 m) soil depths, and their impacts on soil temperature at shallow depths were significantly greater during spring melting periods than summer. The impact was minimal during freeze periods and in deep soil layers. During thaw periods, temperatures at the shallow and intermediate soil depths simulated under the scenario considering CHT were on average about 0.9 and 0.4°C higher, respectively, than under the scenarios ignoring CHT. The ending dates of the zero-curtain effect were substantially advanced when CHT was considered due to its heating effect. However, the opposite cooling effect was also present but not as frequently as heating due to upward liquid fluxes and thermal differences between soil layers. In some periods, the advection flow from the cold layer reduced the shallow and intermediate depth temperatures by an average of about -1.0 and -0.4°C, respectively. The overall annual effect of CHT due to liquid flux is to increase soil temperature in the active layer and favor thawing of frozen ground at the study site.

DOI: 10.5194/tc-16-825-2022

2022039155 Klyucherov, Danila Aleksandrovich (Voronezhskiy Gosudarstvennyy Tekhnicheskiy Universitet, Voronezh, Russian Federation) and Baranov, Dmitriy Alekseyevich. Klimaticheskiye izmeneniya v Rossii; istoricheskiye tendentsii razvitiya [Climate change in Russia; historical development trends]: Agrarian History, 8, p. 57-74 (English sum.), illus. incl. geol. sketch map, 27 ref., October 28, 2021.

The article conducted a general analysis of the situation of climate change in Russia, and considered the consequences of climate influence on agriculture, identified the main trends of changes, and provided possible forecasts of the development of climate change in agriculture in Russia. Special attention is paid to such meteorological parameters as temperature, humidity, the number of days with precipitation, the status of permafrost. The changes were revealed on the basis of data from daily and monthly surveys at meteorological stations in Russia. These data have been processed by software and presented in the form of graphical information convenient for further analysis.

DOI: 10.5281/zenodo.5750072

2022041466 Goudie, Andrew S. (University of Oxford, School of Geography and the Environment, Oxford, United Kingdom). The impacts of humans on geomorphologyin The history of the study of landforms or the development of geomorphology; Volume 5, Geomorphology in the second half of the twentieth century (Burt, T. P., editor; et al.), Memoirs of the Geological Society of London, 58, illus. incl. 5 tables, ports., 183 ref., September 24, 2021.

This chapter discusses the factors that have led to an increasing interest in the human impact in geomorphology, and then discusses the literature that appeared between c. 1960 and 2000. These developments were in four main areas: (i) intellectual and policy-related; (ii) technological developments that alter geomorphological processes; (iii) demographic trends; and (iv) proliferation of techniques for the study of landform and process change. Much work was undertaken on landforms produced by construction and excavation. Interest also developed in accelerating ground subsidence, which is a widespread phenomenon that creates engineering problems. Indeed, with increasing exploitation of tundra areas for such activities as oil exploitation, there was an increasing interest in the problems associated with permafrost. Rivers have also been greatly impacted. Humans have modified sediment transport by rivers in two ways. First, as a result of accelerated soil erosion, the delivery of sediment to rivers has increased. Secondly, burgeoning dam construction has caused sediment to be trapped in reservoirs. Far-reaching changes in channel form have been produced by land-use and land-cover changes. In addition to non-deliberate changes to river systems, there have been a whole range of deliberate modifications (e.g. channelization). Some valley bottoms areas have suffered from accelerated sedimentation while others have become incised with gullies ('arroyos'). Studies have indicated an increasing incidence of mass movements. These have been attributed to such factors as deforestation, road cuts, changes in slope drainage and irrigation of farm land. Much work has also been undertaken on wind erosion of dryland surfaces. Human activities, most notably air pollution, have changed the nature and rate of weathering, although enhanced weathering by salt can also be accelerated by irrigation. Large numbers of people live in coastal zones, and have had a major impact on coastal landforms and processes. Many of the world's shorelines have been eroding and the complex mix of causes, natural and anthropogenic, that could be responsible have been analysed. Finally, since the 1980s there has been a growing realization of the importance of global heating for geomorphological phenomena.

DOI: 10.1144/M58-2020-24

2022039989 Sokolov, Kirill Olegovich (Rossiskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Gornogo Dela Severa imeni N. V. Cherskogo, Yakutsk, Russian Federation). Razrabotka modeli georadiolokatsionnogo razreza massiva merzlykh gornykh porod s treshchinoy [Modeling of a ground-penetrating radar section of fractured frozen ground]: Izvestiya Ural'skogo Gosudarstvennogo Gornogo Universiteta = Izvestiya of the Ural State Mining University, 62(2), p. 134-139 (English sum.), illus., 15 ref., June 2021.

Revelance of the work. The presence of cracks significantly affects the physical and mechanical properties of rocks, which should be taken into account when planning mining operations and building mining facilities. In the conditions of the spread of permafrost rocks, characteristic of northeastern Russia, the study of fracturing is possible by the GPR method, which is used to assess the structure of rock massifs in placer deposits. The criteria for detecting cracks based on the features of wave georadar fields are currently known, and the main problem that prevents the full use of the georadar method for studying cracks in subsurface layers of rocks is the labour-consuming nature of processing and interpreting data from georadar measurements. Purpose of the work - to determine the patterns of cracks occurrence in frozen rocks in GPR wave fields. Methodology of the work. Based on the results of longstanding field work at the developed areas of alluvial diamond deposits in the Anabar region of the Republic of Sakha (Yakutia), the main elements of the radarogram structure were determined and presented in the form of a single formula. The developed formula is implemented in programs in the SCM Matlab and the results of its execution are compared with the results of modeling in the gprMax system. Results of the work and the scope of their application. The resultant formula describes the main elements of GPR radarograms quite correctly, which confirmed their comparison with the obtained model data. The correlation coefficient between the obtained matrices (Matlab and gprMax) without the low-amplitude values of multiple reflections was 0.91, which shows the identity of the structure of GPR wave fields. Conclusions. The studies carried out have confirmed the possibility of a mathematical description of the ground penetrating radar wave field obtained by sounding a mass of frozen rocks with a crack. The high correlation coefficient showed the adequacy of the developed radarogram model, which will be finalized taking into account the directional diagrams of existing georadars.

DOI: 10.21440/2307-2091-2021-2-134-139

2022039834 Coe, Jeffrey A. (U. S. Geological Survey, Denver, CO). Bellwether sites for evaluating changes in landslide frequency and magnitude in cryospheric mountainous terrain; a call for systematic, long-term observations to decipher the impact of climate change: Landslides, 17(11), p. 2483-2501, illus. incl. 2 tables, geol. sketch maps, 189 ref., November 2020.

Permafrost and glaciers are being degraded by the warming effects of climate change. The impact that this degradation has on slope stability in mountainous terrain is the subject of ongoing research efforts. The relatively new availability of high-resolution (≤&eq; 10 m) imagery with worldwide coverage and short (≤&eq; 30 days) repeat acquisition times, as well as the emerging field of environmental seismology, presents opportunities for making remote, systematic observations of landslides in cryospheric mountainous terrain. I reviewed the literature and evaluated landslide activity in existing imagery to select five » 5000-km2 sites where long-term, systematic observations could take place. The five proposed sites are the northern and eastern flanks of the Northern Patagonia Ice Field, the Western European Alps, the eastern Karakoram Range in the Himalayan Mountains, the Southern Alps of New Zealand, and the Fairweather Range in Southeast Alaska. Systematic observations of landslide occurrence, triggers, size, and travel distance at these sites, especially if coupled with observations from in situ instrumental monitoring, could lead to a better understanding of changes in slope stability induced by climate change. The suggested sites are not meant to be absolute and unalterable. Rather, they are intended as a starting point and discussion starter for new work in this expanding landslide research frontier.

DOI: 10.1007/s10346-020-01462-y

2022039840 Masyagina, Oxana V. (Russian Academy of Sciences, Siberian Branch, Sukachev Institute of Forest, Krasnoyarsk, Russian Federation); Evgrafova, Svetlana Yu.; Kholodilova, Valentina V. and Prokushkin, Stanislav G. A comparative study of soil processes in depletion and accumulation zones of permafrost landslides in Siberia: Landslides, 17(11), p. 2577-2587, illus. incl. 2 tables, sketch map, 17 ref., November 2020.

Landslides are one of the main reasons for permafrost degradation in high latitudes. Any landslides consist of different top-down slope zones: removal, transit-depletion, and accumulation zones. These slope parts can demonstrate different successional behavior of plant community and carbon (C) cycling during post-sliding seral stages. To address this issue, soil respiration (SR), hydrothermal conditions (mineral soil temperature at a depth of 5 cm (ST5, °C), and gravimetric soil water content at a depth of 0-5 cm in mineral soil horizon (SWC5, %)), total soil C (TC) and nitrogen (TN) contents, and soil microbial activity at the middle (depletion zone) and lower (accumulation zone) slope parts of the landslides with different history have been studied. The most significant differences between the middle and lower slope positions were found at the ground microsites (or G-plots) of the L2001 landslide. Thus, here, a midslope part occurred to be a high source of C compared to the lower part. Midslope of L2001 was characterized by significantly higher SR at G-plots as well because of better hydrothermal conditions and more intensive vegetation regeneration. The accumulation zone of L2001 characterized by the lower SR despite significantly higher microbial activity due to the high nutrient level of the soil moved from the top, likely favored to promotion of the soil C stabilization processes. Despite the registered ST5 differences in the E-plots and the G-plots between middle and lower slope positions of the L1972 landslide, SR, TC, TN, and soil microbial activity did not differ significantly.

DOI: 10.1007/s10346-020-01550-z

2022037360 Yakovleva, E. V. (Russian Academy of Sciences, Institute of Biology, Komi Science Center, Syktyvkar, Russian Federation); Gabov, D. N.; Vasilevich, R. S. and Goncharova, N. N. Participation of plants in the formation of polycyclic aromatic hydrocarbons in peatlands: Eurasian Soil Science, 53(3), p. 317-329, illus. incl. 3 tables, 29 ref., March 2020.

The composition of polycyclic aromatic hydrocarbons (PAHs) in vegetation of natural hummocky peatlands in the forest-tundra subzone of the Komi Republic and its possible impact on the composition of polyarenes in peat were assessed. The content of polyarenes was estimated by the method of highly efficient liquid chromatography. The accumulation of polycyclic aromatic hydrocarbons was the highest in Polytrichum strictum, Betula pubescens, and shoots of Picea abies and smaller in Betula nana L., Salix lapponum L., and Carex limosa L. with the domination of low-molecular-weight PAHs. We did not reveal dibenz[a,h]anthracene and benzo[ghi]perylene in plants: they could be the products of soil-forming processes. It is shown that distribution patterns of PAHs in the permafrost-affected soils of peat mounds (Hemic Folic Cryic Histosols) and in the soils of open-water mire pools (Fibric Floatic Histosols) are similar. Small quantities of low-molecular-weight polyarenes were normally accumulated in the seasonally thawed layer. The content of heavy structures (mainly, benzo[ghi]perylene) strongly increased at the contact with permafrost and then slightly decreased in the underlying permafrost. The composition of PAHs in the active layer mainly depended on composition of polyarenes in plants. At the contact with permafrost, the active synthesis or release of high-molecular-weight compounds took place. The influence of the composition of PAHs in plants on their composition in peat greatly depended on the degree of peat decomposition. Reasoning from the natural model of peat formation in open-water mire pools, the composition of polyarenes in the upper peat horizons of such sites was affected by recombination of low-molecular-weight hydrocarbons in Sphagnum riparium and Eriophorum sp. In the course of long-term soil development, the decomposition of complex organic compounds in plant tissues (particularly, in Eriophorum sp.) results in the formation of heavy PAHs with a simultaneous increase in the content of low-molecular-weight polyarenes.

DOI: 10.1134/S1064229320030102

2022038544 Kasprzak, Marek (University of Wroclaw, Institute of Geography and Regional Development, Wroclaw, Poland). Seawater intrusion on the Arctic coast (Svalbard); the concept of onshore-permafrost wedge: Geosciences (Basel), 10(9), Article 349, illus. incl. sketch map, 70 ref., 2020. Part of a special issue entitled Permafrost and glaciers; perspectives for the Earth and planetary sciences, edited by Dobinski, W. and Kneisel, C.

Numerous hydrogeological studies on the coastal zone describe the intrusion of sea water inland, salting underground aquifers. The phenomenon is commonly observed in the coasts outside polar areas. However, the impact of sea water has so far not been an object of detailed investigation in a periglacial environment devoid of subsea permafrost. Geophysical measurements at the west coast of the Wedel-Jarlsberg Land in Svalbard indicate that the border between the unfrozen seabed and the frozen ground onshore is not delimited by the shoreline. A zone of coastal unfrozen ground is located under a thin layer of permafrost reaching toward the sea. This state was observed with the use of electrical resistivity tomography under rocky headlands and capes, uplifted marine terraces located at the foot of mountain massifs and valley mouths as well as in the marginal zone of the Werenskiold Glacier. This short article presents the results of such a measurement, supplemented with electromagnetic detection. The measurements are unique in that they were conducted not only on the land surface, but also at the floor of the sea bay during the low water spring tide. The author proposes name structures detected in the coastal zone as a "permafrost wedge", extending an identification of the permafrost base between the coast and the glaciers of Svalbard. However, in the absence of boreholes that would allow determining the thermal state of the ground in the study sites, the concept is based only on the interpretation of the geophysical imaging. Therefore, further discussion is required on whether the identified contrasts in electrical resistivity indeed result from thermal differences between the rocks or if they only indicate the cryotic state of the ground (saline cryopeg) within the range of seawater intrusion.

DOI: 10.3390/geosciences10090349

2022038591 Lobkovsky, Leopold (Moscow Institute of Physics and Technology, Moscow, Russian Federation). Seismogenic-triggering mechanism of gas emission activizations on the Arctic shelf and associated phases of abrupt warming: Geosciences (Basel), 10(11), Article 428, illus. incl. sketch map, 28 ref., 2020. Part of a special issue entitled Gas emissions and crater formation in Arctic permafrost, edited by Chuvilin, E.

A seismogenic trigger mechanism is proposed to explain the abrupt climate warming phases in the Arctic as a result of strong mechanical disturbances in the marginal region of the Arctic lithosphere. Those disturbances might have been caused by great earthquakes in the Aleutian subduction zone, and slowly propagated across the Arctic shelf and adjacent regions, triggering the methane release from permafrost and metastable gas hydrates, followed by greenhouse gas emissions into the atmosphere. The proposed mechanism is based on the identified correlation between the series of the great earthquakes in the Aleutian island arc, which occurred in the early and middle of the 20th century, and the two phases of sharp climate warming, which began in 1920 and 1980. There is a 20-year time lag between these events, which is explained by the time of arrival of deformation waves in the lithosphere (propagating with a velocity of about 100 km per year) at the Arctic shelf and adjacent land from the Aleutian subduction zone, the region of their generation. The trigger mechanism causing the methane release from permafrost and metastable gas hydrates is related to the destruction of micro-sized ice films covering gas hydrate particles, the elements highly important for hydrate self-preservation, as well as destruction of gas-saturated micropores in permafrost rocks due to the slight additional stresses associated with deformation waves, and thus emergence of conditions favorable for gas filtration and its subsequent emission.

DOI: 10.3390/geosciences10110428

2022038602 Semenov, Petr (All-Russia Institute for Geology and Mineral Resources of the World Ocean, St. Petersburg, Russian Federation); Pismeniuk, Anfisa; Malyshev, Sergei; Leibman, Marina; Streletskaya, Irina; Shatrova, Elizaveta; Kizyakov, Alexander and Vanshtein, Boris. Methane and dissolved organic matter in the ground ice samples from central Yamal; implications to biogeochemical cycling and greenhouse gas emission: Geosciences (Basel), 10(11), Article 450, illus. incl. sketch map, 5 tables, sect., 54 ref., 2020. Part of a special issue entitled Gas emissions and crater formation in Arctic permafrost, edited by Chuvilin, E.

Permafrost thawing leads to mobilization of the vast carbon pool into modern biogeochemical cycling through the enhanced release of dissolved organic matter (DOM) and production of greenhouse gases (CO2 and CH4). In this work, we focus on the study of methane and DOM distribution and genesis in the ground ice samples of thermodenudational exposure in the Central Yamal (Russian Arctic). We propose that the liberation of the ice-trapped CH4 and generation of CO2 by DOM mineralization are the earliest factors of atmospheric greenhouse gases emission as a result of permafrost thawing. The observed enormously "light " isotope signatures of methane (d13C < -80ppm, dD < -390ppm) found in the tabular ground ice units significantly divergent in morphology and localization within the exposuremay be related to subzero (cryogenic) carbonate reduction a as significant factor of the local methane enrichment. DOM is mainly formed (>88%) by biochemically refractory humic acids. Distribution of the labile protein-like DOM reflects the specific features of carbon and nitrogen cycles in the tabular ground ice and ice wedge samples. Tabular ground ice units are shown to be a significant source of methane and high quality organic matter as well as dissolved inorganic nitrogen (DIN). Ice wedges express a high variation in DOM composition and lability.

DOI: 10.3390/geosciences10110450

2022038534 Wierzbicki, Grzegorz (Warsaw University of Life Sciences, Institute of Environmental Engineering, Warsaw, Poland); Grygoruk, Mateusz; Grodzka-Lukaszewska, Maria; Bartold, Piotr and Okruszko, Tomasz. Mire development and disappearance due to river capture as hydrogeological and geomorphological consequences of LGM ice-marginal valley evolution at the Vistula-Neman watershed: Geosciences (Basel), 10(9), Article 363, illus. incl. sketch maps, sect., 66 ref., 2020. Part of a special issue entitled Hydrological systems and models applied in permafrost, edited by Leibman, M.

The advances and retreats of ice sheets during Pleistocene significantly changed high- and mid-latitude landscapes and hydrological systems, albeit differently, in North America and Europe. On the southern margin of the Last Glacial Maximum (LGM) in the Baltic Sea basin, a specific type of valley has developed between glacial margins and upland or mountain slopes. We studied new geological data (boreholes, electrical resistivity imaging (ERI) from this geomorphic setting in Northeast Poland to understand: (1) how the landscape and river network evolved to eventually produce peat mires during the Holocene, and (2) the nature of groundwater recharge to fens in the upper Biebrza Valley. We present the results on a geological cross-section with hydrogeological interpretation. We also discuss regional geomorphology. In addition, we present the LGM extent derived from a spatial distribution of Vistulian (Weichselian) terminal moraines. These end moraines are also interpreted as Saalian kames. Thus, we additionally present another method of LGM extent delineation from a physicogeographical division. We link the steep slopes of the studied valley walls (kame terrace fronts) with thermokarst erosion in the periglacial zone. We then document the hydrogeological window (DISCONTINUITY in the till layer over the confined aquifer), which enables the outflow of groundwater into the peat bog. Although minerotrophic fen mire development in the study area is likely to be sustained in the near future through sufficient groundwater supply, the projected capture of the Biebrza River by the Neman River will not allow for sustaining peatland development.

DOI: 10.3390/geosciences10090363

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2022041588 Abolhosseini, Pejman (Institut Nationale de la Recherche Scientifique, Centre-Eau, Terre et Environnement, Quebec City, QC, Canada); Robert, Thomas; Martel, Richard and Brar, Satinder Kaur. Effect of surfactant concentration on the decomposition rate of alkaline activated persulfate [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2112, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Hydrocarbon contamination is among the most frequent sources of soil and water environmental impacts. Many remediation methods have been implemented to clean up the contaminated environment so far. In-Situ Chemical Oxidation has attracted attention as it has shown efficiency in contaminants removal and cost-effectivity. In addition, soil washing by surfactant foam has been recently proven as a promising method. The combination of these two methods can take the advantage of oxidation while eliminating the challenges regarding the poor distribution of treatment fluid in a heterogeneous porous media. The ultimate goal of this study is to use surfactant foam for delivering oxidant (persulfate) through diesel-contaminated soil in permafrost. However, the interaction between the surfactant and the oxidant needs to be studied first. A better understanding of the impact of surfactants and oxidants on each other can lead to an optimized process. At the first stage of this study, different concentrations of surfactant solutions (sodium dodecyl sulfate: cocamidopropyl betaine in a mass ratio of 1:1) were mixed with a constant persulfate concentration activated with alkali, in absence of hydrocarbon. The preliminary results showed that the initial concentration of the oxidant has no significant effect on its decomposition rate. Also, as the concentration of surfactant was increased above the Critical Micellar Concentration (CMC), the persulfate decomposition rate decreased, likely due to the formation of micelles. However, as the micelles started to be destroyed, the decomposition rate of the oxidant increased gradually and the highest rate was observed when the concentration of surfactant was close to the CMC. When no micelle was left in the solution, the decomposition rate of the oxidant waned to a low value. Thus, coupling the surfactant and the oxidant can be effective for the degradation of hydrocarbon contaminants. Micelles bring part of the hydrocarbon into the aqueous phase and then the micelles are destroyed by the oxidant that can also degrade the hydrocarbon effectively over time. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2112

2022041617 Beck, Inga (Environmental Research Station Schneefernerhaus, Germany); Delleske, Robert; Scandroglio, Riccardo; Rehm, Till; Keuschnig, Markus and Krautblatter, Michael. Unmanned areal vehicles for permafrost monitoring in high alpine regions within the new EU framework [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3860, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The deployment of Unmanned Aerial Vehicles (UAV) for scientific purposes gained a lot of importance during the last years. The new EU regulations for the use of civil drones, in effect since January 2021, set out a new framework for their safe operation in the European skies. With a risk-based approach the purpose of the drone (leisure or civil) is no longer relevant, but only it's weight, specifications and operations is considered. Also for scientific use these new rules mean a more elaborate project preparation and require the compilation of a so-called Specific Operational Risk Assessment (SORA) for each individual case. Here we report on a three years project, in which drones will be flown at altitudes around and above 3000 m asl from the Environmental Research Station Schneefernerhaus (UFS), located on the Zugspitze (Northern Limestone Alps, Germany). It is a collaborative initiative of the UFS as lead and coordinator, the TUM Chair of Landslide Research as scientific partner as well as the Georesearch mbH as technical partner. The project is financed by the Bavarian State Ministry of the Environment and Consumer Protection and started in June 2021. It stands out as an innovative pilot project, pursuing two different goals: Expertise should be collected in writing a SORA for the use of drones in high alpine areas, crossing national borders (D/A) and operating beyond the visible line of site. Thereby a broad know-how will be gained that will facilitate future scientific drone missions with the Schneefernerhaus as starting point. Scientific data will be collected by means of an IR camera and will record the temperature of the ground, delivering information about the current status of the permafrost-affected steep rockwalls. This will extend the present permafrost monitoring conducted on the Zugspitze (Scandroglio et al., 2021) to wider and unexplored areas. Furthermore the influence of infrastructures and their influence on the bedrock thermal behavior will be identified and monitored. An inventory of potential rockfall areas will be recorded by means of optical sensors. In fall 2021 areas of interest, flight routes and starting positions have been defined. After the installation of targets and rock surface temperature loggers, the first flight has been conducted with a drone of the open category, allowing the collection of the first thermal and RGB datasets. Currently a user-defined UAS gets manufactured and the SORA process -- supervised by bavAIRia e. V. -- is in process. The next steps will be the use of the new drone at least twice this year (2022) in order to collect more data. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3860

2022041585 Beer, Alexander R. (Eberhard Karls Universität Tübingen, Department of Geoscience, Tubingen, Germany); Krumrein, Nikolaus; Mutz, Sebastian G.; Rink, Gregor M. and Ehlers, Todd A. Spatial rockfall susceptibility prediction from rockwall surface classification [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1866, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Rockfall both is a major process in shaping steep topography and a hazard in mountainous regions. Besides increasing thread due to thawing permafrost-stabilization in high-elevation areas, there are abundant permafrost-free over-steepened rockwalls releasing rockfall due to other triggers. General rockfall event susceptibility is addressed to frost cracking, earthquake shacking and hydrologic pressure in the walls, and to geotechnical rock properties. Spatial rockwall surface surveys or scans (delivering 3D point clouds) have been used to both deduce rock fracture patterns and to measure individual rockfall events from comparing subsequent scans. Though, the actually measured rockwall topography data has rarely been used as a general predictor of rockfall susceptibility against the background of observed events. In this study, we use a series of dm-resolved annual (2014 to 2020) terrestrial laser scan surveys along 5 km2 of limestone cliffs in the Lauterbrunnen Valley, Switzerland. The annual scan data were hand-cut to remove vegetation and fringes, and then referenced to detect subsequent topographic change in the direction of the wall. From the change-detection point clouds individual rockfall event volumes were detected from cluster and filtering analyses. One surveyed rockwall section of 2014 was used as training data for our Bayesian classification model of rockfall susceptibility, while the adjacent remaining section served for model validation. We rasterized their 3D data points and calculated several surface parameters per cell, including roughness, topography, mean distances for the three main fracture systems, fracture density, local dip, percent of overhang area, normal vector change rate (called edge) and percentage of overhang area. For various parameter sets and different cell sizes (32 m2, 52 m2, 102 m2, 152 m2, 252 m2, and 402 m2), we trained Naive-Bayes-Classifier models. These were then used to predict rockfall susceptibility per cell, based on our observations of surface parameters, and assessed using Kullback-Leibler Divergence analysis and the misclassification cost score. Results indicate the overall best model (accounting for the parameters roughness, edge, topography and overhang area) and for the lowest cell size (32 m2) could predict rockfall cells with a probability of 0.73 (against a mean of 0.3 for all cells). Predictions on another rockwall section with observed rockfall, located on the opposite side of the valley, verified the model's applicability by both comparable probabilities (0.6 vs 0.25) and visual surveys on overhangs. We find our approach could reliably extend this spatial rockfall susceptibility classification to all Lauterbrunnen rockwalls. The classification model generally identified overhang areas and fractured zones as high rockfall risks, matching the general insight of these zones to be of major susceptibility. Interestingly, our method is based only on orientation-independent variables that are directly calculated from the 3D point cloud. Thus, it should be principally transferable to other sites of fractured limestone walls. Specifically, there is no need to determine fracture sets from the point cloud as is generally done for susceptibility studies, since we account for topography that would anyway be used to calculate fracture planes (facets). Hence, this method provides a simple means to predict spatial rockfall susceptibility, applicable for both hazard mapping and landscape evolution studies. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-1866

2022041576 Berghuijs, Wouter (Vrije Universiteit Amsterdam, Department of Earth Sciences, Amsterdam, Netherlands); Allen, Scott; Jasechko, Scott; Moeck, Christian; Luijendijk, Elco and van der Velde, Ype. A more active role for groundwater in the land water cycle [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1009, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

How much precipitation recharges groundwaters varies enormously across Earth's surface, but recharge rates are uncertain because field observations are sparse and modeled global estimates remain largely unvalidated. Here we show that annual recharge is predictable as a simple function of climatic aridity--the ratio of long-term potential evapotranspiration to precipitation--using a global synthesis of measured recharge of 5237 sites across six continents. We use this relationship to estimate long-term recharge globally outside of permafrost regions. Our estimates double previous global hydrological model estimates and are more consistent with empirical field observations. These revised higher estimates of global groundwater recharge imply that groundwater contributes more actively to evapotranspiration and streamflow than previously represented in global water cycle depictions or global hydrological and Earth system models. In addition, we quantify the sensitivity of groundwater recharge to changes in aridity using the empirical relationship between groundwater recharge rates and climatic aridity. This analysis indicates that recharge is most sensitive to climate aridity in mesic regions, where changes in the replenishment of aquifers will be amplified relative to projected changes in precipitation. Global hydrological models seem to underestimate changes in recharge with climate aridity. Thus, the impacts of climatic changes on the replenishment of Earth's largest liquid freshwater stores may be larger than previously anticipated. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-1009

2022041659 Blöthe, Jan Henrik (Albert-Ludwigs-Universität Freiburg, Institute of Environmental Social Sciences and Geography, Freiburg, Germany); Baldis, Carla Cintia Tapia; Halla, Christian; Bottegal, Estefania; Liaudat, Dario Trombotto and Schrott, Lothar. Dynamic changes of a large ice-debris complex in the Central Andes of Argentina [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7098, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Active rock glaciers and ice-debris complexes constitute important indicators of permafrost in periglacial environments of high mountain regions. Within the permafrost body and the seasonally frozen active layer, these cryogenic landforms potentially store significant amounts of water. Especially in dry mountain belts, such as the central Andes of Argentina, rock glaciers and ice-debris complexes attain several kilometres in length, even outranging glaciers in size and number. This intriguing observation fostered discussions on their importance as water reservoirs in this semiarid part of the Andes, yet studies addressing this issue in the region remain sparse. Here we present data on the internal composition, surface velocities and volumetric changes of the Morenas Coloradas ice-debris complex (>2 km2), located close to the City of Mendoza in the central Argentinian Andes that we derive from Electrical resistivity tomography (ERT) measurements and repeated aerial surveys collected in the years of 2016 and 2019. In addition, we compare our newly gathered data with earlier studies as well as aerial imagery from the late 1960s. Our geophysical data indicate massive ice in the central upper part of the Morenas Coloradas complex, which is supported by field observations and remote sensing data, showing a zone of active thermokarst development with massive ice capped by a 2-4 m thick layer of debris. In the lower parts of the ice-debris complex, thermokarst phenomena are absent. Still, our geophysical data point to frozen subsurface conditions, but lower resistivities indicate ice-debris mixtures instead of massive ice here. Between 2017 and 2019, surface velocities of the Morenas Coloradas ice-debris complex largely varied between 0.5 and 4 m yr-1. The highest displacement rates are found in the central upper part of the landform, where two tributaries join the main stem of the complex, as well as in the lower part of the extensive tongue that reaches down to ~3600 m asl. While the landform shows active deformation on the full width of ~500 m in the upper and central parts, active displacement is funnelled into a small band in the lower part approaching the frontal position. Comparing our results to aerial imagery from the late 1960s, we find surprisingly little variation in the displacement pattern and magnitude, despite the considerable dynamics during more than five decades of warming climate and changes in precipitation patterns. In terms of volumetric changes, however, we find that the Morenas Coloradas ice-debris complex has lost roughly 110,000 m3 between 2017 and 2019 in the lower 2/3 of the landform that is covered by our data. Interestingly, volumetric loss is focused on the central upper part (~80% of total loss) where large thermokarst ponds attest the rapid degradation. The lateral parts and lower reaches, in contrast, show little absolute volumetric change over observation period from 2017 to 2019. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7098

2022041643 Cazaurang, Simon (Toulouse National Polytechnical Institute, Toulouse Fluid Mechanics Institute, Toulouse, France); Marcoux, Manuel; Pokrovsky, Oleg S.; Loiko, Sergey V.; Lim, Artem G.; Audry, Stéphane; Shirokova, Liudmila S. and Orgogozo, Laurent. Arctic vegetation cover seen as a porous media; numerical assessment of hydraulic and thermal properties of Sphagnum moss, lichen and peat from western Siberia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5810, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Sphagnum moss, lichen and peat are widely present in arctic regions, covering millions of km2 in permafrost-dominated regions. This multi-component low vegetation strata plays a key role in surfaces fluxes in these areas, as they are the most widespread interface between the atmosphere and the geosphere. Therefore, characterizing their transfer properties such as hydraulic and thermal conductivities is crucial for climate change impacts forecasting in arctic regions. In this work, 12 samples were collected in a discontinuous permafrost arctic area (Khanymey Research Station, Russian Federation) and dried to ensure their conservation. Collected samples have been digitally reconstructed by X-ray scanning. After having assessed morphological and hydraulic properties using numerical analysis of the obtained 3D digital tomographies (Cazaurang et al, submitted), we aim here at developing and using both experimental and numerical methodologies to characterize thermal properties of these samples of Sphagnum, lichen and peat. This new study consist in comparisons of numerically and experimentally estimated thermal properties for contributing to the existing knowledge on Sphagnum, lichen and peat transfer properties. Experiments consist of a steady-state thermal conductivity estimation using a hot plate source on real arctic vegetation cover samples. For this purpose, samples are placed in a confined thermal atmosphere and a constant heat flux is applied at sample base. Thermal conductivity is then retrieved with the resolution of Fourier's heat conduction law. Similarly, numerical computations are conducted on the same digital reconstructions than those used for hydraulic properties determination. Simulations consist of a numerical reproduction of previously described experiments, allowing to strengthen the analysis of the experimental data. Additionally, the definition of representative elementary volumes of the studied samples is also undertaken using the numerical results. Compiling these assessments of transfer properties will represent essential information to simulate the dynamics of the permafrost underneath the arctic bryophytic layers with a devoted catchment-scale permafrost models. For instance in the framework of the HiPerBorea project (, this approach will be used to forecast the impacts of climate warming on boreal permafrost-dominated catchments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5810

2022041640 Chen, Yueli (Ludwig-Maximilians-Universität München, Department of Geography, Munich, Germany); Wang Lingxiao; Bernier, Monique and Ludwig, Ralf. Retrieving freeze/thaw-cycles using machine learning approach in Nunavik (Québec, Canada) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5612, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

In the terrestrial cryosphere, freeze/thaw (FT) state transition plays an important and measurable role for climatic, hydrological, ecological, and biogeochemical processes in permafrost landscapes. Satellite active and passive microwave remote sensing has shown its principal capacity to provide effective monitoring of landscape FT dynamics. Many algorithms have been developed and evaluated over time in this scope. With the advancement of data science and artificial intelligence methods, the potential of better understanding the cryosphere is emerging. This work is dedicated to exploring an effective approach to retrieve FT state based on microwave remote sensing data using machine learning methods, which is expected to fill in some hidden blind spots in the deterministic algorithms. Time series of remote sensing data will be created as training data. In the initial stage, the work aims to test the feasibility and establish the basic neural network based on fewer training factors. In the advanced stage, we will improve the model in terms of structure, such as adding more complex dense layers and testing optimizers, and in terms of discipline, such as introducing more influencing factors for training. Related parameters, for example, land cover types, will be included in the analysis to improve the method and understanding of FT-related processes. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5612

2022041571 Chuvanov, Stanislav (Dokuchaev Soil Science Institute, Moscow, Russian Federation); Matyshak, George; Trifonova, Victoria and Timofeeva, Maria. Permafrost thawing and changes on peat biological activity of palsa mire in western Siberia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-429, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Peatlands comprise 19% of the permafrost area in the subarctic zone, they store 277 Pg of organic carbon. Peatlands in that area are represented by palsa mire. The palsa mire consists of frozen peat mounds (palsa), thermokarst depression and the wet bog without permafrost. Climate change and thawing of permafrost leads to a change in soil moisture, both drying and wetting. This can lead to a change in the carbon balance of the ecosystem and increase or decrease the emission of greenhouse gases (CO2 and CH4). The aim of the work was to study the effect of changes in soil moisture on the biological activity of palsa mire peat soils in the north of Western Siberia (65°18'52"N, 72°52'32"E). The studies were conducted in 2018-2021 in the northern taiga in the discontinuous permafrost zone. The two palsas (Cryic Histosol) and the surrounding bog (Fibric Histosol) were examined. Palsa soils were characterized by high variability of the studied parameters; active layer thickness was 0.66±0.07 m, soil moisture--30.98±2.49%, soil temperature--8.31±0.45°C. The soils of the bog were characterized by the absence of permafrost, a higher soil temperature--13.58±0.26°C and soil moisture--74.59±0.26%. Despite the difference in the studied parameters of these ecosystems, no significant differences in biological activity were found (185.97±30.51 mgCO2/m2/h). Based on field measurements, 3 plots were identified with the same type of vegetation and soil temperature, but significantly differ in soil moisture. Depending on soil moisture, the plots were named "Dry" (25.73±1.89%), "Wet" (38.44±0.70%) and "Moist" (53.09±1.06%). Biological activity did not vary significantly between the studied sites but had a multidirectional dynamic in different years. This shows the complexity of palsa, their multifactorial nature and an ambiguous response to changes in moisture. An added experiment was set up to change soil moisture-transplantation. Measured of CO2 emissions from undisturbed peat soil of a large volume transferred from dry palsa to a wetting bog. And vice versa. The biological activity of the soils did not differ considerable both during wetting and draining. In different years, there was a vary dynamics in CO2 emissions. According to the results of the study, with climate change, thawing of permafrost and palsa degradation, there will be no significant CO2 flux. This may be due to the multifactorial nature of ecosystems, a wide optimum of soil moisture for peat soils. The influence of additional factors is also significant: the size of the methanotrophic barrier, the transport of CO2 with solutions over the surface of the palsa permafrost. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-429

2022041593 Costa, Bernardo (Universidade de Lisboa, Institute of Geography and Spatial Planning, Lisbon, Portugal); Vieira, Goncalo and Whalen, Dustin. The fast-changing coast of Tuktoyaktuk Peninsula (Beaufort Sea, Canada); geomorphological controls on changes between 1985 and 2020 [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2426, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The average rate of coastal change in the Arctic Ocean is -0.5 m/yr, despite significant local and regional variations, with large areas well above -3 m/yr. Recent data suggest an acceleration of coastal retreat in specific areas due to an increasingly shorter sea ice season, higher storminess, warmer ocean waters and sea-level rise. Moreover, climate warming is inducing the subaerial degradation of permafrost and increasing land to sea sediment transportation. This work consists of the characterization and analysis of the main controlling factors influencing recent coastline change in the Tuktoyaktuk Peninsula, Northwest Territories, Canada. The specific objectives are I. mapping Tuktoyaktuk Peninsula's coastline at different time-steps using remote sensing imagery, II. quantifying the recent coastal change rates, III., characterizing the coastal morphology, IV. identifying the main controlling factors of the coastal change rates. A very high-resolution Pleiades survey from 2020, aerial photos from 1985 and the ArcticDEM were used. Results have shown an average coastline change rate of -1.06 m/yr between 1985 and 2020. While this number is higher than the Arctic average rate, it neglects to show the significance of extreme cases occurring in specific areas. Tundra cliffs are the main coastal setting, occupying c. 56% of the Tuktoyaktuk Peninsula coast and foreshore beaches represent 51%. The results display an influence of coastal geomorphology on change rates. The coastal retreat was higher in backshore tundra flats (-1.74 m/yr), whereas more aggradation cases exist in barrier beaches and sandspits (-0.81 m/yr). The presence of ice-wedge polygons contributes to increasing cliff retreat. Foreshore assessment may be crucial, as beaches present a hindering impact on coastal retreat (-0.76 m/yr), whereas foreshore tundra flats promote it (-1.74 m/yr). There are 48 areas with retreat rates higher than -4 m/yr, most being submersion cases. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2426

2022041628 Crippa, Chiara (Universita Milano Bicocca, Department of Earth and Environmental Sciences, Milan, Italy); Codara, Daniele and Agliardi, Federico. Regional characterization of rock glacier activity based on DInSAR phase and permafrost extent [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4668, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Rock glaciers are bodies of frozen debris and ice that move under the influence of gravity in permafrost areas. They are important climatic proxies and can undergo destabilization related to flow of the frontal sectors over steep topography or acceleration related to permafrost degradation and climate change. As consequence, they evolve with complex mechanisms, mirrored by spatial heterogeneity and extremely variable displacement rates. Although a sound quantification of activity is a key component of the study of rock glaciers, only few of them can be characterized by point-like site investigations and ground-based displacement measurements. Their study is thus widely facilitated by remote sensing applications, which proved to be powerful tools for a spatially distributed and temporally continuous characterization on a regional scale Here, we developed a novel methodology to exploit the potential of spaceborne DInSAR analyses to characterize the state of activity of 516 rock glaciers mapped by Scotti et al., (2013) over an area of approximately 1000 km2 in the north-eastern sector of Valtellina (Italian Central Alps) and we exploited Landsat-8 thermal imaging to explore their regional distribution according to the land surface temperature. The original rock glacier inventory, based on orthophotos and DSM mapping, provides a morphological and a dynamic classification (active/inactive vs. relict) of the mapped landforms according to surface evidence. To integrate this dataset with information on the present-day state of activity, we developed a semi-automatic procedure in ArcGIS and Matlab TM combining DInSAR products, morphometric data and available permafrost extent information (APIM). To obtain a spatially distributed characterization of rock glacier activity patterns, we processed Sentinel-1 A/B images (2017-2020) with increasing temporal baselines (Bt from 12 to 120 days) and generated 124 interferograms in ascending and descending geometry to account for all the different topographic orientations. We then implemented an analysis of the interferometric phase to achieve a quantification of each rock glacier activity based on four steps: 1) correcting the phase values inside each rock glacier for the modal phase value inside a surrounding stable area; 2) stacking (median phase values) of all the selected interferograms generated with same temporal baselines; 3) extracting frequency distributions of median phase values inside each rock glacier and stable area; 4) calculating the percentage of phase values inside each rock glacier that falls outside the uncertainty ±s range of the stable area ones. This percentage provides an "Activity Index" that allows defining four classes of rock glacier activity together with the presence (active, inactive) or absence (active debris, relict) of permafrost. Classification results based on DInSAR data at different temporal baselines allow recognizing styles of activity characterized by different ranges of displacement rates and spatial and temporal heterogeneities, possibly correlated with the underlying deformation mechanisms. The integration with land surface temperature finally provides useful insights on the distribution of rock glacier activity classes in different topographic conditions. Our methodology can be applied to other alpine areas and datasets for a wide-area evaluation of rock glacier activity for climatic studies and possible geohazard hot-spot identification. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4668

2022041583 Cuesta-Valero, Francisco José (Helmholtz Centre for Environmental Research, Department of Remote Sensing, Leipzig, Germany); Beltrami, Hugo; Garcia-Garcia, Almudena; Jaume-Santero, Fernando and Gruber, Stephan. Arctic warming; a perspective from the underground [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1838, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The thermal regime of the Arctic subsurface is important, for example, in the context of greenhouse-gas release from thawing permafrost soils. Measurements of Arctic subsurface temperatures, however, are scarce and limited in time, with virtually no observations over climatological time scales. We address this gap in knowledge by estimating the long-term evolution of subsurface temperatures in the Arctic (north of 60°N) since 1600 Common Era (CE) to the present using 110 deep subsurface temperature profiles. The Arctic subsurface has warmed by 1.7±0.8°C during 1970-2000 CE. These estimates are conservative, as the effects of latent heat are not included in the analysis. Although there are significant spatial variations, the Arctic subsurface is warming faster than the global land surface and subsurface (1.2±0.2°C) during the same period. Uncertainties in this analysis arise mostly from deficient knowledge about the subsurface physical properties and limited data coverage. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-1838

2022041607 Czekirda, Justyna (University of Oslo, Department of Geosciences, Oslo, Norway); Etzelmüller, Bernd; Westermann, Sebastian; Isaksen, Ketil and Magnin, Florence. Spatio-temporal variations in rock wall temperature in Norway post the Little Ice Age [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3211, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Warming-induced permafrost degradation is believed to be responsible for the increasing number of rock-slope instabilities, such as rockfalls or rock avalanches, over the past few decades. Relationship between permafrost degradation and geomorphological activity, is nevertheless, hard to establish because often little is known about the permafrost distribution in steep slopes. In the present study, we assess spatio-temporal changes in rock wall temperature in Norway post the Little Ice Age, using the two-dimensional ground heat flux model CryoGrid 2D. We create transects across the monitored rock walls in the Western Norway, in the high alpine range of Jotunheimen and in the Northern Norway. Our results demonstrate that rock wall temperature at 20 m depth increased by an average of 0.2°C decade-1 since the 1980s. Therefore, if atmospheric warming rates remain similar, rock wall permafrost currently at -1°C at 20 m depth could degrade completely at this depth by 2070. Furthermore, we show how rock wall temperature is influenced by: (1) rock wall geometry, (2) rock wall size, (3) magnitude of surface offsets due to the incoming shortwave solar radiation, (4) snow conditions above and below rock walls, (5) blockfield-covered plateaus or glaciers in their vicinity. Multi-dimensional thermal effects are smaller in Norway than in the European Alps due to the dissimilarities in mountain geometry and smaller differences in ground surface temperature between various mountainsides. Rock walls with large surface offsets arising from solar radiation might be warmer than plateaus above or talus slopes below, thus ground heat flux in such rock walls is directed towards colder plateaus or talus slopes. Furthermore, thermal conditions in blockfield-covered plateaus have impact on rock wall temperature and lead to larger warming rates at 20 m depth, whereas large glaciers decrease warming rates at the same depth. Therefore, a potential glaciers retreat would likely increase ground warming rates in the nearby parts of rock walls. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3211

2022041609 Dietz, Andreas (German Aerospace Center, Earth Observation Center, Wessling, Germany); Baumhoer, Celia; Heidler, Konrad; Mou, Li-Chao; Nitze, Ingmar; Scheinert, Mirko; Dinter, Tilman; Frickenhaus, Stephan; Hajnsek, Irena; Fischer, Georg; Christmann, Julia; Roesel, Anja; Loebel, Erik; Duc Phan, Long; Humbert, Angelika; Grosse, Guido and Zhu, Xiao Xiang. The AI-CORE Project; Artificial Intelligence for Cold Regions [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3446, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Artificial Intelligence for Cold Regions (AI-CORE) is a collaborative approach for applying Artificial Intelligence (AI) methods in the field of remote sensing of the cryosphere. Several research institutes (German Aerospace Center, Alfred-Wegener-Institute, Technical University Dresden) bundled their expertise to jointly develop AI-based solutions for pressing geoscientific questions in cryosphere research. The project addresses four geoscientific use cases such as the change pattern identification of outlet glaciers in Greenland, the object identification in permafrost areas, the detection of calving fronts in Antarctica and the firn-line detection on glaciers. Within this presentation, the four AI-based final approaches for each addressed use case will be presented and exemplary results will be shown. Further on, the implementation of all developed AI-methods in three different computer centers was realized and the lessons learned from implementing several ready-to-use AI-tools in different processing infrastructures will be discussed. Finally, a best-practice example for sharing AI-implementations between different institutes is provided along with opportunities and challenges faced during the present project duration. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3446

2022041645 Donner, Anika (Universität Innsbruck, Institute of Geology, Innsbruck, Austria); Töchterle, Paul; Spötl, Christoph; Hajdas, Irka; Li, Xianglei; Edwards, R. Lawrence and Moseley, Gina E. Combined 14C and 230Th/U dating of fine-grained cryogenic cave carbonates from a permafrost cave in Greenland [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5867, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Cryogenic cave carbonates (CCC) have become a valuable tool for providing evidence for past permafrost presence, particularly in low-elevation mid-latitude temperate locations (e.g. Germany and UK) and high-elevation mid-latitude periglacial environments (e.g. Austria and Spain). This study focuses on CCC from a low-elevation high-latitude site in the continuous permafrost of the high Arctic. Specifically, the fine-grained form of cryogenic cave carbonates (CCCfine), which precipitate from rapidly freezing thin water films on top of cave ice, are investigated from Eqik Qaarusussuaq (cave) in northeast Greenland (80.2°N). Under contemporary conditions, the sampling site in the interior of the cave is dry, cold (-14.7°C) and ice-free, thus water infiltration to facilitate CCCfine formation is not possible. Previously, 230Th/U dating efforts of CCCfine have suffered from poor age precision due to high detrital Th contamination. Similarly, 14C dating has been hindered by the unknown reservoir effect (dead carbon fraction). To address these dating issues, we applied a multi-method dating approach to produce a unique dataset comprising eleven 14C ages as well as six 230Th/U ages from a single patch of CCCfine. An isochron indicates that the CCCfine formed synchronously and that the cleanest 230Th/U age is representative for the whole patch. The dead carbon fraction is calculated based on this 230Th/U age. The results of 230Th/U dating (97±34 a BP) agree with the calibrated 14C age range (40-70 a BP (37.9%), 115-139 a BP (28.2%), 226-254 a BP (29.4%)) that the CCCfine from Eqik Qaarusussuaq most likely formed towards the end of the Little Ice Age or shortly after. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5867

2022041653 Dorheim, Kalyn (Pacific Northwest National Laboratory); Bond-Lamberty, Benjamin; Pressburger, Leeya; Woodard, Dawn; Gering, Skylar and Shiklomanov, Alexey. New features, broader accessibility, and improved performance of the Hector v3 simple carbon/climate model [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6522, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Hector is a carbon/climate model capable of emulating Earth System Model outputs at the global scale and is able to reproduce historical observations well. Like other participating models of the Reduced Complexity Model Intercomparison Project, Hector is a computationally efficient source of climate projections and thus has a wide range of applications such as scenario generation, coupling with integrated assessment models, outreach, education, and policy making. Hector version 3 includes a number of new features: carbon tracking, permafrost, improved land-ocean warming contrast, and a web browser-accessible interface. Here we summarize these developments and discuss how they improve the model's performance and broaden its potential user base. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6522

2022041634 Erokhin, Sergey (Institute of Water Problems and Hydro-energy, Laboratory of Exogenous Hydro-geological Processes, Kyrgyzstan); Zaginaev, Vitalii; Allen, Simon and Meleshko, Anna. Assessment and inventory of hazardous mountain lakes in Kyrgyz Republic [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4864, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

More than 90% of territory of Kyrgyz Republic are mountains. More than two thousand lakes have formed but only some lakes pose a threat to lives, assets and livelihoods. Many of these lakes are seasonally dynamic, and form in ice-rich permafrost environments that are characteristic of the region. The objective of this study was to describe and implement an evidence-based expert lake hazard assessment criteria, to produce an updated inventory of hazardous lakes, which are susceptible to outburst within the territory of Kyrgyz Republic. A total of 368 lakes susceptible to outburst in Kyrgyzstan were inventoried and classified into 5 classes: ice-dammed, ice-cored moraine-dammed, ice-free moraine dammed, bedrock-dammed and moraine- dammed, and landslide-dammed lakes. The hazardous lake inventory was most recently updated in 2021 based on field works and remote sensing analysis. All 368 lakes were described by a number of quantitative and qualitative characteristics and were assigned different levels of outburst susceptibility. All studied lakes are situated within the elevational zone between 1200 m.a.s.l. and 4300 m.a.s.l. All lakes were estimated in terms of their surface area from remote sensing data for different years, which ranges from thousands to millions of square meters. For 47 ice cored moraine dammed lakes bathymetry measurements were conducted, for many of them several times. The outburst susceptibility was estimated according to 4 hazard categories and each lake is assigned within a certain category depending on current lake characteristics. A particular feature of the non-stationary lakes found in this region is the rapid changes in outburst susceptibility that can occur over short time-periods. A total of 111 lakes, which at least once have been assigned with the highest hazard levels (the 1st or 2nd category) in the period from 2006-2017 were analyzed for their changes over time. According to the analysis, the hazard level of many lakes varies over time and the number of category 1 and 2 lakes has considerably decreased in the recent decade. Lakes of the 1st and 2nd hazard categories decreased since 2006 by 57% and 45% respectively (from 21 to 9 and 49 to 27), while the number of lakes of the 3rd and 4th categories increased from 35 to 58 and 1 to 16. The lake hazard assessment scheme developed for the Kyrgyz Republic may be a valuable tool for scientists and authorities dealing with outburst flood hazards in other similar environments of Central Asia and elsewhere. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4864

2022041568 Fewster, Richard (University of Leeds, School of Geography, Leeds, United Kingdom); Morris, Paul; Ivanovic, Ruza; Swindles, Graeme; Peregon, Anna and Smith, Chris. Future climatic suitability of permafrost peatlands in Europe and western Siberia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-86, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Human-induced climate change during the 21st century is expected to thaw large expanses of permafrost peatlands--one of Earth's largest terrestrial carbon stores. Whilst frozen, peatland carbon fluxes are inhibited by cold temperatures, but emissions of carbon dioxide (CO2) and methane (CH4) are expected to substantially increase post-thaw. Peatland permafrost is often characterised by the presence of frost mounds, termed palsas/peat plateaus, or by ice-wedge polygons in more northerly regions. The spatio-temporal dynamics of future permafrost peatland thaw remain highly uncertain due to incomplete mapping of their modern distribution, the insulating properties of organic soils, and the variation in model projections of future climate. Here, we present simulations of the modern and future climate envelopes of permafrost peatlands in Europe and Western Siberia. We collated >2,000 site observations from across the northern hemisphere to quantify the modern distributions of palsas/peat plateaus and polygon mires. We fitted novel climate envelope models by relating landform distributions to modern climate data. We forced our climate envelope models with decadal projections of future climate under four Shared Socioeconomic Pathway (SSP) scenarios from 2020-2090, taken from an ensemble of 12 general circulation models included in the Coupled Model Intercomparison Project 6 (CMIP6). We then combined our simulations with recent soil organic carbon maps to estimate the total peat carbon stocks that may be at risk from future losses of suitable climate space. Our simulations indicate that permafrost peatlands in Europe and Western Siberia will soon surpass a climatic tipping point under scenarios of moderate-to-high warming (SSP2-4.5, SSP3-7.0, and SSP5-8.5). We show that permafrost peatlands in Fennoscandia currently exist under warmer, wetter climates than those in Western Siberia. Our projections suggest that Fennoscandia will no longer be climatically suitable for peatland permafrost by 2040. Projected climate space losses by 2100 under these scenarios would affect peatlands containing 37.0-39.5 Gt carbon in Europe and Western Siberia (equivalent to twice the amount of carbon stored in European forests). Under a scenario with strong climate change mitigation (SSP1-2.6), our analyses show that permafrost peatlands storing 13.9 Gt carbon in the northernmost parts of Western Siberia would remain climatically supported by the 2090s. These results indicate that the rate and extent of 21st century permafrost peatland thaw will be determined by near-future socioeconomic developments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-86

2022041590 Hamm, Alexandra (Stockholm University, Department of Physical Geography, Stockholm, Sweden) and Frampton, Andrew. Modeling groundwater flow and solute transport in the active layer of hillslope system in permafrost environments [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2251, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Subsurface hydrology in regions dominated by permafrost is expected to change as a response to global climate change. Groundwater transports energy as well as dissolved solutes such as contaminants and carbon. To investigate the changes in advected energy as well as potential implications for solute transport, we created a permafrost hillslope modeling study that simulates current day active layer hydrology as well as future conditions based on climate projections. Simulations are conducted with a state-of-the-art physically based numerical model (ATS) and combine a generic modeling approach with site-specific boundary conditions representative of the Adventdalen valley in Svalbard. We find that in the current climate, the subsurface hydrothermal state of the active layer along the hillslope transect is affected by lateral groundwater flow through differences in moisture distribution up- and downhill. Although lateral heat advection along the transect was found to be negligible, we show that the moisture distribution by gravitationally-driven seepage flow along the hillslope leads to unexpected temperature differences between the uphill and downhill parts of the transect. A non-negligible warming effect is observed uphill, resulting in deeper active layer depths than downhill. Additionally, preliminary results based on transport modeling indicate that solute migration is mostly longitudinal and slow due to low liquid saturation of the active layer in summer. Under warmer conditions (increased air temperatures), lateral heat advection is expected to increase with more available energy, but solute migration may be partially counteracted by a greater volume of unfrozen soil in summer caused by less saturated conditions closer to the surface. Furthermore, we discuss the potential implications this has for subsurface transport of solutes and dissolved constituents, and highlight challenges for numerical modeling of these systems. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2251

2022041592 Han, Li (Ruprecht-Karls-Universität Heidelberg, Department of Geography, Heidelberg, Germany); Park, Hotaek and Menzel, Lucas. How does thawing permafrost change groundwater discharge? A case study from southern Siberia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2374, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

In permafrost environments, groundwater recharge and groundwater flow are strongly affected by seasonal thawing and freezing cycles, the depth of the active layer, and the spatial coverage of permafrost. In such areas, groundwater is an important supply to the regional water resources, especially during the cold season when the frozen ground strongly restricts the water flows close to the ground and the runoff in rivers. However, due to absent or very limited groundwater observations in the permafrost domain, in combination with remoteness and harsh environments such as in Siberia, key processes and factors that control the subsurface dynamics on the large scale are not well understood yet. In a warming climate, the storage and movement of water in the subsurface system are expected to be altered through degrading permafrost and changing underground connections. However, due to the lack of corresponding studies, assumptions in this regard are very speculative. Based on long-term daily river flow records (1950-2010) of large southern Siberian catchments (about 1,600,000 km2 in total) with different permafrost conditions, we investigate the historical variations in magnitude, timing, and duration of low flow (as an indicator of groundwater dynamics) during the winter period. Our results show that the magnitude of low flow in the catchments has increased during 1950-2010, with the most considerable rise being noticed in the late 30-years period since 1980. Furthermore, we also found that the occurrence of the minflow (i.e., the minimum value of low flow) fluctuates between early and late winter in the catchments with sparse permafrost coverage. In contrast, in the catchments where continuous permafrost prevails, the minflow always occurs in late winter. Finally, for the catchments underlain by discontinuous permafrost, the timing of minflow shows relatively stable conditions in the earlier 30-year period. However, it starts fluctuating between early and late winter during the latter 30 years when a significant rise in low flow is observed. Given the unprecedented warming over the last decades in southern Siberia, these significant changes in both the magnitude and timing of low flow could be induced by the altered surface water-groundwater interactions that are triggered by the degrading permafrost. Overall, our results provide insights into the potential evolutions in the large-scale groundwater dynamics over varied temporal and spatial distributions of permafrost under a warming climate. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2374

2022041654 Herring, Teddi (University of Ottawa, Ottawa, ON, Canada) and Lewkowicz, Antoni. Creating a database of electrical resistivity tomography surveys of permafrost in Canada and establishing best practices for data processing and sharing [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6575, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Electrical resistivity tomography (ERT) is a geophysical method that produces an estimate of subsurface resistivity distribution, which can be used to infer the presence and extent of frozen ground. Repeated ERT surveys indicate how subsurface temperature and ground ice conditions are changing over time, which is particularly important for evaluating the changes and risks associated with climate change. However, there is no existing framework for sharing ERT data and datasets are rarely published, making it difficult to find and use historical data to assess subsurface changes. To facilitate data sharing, we are developing a Canadian database for ERT surveys of permafrost. A key component of this project is the development of an automated ERT data processing workflow to prepare datasets. Establishing best practices for data processing ensures that ERT results are optimized and standardized, which is essential so that changes in subsurface conditions can be reasonably interpreted. We also present our web-based data visualization tool that allows for targeted searching of surveys and plotting of selected results. By storing ERT data in a standardized and accessible way, our goal is to facilitate interpretations of permafrost change on a range of spatial and temporal scales and guide future research in permafrost science. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6575

2022041629 Jiang Huiru (Sichuan University, Laboratory of Hydraulics and Mountain River, Chengdu, China); Yi Yonghong; Zhang Wenjiang; Chen, Deliang and Li Rongxing. Investigating the impact of active layer thickening on vertical soil moisture distribution in the Tibetan Plateau [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4672, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost degradation caused by climate warming has potentially large impact on the hydro-eco environment in the Tibetan Plateau (TP) through affecting soil water redistribution, and it is critical to investigate the soil moisture changes and estimate their response to future climate conditions. In this study, we first analyzed the in-situ soil temperature and moisture data to examine the impact of active layer thickening on soil moisture redistribution. There is generally a "water-rich zone" around the bottom of the active layer at sites with the active layer thickness (ALT) greater than ~2 m, and a relative low soil moisture zone occurs approximately between the bottom of the root zone (~0.4 m) and the bottom of the active layer. However, at shallower-ALT sites (e.g., ALT<2 m), a "soil water rich zone" occurs at the upper active layer rather than at the bottom of the active layer, and soil moisture at the deeper active layer generally shows a decreasing trend along soil depth. We used a process-based permafrost hydrology model to represent the above effects of active layer thickening on soil moisture redistribution through modifying the soil hydraulic profile. Model sensitivity runs indicate that soil moisture redistribution with active layer thickening is largely due to dramatic changes of hydraulic conductivity between the root zone and deeper layers (>~1 m). The saturated hydraulic conductivity tends to increase a little in the root zone and then show a sharp exponential decline along soil depth, while the pedo-transfer functions that are commonly used in models cannot reproduce this process well. Our results indicate that shallower ALT helps to retain soil moisture in the soil root zone; however, when ALT increases to a certain depth, the root-zone soil layer tends to lose water because of little recharge from deeper (>~1 m) soils due to the dramatical decreases in soil hydraulic conductivity. Therefore, active layer thickening may exacerbate soil drying in the root-zone, which will have negative impacts on the vegetation growth and performances of ecosystem functioning. We will further investigate the soil moisture changes under different climate scenarios in order to better project the future hydro-eco response in the TP permafrost region. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4672

2022041611 Jiao, Yi (University of Copenhagen, Department of Biology, Copenhagen, Denmark); Davie-Martin, Cleo; Kramshoj, Magnus; Christiansen, Casper; Lee, Hanna; Althuizen, Inge and Rinnan, Riikka. Volatile carbon emissions from a degrading permafrost peatland [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3481, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost in the north Polar Regions stores more than 1,500 Pg of organic carbon, which is nearly twice as much as the atmospheric carbon pool. As the Arctic region is experiencing unprecedented warming, accelerated decomposition in permafrost is potentially switching it to a hotspot of carbon emissions. In addition to the widely studies carbon dioxide and methane, permafrost may also be a source of biogenic volatile organic compounds (BVOCs), a reactive group of trace gases which have so far received much less attention. BVOCs can prolong the lifetime of methane through the depletion of hydroxyl radicals, contribute to ozone formation, and lead to the formation of secondary organic aerosol, and thus exert significant impact on climate forcing, especially in unpolluted Arctic region. Here, we conducted in situ measurements of soil BVOC emissions on an actively degrading permafrost peatland during a growing season. We compared emissions along a gradient of landscape units from soil palsa and vegetated palsa to thaw slump, thaw pond and vegetated thaw pond. BVOC samples were collected onto absorbent cartridges using dynamic enclosure chamber method, and then analyzed with a gas chromatograph coupled with a mass spectrometer (GC/MS), based upon which the emission rates were calculated. Results suggested that all landscapes units across the peatland showed net emissions of BVOCs during the summertime. Major BVOC groups included monoterpenes, sesquiterpenes, isoprene, hydrocarbons, methanol, acetone, other oxygenated VOCs and other compounds, and these groups were present in all landscape units. All VOC groups also exhibited seasonal and spatial variations across the different sampling months and landscape units. For example, the actively degrading thaw slump showed higher monoterpene emissions that other landscape units, while sesquiterpene emissions were highest from the vegetated thaw ponds. Principal component analysis further revealed temporal and spatial patterns in the relative compositions of the BVOC profiles. Our results show that soil BVOC emissions change in response to active permafrost thaw. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3481

2022041652 Joshi, Prachi (Eberhard Karls Universität Tübingen, Department of Geomicrobiology, Tubingen, Germany); Patzner, Monique; Chauhan, Ankita; Voggenreiter, Eva; Wunsch, Katrin; Bryce, Casey and Kappler, Andreas. Role of iron-carbon interactions in the release of greenhouse gases from permafrost systems [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6418, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

As permafrost thaws, vast stocks of organic carbon previously accumulated within these systems are vulnerable to microbial decomposition and may be released as the greenhouse gases CO2 and CH4. The release of carbon from permafrost systems is expected to lead to runaway positive feedbacks. The timescale and magnitude of the permafrost-climate feedback is highly uncertain as knowledge gaps remain regarding the rate of decomposition of permafrost organic carbon. These knowledge gaps stem, in part, from poor understanding of the association between organic carbon (in the form of organic matter) and minerals, especially high surface area iron minerals. In this work, we investigated the coupling of iron and carbon cycles in permafrost peatlands and its effect on greenhouse gas release. We first showed that up to 20% of the organic carbon in intact permafrost sites may be associated with iron(III) (oxyhydr)oxides and thereby protected from microbial decomposition. At the onset of thaw, this association is broken down, likely due to the microbial reduction of iron(III), and previously protected carbon is thus released. Using microbiological and molecular biological tools, we linked this breakdown to an increase in the abundance of methanogenic microorganisms and concentrations of methane. Preliminary work also suggests that part of the released organic carbon may re-associate with dissolved iron in thaw ponds to form flocs. Currently, we are investigating the molecular composition of organic matter as it undergoes these redox processes with the goal of linking bioavailability to composition. We complement this work with enrichment experiments and microbial community analyses to determine the microbial key players controlling iron(III) reduction and the potential for subsequent microbial Fe(II) oxidation. Collectively, the results of this project suggest that upon thawing, organic matter previously associated with minerals is mobilized and is likely susceptible to microbially-mediated release as CO2 and CH4. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6418

2022041613 Kellerer-Pirklbauer, Andreas (Universität Graz, Institute of Geography and Regional Science, Graz, Austria); Abermann, Jakob; Bernsteiner, Felix; Langley, Kirsty; Strozzi, Tazio and Mergili, Martin. Rock glaciers in the low Arctic of Greenland; surface and subsurface structure, permafrost conditions, long-term evolution, and present kinematics of a large rock glacier system at Bjorneo Island, SW Greenland [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3663, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Active rock glaciers in Greenland have been studied since the 1980s focusing on two regions (Disko Island and Zackenberg) located north of 69°13'N. As judged from permafrost models, widespread existence of permafrost and thus active rock glaciers are also possible south of this latitude. Therefore, research on a large rock glacier on the island of Bjorneo (size: 1 km2; elevation 250-600 m a.s.l.; NNW-exposed) at 64°30'N was initiated in 2016. Research focused until 2020 on repeated differential GPS measurements at several fixed ground control points, on the analysis of the bottom temperature of the winter snow cover, and on the assessment of high-resolution orthophotos and digital terrain models based on UAV campaigns. Results up to 2020 indicate that permafrost influences a large part of the rock glacier and surface displacement takes place in the order of cm per year particularly in the central part. Within an INTERACT research project we continued and expanded research at this rock glacier in 2021 applying two types of geophysics (electrical resistivity tomography, ground penetrating radar), differential GPS, relative surface dating, geomorphic mapping, clast form analysis, and monitoring of ground, air, and water temperatures. We find that widespread permafrost is likely along the measured geophysical profiles, that ground and water temperatures generally support the assumption of present permafrost conditions, and that the rock glacier evolved over a period of several thousand years, starting to form soon after the recession of the Greenland Ice Sheet from the coast some 10.4 to 11.4 ka BP. In addition to fieldwork, different types of remote sensing- and modelling based research at this rock glacier were accomplished. Clast size distribution was semi-automatically quantified using a high-resolution digital terrain model. Results reveal distinct clast size-differences along a longitudinal profile of the rock glacier. Analyses of time-series of Sentinel-1 differential SAR interferograms for the period 2016 to 2021 showed minor motion in the uppermost part of the landform during a period of two months, distinct compressive flow (few cm) of two lobes of the landform after several months, and landform-wide movement over a period of 3 years. The terrain surface before the formation of the rock glacier, and thus the rock glacier volume, were reconstructed on the basis of field observations and terrain data. The volume of material relocated due to rock glacier activity was approx. 10 million m3. Finally, the present rock glacier extent and morphology were numerically reproduced as a steadily evolving and slowly moving viscous mass using a model implemented in the GIS-based open-source mass flow simulation framework r.avaflow. Our chosen multidisciplinary approach is a significant step forward in understanding the long-term evolution and present conditions of large rock glacier systems in the low Arctic region of Greenland. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3663

2022041638 Kjaer, Sigrid Trier (ETH Zürich, Department of Environmental Systems Science, Zurich, Switzerland); Nedkvitne, Nora; Westermann, Sebastian and Dörsch, Peter. The long-term biogeochemical fate of C in subarctic thawing peat plateaus [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5257, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Global warming causes permafrost to thaw at an unprecedented rate. In Northern Scandinavia, permafrost peat plateaus have been found to decline rapidly during the last decades, releasing old organic carbon to decomposition and runoff. Thawing peat plateaus can partly turn into thermokarst ponds, with consequences for the biogeochemical fate of the released carbon. We investigated carbon degradation of thawing permafrost peat by incubating permafrost peat and thermokarst sediments from three peat plateaus in Northern Norway. The samples were incubated field moist at 10°C for almost one year. Initial decomposition was dominated by CO2 production which strongly responded to oxygen availability, while methane (CH4) production was small. Methane production increased drastically after more than ten months, indicating that thawed permafrost peat has a considerable potential to produce CH4 after a time lag. The cumulative CH4 production of thawed permafrost peat after one year of incubation exceeded that of overlaying active layer peat by up to 641 times, illustrating the potential of thawing subarctic permafrost to act as an additional CH4 source. Comparing laboratory thawed permafrost peat to thermokarst peat revealed remarkable differences in CH4 production, with much higher CH4 production potentials in thermokarst sediments during the first months of incubation and in some samples exceeding CH4 production measured in permafrost peat after one year. This suggests that the potential to produce CH4 increases dramatically with thermokarst formation. Interestingly, thawed permafrost peat produced more DOC over the period of one year than gaseous C (CO2 and CH4), which suggests that hydrological conditions are key to the understanding of the fate of C released from thawing peat plateaus. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5257

2022041658 Kraushaar, Sabine (Universität Wien, Department of Physical Geography, Vienna, Austria) and Bloethe, Jan Henrik. Towards deciphering the contribution of permafrost and active layer to summer runoff in a small alpine catchment [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7052, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

High-mountain regions are very sensitive to climatic changes, which is particularly visible in the drastic retreat of Alpine glaciers. Concomitant with retreating glaciers, permafrost degradation affects large parts of high-mountain regions. In recent years, the hydrological significance of permafrost ice has therefore increasingly come into focus. However, surprisingly little is known about the current state and size of water resources in alpine permafrost. Moreover, it remains unknown whether the thawing of permafrost is already making a significant contribution to late summer runoff in alpine catchments. In this study we combine UAV-derived volumetric change detection with the hydro-chemical analysis of d18O and 32D2H isotope signatures and the radio nuclide 129I in the discharge from the Kaiserberg rock glacier in the Austrian Alps. The combination of these methods allows a direct and indirect quantification of permafrost degradation. Furthermore, the isotopic signatures help to decipher the relative and absolute permafrost contribution to discharge over the summer months. First results from the analysis of digital elevation models show an average volume loss of several thousand cubic metres per year between 2017 and 2019. In addition, geochemical data on d18O-and d2H-isotopes and the radionuclide 129I indicate an increased contribution of meltwater from the permafrost body of the Kaiserberg rock glacier in the summer months, which is dominant on single days in late summer. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7052

2022041662 Lakshmiprasad, Radhakrishna Bangalore (Gottfried Wilhelm Leibniz Universität Hannover, Institute of Fluid Mechanics and Environmental Physics in Civil Engineering, Hanover, Germany); Graf, Thomas; Zhang Fan; Xiao Xiong and Coon, Ethan T. A comparison study of process complexity in permafrost dominated regions [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7266, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Qinghai-Tibet Plateau (QTP), also known as the "Water tower of Asia", is threatened by climate warming. Climate warming leads to permafrost degradation, which in turn affects the natural and man-made environment. Permafrost is defined as ground where temperatures remain at or below 0°C for a minimum period of two consecutive years. Near-surface atmospheric processes give rise to seasonal thawing and freezing of permafrost. The thawing promotes groundwater movement because of the increase in liquid water content and hydraulic conductivity. The pore water phase change from ice to liquid also causes variation in the thermal parameters of the soil leading to nonlinear coupled processes. Therefore, complex interactions exist between hydraulic and thermal surface and subsurface processes. Numerical models are useful tools to study coupled processes. Model complexity arises as several physical processes need to be considered, especially due to the presence of permafrost. The amount of input data, parameters, boundary conditions and hence the difficulty increases as the number of physical processes increases. The main aim of this research work is to therefore conduct a comparison study of three modelling scenarios: (i) Coupled subsurface flow and energy transport with ice content, (ii) including coupled surface flow and surface energy balance to scenario (i), (iii) including snow component to scenario (ii). The Advanced Terrestrial Simulator (ATS) and Parameter ESTimation (PEST) codes were applied for simulation and calibration, respectively. The near-surface temperature and moisture measurements from a meteorological station at QTP were used for calibration. Results show that all three models have good agreement with the measurement dataset, however scenario (i) exhibited the best performance in terms of both matching the measured data and representative literature parameter values. Future work will focus on predicting permafrost behavior under various climate change scenarios. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7266

2022041578 Lattaud, Julie (ETH Zurich, Biogeoscience Group, Zurich, Switzerland); Bröder, Lisa; Haghipour, Negar; Giosan, Liviu and Eglinton, Timothy. Radiocarbon and stable isotope constraints on the sources and cycling of organic carbon in Mackenzie Delta lakes [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1095, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Arctic is undergoing accelerated changes in response to ongoing alterations to the climate system (Arctic report card 2019), and there is a need for local to regional scale records of past climate variability in order to put these changes into historical context. The Mackenzie Delta region (Northwestern Territories, Canada) is populated by numerous small shallow lakes. They are classified as no-, low- and high-closure lakes, reflecting varying degrees of connection to the river main stem, and as a result, have different sedimentation characteristics. As for much of the Arctic region, the Mackenzie Delta is expected to undergo marked environmental perturbations such as earlier melting of river ice. As a consequence, the annual flood pulse (freshet) may decline, potentially resulting in the disconnection of some lakes from the river, leading to their subsequent desiccation (Lesack et al., 2014; Lesack & Marsh, 2010). In contrast, abrupt permafrost thaw and enhanced thermokarst-related processes might lead to additional lake formation and deepening of already formed lakes. In this study, we used sediment cores originating from several lakes within the Mackenzie Delta, representing the three types of connectivity to the river (Lattaud et al., 2021). Radiocarbon and stable carbon isotopic signatures of two groups of compounds--fatty acids and isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs)--are employed as tracers of carbon supply to, and cycling within the different lakes. Short-chain fatty acids as well as GDGTs serve as putative tracers of microbial production while long-chain fatty acids originate from higher terrestrial plants. The carbon isotopic signatures are used to distinguish between the relative importance of carbon inputs derived from in situ production, as well as from proximal (lake periphery) and distal (Mackenzie River) sources to the different lakes in the context of their degree of connectivity. Down-core molecular 14C measurements provide insights into the temporal evolution of the lakes, providing context for their response to past and future climate change. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-1095

2022041621 Lee, Hanna (Norwegian University of Science and Technology, Department of Biology, Trondheim, Norway); Christiansen, Casper; Althuizen, Inge; Michelsen, Anders; Dörsch, Peter; Westermann, Sebastian and Risk, David. Long lasting greenhouse gas emissions beyond abrupt permafrost thaw event in permafrost peatlands [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4211, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Abrupt permafrost thawing is expected to release large amounts of greenhouse gasses to the atmosphere, creating a positive feedback to climate warming. There is, however, still large uncertainty in the timing, duration, magnitude, and mechanisms controlling this process, which hampers accurate quantification of permafrost carbon climate feedback cycles. The current understanding supports that abrupt permafrost thaw will lead to surface inundation and create anaerobic landscapes, which dominantly produce methane during the decomposition process. Over time, natural succession and vegetation growth may decrease methane release and increase net carbon uptake. We investigated how rapid permafrost thawing and subsequent natural succession over time affect CO2, CH4, and N2O release at a field site in northern Norway where recent abrupt degradation of permafrost created thaw ponds in palsa peat plateau-mire ecosystems. The site exhibits a natural gradient of permafrost thaw, which also corresponds to a strong hydrological gradient (i.e. dry peat plateau underlain by intact permafrost, seasonally inundated thaw slumps, thaw ponds, and natural succession ponds covered by sphagnum and sedges). Since 2017, we used a range of manual and automated techniques to measure changes in vegetation, soil and water microclimate, biogeochemistry, and soil CO2, CH4, and N2O concentrations and fluxes across the permafrost thaw gradient. In the three-year observations, we show that abrupt permafrost thaw and land surface subsidence -- both intermediate slumping and pond formation -- increase net annual carbon loss. Permafrost thaw accelerated CO2 release greatly in thaw slumps (177.5 gCO2 m-2) compared to intact permafrost peat plateau (59.0 gCO2 m-2). During the growing season, peat plateau was a small sink of atmospheric CH4 (-2.5 gCH4 m-2), whereas permafrost thaw slumping and pond formation increased CH4 release dramatically (ranging from 9.7 to 36.1 gCH4 m-2). Furthermore, CH4 release continues to increase even in natural succession pond likely due to aerenchyma transport of CH4 from deeper soil. The overall N2O release was negligeable except in the bare soil peat plateau. The net radiative forcing of ecosystem carbon balance will depend on the carbon uptake from the natural succession of vegetation, but we show that greenhouse gas emissions continue to increase beyond abrupt permafrost thaw event towards natural succession. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4211

2022041597 MacDougall, Andrew H. (Saint Francis Xavier University, Department of Climate & Environment, Antigonish, NS, Canada). Estimated effect of the permafrost carbon stability on the zero emissions commitment to climate change [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2539, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Zero Emissions Commitment (ZEC), the expected change in global temperature following the cessation of anthropogenic greenhouse gas emissions has recently been assessed by the Zero Emissions Commitment Model Intercomparison Project (ZECMIP). ZECMIP concluded that the component of ZEC from CO2 emissions will likely be close to zero in the decades following the cessation of emissions. However, of the 18 Earth system models that participated in ZECMIP only two included a representation of the permafrost carbon feedback to climate change. To better assess the potential impact of permafrost carbon decay on ZEC a series of perturbed parameter experiments were conducted with an Earth system model of intermediate complexity. The experiment suggest that the permafrost carbon cycle feedback will directly add 0.06 [0.02 to 0.14]°C to the benchmark ZEC value assesses 50 years after 1000 PgC of CO2 has been emitted to the atmosphere. An additional 0.04 [0 to 0.06]°C is likely to been added relative to the benchmark ZEC value from the thaw-lag effect unaccounted for in the ZECMIP experiment design. Overall we assess that the permafrost carbon feedback is unlikely to change the assessment that ZEC is close to zero on decadal timescales, however the feedback is expected to become more important over the coming centuries. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2539

2022041636 Martin, Léo (Universiteit Utrecht, Department of Physical Geography, Utrecht, Netherlands); Westermann, Sebastian; Magni, Michele; Brun, Fanny; Fiddes, Joel; Lei Yanbin; Kraaijenbrink, Philip; Mathys, Tamara and Immerzeel, Walter. Impact of recent ground thermal changes on the hydrology of a Tibetan catchment and implications for lake level changes [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5028, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

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 continental-scale 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 to discuss their implications on the lake level changes. We use the Cryogrid model to simulate the surface energy balance, snow pack dynamics 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 to account for this spatial variability. 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, an significant part of the basin is underlaid by permafrost (>20%). We also show that over the 1980-2020 period, ground temperature warmed up by 1.5 to 2°C per centuries. The permafrost limit rose from 5100 to 5300 m asl (in 40 years). Unfrozen surface conditions increased by around 25 days per century and evaporation increasing by +22% over the period. To represent the impact of these changes on the lake level, we included them in a simple hydrological budget calculation including the contribution of glacier melt and lake evaporation. This approach shows that ground thermo-hydric changes in the catchment have significantly contributed to the lake level changes. These first results highlight the potential of thermo-hydric simulation to better quantify hydrological changes to come in the QTP. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5028

2022041660 Miesner, Frederieke (Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany); Cable, William L.; Boike, Julia and Overduin, Pier Paul. In-situ measurements of sediment temperature under shallow water bodies in arctic environments [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7154, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The thermal regime under lakes, ponds, and shallow near shore zones in permafrost zones in the Arctic is predominantly determined by the temperature of the overlying water body throughout the year. Where the temperatures of the water are warmer than the air, unfrozen zones within the permafrost, called taliks, can form below the water bodies. However, the presence of bottom-fast ice can decrease the mean annual bed temperature in shallow water bodies and significantly slow down the thawing or even refreeze the lake or sea bed in winter. Small changes in water level have the potential to drastically alter the sub-bed thermal regime between permafrost-thawing and permafrost-forming. The temperature regime of lake sediments is a determining factor in the microbial activity that makes their taliks hot spots of methane gas emission. Measurements of the sediment temperature below shallow water bodies are scarce, and single temperature-chains in boreholes are not sufficient to map spatial variability. We present a new device to measure in-situ temperature-depth profiles in saturated soils or sediments, adapting the functionality of classic Bullard-type heat flow probes to the special requirements of the Arctic. The measurement setup consists of 30 equally spaced (5 cm) digital temperature sensors housed in a 1.5 m stainless steel lance. The lance is portable and can be pushed into the sediment by hand either from a wading position, a small boat or through a hole in the ice during the winter. Measurements are taken continuously and 15 minutes in the sediment are sufficient to acquire in-situ temperatures within the accuracy of the sensors (0.01 K after calibration at 0°C). The spacing of the sensors yield a detailed temperature-depth-profile of the near-surface sediments, where small-scale changes in the bottom water changes dominate the temperature field of the sediment. The short time needed for a single measurement allows for fine-meshed surveys of the sediment in areas of interest, such as the transition zone from bottom-fast to free water. Test campaigns in the Canadian Arctic and on Svalbard have proven the device to be robust in a range of environments. We present data acquired during winter and summer, covering non-permafrost, thermokarst lake and offshore measurements. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7154

2022041579 Miner, Kimberley N. (NASA, Jet Propulsion Laboratory, Pasadena, CA). Biotoxicological risks and hazards of a warming Arctic [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1132, 3 ref., 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Climate change accelerates permafrost degradation throughout the Arctic, introducing previously sequestered known and unknown biotoxicological hazards. 1- While infrastructure failures due to permafrost thaw are well documented, biological and chemical hazards are less understood. Minimally characterized bacteria, viruses, and pathogens are bringing unknown paleo-ecosystem dynamics into the modern age. 2- These species join various anthropogenic materials, including banned organic pesticides, mercury, oil, and nuclear remnants. Though research is ongoing, Arctic permafrost variability presents additional uncertainty in the location, timing, and rate of emergence for these hazards. In order to understand the dynamics of this emergent risk from the new Arctic, there is an urgent need to quantify the risks before they emerge. To do this, a combination of remote sensing, in-situ field work, and modeling are needed to better integrate micro-scale dynamics (including permafrost thaw) into Earth systems models. Paralleling the growing impacts of Arctic carbon release, biotoxicological hazards are poised to become a new source of contaminants across the Arctic environment.

DOI: 10.5194/egusphere-egu22-1132

2022041650 Morard, Sarah (Université de Fribourg, Fribourg, Switzerland); Hilbich, Christin; Mollaret, Coline; Pellet, Cécile; Wagner, Florian; Westermann, Sebastian and Hauck, Christian. Analysis of the 20-year long permafrost evolution at the long-term monitoring site Stockhorn, Swiss Alps, by applying a petrophysical joint inversion and a thermal model (Cryogrid3) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6195, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Stockhorn plateau, an east-west oriented crest located at an elevation of around 3410 m a.s.l. in the Swiss Alps, is a measurement site belonging to the Swiss Permafrost Monitoring Network (PERMOS). In this study we present a combined analysis of thermal and geophysical data by applying the so-called petrophysical joint inversion (PJI) scheme (Wagner et al., 2019). By using the PJI approach with different petrophysical relationships (Archie's law and Resistivity Geometric Mean model) (see Mollaret et al., 2020), we attempt to quantify the ice and water content changes in the subsurface over the past 20 years and analyse their spatial heterogeneity. The results will be validated with the borehole data. Many different data sets are available for the Stockhorn plateau and they give evidence of permafrost degradation in the past 20 years. Two boreholes were drilled in 2000 and provide temperature measurements to a depth of 17 m and 100 m, respectively. From 2002 to 2020, the active layer depth has increased by 2 m for the northern borehole and by 3.3 m for the southern borehole. A weather station provides measurements since 2002 (PERMOS, 2021). The meteorological data show an increasing air temperature trend from 2003 to 2018 (Hoelzle et al., 2020). Since 2005, annual geoelectrical surveys (ERT) have been performed with collocated seismic surveys (RST) in almost every year. The geophysical data from 2007 to 2021 show a decreasing trend for specific electrical resistivities and P-wave velocities, but a detailed interpretation of the geophysical data is however not straightforward because of heterogeneous lithology as well as the small-scale topography effects causing a complex thermal regime. The north-south geophysical profile is hereby situated at the boundary between two different rock formations. This is visible through the occurrence of a conductive anomaly observed in the geoelectrical surveys between the two boreholes. In addition, the plateau is covered by different materials such as fine debris, blocky and fine-grained materials, and bedrock, which implies different porosity values along the geophysical profiles in the subsurface. Due to large spatial heterogeneities in the observed temperature and geophysical data, the impact of permafrost degradation on the ground properties such as water and ice content is unclear. In contrast to the formerly used four-phase model (4PM, Hauck et al., 2011), where ERT and RST inversions are computed individually and a porosity distribution had to be prescribed, the PJI scheme has the advantage of obtaining physically consistent results of water and ice content distributions in the ground by inverting the ERT and RST results simultaneously (Wagner et al., 2019). In addition to the validation of the PJI results with the borehole data, it could be possible to validate the results with the thermal model simulations using Cryogrid3 (Westermann et al., 2016). [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6195

2022041569 Nesterova, Nataliia (Melnikov Permafrost Institute, North-Eastern Permafrost Station, Magadan, Russian Federation); Makarieva, Olga; Ostashov, Andrey; Zemlianskova, Anastasiya; Shikhov, Andrey and Alexeev, Vladimir. Aufeis impact on the hydrological cycle in the north-eastern Russia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-172, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Aufeis are produced annually in the rivers valleys in permafrost environment as the result of layer-by-layer freezing of groundwater flowing to the surface. Aufeis are widespread in the territory of the North-East of Eurasia (including the basins of large rivers in permafrost, such as the Yana, Indigirka, Kolyma, Anadyr, Penzhina Rivers and rivers of the Chukchi Peninsula (total area about 2 mln. km2). They comprise an important water resource of the study region. Based on the analysis of Landsat satellite images for the period 2013-2019 the number and total maximum area were estimated. As Landsat images do not always allow correctly assess the maximum area of aufeis, it was adjusted to get the maximum value before the beginning of ablation period for the assessment of aufeis resources. Total number of giant aufeis (>0.1 km2) formed by groundwater reaches 6217 with maximum area of about 4500 km2 (in average 0.22% of studied area). For each aufeis field the assessment of maximum ice reserves was conducted. The aufeis resources of the North-East are at least 10.6 km3 or 5 mm of aufeis runoff. The aufeis resources vary from 0.4 to 4.25 km3 (or 3.7 - 11 mm) for individual basins of large rivers. The greatest aufeis resources in absolute values are found in the Indigirka River basin. The contribution of aufeis runoff to streamflow in different seasons was calculated for 58 hydrological gauges (area 523-526000 km2). Aufeis annual runoff varies from 0.3 to 29 mm (0.1-22%, average 3.8%) with the share in winter runoff amount about 6-712% (average 112%) and the spring freshet 0.2-43% (average 7.1%). The influence of aufeis and glaciers on the water balance is compared--in general, the aufeis runoff exceeds the glacial runoff. The response of aufeis to climate change depends on different factors of the natural system. The dynamics of aufeis formation is directly related to the winter runoff, which changes are observed in different parts of the cryolithozone. The presented results are relevant for studying the impact of climate change on the hydrological cycle and its components in the permafrost regions of the Northern Hemisphere. The study was carried out with the support of RFBR (19-55-80028, 20-05-00666) and St. Petersburg State University (project 75295879). [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-172

2022041582 Opel, Thomas (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Polar Terrestrial Environmental Systems, Potsdam, Germany); Wetterich, Sebastian; Meyer, Hanno and Murton, Julian B. Cryostratigraphy, chronology, and ground-ice stable isotopes of the Batagay megaslump in east Siberia indicate climate-permafrost interactions during the middle and late Pleistocene [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1637, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Batagay megaslump (67.58°N, 134.77°E) is the largest known retrogressive thaw slump on Earth, and located in the Yana River Uplands near the town of Batagay in east Siberia. The slump headwall is about 55 m high and exposes ancient permafrost deposits that provide a discontinuous record of the Middle and Late Pleistocene that dates back to at least 650 ka. Such deposits are usually deeply (>45 m) buried in frozen ground. The cryostratigraphy of the Batagay megaslump provides evidence for several periods of both permafrost formation and degradation. Permafrost formation and stability are reflected by the presence of deposits with syngenetic ice wedges and composite (i.e., ice-sand) wedges, whereas permafrost thaw and erosion are shown by sharp erosional discordances above reddish and organic-rich layers and by the accumulation of woody (forest) remains in erosional downcuts. The main cryostratigraphic units with syngenetic ice and composite wedges indicate the formation of permafrost during MIS 16 or earlier (lower ice complex), MIS 7-6 or earlier (lower sand unit), MIS 4-2 (upper ice complex), and MIS 3-2 (upper sand unit). Intense permafrost thaw and erosion likely took place during one or several periods between MIS 16 and MIS 7-6, including MIS 5 and the late Pleistocene-Holocene transition. In this contribution we compile cryostratigraphic observations and dating results for the permafrost exposed in the Batagay megaslump. To draw large-scale conclusions on climate-permafrost interactions we compare our data to independent climate and permafrost reconstructions from terrestrial (cave deposits, lake sediment cores, and permafrost deposits) and marine sediment cores across the Arctic with a focus on East Siberia. To gain regional climate signals for this extremely continental region, we also present ground-ice stable-isotope data from all four main stratigraphic units of the Batagay megaslump. We consider ice and composite wedges (winter signals) and pore ice (summer to annual signals) to derive seasonal-scale information and to assess continentality for selected time periods. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-1637

2022041651 Osy, Cécile (UCLouvain, Earth and Life Institute, Louvain-la-Neuve, Belgium); Massonnet, François and Opfergelt, Sophie. Drivers of changes in the permafrost late shoulder season [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6289, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Arctic has been warming two to four times more rapidly than the global mean in the last decades--a phenomenon known as Arctic Amplification. This warming induces changes for the whole cryosphere, including the permafrost. A first-order marker of permafrost health is the timing of snowfall compared to the timing of the freezing of the upper soil layer, which together determine the length of its late shoulder season. The late shoulder season of permafrost is the period after plant senescence and before the freezing of the active layer of the permafrost. Its length depends on the air temperature, but also on the timing of snowfall. The snow insulates the ground from the atmosphere, and snow cover will delay the freezing of the ground if it falls before the air temperature drops below freezing point. On the other hand, if the snowfall occurs after the ground freezing, it is expected that the freezing will be more persistent and will reach deeper soil layers more rapidly. There is to date no large-scale view of the late shoulder season characteristics in the Arctic permafrost regions and how this shoulder season is evolving in a warming Arctic. Here, a study of the temporal variability of the late shoulder season of the permafrost is proposed. To that end, the temporality of the first relevant snowfall and freeze of the top layer of the ground is studied from 1950 to 2020 in the ERA5-Land reanalysis. The temporal trends will be spatialized to account for the spatial heterogeneity of the study area, and to study which variables other than the snow (vegetation, topography, ...) influence the length of the shoulder season. The surface pressure and atmospheric circulation in the ERA5 reanalysis is also looked at to explain punctual extreme events and interannual trends. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6289

2022041657 Ota, Mitsuaki (Swedish University of Agricultural Sciences, Department of Soil and Environment, Uppsala, Sweden); Muller, Amanda; Dhilon, Gurbir and Siciliano, Steven. Biogeochemical and ecological responses to warming climate in high Arctic polar deserts [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6825, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

High Arctic polar deserts cover 26% of the Arctic and are predicted to transform dramatically with rapidly rising temperatures. Previous studies found that polar deserts store larger amounts of soil organic carbon (SOC) in the permafrost than previously expected and can emit greenhouse gases (GHGs) at rate comparable to mesic Arctic ecosystems. However, the mechanism of the GHG production is not clear, which contributes to a great source of uncertainty regarding ecological feedbacks to the warming climate. Extreme climate conditions thaw the uppermost part of the permafrost, and the accumulated soil nutrients are ejected into the overlying soil layers where the subsurface nutrient patches (diapirs) form to increase carbon and nitrogen (N) contents by 7% and 20%, respectively. Previous mechanical models suggest that the ejection is facilitated by the increase in soil viscosity in the overlying soil layer. We previously found that diapirs developed about 30% of sorted circles in our study site and that the dominant vascular plant (Salix arctica) increased root biomass and nitrogen uptake from diapirs. To understand a GHG-feedback to the warming climate, we collected 40 soil samples with diapirs and 40 without diapirs during July and August 2013 to investigate gross N transformation rates and GHG emissions associated with diapirs in laboratory. Our study site encompasses two Canadian High Arctic polar deserts and is located near Alexandra Fjord (78°51'N, 75°54'W), Ellesmere Island, Nunavut, Canada. To deal with small amounts of nitrous oxide (N2O) emissions near or below the detection limit, we employed the hurdle models including (1) a Bernoulli component that models whether the data cross the detection limit based on covariates and (2) generalized linear model component that models the data above the detection limit. Our results showed that diapirs decreased gross N mineralization up to 48% and slowed carbon dioxide and methane emissions. Consistently, we found that diapirs contained more recalcitrant SOC using attenuated total reflectance Fourier transformed mid-infrared (ATR-FTIR) spectroscopy. ATR-FTIR also showed higher amounts of polysaccharides known to raise soil viscosity. The hurdle model approach showed that diapirs increased the estimated N2O emissions by up to 49% under wet conditions and suggested that the increase links to the increase in the probability of N2O emissions. On the other hand, under dry conditions, the hurdle models suggested that the increase in the estimated N2O emissions from diapirs links to the increase in the magnitude of the N2O emissions. The higher abundance of polysaccharides and recalcitrant SOC may indicate that biological factors are involved in forming diapirs and that diapirs supply vascular plants with nutrients as a result of a mutualistic relationship. Our study showed that diapirs altered GHG emissions and suggest that future research should include plant-microbe relationship in diapirs and other factors such as occlusion in soil aggregates for a more robust evaluation of diaper-GHG production. Furthermore, we suggest that the hurdle model may be a useful tool for evaluating N2O emissions that are locally small but could be critical in total in the Arctic. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6825

2022041608 Park, Hansu (Seoul National University, Laboratory for Ice Core & Paleoclimate, Seoul, South Korea); Ko, Na-Yeon; Kim, Jeong-Eun; Opel, Thomas; Meyer, Hanno; Wetterich, Sebastian; Fedorov, Alexander; Shepelev, Andrei and Ahn, Jinho. Compositions and origins of greenhouse gas species in permafrost ice wedges at the Batagay megaslump, Yana uplands, northeast Siberia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3437, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost has a huge potential as a source for greenhouse gas release under global warming. In this context, it is very important to understand biogeochemical mechanisms of permafrost-related greenhouse gas formation and capacity. As ice wedges are an essential component of ice-rich permafrost and often occupy a large volume fraction of permafrost deposits, it is necessary to study the their gas chemistry. The Batagay megaslump (Yana Uplands, Northeast Siberia) exposes ice-rich permafrost deposits (Ice Complex) that have formed in the Middle and Late Pleistocene. Previous studies suggest the ages of these deposits as MIS 4-2 and at least MIS 16 for the Upper and Lower Ice Complexes, respectively. In this study, we analyzed mixing ratios of gas in air bubbles occluded in ice wedges of both ice complexes. We extracted gas by both, wet and dry extraction methods that connected with a gas chromatography system to analyze CO2, N2O, and CH4 concentrations. We observe CO2 concentrations of 1.9-10.3%, N2O of 0.1-8 ppm, and CH4 of 30-170 ppm for the Lower Ice Complex, and CO2 of 0.03-8.89%, N2O of 0.3-70 ppm, and CH4 of 5-980 ppm for the Upper Ice Complex. Greenhouse gas mixing ratios higher than atmospheric level indicate active microbial activity. This is supported by the d(O2/Ar) values, which range from -89.01 to -67.43% and from -98.07 to -47.06% for the Lower and Upper Ice Complexes, respectively. The highly depleted d(O2/Ar) values may indicate strong oxidation reactions by microbial activity and/or non-biological oxidation reactions. Even though there is no significant correlation between CO2 and CH4, abiotic CH4 formation might be negligible because it is unlikely to occur under permanently frozen conditions. Interestingly, CH4 and N2O show a weak negative correlation in both ice complexes, which can be explained by the nitrogen compounds' inhibitory effect for methanogenesis. The d(N2/Ar) values range from -8.06% to 33.86% for the Lower Ice Complex and from -5.49% to 30.64% for the Upper Ice Complex. Since nitrogen is more soluble in water than argon, this might indicate that ice wedges may have formed without a major contribution of snowmelt but mainly by dry snow compaction, which is also supported by the spherical shape of gas bubbles within the wedge ice. Furthermore, in ice the argon permeation coefficient is higher than that of nitrogen. Thus, high d(N2/Ar) values (>10%) are due to argon's diffusion through ice. Our future research will focus on deciphering the biogeochemical process of greenhouse gas formation for both ice complexes by comparison with ice wedges from other Siberian locations which have experienced different biogeochemical conditions in the past. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3437

2022041644 Pavoni, Mirko (Universita di Padova, Department of Geosciences, Padua, Italy); Boaga, Jacopo; Wagner, Florian; Bast, Alexander and Phillips, Marcia. Combined use of structurally-coupled and petrophysically-coupled joint inversion for the characterization of rock glaciers [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5861, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The monitoring of alpine rock glaciers has both scientific and economic relevance. The degradation of mountain permafrost is a relevant proxy of climate change and global warming, but also a possible source of hazards for mountain communities since it can trigger natural processes such as rockfalls, debris flows, and floods. Geophysical techniques have been used to study these periglacial forms, particularly electrical and seismic refraction methods. Nevertheless, the independent data processing applied to these measurements does not lead to quantitative estimation of the physical components (air, water, ice, and rock) in the frozen subsoil. Moreover, the structural interpretation of the ground with independent resistivity and seismic sections can introduce ambiguities. To quantify the composition of the mountain permafrost, Wagner et al. (2019) developed a petrophysical joint inversion approach of electrical resistivity and seismic refraction datasets. We applied this method to several datasets collected in the rock glaciers of Schafberg (Engadin, Switzerland) and Ritigraben (Canton of Valais, Switzerland). To estimate the parameters in Archie's and Timur's laws, we performed the petrophysical joint inversion with a range of plausible values, selecting the ones that guaranteed the lowest final root-mean-square (RMS) error between the model response and the observed data. Our approach can be applied wherever information from boreholes is unavailable. This is a common situation in rock glacier studies since drilling in high mountain environments is very complicated and expensive. Finally, to improve the quality of individual resistivity and seismic velocity sections, we applied the structurally-coupled cooperative joint inversion method to our datasets, developed by Gunther and Rucker (2008). This approach is based on the exchange of structural information between the independent geophysical inversions of electrical and seismic datasets. The process is driven by 3 different coupling parameters and the choice of their values has been done again by running the inversion with a range of values, choosing those that guaranteed the lowest final RMS. This method can be useful to better define the active layer thickness and the lower boundary of frozen ground. From the obtained results, it is clear that combined use of petrophysically-coupled and structurally-coupled joint inversion can represent a significant improvement for the characterization of mountain permafrost, in comparison to the traditional independent geophysical inversions, even in the absence of prior information from boreholes. In future studies, both structural and petrophysical coupling could be incorporated into a single inversion framework to adaptively allow structural agreement if quantitative petrophysical agreement cannot be satisfied. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5861

2022041606 Popescu, Razvan-Andrei (University of Bucharest, Faculty of Geography, Bucharest, Romania); Vespremeanu-Stroe, Alfred; Vasile, Mirela; Calisevici, Sabina and Andrian, Ilie. Core drilling in a low altitude permafrost site from temperate regions; case study, Detunata Goala, Romanian Carpathians [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-3193, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Detunata Goala scree is a talus slope-rock glacier system characterized by persistent snow and ice during springtime and summer in spite of a mean annual air temperature of around +7°C. This is a porous talus made of andesitic basaltic columns affected by chimney circulation that seems to allow for a extrazonal permafrost of low altitude in a temperate climate much lower than the regional limit of alpine permafrost. In the postdoctoral project FrozenCORE electrical resistivity tomography (ERT) and seismic refraction tomography (SRT) were applied in October 2020 in order to check permafrost presence at the end of the warm season and to determine the internal structure of the deposit. The two methods indicated contradictory results, as ERT indicated a high resistive layer in the first 10-15 m while the SRT indicated a high velocity layer at depths greater than 15 m. A borehole was drilled in June 2021 in the coldest sector of the scree and the cores recovered indicated that: 1) the talus is relatively thin, less than 13 m; 2) the deposit has a low amount of ice, several lenses were found between 3 and 10 m each of at most a few centimeters thick; 3) the scree porosity is relatively low, much smaller than at the surface. A thermistor chain was installed in the borehole at depths according to the GTN-P recommendations for future monitoring of the temperatures in the underground. Ice samples were collected from the cores for isotopic analyses in order to check if the ice from the greater depths is older than the upper one assumed to be seasonal. The drilling indicated that ERT is a better method for assessing the stratigraphy of such talus deposits. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-3193

2022041591 Sabova, Zuzana (Slovak University of Technology, Bratislava, Slovakia); Tomascik, Matus; Nemetova, Zuzana; Kohnova, Silvia; Krajewski, Adam and Banasik, Kazimierz. The role of intense rainfall events on the land degradation processes in the Slovak and Polish catchments [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2306, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Land degradation caused by anthropogenic activities (deforestation, overgrazing, unsuitable land-use and management practices) negatively influence the well-being of people and also accelerates soil erosion processes. The main evidence for a link between soil degradation and water erosion can be seen in the following elements: increasing rainfall intensity, permafrost thawing, biomass production, tillage, cultivation overgrazing, deforestation/ vegetation clearing, vegetation burning, poorly designed roads and paths to a global extent. Therefore, it is significant to investigate degradation processes in order to point out the possible adverse effects of unsuitable management practices of the landscape in the scale of past and future periods. A future prediction of the development of any processes requires long-term investigation and analysis of the phenomenon predetermined to assess future behaviour. On the contrary, analysis of past processes shows us precipitation patterns and reveals their effect on the generation of degradation processes. The study describes the role of rainfall events on a generation of erosion processes, especially soil water erosion in the catchments located in Poland (Zagozdzonka) and Slovakia (Svacenicky Jarok). A common characteristic of these catchments is the susceptibility to degradation processes, the predominance of arable land and the dominant agricultural use of catchments. In the case of Zagozdzonka catchment (Poland) the modelling period covers the years 1963-2020 with the real measured rainfall events. On the contrary, in the case of Svacenicky jarok the future development of degradation processes was analyzed based on the future prediction of rainfall events covering the period 2020-2100 and generated by CLM model (Climate Land Model). In both cases, the simulations were performed using the physically-based EROSION-3D model and three scenarios were created in order to model different land cover, land use, soil types and crops on agricultural land. The first scenario reflects current catchment conditions, the second reflects the best conditions (more forests, fewer pastures and unprotected land) and the third involves worst-case conditions (no protective measures or changes of inappropriate management practices). The results provide insight into the development of degradation processes, illustrate how changes in rainfall patterns affect soil degradation processes in the past and future and take into account different scenarios of management practices together with an analysis of the impact of rainfall events on these processes. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2306

2022041655 Safsari, Shaghayegh Akbarpour (University of Waterloo, Department of Civil and Environmental Engineering, Waterloo, ON, Canada) and Craig, James. A machine-learning model to predict uncertainty in permafrost thaw-induced land cover transition [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6665, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

This study addresses the effects of future climate-induced permafrost thaw on the distribution of land cover in the discontinuous permafrost zones of Northwest Territories (NWT) of Canada. The rapid transition from a landscape dominated by peat plateaus to one dominated by connected wetlands (fens) and isolated wetlands (bogs) is intricately connected to permafrost thaw. To be able to predict and estimate the potential long-term evolution of these three dominant land covers, we developed a machine learning-based time series land cover change model (TSLCM). The TSLCM is trained on a set of spatio-temporal variables as driving factors of change including: the estimated summertime land surface temperature anomaly (LST), the distance to land cover interfaces, time intervals between observations, time-accumulated land surface temperature, and classified land cover maps from 1970-2008. The TSLCM is used to capture spatial patterns of change, replicate historical land cover change, and generate reasonable estimates of future land cover evolution over time. The output of TSLCM model is the spatial distribution of fen, bogs, and peat plateaus consistent with a default 50% threshold applied on the predicted probability maps. We here use the TSLCM to simulate land cover change under multiple plausible futures scenarios by using the most recent set of climate model projections. The simulation of the TSLCM under different scenarios helps us to: visualize the spatial pattern of change calculate the pace of evolution over time and compare results between climate scenarios explore the sensitivity of the model to driving factors of change In addition to examining uncertainty due to climate uncertainty, a probabilistic approach is used to sample the threshold value to generate a range of land cover realizations. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6665

2022041639 Scheel, Maria (University of Aarhus, Department of Ecoscience, Aarhus, Denmark); Zervas, Athanasios; Jacobsen, Carsten Suhr and Christensen, Torben Rojle. Should I grow or should I go? Transcriptomic responses of permafrost soil microbiomes to sudden thaw and erosion [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5516, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost soils usually remain frozen in summer, often even for millennia. Due to low temperatures, decomposition rates are low and alone Arctic permafrost is estimated to store 1850 Gt carbon (C). This currently corresponds to about twice the amount of atmospheric CO2. While microorganisms within their seasonally thawing surface (active) layer are adapted to enormous temperature fluctuations, the intact permafrost microbiome contains spore-formers and extremophiles at low metabolic states. With global warming, seasonal thaw depth increases, not only leading to loss of ancient communities, but also to a growing availability of soil carbon for decomposition. Much of permafrost microbial taxonomic and metabolic diversity is unknown still, but our most urgent gaps of knowledge exist in monitoring this vulnerable microbiome's ecological and metabolic adaptation in situ during permafrost thaw and erosion. Insights about microbial carbon sequestration in thawing soils is crucial - yet understudied, as permafrost environments are usually remote and modern sequencing techniques require elaborate sample storage and transport. Here, we present our results of total RNA sequencing of abruptly eroding as well as intact 26200-year-old permafrost soils, from the high Arctic Northeast Greenland. Gene expression of samples describes the community composition (rRNA) and active metabolic pathways (mRNA) in zones of intensely degrading permafrost. The impact of changing physicochemical soil parameters with depth, such as pH, age, soil moisture and organic matter content was compared to determine possible metabolic and community-level responses. We revealed taxonomic composition and diversity, as well as metabolic pathways of microbial organic carbon remineralization especially at the crucial freshly thawed permafrost depths. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5516

2022041600 Schiedung, Marcus (Universität Zürich, Department of Geography, Zurich, Switzerland); Bellè, Severin-Luca and Abiven, Samuel. Fate of pyrogenic and organic matter in permafrost-affected soils; a two years in-situ incubation [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2733, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost-affected mineral soils store large amounts of the soil organic matter (SOM) in high-latitude regions. These regions are large terrestrial carbon reservoirs and highly vulnerable to the global climate change. Global warming will cause rapid permafrost thaw and potentially accelerate decomposition of SOM. High-latitude regions, such as boreal and arctic ecozones, are regularly affected by wildfires with increasing intensity and frequency caused by global climate change. Wildfires produce pyrogenic organic matter (PyOM) during incomplete combustion of the fuel biomass. Little is known about the cycling of SOM and especially PyOM in permafrost-affected mineral soils, which limits our understanding of potential shifts in cycling and interaction with the soil mineral phase over time. Here we study the fate of highly 13C-labelled (2-3 atm%) ryegrass organic matter and PyOM from the same feedstock (pyrolyzed at 400°C for 4h) during two years of in-situ incubation in boreal forest mineral soils. Soil cores (10 cm length and 6 cm diameter) were buried in the upper 10 cm of mineral soils under continuous and discontinuous to sporadic permafrost conditions at eleven forest locations (with six replicates) in Northern Canada. At the same locations, litter bags (green and rooibos teabags) were buried and soil temperatures were recorded. The soils cores were separated in three depth (0-3, 3-6 and 6-10 cm) to trace the vertical allocation of the applied organic matter. Density and particle fractionations are applied to identify mineral interactions of the ryegrass and pyrolyzed organic matter. Preliminary d13C results from the soil cores show a more extensive vertical allocation of ryegrass organic matter and PyOM in continuous permafrost-affected soils within the cores. This can be associated to the importance of freeze and thaw cycles for the carbon dynamics of permafrost-affected mineral soils. Tracing the labelled ryegrass organic matter and PyOM offers not only the opportunity to quantify the translocated fraction but also the decomposed proportion of the freshly added organic matter and thus understand short-term carbon dynamics. Preliminary results from the litter bags indicate a larger mass loss of slow cycling woody organic matter (rooibos tea) in discontinuous to sporadic permafrost-affected mineral soils, while larger mass losses of fast cycling organic matter (green tea) were observed in continuous permafrost-affected soils. These initial results indicate a complex cycling of organic matter in soils under different permafrost conditions. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2733

2022041635 Scholten, Rebecca Christine (Vrije Universiteit Amsterdam, Department of Earth Sciences, Amsterdam, Netherlands); Chen, Yang; Randerson, James T. and Veraverbeke, Sander S. N. Development of an arctic-boreal fire atlas using visible infrared imaging radiometer suite active fire data [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4922, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Intensifying wildfires in high-latitude forest and tundra ecosystems are a major source of greenhouse gas emissions, releasing carbon through direct combustion and long-term degradation of permafrost soils and peatlands. Several remotely sensed burned area and active fire products have been developed, yet these do not provide information about the ignitions, growth and size of individual fires. Such object-based fire data is urgently needed to disentangle different anthropogenic and bioclimatic drivers of fire ignition and spread. This knowledge is required to better understand contemporary arctic-boreal fire regimes and to constrain models that predict changes in future arctic-boreal fire regimes. Here, we developed an object-based fire tracking system to map the evolution of arctic-boreal fires at a sub-daily scale. Our approach harnesses the improved spatial resolution of 375 m Visible Infrared Imaging Radiometer Suite (VIIRS) active fire detections. The arctic-boreal fire atlas includes ignitions and daily perimeters of individual fires between 2012 and 2021, and may be complemented in the future with information on waterbodies, unburned islands, fuel types and fire severity within fire perimeters. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4922

2022041631 Sidle, Roy C. (University of Central Asia, Mountain Societies Research Institute, Khorog, Tajikistan); Caiserman, Arnaud; Salazar, Alvaro and Khojazoda, Zulfiqor T. Water towers of the Pamirs; II, Cryosphere dynamics and implications for runoff and livelihoods [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4705, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Cryosphere components in the Pamirs play an important role in the release of water to the Vakhsh and Panj river systems where both mountain and downstream communities rely on sustainable water supplies for their agriculture, potable water, and hydropower. Of the three primary cryosphere sources of water (glacial, snow, and permafrost melt), glacial melt is the most predictable and constitutes and intermediate supply of runoff to streams, while almost no estimates of permafrost contributions are available. Snowmelt is highly variable from year to year and because it is the largest water supply to these rivers, understanding the potential amount and timing of snowmelt is critical for local communities. Based on our remote sensing investigations during the past 20 years, we water found wide interannual variations in snow water, snowline elevation, and snow persistence throughout the Vakhsh and Paji basins, but no clear evidence of basin-wide climate change trends. Specific locations of the central Pamirs appear to be shifting from snow to rain due to climate warming, approximately offsetting each other, but likely producing more runoff in late spring to early summer and less in mid to late summer. In the high, glaciated Vakhsh basin, temperature increases have been offset by higher snowfall, resulting in little glacial ice change. By overlaying maps of glaciers on a digital elevation model (Alos Palsar 12.5 m) containing stream networks, we estimated that about 75% of the glaciers were closely connected to first-order or larger channels; however, this may be a liberal estimate because some first-order streams are not connected to major river systems. Based on the TTOP model nearly 24,000 km2 of continuous permafrost terrain exists throughout the Panj and Vakhsh basins, the majority of which is located at elevations >3577 m. Streamflow contributions from permafrost thaw during the summer were estimated as subsurface flux from streambanks; ~638´106 m3 each summer, which represents about 1.5% of the average annual river discharge for both basins. The climate variability and localized changes we observed pose challenges for predicting runoff from high elevation cold regions due to the altered patterns of the timing of snow, glacier, and permafrost accumulation and melt, including temporal changes, interannual variability, and hydrological connectivity of sources. The various water sources will respond differently in a changing climate, generating complex runoff scenarios and socioeconomic consequences downstream. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4705

2022041627 Sjogersten, Sofie; Bautista, Betsabe de la Barreda; Boyd, Doreen; Ledger, Martha; Siewert, Matthias; Chandler, Chris; Bradley, Andrew; Gee, David; Large, David; Olofsson, Johan and Sowter, AndrewTowards a monitoring approach for understanding permafrost degradation and linked subsidence in Arctic peatlands [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4644, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost thaw resulting from climate warming is threatening to release carbon from high latitude peatlands. The aim of this research was to determine subsidence rates linked to permafrost thaw in sub-Arctic peatlands in Sweden using historical orthophotographic (orthophotos), Unoccupied Aerial Vehicle (UAV) and Interferometric Synthetic Aperture Radar (InSAR) data. The orthophotos showed that the permafrost palsa on the study sites have been contracting in their areal extent, with the greatest rates of loss between 2002-2008. The surface motion estimated from differential digital elevation models from the UAV data showed high levels of subsidence (maximum of -25 cm between 2017-2020) around the edges of the raised palsa plateaus. The InSAR data analysis showed that raised palsa areas had the greatest subsidence rates with maximum subsidence rates of 1.5 cm between 2017-2020, however, all wetland vegetation types showed subsidence. We suggest that the difference in spatial units associated with each sensor explains parts of the variation in subsidence levels recorded. We conclude that InSAR was able to identify areas most at risk of subsidence and that it can be used to investigate subsidence over large spatial extents, whereas UAV data can be used to better understand dynamics of permafrost degradation at a local-level. These findings underpin a monitoring approach for these peatlands.

DOI: 10.5194/egusphere-egu22-4644

2022041574 Stadelmaier, Kim Helen (Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Karlsruhe, Germany); Ludwig, Patrick; Bertran, Pascal; Antoine, Pierre; Shi, Xiaoxu; Lohmann, Gerrit and Pinto, Joaquim G. A new perspective on permafrost boundaries in France during the last glacial maximum [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-766, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

During the Last Glacial Maximum (LGM), a very cold and dry period around 26.5-19 kyr BP, permafrost was widespread across Europe. In this work, we explore the possible benefit of using regional climate model data to improve the permafrost representation in France, decipher how the atmospheric circulation affects the permafrost boundaries in the models, and test the role of ground thermal contraction cracking in wedge development during the LGM. With these aims, criteria for possible thermal contraction cracking of the ground are applied to climate model data for the first time. Our results show that the permafrost extent and ground cracking regions deviate from proxy evidence when the simulated large-scale circulation in both global and regional climate models favours prevailing westerly winds. A colder and, with regard to proxy data, more realistic version of the LGM climate is achieved given more frequent easterly winds conditions. Given the appropriate forcing, an added value of the regional climate model simulation can be achieved in representing permafrost and ground thermal contraction cracking. Furthermore, the model data provide evidence that thermal contraction cracking occurred in Europe during the LGM in a wide latitudinal band south of the probable permafrost border, in agreement with field data analysis. This enables the reconsideration of the role of sand-wedge casts to identify past permafrost regions. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-766

2022041604 Stammler, Melanie A. (Rheinische Friedrich-Wilhelms-Universität Bonn, Department of Geography, Bonn, Germany); Ortiz, Diana A.; Koehler, Tamara and Schrott, Lothar. Andean permafrost in taluses and blockslopes in the Agua Negra catchment, Argentina; distribution and hydrological significance [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2889, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Extensive areas in mountain regions are under permafrost conditions with periglacial processes in the arid Andes of Argentina being mostly associated with high mountain permafrost. The most visible expression of creeping mountain permafrost within the periglacial altitudinal belt (between 35° and 27°S), is the occurrence of rock glaciers. Beside snow and ice melting, active layer thawing and degrading permafrost contribute to river runoff; an essential resource in the arid Andes and their forelands. Halla et al. (2021) calculated for the first time rock glacier ice content using geophysical methods and four-phase modeling. Besides rock glaciers, taluses (including protalus ramparts) and blockslopes are widespread above an altitude of 4000 m a.s.l., with a first quantitative assessment revealing a surface coverage of about 73 %. We hypothesize that beside rock glaciers, taluses and blockslopes present a high potential for ice content, having a comparable or even more significant importance as valuable water reserves. However, taluses and blockslopes have not yet been properly investigated and little research has focused on the permafrost distribution and stratigraphy of these landforms. This study determines the characteristics and the influence of climatic, topographical, and lithological conditions on the permafrost, using a multi-method approach: Electrical Resistivity Tomography (ERT), Seismic Refraction Tomography (SRT), hydrological monitoring along the course of Agua Negra river (discharge, water sampling), and UAV-, as well as spaceborne remote sensing analysis. While the use of ERT is beneficial due to the contrasting electrical resistivities of lithological media, water and ice, SRT complements the data with detailed p-wave based information on the upper layer. Hydrological monitoring aids in distinguishing different water resources and in estimating their contributions to runoff. In addition, the repeated application of remote sensing techniques allows for an acquisition of high resolution digital elevation models with models of difference providing insight in the magnitude, timing and spatial pattern of vertical and horizontal surface changes. The possibility of determining with greater precision the distribution of permafrost in the arid Andes will lead to a more accurate estimation of solid-state water reserves stored in periglacial landforms in arid Andean catchments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2889

2022041648 Steinert, Norman Julius (Universidad Complutense de Madrid, Department of Earth Physics and Astrophysics, Madrid, Spain); González-Rouco, Jésus Fidel; de Vrese, Philipp; Garcia-Bustamante, Elena; Hagemann, Stefan; Jungclaus, Johann; Lorenz, Stephan; Brovkin, Victor; Melo-Aguilar, Camilo Andres; Garcia-Pereira, Félix and Navarro, Jorge. Modified soil hydro-thermodynamics cause large spread in projections of arctic and subarctic climate [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-6020, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The representation of the terrestrial thermal and hydrological states in current-generation climate models is crucial to have a realistic simulation of the subsurface physical processes and land-atmosphere coupling. This is particularly important for high-latitude permafrost regions since these areas are prone to the release of substantial amounts of carbon from degrading permafrost under climate-change conditions. Many current-generation climate models still have deficiencies in the representation of terrestrial structure and physical mechanisms, such as too shallow land depth or insufficient hydro-thermodynamic coupling. We therefore introduce a deeper bottom boundary into the JSBACH land surface model. The associated changes in the simulated terrestrial thermal state influence the near-surface hydroclimate when sufficient coupling between the thermodynamic and hydrological regimes is present. Hence, we also assess the influence of introducing various physical modifications for the representation of soil hydro-thermodynamic processes in climate projections of the 21st century. The results show significant impacts on terrestrial energy uptake, as well as changes in global near-surface ground temperatures when introducing the physical modifications. The resulting simulation of high-latitude permafrost extent is subject to large variations depending on the model configuration, reflecting the uncertainty of carbon release from permafrost degradation. We further use the modified model to assess the sensitivity of simulated high-latitude climate dynamics to different hydrological configurations in the coupled MPI-ESM. The differences in soil hydrological representation in permafrost regions could explain a large part of CMIP6 inter-model spread in simulated Arctic climate, with remote effects on subarctic dynamical systems. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-6020

2022041586 Stoffel, Markus (Université de Genève, Institute for Environmental Sciences, Geneva, Switzerland); Corona, Christophe and Ballesteros, Juan. Climate warming enhances rockfall activity from permafrost environments, but rockfall risk increases primarily due to larger exposure and vulnerability [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-2010, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Rockfall in high mountains is perceived to change more than other mass-wasting processes, presumably as a result of ongoing climate warming and the related, increasing degradation of permafrost. However, the systematic lack of longer-term observational records of rockfall largely hampers any in-depth assessment of how process activity may have been altered by a warming climate and its variability since pre-industrial times. Here, we present evidence that the ongoing climate warming in the Swiss Alps indeed controls rockfall activity from degrading permafrost, and that changes in rockfall frequency correlate significantly with warming air temperature since the 1880s. Using this dataset, we then look into rockfall risk by combining changes in process activity with socio-economic developments at the study site. We illustrate how rockfall risk has changed over the past 140 years and how it might change over the course of the 21st century. While more rockfall and larger volumes occur nowadays as compared to the early 20th century, rockfall risk has increased mostly due to changes in exposure and vulberability and only partly due to changes in process activity itself. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-2010

2022041647 Thompson, Lauren (University of Alberta, Edmonton, AB, Canada); Shewan, Renae; Harris, Lorna; Mangal, Vaughn and Olefeldt, David. Methylmercury in thawing peatlands on a trophic gradient in boreal Western Canada [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-5986, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Ongoing permafrost thaw in the extensive peatlands of boreal western Canada may mobilize previously frozen mercury (Hg) and result in enhanced production of the neurotoxin methylmercury (MeHg). The often waterlogged conditions in thermokarst wetlands may represent ideal environments for Hg methylation to MeHg, but methylation potential could vary across distinct wetland types (i.e., nutrient-poor bogs and nutrient-rich fens) that emerge after the thawing of drier peat plateaus, depending on landscape position and groundwater connectivity. Here, we examined MeHg concentrations in twelve wetlands of varying nutrient richness in the Taiga Plains of western Canada across a 500 km permafrost gradient. We analyzed peat porewater chemistry (Hg, MeHg, dissolved organic matter composition), inferred the degree of groundwater connection (electrical conductivity, ions), and assessed the vegetation composition at each wetland. The key research objectives of this study were to 1) determine how methylmercury concentrations vary amongst wetland types in the Taiga Plains and amongst permafrost zones, and 2) understand how physicochemical characteristics and groundwater connectivity may influence methylation potential. Through this, we hope to understand the factors that lead to hotspots of MeHg production in the rapidly thawing peatlands of the Taiga Plains. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-5986

2022041623 Toechterle, Paul (University of Innsbruck, Institute of Geology, Innsbruck, Austria); Edwards, R. Lawrence; Gunn, John; Atkinson, Tim; Murton, Julian B.; Luetscher, Marc and Moseley, Gina E. Permafrost evolution on the British Isles during the last deglaciation [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4293, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Globally, near-surface permafrost is likely to warm, thin or disappear in many areas subject to future climate warming and wetting, creating a positive atmospheric feedback where the permafrost is rich in carbon. Unfortunately, substantial uncertainty exists as to the extent and timing of thawing in response to atmospheric forcing. Cryogenic cave carbonates (CCCs), a recently described type of speleothem, precipitate when cave ice forms and thus provide opportunities to constrain periods when permafrost was present at a given cave site. Here, we present a unique dataset comprising 38 230Th/U ages of CCCs from two caves in the Mendips, southwest England (51°N), and two caves in the Peak District, central England (53°N), all of which are currently ice-free. Whilst many ages are clean, reliable and high precision, the accuracy of those containing initial 230Th is improved greatly by constructing isochrons and applying further statistical methods. The ages of CCCs reveal two distinct periods of isothermal permafrost conditions, peaking during i) the early Bolling-Allerod interstadial at approximately 14,463±145 yBP* and ii) the late Younger Dryas around 11,719±229 yBP. Such isothermal conditions (i.e., where values of mean annual ground temperature are commonly a fraction of a degree below 0°C and exist through much of the depth profile of permafrost) are thought to represent the later stages of permafrost warming prior to its disappearance. We attribute this isothermal, disequilibrium permafrost evolution during the last deglaciation of the British-Irish Ice Sheet to climatic variations linked to North Atlantic sea-ice extent and seasonality. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4293

2022041630 van Gerrevink, Max J. (Vrije Universiteit Amsterdam, Amsterdam, Netherlands); Veraverbeke, Sander N. N.; Cooperdock, Sol; Potter, Stefano; Moubarak, Michael; Goetz, Scott J.; Mack, Michelle C.; Randerson, James T.; Turetsky, Merritt R. and Rogers, Brendan M. Integrated climate radiative forcing from arctic-boreal fires [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4696, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Fire is a major disturbance mechanism in arctic-boreal ecosystems and results in warming and cooling feedbacks to the climate system. Greenhouse gas emissions from fires are a major positive feedback, yet post-fire carbon sequestration in recovering ecosystems partly offsets this. In addition, fire removes part of the organic soil layer and may result in permafrost thaw and consequent greenhouse gas emissions. Yet, fire-induced changes in ecosystem structures result in a larger spring-time snow cover compared to unburned areas, and this imposes a negative climate feedback through increased surface albedo. These various climate forcings are spatially and temporally heterogeneous and depend on various landscape components and fire regime characteristics. Understanding the net climate forcing effect is crucial in managing and mitigating climate change impacts on carbon cycling. We applied the concept of radiative forcing in a quantitative spatial assessment of the net climate feedbacks induced by arctic-boreal North American fires. We capitalize upon the state-of-the-art carbon combustion estimates by the Arctic Boreal Vulnerability Experiment Fire Emissions Database (ABoVE-FED) and a novel climate forcing framework to predict fire-driven changes in net forcing under historical and future climate scenarios. In our analyses we incorporated all fires between 2001 and 2019, evaluating the net fire-induced forcing over the regrowth successional phase (at 20-years after fire) and after full succession (at 80-years after fire). Our results highlight the spatial and temporal heterogeneity in climate forcings from arctic-boreal fires, and in future work we plan to characterize spatiotemporal patterns of the net climate feedback. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4696

2022041625 Verhoef, Anne (University of Reading, Department of Geography and Environmental Science, Reading, United Kingdom); Zeng, Yijian; Cuntz, Matthias; Gudmundsson, Lukas; Thober, Stephan; McGuire, Patrick C.; Bergner, Hannah; Boone, Aaron; Ducharne, Agnès; Ellis, Rich; Kim, Hyungjun; Koirala, Sujan; Lawrence, Dave; Oleson, Keith; Swenson, Sean; Tafasca, Salma; de Vrese, Philipp; Seneviratne, Sonia; Or, Dani and Vereecken, Harry. Assessing the variability of soil temperatures in Land Surface Models using outputs from the Soil Parameter Model Intercomparison Project (SP-MIP) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4349, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Results: Soil temperature is a crucial variable in Land Surface Models (LSMs) because it affects the fractions of frozen and unfrozen water content in the soil. For example, getting the coupling between below-ground heat- and water transfer correct in LSMs is very important in permafrost regions because these are particularly sensitive to climate change. Poor predictions of the energy-and water balance in these regions will lead to large uncertainties in predicted carbon fluxes, and related land-atmosphere feedbacks. Also, simulated near-surface soil temperatures can be used to diagnose and explain model differences in skin temperatures and soil heat fluxes, both of which are pivotal in the prediction of the surface energy balance. Soil temperature is generally under-researched as part of LSM intercomparisons. Here we present an analysis of the spatial distribution (including the vertical distribution along the soil profile) and seasonal evolution of soil temperature simulated by eight LSMs as part of the Soil Parameter Model Intercomparison Project (SP-MIP). We found large inter-model differences in key metrics of the annual soil temperature wave, including the amplitude, phase shift and damping depth, which were partly attributed to diversity in hydraulic as well as thermal soil properties. Soil layer discretisation also played a role. Methods: Via manipulation of model soil hydraulic properties, and the soil texture inputs required to calculate these properties, controlled multi-model experiments have been conducted as part of SP-MIP, this MIP was originally proposed at the GEWEX-SoilWat workshop held in Leipzig (June 2016). The model experiments closely followed the LS3MIP protocol (van den Hurk et al. 2016). Eight land models (CLM5, ISBA, JSBACH, JULES, MATSIRO, MATSIRO-GW, NOAH-MP and ORCHIDEE) were run globally on 0.5° with GSWP3 forcing, from 1980-2010, for vertically homogeneous soil columns. There were 4 model experiments, leading to 7 model runs: Experiment 1. Global soil hydraulic parameter maps provided by SP-MIP; Experiment 2. Soil-hydraulic parameters derived from common soil textural properties, provided by SP-MIP, using model-specific pedotransfer functions (PTFs); Experiment 3. Reference run with all models applying their default soil hydraulic settings (including their own soil maps to derive the parameters); Experiment 4: four runs using spatially uniform soil hydraulic parameters for the whole globe (loamy sand, loam, clay and silt) provided by SP-MIP. Differences between the model experiments will allow the assessment of the inter-model variability that is introduced by the different stages of preparing model parameters. Soil parameters for Experiments 1 and soil textures for Experiment 2 at 0.5° resolution were prepared from dominant soil classes of the 0-5 cm layer of SoilGrids (Hengl et al. 2014) at 5 km resolution. Brooks and Corey hydraulic parameters come from Table 2 of Clapp and Hornberger (1978), Mualem-Van Genuchten hydraulic parameters are ROSETTA class average hydraulic parameters (Schaap et al. 2001), and soil textures are from Table 2 of Cosby et al. (1984). Experiments 4 a-d use the USDA soil classes, using the same PTFs for Brooks and Corey and Mualem-van Genuchten parameters as in Experiment 1. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4349

2022041619 Villani, Maëlle (Université Catholique de Louvain, Earth and Life Institute, Louvain-la-Neuve, Belgium); Mauclet, Elisabeth; Agnan, Yannick; Druel, Arsène; Jasinski, Briana; Taylor, Meghan; Schuur, Edward A. G. and Opfergelt, Sophie. Does vegetation shift in Arctic tundra upon permafrost degradation influence mineral element recycling in the topsoil? [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4024, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Climate change affects the Arctic and Subarctic regions by exposing previously frozen permafrost to thaw, unlocking nutrients, changing hydrological processes, and boosting plant growth. As a result, Arctic tundra is subject to a shrub expansion, called "shrubification" at the expense of sedge species. Depending on intrinsic foliar properties of these plant species, changes in foliar fluxes with shrubification in the context of permafrost degradation may influence topsoil mineral element composition. Despite the potential implications for the fate of organic carbon in the topsoil, this remains poorly quantified. Here, we investigate vegetation foliar and topsoil mineral element composition (mineral elements that influence organic carbon decomposition: Si, K, Ca, P, Mn, Zn, Cu, Mo and V) from a typical Arctic tundra at Eight Mile Lake (Alaska, USA) across a natural gradient of permafrost degradation. Results show that foliar element concentrations are higher (up to 9 times; Si, K, Mo, and for some species Zn) or lower (up to 2 times; Ca, P, Mn, Cu, V, and for some species Zn) in sedge than in shrub species. This induces different foliar flux with permafrost degradation and shrubification. As a result, a vegetation shift over ~40 years from sedges to shrubs has resulted in lower topsoil concentrations in Si, K, Zn and Mo (respectively of 52, 24, 20 and 51%) in poorly degraded permafrost sites compared to highly degraded permafrost sites. For other mineral elements (Ca, P, Mn, Cu and V), the vegetation shift has not induced a marked changed in topsoil concentrations at this stage of permafrost degradation. This observed change in topsoil composition involving beneficial or toxic elements for decomposers is likely to influence organic carbon decomposition. These data can serve as a first estimate to assess the influence of other shifts in vegetation in Arctic tundra such as sedge expansion with wildfires. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4024

2022041624 Wittig, Sophie (CNRS, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France); Berchet, Antoine; Paris, Jean-Daniel; Saunois, Marielle; Arshinov, Mikhail; Machida, Toshinobu; Sasakawa, Motoki; Worthy, Doug and Pison, Isabelle. Evaluating methane emissions between 2008 and 2019 in high northern latitudes by using inverse modeling [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4297, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Arctic is particularly sensitive to global warming and the effects of the increasing temperatures can already be detected in this region by occurring events such as thawing permafrost and decreasing Arctic sea ice area. One of the possible consequences is the risk of enhanced regional greenhouse gas emissions such as methane (CH4) due to the exposure of large terrestrial carbon pools or subsea permafrost which have previously been shielded by ice and frozen soil. Various sources, both natural and anthropogenic, are presently emitting methane in the Arctic. Natural sources include wetlands and other freshwater biomes, as well as the ocean and biomass burning. Despite the relatively small population in this region, CH4 emissions due to human activities are also significant. The main anthropogenic sources are the extraction and distribution of fossil fuels in the Arctic nations and, to a lesser extent, livestock activities and waste management. However, assessing the amount of CH4 emissions in the Arctic and their contribution to the global budget still remains challenging due to the difficulties in carrying out accurate measurements in such remote areas. Besides, high variations in the spatial distribution of methane sources and a poor understanding of the effects of ongoing changes in carbon decomposition, vegetation and hydrology also complicate the assessment. Therefore, the aim of this work is to reduce uncertainties on methane emissions in high northern latitudes. In order to achieve that, an inverse modeling approach has been implemented by using observational data sets of CH4 concentrations obtained at 42 surface stations located in different Arctic regions for the period from 2008 to 2019, the atmospheric transport model FLEXPART, as well as available bottom-up estimates of methane emissions provided by process-based surface models and CH4 emission inventories. The results have been analysed with regards to seasonal and inter-annual fluctuations, spatial differences and trends over the period of study. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4297

2022041570 Zemlianskova, Anastasiia (Saint Petersburg State University, St. Petersburg, Russian Federation); Alexeev, Vladimir; Makarieva, Olga; Nesterova, Nataliia; Shikhov, Andrey and Ostashov, Andrey. Temporal dynamics of the giant Anmangynda aufeis characteristics in changing climate, 1962-2021 (north-eastern Eurasia) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-300, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Significant changes are observed in the water exchange system of the North-Eastern Eurasia which still is the remote and poorly studied region of the cryosphere. Aufeis which are well recognized from the space may serve as the indicators of such changes. Aufeis are the ice sheets formed in permafrost environment due to the layer-by-layer freezing of discharged underground or surface water, their size may reach tenths of square kilometers. The primary goal of this study is to assess the changes in the dynamics of the characteristics (area and volume) of the giant Anmangynda aufeis based on historical and modern observational data. It is located in the zone of mountainous continuous permafrost of the Magadan region of Russia and was extensively studied in 1962-1992. We combined and analyzed the data of historical materials (1962-1992) with recent data from Landsat and Sentinel images (2000-2020) and our own ground-based observations on the perennial and annual dynamics of aufeis area (2020-2021). Aufeis volume was measured in 1962-1992 and in 2020-2021, but for the period of 2000-2019 the values were estimated based on the regional formula developed by [Sokolov, Sarkysyan, 1981]. Maximum area of aufeis reached 6.6 km2 (about 1.6% of the basin area) in 1967. According to the data of 1969 its volume may grow up to 15.7 million m3. The greatest amplitude of fluctuations in the size of the aufeis (up to 30% of the average long-term value) was observed in the period up to 1976, then it did not exceed 10-15%. The smallest sizes of aufeis were 4.1 km2 and 5.3 million m3 in 1974, 4.3 km2 and 6.4 million m3 in 1990. Thus, over the thirty-year period of observations, the volume of aufeis has halved. In the recent period, according to satellite data, these values reached the maximum of 5.8 km2 and 12.4 million m3 (2002). The lowest values were 2 times lower than the historical ones (1.9 km2 and 3.6 million m3, 2014). Now, to study the dynamics of aufeis area and volume, the authors have been using UAV shooting. The thickness of the ice is determined by measuring the height of the surface at different periods of the aufeis development. In 2021, the maximum ice thickness reached 4.4 m, and the historical maximum was 8 m. The intra-annual dynamics of aufeis has also changed. Now the aufeis gets melted completely by August-September, and in the earlier periods the part of the ice sheet (about 4% of its maximum area) remained and was included in the formation of aufeis for the next year. According to natural and climatic conditions, the river basin in which the Anmangynda aufeis is formed is representative for the mountainous landscapes of the North-Eastern Eurasia. Comprehensive interdisciplinary observations at this site are important to characterize the impact of climate change on natural processes in this region. The study was carried out with the support of RFBR (19-55-80028, 20-05-00666), Russian Geographical Society (project 07/2021-I (continue)) and St. Petersburg State University (project 75295776). [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-300

2022041577 Zhang, Ting (National University of Singapore, Department of Geography, Singapore, Singapore); Li, Dongfeng; Kettner, Albert J. and Lu, Xixi. Basin-scale sediment transport and sediment concentration-discharge relationship modeling in a permafrost-dominated basin [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-1038, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost degradation by ongoing climate warming has expanded the erodible thermokarst landscapes, enhanced the thermal erosion, and altered the sediment transport processes in cryosphere basins. Thermal-activated sediment sources and enhanced sediment export due to developed hillslope-channel connectivity can increase the annual sediment flux and accelerate the sediment response to hydroclimatic disturbances, thus complicating suspended sediment concentration (SSC) and discharge (Q) relationships and forming various hysteretic patterns. Yet, the commonly used sediment rating curve (SSC=a´Qb with a and b as static fitting parameters) is unable to capture the SSC-Q hysteretic patterns and most single-event-scale hysteresis models mainly emphasize the pluvially enhanced sediment transport (e.g. rainstorms), but overlook the thermally-erosional processes. To rebuild dynamic SSC-Q relationships and hysteresis in sediment transport in cryosphere basins, we propose a Sediment-Availability-Transport (SAT) model by extending traditional rating curves to incorporate the time-varying sediment availability regulated by thermal-fluvial processes and long-term storage exhaustion. In the SAT-model, increased thermal erosion is represented by basin temperature; enhanced fluvial erosion is represented by runoff increase; sediment transport capacity is represented by total runoff. Specifically, thawing permafrost as temperature rising can enhance sediment generation by forming active layer detachment, retrogressive thaw slump, and thermal erosion gully from hillslopes, and fluvio-thermal erosion along the riverbank, associated with a time-lag in the sediment response due to the time for temperature accumulation to melt cryosphere and long-travel distance from thermal-activated sediment sources to the basin outlet. A surge in basin water supply during intense rainfall and excessive melting with a certain time-lag can increase sediment availability and fluvial erosion by flushing the erodible slope and scouring the river channel. Moreover, sediment storage is assumed to be continuously depleted throughout a hydrological year and leads to sediment exhaustion. With the support of multi-decadal daily SSC and Q in-situ observations (1985-2017), the SAT-model can be parameterized and validated in the permafrost-dominated Tuotuohe basin on Tibetan Plateau. In Tuotuohe, thermal erosion processes are found to be best captured by an eight-day average temperature, associated with an exponential amplification of SSC. Fluvial erosion is best captured by a two-day runoff increase and shows a linear amplification of SSC. Moreover, the warming-wetting climate over the past decades has expanded the thermokarst landscapes and boosted the slope-channel connectivity by thermal gullies, which leads to the significant inter/intra-annual variation in SSC-Q relationships and reduces the performance of the sediment rating curve. Yet, the SAT-model can robustly reproduce the long-term evolution, seasonality, and various event-scale hysteresis of SSC, including clockwise, counter-clockwise, figure-eight, counter-figure-eight, and more complex hysteresis loops. Overall, the SAT-model can explain over 75% of long-term SSC variance, outperforming the sediment rating curve approach by 20%, with stable performance under an abrupt hydroclimate change. Part of the results is also published in Water Resources Research: Zhang et al., 2021. Constraining dynamic sediment-discharge relationships in cold environments: The sediment-availability-transport (SAT) model; Li et al., 2021. Air temperature regulates erodible landscape, water, and sediment fluxes in the permafrost dominated catchment on the Tibetan Plateau. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-1038

2022041633 Zhao Zhiyi (Chinese Academy of Sciences, Institute of Atmospheric Physics, Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics, Beijing, China); Lin Zhongda; Li Fang and Rogers, Brendan M. Influence of atmospheric teleconnections on interannual variability of arctic-boreal fires [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-4831, 2022. (Hybrid conference). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Fires across the Arctic-boreal zone (ABZ) play an important role in the boreal forest succession, permafrost thaw, and the regional and global carbon cycle and climate. These fires occur mainly in summer with large interannual variability. Previous studies primarily focused on the impacts of local surface climate and tropical El Nino-Southern Oscillation (ENSO). This study, for the first time, comprehensively investigates the influence of summer leading large-scale atmospheric teleconnection patterns in the Northern Hemisphere extra-tropics on interannual variability of ABZ fires. We use correlation and regression analysis of 1997-2019 multiple satellite-based products of burned area and observed/reanalyzed climate data. Results show that eight leading teleconnection patterns significantly affect 63±2% of burned areas across the ABZ. Western North America is affected by the East Pacific/North Pacific pattern (EP/NP) and the West Pacific pattern (WP); boreal Europe by the Scandinavia pattern (SCA); eastern North America, western and central Siberia, and southeastern Siberia by the North Atlantic Oscillation (NAO); and eastern Siberia/Russian Far East by the East Atlantic pattern (EA). NAO/EA induces lower-tropospheric drier northwesterly/northerly airflow passing through the east of boreal North America/Eurasia, which decreases surface relative humidity. Other teleconnections trigger a high-pressure anomaly, forcing downward motion that suppresses cloud formation and increases solar radiation reaching the ground to warm the surface air as well as brings drier air downward to reduce surface relative humidity. The drier and/or warmer surface air can decrease fuel wetness and thus increase burned area. Our study highlights the important role of the extra-tropical teleconnection patterns on ABZ fires, which is much stronger than ENSO that was thought to control interannual variability of global fires. It also establishes a theoretical foundation for ABZ fire prediction based on extra-tropical teleconnections, and has the potential to facilitate ABZ fire prediction and management. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-4831

2022036706 Mokhov, I. I. (A.M. Obukhov Institute of Atmospheric Physics, Moscow, Russian Federation); Chernockulsky, A. V. and Repina, I. A., prefacers. Climate change; causes, risks, consequences, problems of adaptation and management: IOP Conference Series. Earth and Environmental Science, 606(1), variously paginated, November 2020. Meeting: Climate change; causes, risks, consequences, problems of adaptation and management (CLIMATE-2019), Nov. 26-28, 2019, Moscow, Russian Federation. Individual papers within scope are cited separately.

2022036708 Kazantsev, V. S. (Russian Academy of Sciences, A. M. Obukhov Institute of Atmospheric Physics, Moscow, Russian Federation); Krivenok, L. A. and Dvornikov, Y. A. Preliminary data on the methane emission from lake seeps of the western Siberia permafrost zonein Climate change; causes, risks, consequences, problems of adaptation and management (Mokhov, I. I., prefacer; et al.), IOP Conference Series. Earth and Environmental Science, 606(1), Article 012022, illus. incl. 3 tables, 22 ref., November 2020. Meeting: Climate change; causes, risks, consequences, problems of adaptation and management (CLIMATE-2019), Nov. 26-28, 2019, Moscow, Russian Federation.

Lakes are one of the most important sources of the greenhouse gas methane. Usually, only diffusive emission is counted towards in estimates of the Arctic lakes contribution to the atmospheric methane budget. At the same time, for some regions, giving the importance for the ebullition of various genesis significantly increases previous assessments of ecosystem-based lake methane emission. This paper presents the results of a study of two gas seeps on the Central Yamal lake. The methane concentration in seep gas varies from 94.2 to 100%. Mean annual methane emission from each seep is estimated as 46.1 and 67.1 kgCH4 per year respectively. According to the analysis of the methane isotopic composition, it is of biogenic origin. Studied gas seeps are obviously direct channels of methane emission from permafrost to the atmosphere. Copyright Published under licence by IOP Publishing Ltd

DOI: 10.1088/1755-1315/606/1/012022

2022036709 Malakhova, V. V. (Russian Academy of Sciences, Institute of Computational Mathematics and Mathematical Geophysics, Novosibirsk, Russian Federation). The response of the Arctic Ocean gas hydrate associated with subsea permafrost to natural and anthropogenic climate changesin Climate change; causes, risks, consequences, problems of adaptation and management (Mokhov, I. I., prefacer; et al.), IOP Conference Series. Earth and Environmental Science, 606(1), Article 012035, illus., 42 ref., November 2020. Meeting: Climate change; causes, risks, consequences, problems of adaptation and management (CLIMATE-2019), Nov. 26-28, 2019, Moscow, Russian Federation.

We present an assessment of changes in the gas hydrates stability zone of the Arctic Ocean associated with subsea permafrost conditions. To evaluate the formation and dissociation of gas hydrates under the climatic conditions of the last glacial cycle, it is necessary to understand how the thickness of the permafrost has changed after flooding by the sea. To do this, we have combined two numerical models: a model of permafrost dynamics based on the paleoclimatic scenario of changes in temperature and ocean level, and a model of the methane hydrates stability zone (MHSZ). Calculations of changes in the thickness of the submarine permafrost and the MHSZ were carried out for the period of 120 thousand years. Our results show that, although changes in the bottom water temperature over the last-decades period affect the hydrate stability zone, the main changes with this zone occurring after flooding the Arctic shelf with the seawater. As a result of the combined simulation of the permafrost and state of MHSZ, it was found that in the shallow shelf areas (lower 50 m water depth) after flooding, the hydrate presence conditions in the upper 100-meter layer of the MHSZ are violated. This suggests that the methane coming from this reservoir is concentrated in the bottom sediments of the shelf, and then released into the water, continuing to adapt to changing sea levels, rising bottom water temperatures, and subsea permafrost melting. Copyright Published under licence by IOP Publishing Ltd

DOI: 10.1088/1755-1315/606/1/012035

2022041322 Nield, Catherine (University of Cincinnati, Department of Geology, Cincinnati, OH); Yanes, Yurena; Miller, Joshua; Druckenmiller, Patrick and Sniezak, Thomas. Oxygen isotope values of modern and fossil land snails from Fairbanks, Alaska [abstr.]: in Geological Society of America, North-Central Section, 56th annual meeting; Geological Society of America, Southeastern Section, 71st annual meeting, Abstracts with Programs - Geological Society of America, 54(4), Abstract no. 1-2, April 2022. Meeting: Geological Society of America, North-Central Section, 56th annual meeting; Geological Society of America, Southeastern Section, 71st annual meeting, April 7-8, 2022, Cincinnati, OH.

Polar regions are critically impacted by accelerated climate warming. Snails and other Arctic species are well adapted to cold environments and are likely to struggle in future warmer scenarios. Additionally, sub-fossil and fossil records in permafrost deposits are facing disturbance and destruction due to fast-rising temperatures and accelerated melting. Therefore, there is an urgent need to study these records and generate proxy data useful to investigate paleoclimate cycles for predicting the trajectory of current and future climate scenarios. Terrestrial gastropods, or land snails, are abundantly preserved in Quaternary permafrost and loess deposits in Alaska, but they remain poorly studied. Here, we analyze the oxygen isotope values of modern (live collected) and fossil land snail shells preserved in the Fox permafrost tunnel near Fairbanks, Alaska, to evaluate differences in precipitation d18O between the modern and the recent past. We isotopically analyzed the three most abundant genera of land snails (Succinea, Euconulus, and Vertigo). Preliminary radiocarbon dates (n=3) indicate that fossil snails are from ~14 cal kya. The three snail species exhibited significantly different oxygen isotope values, suggesting that sympatric snail taxa should be considered separately in local or regional paleoclimate studies. In sharp contrast to ice-core records, the preliminary oxygen isotope results of snails from the end of the Pleistocene are statistically indistinguishable from modern shells of the same species. The similarity in oxygen isotope values may be explained by the influence of 18O-enriched glacial ocean waters, and/or increased aridity during glacial intervals. Future research aims to isotopically analyze and date more snails throughout the Fox Tunnel to assess if this pattern holds true with increasing sample sizes and across time intervals.

DOI: 10.1130/abs/2022NC-374507

2022039425 Lombardo, Carly (University of Massachusetts at Amherst, Department of Geosciences, Amherst, MA); Daniels, William; Castañeda, Isla S. and Brigham-Grette, Julie. Burning in Beringia; glacial-interglacial wildfire variability at Lake El'gygytgyn [abstr.]: in Geological Society of America, Northeastern Section, 57th annual meeting, Abstracts with Programs - Geological Society of America, 54(3), Abstract no. 29-9, March 2022. Meeting: Geological Society of America, Northeastern Section, 57th annual meeting, March 20-22, 2022, Lancaster, PA.

Arctic tundra fires have the potential to release large amounts of permafrost soil carbon into the atmosphere as carbon dioxide. Understanding the environmental controls of tundra fires is therefore essential for predicting future climate feedbacks from burning. Aridity, lightning frequency, and vegetation assemblages are key factors affecting the frequency and severity of tundra wildfires. For example, the Last Glacial Maximum was cold and dry in parts of the Arctic, and wildfires were more common than during the relatively warm and moist Holocene. Contrastingly, current warming and moistening appear to be moving the Arctic into a more fire-prone climatic state. Paleoclimate records of past warm periods are needed to elucidate if future climate change will ultimately suppress or stoke tundra fire activity. Here, we investigate molecular proxies of fire and climate across Marine Isotope Stages (MIS) 20-22 (860-720 ka) in the Lake El'gygytgyn drillcore from NE Russia. Fire activity is reconstructed using a combination of polycyclic aromatic hydrocarbons (PAHs) and monosaccharide anhydrides (MAs), while temperatures are reconstructed using branched glycerol dialkyl glycerol tetraethers, and vegetation change is inferred from leaf wax n-alkanes and pollen assemblages. We find that MIS 20-22 experienced large climatic and vegetation shifts at Lake El'gygytgyn. Interglacial stage MIS 21 is approximately 4-6 °C warmer than the preceding and following glacial periods. Tundra and cold steppe biomes characterize the study interval, but there are periods with elevated deciduous and coniferous tree species as well. We use the PAH and MA ratios to determine fire biomarker source regions and source fuel types across this glacial-interglacial cycle and further discuss how the wildfire proxies vary in response to environmental change.

DOI: 10.1130/abs/2022NE-375023

2022039420 Mahar, Isabelle (Columbia University, Environmental Science Department, New York, NY); Thomas, Elizabeth; Jensen, Britta; Castañeda, Isla S. and Cluett, Allison. Multi-proxy analysis of Alaskan loess deposits through Quaternary interglacial-glacial cycles [abstr.]: in Geological Society of America, Northeastern Section, 57th annual meeting, Abstracts with Programs - Geological Society of America, 54(3), Abstract no. 29-4, March 2022. Meeting: Geological Society of America, Northeastern Section, 57th annual meeting, March 20-22, 2022, Lancaster, PA.

The Arctic is currently warming at least twice as fast as the rest of Earth. This warming drives glacier retreat, while melting permafrost releases additional greenhouse gases, further amplifying warming. Climate records from past warm periods provide context for ongoing changes. Such records are rare in the north because ice sheets covered much of this region during glaciations, scouring the landscape and removing sediments. This has led to a critical gap in understanding how current changes relate to those in past warmer conditions. Beringia, comprising Alaska, the Yukon Territory, and eastern Siberia, was not blanketed by ice sheets during glaciations. Throughout Beringia, loess (wind-blown dust) accumulated in thick sections that provide near-continuous climate archives spanning the past 3 million years. During a National Geographic-funded expedition in summer 2019, we collected loess and paleosol samples from Gold Hill and the Largent Mine near Fairbanks, Alaska. We will present stratigraphy and age control at these sites, which contain paleosols from at least three interglacial periods. We will also present multiple paleoclimate proxies measured in the paleosols and adjacent loess (deposited during glacial periods). These proxies include magnetic susceptibility, loss on ignition, leaf wax chain length distributions and hydrogen isotopes, and glycerol dialkyl glycerol tetraethers (GDGTs). Leaf wax distributions reflect plant community changes through time while leaf wax hydrogen isotopes reflect changes in the water cycle through time. Magnetic susceptibility and loss on ignition reflect soil maturity and primary production. We will compare climate between these interglacial periods and assess this region's response to forcing mechanisms during ancient interglacials, including insolation and CO2. Our results will elucidate how high-latitude climate responds to global warmth, while laying the groundwork for future detailed analyses of samples in this same area.

DOI: 10.1130/abs/2022NE-374775

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