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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August 2022 PMA

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


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2022043184 Burn, Christopher R. (Carleton University, Department of Geography and Environmental Studies, Ottawa, ON, Canada) and Lewkowicz, Antoni G. Permafrost 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. sects., 170 ref., June 6, 2022.

Permafrost geomorphology came of age in 1965-2000, evolving from a field-based subdiscipline largely based on qualitative observation to one of detailed process measurement, field experimentation, and analytical modelling. In this, the development of permafrost geomorphology exemplified the change in geomorphology as a whole. Fundamental advances were made in understanding the development of ice wedges and ice-wedge polygons and the genesis and growth of closed-system pingos, especially by J. Ross Mackay working in the continuous permafrost terrain of the western Canadian Arctic coastlands. Mackay also investigated moisture movement in relation to ground thermal regime which led to seminal insights regarding ground freezing, frost heave, near-surface ground ice development, and hummocky micro-relief. Others used these ideas to examine frost shattering of rocks and the development of sorted circles, as most well-known from Svalbard. In the second half of the period measurements of permafrost creep and deformation of hill slopes and rock glaciers were presented, complementing antecedent measurements of solifluction in the active layer. Significant investigations of thermokarst development foreshadowed the preoccupation with permafrost thaw that now gathers so much attention.

DOI: 10.1144/M58-2022-11

2022047734 Chen Rui (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, State Key Laboratory of Cryospheric Science, Lanzhou, China); Yang Meixue; Wang Xuejia; Wan Guoning and Li, Haoying. Thermal regime variations of the uppermost soil layer in the central Tibetan Plateau: Catena (Giessen), 213, Article 106224, illus. incl. 2 tables, geol. sketch map, 97 ref., June 2022.

Permafrost degradation related to global warming has been widespread in the Tibetan Plateau (TP), manifesting prominently as variations in the soil thermal regime, an essential characteristic of permafrost. Altered soil thermal conditions can influence the energy and water balance between the atmosphere and land, leading to the release of stored carbon dioxide and methane. In this study, reanalysis and observed soil temperature data were combined to analyze the long-term changes in the thermal regime of the uppermost soil layer at six sites in the central TP. MERRA2 and ERA5-Land had the highest quality in matching the observed data at each site. The mean annual soil temperature ranged from -0.11 °C to 4.75 °C (averaging 1.73 °C) and warms at 0.059°C a-1. The mean annual first dates of freezing and thawing and the mean duration of freezing were 123.23 ± 10.85d, 285.67 ± 10.34d, and 161.44 ± 20.54 d, respectively, indicating lagged, advanced, and shortened trends with 0.54 ± 0.49d a-1, 0.50 ± 1.06 d a-1, and 1.05 ± 1.16 d a-1, respectively. The mean annual freezing and thawing N-factors were 0.53 ± 0.13 and 2.43 ± 2.09, respectively. The maximum and minimum monthly average soil temperatures were 11.81 ± 2.17 °C in July and -9.54 ± 3.24 °C in January, respectively. Partial correlation analysis was used to quantify the influences of factors (including surface air temperature, snow depth, rainfall, normalized difference vegetation index [NDVI], shortwave radiation, and soil moisture) on soil temperature implicated surface air temperature as the most significant influencing factor in the increased soil temperature. Rainfall and NDVI were implicated as being likely to suppress the soil temperature warming. This study provides detailed information about the thermal regime of the uppermost soil in the central TP and facilitates validation of the land surface model.

DOI: 10.1016/j.catena.2022.106224

2022047720 Schiedung, Marcus (University of Zurich, Department of Geography, Zurich, Switzerland); Bellè, Severin-Luca; Malhotra, Avni and Abiven, Samuel. Organic carbon stocks, quality and prediction in permafrost-affected forest soils in north Canada: Catena (Giessen), 213, Article 106194, illus. incl. 2 tables, sketch map, 83 ref., June 2022.

High-latitude soils store a large amount of the global soil organic carbon (SOC). The SOC stocks in mineral soils under different permafrost conditions, however, are underrepresented in global carbon databases. We sampled mineral forest soils under continuous and discontinuous to sporadic permafrost conditions on the Canadian Boreal and Taiga Plain. We determined the SOC stocks in the upper 60 cm of 94 soil pits across eleven sites (5-9 pits per site) and SOC quality using 13C isotopic signatures, C:N ratios and composition of aliphatic/aromatic and cellulose/lignin-like compounds obtained from mid-infrared spectra analyses. Lastly, we evaluated the prediction of SOC stocks in these soils using mid-infrared spectra and partial least square regression modeling (PLSR). The SOC stocks were on average four times higher in soils under continuous permafrost conditions (93.7-203.8 Mg SOC ha-1 in 0-45 cm) compared to soils under discontinuous to sporadic permafrost conditions (26.7-60.2 Mg SOC ha-1 in 0-60 cm). In addition, the SOC stocks were larger at moist and wet locations compared to dryer locations and varied significantly between sites, stressing the importance of small-scale geomorphic differences in controlling SOC in boreal mineral forest soils. Continuous permafrost SOC had a lower degree of decomposition compared to soils under discontinuous and sporadic permafrost. This indicates a potentially large proportion of SOC in boreal mineral soils to be vulnerable to warming associate increases in decomposition. The combination of mid-infrared with PLSR was suitable to predict the SOC stocks (R2 > 0.8) with an average uncertainty of 14-23%, which was less than the observed spatial variability of the field replicates (29-41%). Mid-infrared spectroscopy can thus offer an alternative to fill SOC data gaps of high latitude mineral forest soils and reduce uncertainties originating from the limited number of currently available SOC observations of Canadian boreal mineral forest soils.

DOI: 10.1016/j.catena.2022.106194

2022044639 Joss, Hanna (University of Tubingen, Center for Applied Geoscience, Tubingen, Germany); Patzner, Monique S.; Maisch, Markus; Mueller, Carsten W.; Kappler, Andreas and Bryce, Casey. Cryoturbation impacts iron-organic carbon associations along a permafrost soil chronosequence in northern Alaska: Geoderma, 413, Article 115738, illus. incl. 1 table, 81 ref., May 1, 2022.

In permafrost soils, substantial amounts of organic carbon (OC) are potentially protected from microbial degradation and transformation into greenhouse gases by association with reactive iron (Fe) minerals. As permafrost environments respond to climate change, increased drainage of thaw lakes in permafrost regions is predicted. Soils will subsequently develop on these drained thaw lakes, but the role of Fe-OC associations in future OC stabilization during this predicted soil development is unknown. To fill this knowledge gap, we have examined Fe-OC associations in organic, cryoturbated and mineral horizons along a 5500-year chronosequence of drained thaw lake basins in Utqiagvik, Alaska. By applying chemical extractions, we found that ~17% of the total OC content in cryoturbated horizons is associated with reactive Fe minerals, compared to ~10% in organic or mineral horizons. As soil development advances, the total stocks of Fe-associated OC more than double within the first 50 years after thaw lake drainage, because of increased storage of Fe-associated OC in cryoturbated horizons (from 8 to 75% of the total Fe-associated OC stock). Spatially-resolved nanoscale secondary ion mass spectrometry showed that OC is primarily associated with Fe(III) (oxyhydr)oxides which were identified by 57Fe Mössbauer spectroscopy as ferrihydrite. High OC:Fe mass ratios (>0.22) indicate that Fe-OC associations are formed via co-precipitation, chelation and aggregation. These results demonstrate that, given the proposed enhanced drainage of thaw lakes under climate change, OC is increasingly incorporated and stabilized by the association with reactive Fe minerals as a result of soil formation and increased cryoturbation.

DOI: 10.1016/j.geoderma.2022.115738

2022046346 Yang Suiqiao (Northeast Forestry University, School of Civil Engineering, Institute of Cold Regions Science and Engineering, Harbin, China) and Zhang Hu. Simulation of geothermal evolution of an opencast coal mine during the excavation-backfilling process in permafrost region: Environmental Earth Sciences, 81(9), Article 252, illus. incl. 3 tables, 24 ref., May 2022.

The excavation and backfilling of opencast coal mines in permafrost regions inevitably changes the geothermal state and degenerates surrounding permafrost, causing severe engineering and environmental problems-thaw slumping, ground fissures, vegetation degradation and desertification. Therefore, it is desirable to investigate the thermal regime evolution within the mining area during the whole excavation-backfilling process to evaluate permafrost degradation and related negative effects. Numerical simulations were performed for different mean annual ground temperature (MAGT) and backfill temperature conditions. Measured ground temperatures confirmed the reliability of the numerical model and simulation parameters. During excavation, 4.0-5.0 m thick permafrost beneath mine pit base or slopes becomes an active layer. Deepening of the mine pit continually reduces the thickness of the underlying permafrost, or might pierce it if the MAGT is high. An abrupt change in temperature initially forms in the transitional segment between backfill and natural ground following backfilling, which may postpone the warming of cold backfill or the cooling of warm backfill. Backfill temperature and MAGT are both key factors in controlling frozen ground recovery in the mine pit. A lower backfill temperature is more favorable than a lower MAGT in refreezing the soil in the pit. Higher thermal conductivity induces faster refreezing than that caused by lower thermal conductivity. The cold season is recommended to backfill the mine pit for faster recovery of the frozen ground by lowering the backfill temperature. This study provides a theoretical reference for green coal mining and rapid environmental recovery in permafrost regions.

DOI: 10.1007/s12665-022-10366-0

2022046117 Bogoyavlensky, Vasily (Oil and Gas Research Institute of the Russian Academy of Sciences, Moscow, Russian Federation); Kishankov, Aleksei; Kazanin, Aleksei and Kazanin, Gennady. Distribution of permafrost and gas hydrates in relation to intensive gas emission in the central part of the Laptev Sea (Russian Arctic): Marine and Petroleum Geology, 138, Article 105527, illus. incl. geol. sketch maps, sects., 128 ref., April 2022.

This article describes the results of a comprehensive analysis of the causes of intensive gas emission over a large zone (ca. 80 ´ 220 km) of the Central Laptev shelf area. The upper parts of 28 sections of common depth point (CDP) seismic lines acquired by the JSC MAGE, covering a total length of 5930 km over an area of 55,000 km2, were interpreted and 519 anomalous objects potentially connected with gas saturation were revealed. For the first time, the boundary between frozen and thawed sediments was defined in the Laptev Sea. The absence of subsea permafrost and gas hydrates in the intensive gas seepage zone was determined. The connection between gas seeps and deep-seated faults identified in seismic sections was substantiated. This study demonstrated that seismotectonic factors caused a large spatial window of long-term Earth degassing with direct intensive migration of deep thermogenic gas to the hydrosphere through a system of faults. A zone of potential gas hydrate distribution was observed on the continental slope.

DOI: 10.1016/j.marpetgeo.2022.105527

2022046138 Chuvilin, E. (Skolkovo Institute of Science and Technology, Skolkovo Innovation Centre, Moscow, Russian Federation); Bukhanov, B.; Yurchenko, A.; Davletshina, D.; Shakhova, N.; Spivak, E.; Rusakov, V.; Dudarev, O.; Khaustova, N.; Tikhonova, A.; Gustafsson, Orjan; Tesi, Tommaso; Martens, J.; Jakobsson, M.; Spasennykh, M. and Semiletov, I. In-situ temperatures and thermal properties of the East Siberian Arctic shelf sediments; key input for understanding the dynamics of subsea permafrost: Marine and Petroleum Geology, 138, Article 105550, illus. incl. 3 tables, sketch maps, 84 ref., April 2022.

Significant reserves of methane (CH4) are held in the Arctic shelf, but the release of CH4 to the overlying ocean and, subsequently, to the atmosphere has been believed to be restricted by impermeable subsea permafrost, which has sealed the upper sediment layers for thousands of years. Our studies demonstrate progressive degradation of subsea permafrost which controls the scales of CH4 release from the sediment into the water-atmospheric system. Thus, new knowledge about the thermal state of subsea permafrost is crucial for better understanding of the permafrost -hydrate system and associated CH4 release from the East Siberian Arctic Shelf (ESAS) - the broadest and shallowest shelf in the World Ocean, which contains about 80% of subsea permafrost and giant pools of hydrates. Meanwhile, the ESAS, still presents large knowledge gaps in many aspects, especially with respect to subsea permafrost distribution and physical properties of bottom sediments. New field data show that the ESAS has an unfrozen (ice-free) upper sediment layer, which in-situ temperature is -1.0 to -1.8 °C and 0.6°S above the freezing point. On one hand, these cold temperature patterns may be related to the presence of subsea permafrost, which currently primarily occurs in the part of the ESAS that is shallower than 100 m, while ice-bearing sediments may also exist locally under deeper water in the Laptev Sea. On the other hand, the negative bottom sediment temperatures of -1.8 °C measured on the Laptev Sea continental slope sediments underlying water columns as deep as down to 330 m may result from dissociation of gas hydrates or possibly from dense water cascading down from the shelf. In contrast, data collected on recent expeditions in the northern Laptev shelf, zones of warmer bottom temperatures are coinciding with methane seeps, likely induced by seismic and tectonic activity in the area. These warm temperatures are not seen in the East Siberian Sea area, not even in areas of methane seeps, yet with little seismic activity. The thermal conductivity and heat capacity of bottom sediments recorded in the database of thermal parameters for the ESAS areas mainly depend on their lithification degree (density or porosity), moisture content, and particle size distribution. The thermal conductivity and heat capacity average about 1.0 W/(m·K) and 2900 kJ/(m3·K), with ±20% and ±10% variance, respectively, in all sampled Arctic sediments to a sub-bottom interval of 0-0.5 m.

DOI: 10.1016/j.marpetgeo.2022.105550

2022046301 Schaetzl, Randall J. (Michigan State University, Department of Geography, Environment, and Spatial Sciences, East Lansing, MI); Running, Garry, IV; Larson, Phillip; Rittenour, Tammy; Yansa, Catherine and Faulkner, Douglas. Luminescence dating of sand wedges constrains the late Wisconsin (MIS 2) permafrost interval in the upper Midwest, USA: Boreas, 51(2), p. 385-401, illus. incl. 2 tables, April 2022. Based on Publisher-supplied data.

Large parts of the upper Midwest, USA were impacted by permafrost during the Last Glacial Maximum (LGM). Even though permafrost persisted as the Laurentide Ice Sheet began to recede, direct age control of this interval is largely lacking. To better temporally constrain the permafrost interval in western Wisconsin, we identified two sites, outside the Late Wisconsin (MIS 2) glacial limit, that contain relict, ice-wedge pseudomorphs, initially interpreted to be sand wedges, hosted within well-drained outwash deposits. The pre-Wisconsin (>MIS 5) host material commonly displays up-turned bedding near the contact with the wedges, indicative of well-formed features. The wedges are filled with well-sorted, gravel-free, medium and fine sands, and lack evidence of post-formational disturbance, pointing to an aeolian sand infill and confirming them as sand wedges. Ventifacts on nearby uplands attest to windy conditions here in the past. Optically stimulated luminescence (OSL) ages on five sand wedges indicate that they filled with sand between c. 19.3 and 18.3 ka at the southerly site and between c. 15.1 and 14.7 ka at the northerly site, which is closer to the LGM margin. Sand wedges at the latter site were wider and had more complex morphologies, possibly suggesting a longer interval of formation and/or more intense permafrost. We also examined a site along a ridge crest, between the two wedge sites, which displayed interbedded loess and sand, dated by OSL to 12.7 ka. Together, these results point to dry, cold, windy conditions in west-central Wisconsin, within 100 km of the LGM limit. At this time, aeolian sands were being transported across a landscape with (at least scattered) permafrost. The OSL results suggest multiple phases, or perhaps time-transgressive, sand-wedge formation, associated with permafrost between c. 19 and 15 ka, with dry, windy (and likely, cold) conditions persisting until at least 12.7 ka. Abstract Copyright (2022), John Wiley & Sons, Ltd.

DOI: 10.1111/bor.12550

2022047465 Lv Mingxia (Lanzhou University, College of Earth and Environment Sciences, Lanzhou, China); Wang Yibo and Gao Zeyong. The change process of soil hydrological properties in the permafrost active layer of the Qinghai-Tibet Plateau: Catena (Giessen), 210, Article 105938, illus. incl. 4 tables, sketch map, 57 ref., March 2022.

The hydrological properties of the active soil layer are the key parameters that regulate soil water-heat-solute migration and alter hydrologic cycles in a permafrost region. To date, much remains unknown about the interaction mechanism between permafrost degradation and eco-hydrological processes in the permafrost regions of the Qinghai-Tibet Plateau (QTP). In this study, the soil texture, soil hydrological properties, the soil moisture status, and the hydrothermal processes were measured and analyzed in different degradation degrees of alpine meadow soils on the QTP. The results showed a close relationship between soil hydrological properties and soil physicochemical properties. Freeze-thaw cycles changed the physicochemical and hydrological properties, that is, frequent freeze-thaw cycles promote to permafrost degradation in terms of soil basis properties of active layer. In addition, vegetation on the ground delayed the degradation of frozen soil. The actual available soil water content (SWC) in the root layer was a key factor in the ecohydrological process. The actual effective SWC in the root layers of different alpine meadows was ranked as follows: non-degraded meadow (NDM)>moderately-degraded meadow (MDM)>seriously degraded meadow (SDM) (1.8-5.0% at NDM and 0.0-4.2% at SDM). In addition, the weak soil permeability in an SDM intensified the deficiency of the available SWC, thereby increasing the difficulty of ecological restoration. This study provides a basis for ecological environmental protection in permafrost regions and provides a hydrological process model for cold regions under future climate change scenarios.

DOI: 10.1016/j.catena.2021.105938

2022045782 Yin Guoan (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, State Key Laboratory of Frozen Soils Engineering, Lanzhou, China); Luo Jing; Niu Fujun; Lin Zhanju and Liu Minghao. Machine learning-based thermokarst landslide susceptibility modeling across the permafrost region on the Qinghai-Tibet Plateau: Landslides, 18(7), p. 2639-2649, illus. incl. geol. sketch maps, 62 ref., July 2021.

Thermokarst landslides (TL) caused by the thaw of ground ice in permafrost slopes are increasing on the Qinghai-Tibet Plateau (QTP), but the understanding of the spatially suitable environmental conditions including terrains and climate for them has not been fully established. Here, we applied multiple machine learning models and their ensemble to explore factors controlling the TL and map its susceptibility at a fine resolution. The models were calibrated and validated using a split-sample approach based on an inventory of TLs from the remote sensing data. The models indicated that summer air temperature and rainfall were the most two important factors controlling the occurrence and distribution of TLs, provided that other geomorphic conditions (i.e., slope, solar radiation, and fine soil) were suitable. The final ensemble susceptibility map based on downscaled climate data and terrain data suggested that ca. 1.4% of the QTP land was classified in high- to very high-susceptibility zone, which is likely to increase in response to future climate change. This study integrated local topography and climate in susceptibility modeling and provided new insights into the geomorphic sensitivity to climate change but also the engineering support over the QTP.

DOI: 10.1007/s10346-021-01669-7

2022047579 Grebenets, V. I. (Moskovskiy Gosudarstvennyy Universitet imeni M. V. Lomonosova, Moscow, Russian Federation) and Tolmanov, V. A. Vliyaniye spetsificheskogo rezhima snezhnykh otlozheniy na vechnomerzlyye osnovaniya v gorodakh kriolitozony (na primere Noril'skogo regiona) [Influence of snow dump regime on building foundations in urban permafrost; examples from the Norilsk region]: Led i Sneg = Ice and Snow, 61(3), p. 457-470 (English sum.), illus. incl. 2 tables, sketch map, 9 ref., 2021.

With increasing snowfalls and rising winter temperatures in the Arctic regions of Russia (against the background of almost the same summer values), the role of solid precipitation in the formation of the temperature and humidity regimes of seasonally thawed and upper horizons of permafrost grounds becomes extremely important. No regular observations of snow accumulation in built-up areas were conducted in the Arctic settlements. This article presents for the first time the results of snow measurements in urbanized areas of the Norilsk region, and assesses the warming effect of snow cover on the permafrost grounds and foundations. The problems that arise during the mechanical redistribution of snow are identified. In some areas the thickness of the snow cover (near the City of Norilsk) by the end of March can reach 200 cm; in February, the average monthly value for the last 15 years amounts 69 cm, and in the city the height of snow dumps ranges from 2 to 5 m. The warming effect of snow cover on the permafrost layer enhances as the snow height increases from 0 to 2-2.5 m, and then remains unchanged. Large masses of snow existing for many decades in almost the same places (together with the snow drifts of the air from the ventilated subfields) result in the development of degradation tendencies within the permafrost. A slight temperature rise was noted in grounds under 30-40% of the operated objects (as compared with the design values), which causes deformation of the structures.

DOI: 10.31857/S2076673421030101

2022045728 Philipp, Marius (University of Wuerzburg, Department of Remote Sensing, Institute of Geography and Geology, Wurzburg, Germany); Dietz, Andreas; Buchelt, Sebastian and Kuenzer, Claudia. Trends in satellite Earth observation for permafrost related analyses; a review: Remote Sensing, 13(6), Article 1217, illus. incl. 5 tables, 485 ref., 2021.

Climate change and associated Arctic amplification cause a degradation of permafrost which in turn has major implications for the environment. The potential turnover of frozen ground from a carbon sink to a carbon source, eroding coastlines, landslides, amplified surface deformation and endangerment of human infrastructure are some of the consequences connected with thawing permafrost. Satellite remote sensing is hereby a powerful tool to identify and monitor these features and processes on a spatially explicit, cheap, operational, long-term basis and up to circum-Arctic scale. By filtering after a selection of relevant keywords, a total of 325 articles from 30 international journals published during the last two decades were analyzed based on study location, spatio-temporal resolution of applied remote sensing data, platform, sensor combination and studied environmental focus for a comprehensive overview of past achievements, current efforts, together with future challenges and opportunities. The temporal development of publication frequency, utilized platforms/sensors and the addressed environmental topic is thereby highlighted. The total number of publications more than doubled since 2015. Distinct geographical study hot spots were revealed, while at the same time large portions of the continuous permafrost zone are still only sparsely covered by satellite remote sensing investigations. Moreover, studies related to Arctic greenhouse gas emissions in the context of permafrost degradation appear heavily underrepresented. New tools (e.g., Google Earth Engine (GEE)), methodologies (e.g., deep learning or data fusion etc.) and satellite data (e.g., the Methane Remote Sensing LiDAR Mission (Merlin) and the Sentinel-fleet) will thereby enable future studies to further investigate the distribution of permafrost, its thermal state and its implications on the environment such as thermokarst features and greenhouse gas emission rates on increasingly larger spatial and temporal scales.

DOI: 10.3390/rs13061217

2022043912 Foley, Neil (University of California, Department of Earth and Planetary Science, Santa Cruz, CA); Tulaczyk, Slawomir; Auken, Esben; Grombacher, Denys; Mikucki, Jill; Foged, Nikolaj; Myers, Krista; Dugan, Hilary; Doran, Peter T. and Virginia, Ross A. Mapping geothermal heat flux using permafrost thickness constrained by airborne electromagnetic surveys on the western coast of Ross Island, Antarctica: Exploration Geophysics (Melbourne), 51(1), p. 84-93, illus. incl. sects., sketch maps, 3 p. ref., 2020. Paper presented at the 7th International workshop of Airborne electromagnetics (AEM 2018) held in Kolding, Denmark, June 17-20, 2018.

DOI: 10.1080/08123985.2019.1651618

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2022047988 Fahnestock, Maria FlorenciaCompound, elemental, and isotopic perspectives on mercury mobilization during thaw in a discontinuous permafrost zone: 158 p., illus. incl. 12 tables, Master's, 2022, University of New Hampshire, Durham, NH.

2022047592 Jacquemart, M. F. Glacier detachments and landslide hazards in a changing climate: 139 p., Doctoral, 2021, University of Colorado at Boulder, Boulder, CO.

The rapid warming of the cryosphere is having a profound effect on natural hazards in glaciated regions. As glaciers retreat and permafrost thaws, new glacial lakes and unstable valley walls are forcing communities to adapt to the evolving hazards. A vivid reminder of the dangers these changes can pose came in 2016, when two low-angle glaciers in Tibet detached from their beds and avalanched down the valley, killing nine people. Of the 28 similar events in the historical record, 17 have occurred since the year 2000 -- suggesting that glacier detachments may be a newly emerging hazard. In this dissertation, I seek to understand what causes glacier detachments and whether we can infer past events from the resulting deposits. I begin by investigating the 2013 and 2015 detachments of Flat Creek Glacier in Alaska's St. Elias Mountains (Chapter 2). I conclude that these detachments were triggered by an unusually high input of meltwater to a glacier system prone to instability due to a weak glacier bed and a glacier tongue partially frozen to the ground. These are the same conditions that are believed to have led to the detachments in Tibet. In revealing this striking similarity, I provide the basis for determining which glaciers may be at risk of detaching. Furthermore, the demonstrated importance of liquid water as a trigger suggests that glacier detachments will increase in frequency as temperatures rise. To determine whether glacier detachments are indeed becoming more frequent, we need to know how often they occurred in the past. With a followup study at Flat Creek (Chapter 3), I provide the first detailed description of a detachment deposit and assess whether it can be distinguished from other types of glacio-fluvial deposits. I find that the detachments left behind unique features, including streamlined furrows, vast fields of densely-packed hummocks, and shallow thermokarst depressions. The deposits also lack a coarse-grained carapace or grain size sorting, further differentiating them from those formed by rock avalanches and debris flows. Based on these findings, glacier detachments can now be taken into account when interpreting the geologic record, both for the reconstruction of (paleo)environments and for reliable hazard assessments. Glacier detachments have demonstrated how incomplete our understanding of cryospheric hazards can be, and highlighted the need for better monitoring tools. In Chapter 4, I evaluate the power of interferometric coherence -- a data-quality metric produced as part of interferometric radar processing -- for assessing the pre-failure activity of slope instabilities. Using the example of the Mud Creek landslide in California, I show that a loss of coherence on the landslide, relative to the surrounding hillslope, can indicate instability months before the failure.

2022047601 Lanagan, KelleenImpact of soil water content on active layer dynamics in the Gates of the Arctic National Park and Preserve, Alaska: 55 p., Master's, 2021, University of Colorado at Boulder, Boulder, CO.

Much is still unknown about the current permafrost and hydrologic conditions of the Gates of the Arctic National Park and Preserve. In the shallow subsurface, ground temperatures are influenced by seasonal changes in atmospheric temperatures. In summer, warmer temperatures propagate downward from the ground surface to seasonally thaw the active layer, while cooler winter temperatures cause the active layer to freeze. Active layer dynamics are important in understanding hydrogeology in permafrost environments because the active layer can act as a shallow seasonal aquifer. The thickness of the active layer can be adequately approximated by solving for temperature with depth using heat conduction models. This study aims to address the questions: how do thermal properties of soil, including water content, affect active layer thickness in arctic soils? And how might warming ground surface conditions affect subsurface temperatures in material with different thermal and hydrogeologic properties? GIPL, a heat conduction model, is applied to peat, silt, and gravel-three soils that are present in the Nutuvukti Lake watershed in Gates of the Arctic National Park and Preserve-to simulate active layer thickness with various hydrothermal properties. GIPL is a 1D finite difference numerical model that simulates subsurface temperature with depth. Model results indicate that active layer thickness can vary by several meters based on the variations of water content in the three soil types. Increased soil water content that changes phase at the initiation of freezing can be achieved by increasing the pore size of the material, thereby decreasing the surface area between water and solid material, as well as increasing the soil porosity. Moreover, as soil water content increases, the effect of the latent heat of fusion also increases, resulting in generally cooler temperatures with depth during the thaw period. This may have implications for future scenarios of ground surface warming, as soils with greater water content may be less susceptible to permafrost thaw.

2022047989 Pedron, Shawn AlexanderImproving estimates of the permafrost carbon-climate feedback with year-round measurements, inventories, and ecosystem manipulations: 123 p., illus. incl. 5 tables, 222 ref., Doctoral, 2021, University of California at Irvine, Irvine, CA. Includes appendices.


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2022046712 Aga, Juditha (University of Oslo, Department of Geosciences, Oslo, Norway); Piermattei, Livia; Girod, Luc and Westermann, Sebastian. Coastal erosion dynamics of High-Arctic rock walls; insights from historical to recent orthoimages and DEMs [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9799, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The thermal regime of permafrost, as well as the retreat of sea ice, influence coastal erosion in Arctic environments. Warming permafrost temperatures might lead to enhanced instabilities, while shorter periods of sea ice expose coastal cliffs to waves and tides for longer periods. Although most studies focus on erosion rates in ice-rich permafrost, coastal cliffs and their permafrost thermal regime are still poorly understood. In this study, we investigate the long-term evolution of the coastline along Brogger Peninsula (~30 km2), Svalbard. Based on high-resolution aerial orthophotos and, when available, digital elevation model (DEMs) we automatically derive the coastline from 1936 (Geyman et al., 2021), 1970, 1990, 2011 and 2021. Therefore, we quantified coastal erosion rates along the coastal cliffs over the last 85 years. Due to their high spatial resolution and accuracy, the two DEMs from 1970 and 2021 are used to calculate the erosion volumes within this time. Elevation data and coastline mapping from 2021 is validated with dGPS measurements from August 2021 along three transects of the coastline. In addition, we measured surface temperature of the coastal bedrock from September 2020 to August 2021. Our preliminary results show erosion rates along the coastal cliffs of Brogger Peninsula. Uncertainties remain due to mapping issues, which include resolution of aerial images and DEMs, and shadow effects. Overall, historical aerial images combined with recent data provide insight into coastal evolution in an Arctic environment where permafrost temperatures are close to the thaw threshold and might become prone to failure in future.

DOI: 10.5194/egusphere-egu22-9799

2022046698 Bartsch, Annett (b.geos, Research and Development, Korneuburg, Austria); Widhalm, Barbara; Pointner, Georg; von Baeckmann, Clemens; Nitze, Ingmar; Grosse, Guido; Lantuit, Hugues; Irrgang, Anna; Boike, Julia and Vieira, Goncalo. Where is Arctic coastal infrastructure at risk? [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9094, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Infrastructure and anthropogenic impacts are expanding across the Arctic. A consistent record of human impact is required in order to quantify the changes and to assess climate change impacts on the communities. We derived a first panarctic satellite-based record of expanding infrastructure and anthropogenic impacts along all permafrost affected coasts (100 km buffer) within the H2020 project Nunataryuk based on Sentinel-1/2 satellite imagery. C-band synthetic aperture radar and multi-spectral information is combined through a machine learning framework. Depending on region, we identified up to 50% more information (human presence) than in OpenStreetMap. The combination with satellite records on vegetation change (specifically NDVI from Landsat since 2000) allowed quantification of recent expansion of infrastructure. Most of the expanded human presence occurred in Russia related predominantly to oil/gas industry. The majority of areas with human presence in this coastal zone will be subject to thaw by mid-21st century based on ground temperature trends derived from the ESA CCI+ Permafrost time series (1997-2019). Of specific concern in this context are also settlements located directly at permafrost affected coasts. An efficient erosion rate monitoring scheme needs to be developed and combined with settlement records and permafrost information in order to assess the risk for local communities and infrastructure. Relevant progress in the framework of the ESA EO4PAC project will be discussed. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-9094

2022046689 Bartsch, Unnur Blaer A. (University of Iceland, Department of Geography, Reykjavik, Iceland); Gisladottir, Gudrun and Grimsdottir, Harpa. Permathawing permafrost [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8176, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost is perennially frozen ground occurring in about 24% of the exposed land surface in the northern hemisphere. The soil categorized as permafrost is named cryosol (or gelisol). Cryosol is widely spread in the Arctic, where it is continuous in the polar regions while in the sub-arctic it is discontinuous or sporadic. Iceland is located on the edge of the Arctic, and therefore permafrost can be found in many regions of the island. In addition, the frost effect is great, due to the unique climate and weather conditions and the high sensitivity of the Icelandic soil (volcanic soil--andosol). Although the distribution of permafrost is widespread it is in many respects dependent on the weather. As the climate warms, as it does now, the permafrost retreats rapidly, causing major changes in the earth's surface. These changes can be accompanied by various dangers. In Iceland the retreat of permafrost in high mountains has led the top slopes to become unstable, leading to increased risk of landslides and similar hazards. In this project, permafrost in Iceland will be examined, more specifically the areas where permafrost is considered to be thawing and the dangers that accompany that thawing. The research area is by Strandartindur mountain in Seydisfjordur. On the slope of Strandartindur is a rock glacier, which is in motion, but it is believed that permafrost is hidden in the ground beneath. The area is a well-known landslide area, where the source of landslides high up in Strandartindur is thick sediments that are partly considered permafrost or rock glaciers. Rock glaciers and thawing of permafrost in the vicinity and/or in the glacier threaten settlements in the area, due to landslides. This will be a threefold multidisciplinary project where aspects of natural hazards and society will be tied together; (i) data from soil thermometers and InSAR data will be examined, (ii) discussed and examined how permafrost can be included in monitoring, (iii) and how information on the dangers associated with permafrost can be disseminated to residents and the general public. The project will be useful for monitoring the hazard area at Strandartindur, while also for monitoring comparable areas in the country. It is hoped that the product of this project will be a monitoring research proposal. The result will show how best to measure permafrost, how best to monitor its thawing and how best to provide information to residents and the general public. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8176

2022046708 Bergstedt, Helena (bgeos, Korneuburg, Austria); Jones, Benjamin; Grosse, Guido; Veremeeva, Alexandra; Breen, Amy; Liljedahl, Anna; Bartsch, Annett; Gaglioti, Benjamin; Bouchard, Frédéric; Hugelius, Gustaf; Nitze, Ingmar; Wolter, Juliane; Hinkel, Kenneth; Farquharson, Louise; Fuchs, Matthias; Kanevskyi, Mikhail; Roy-Leveillee, Pascale and Lantz, Trevor. Drained lake basins on a circumpolar scale; updates from the IPA Action Group [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9681, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Lakes and drained lake basins (DLB) are ubiquitous landforms in permafrost regions. The long-term dynamics of lake formation and drainage is evident in the abundance of DLBs covering 50% to 75% of arctic permafrost lowlands in parts of arctic Alaska, Russia, and Canada. Following partial or complete drainage events, DLBs evolve through time. As the basins age and ground ice enrichment occurs, the surface heaves and vegetation communities evolve, exhibiting spectral and texture differences indicative of these changing conditions. This mosaic of vegetative and geomorphic succession and the distinct differences between DLBs and surrounding areas can be discriminated and used to make a landscape-scale classification employing various indices derived from multispectral remote sensing imagery that, when combined with field sampling and peat initiation timing, can be used to scale across spatial and temporal domains. Previously published local and regional studies have demonstrated the importance of DLBs regarding carbon storage, greenhouse gas and nutrient fluxes, hydrology, geomorphology, and habitat availability. A coordinated pan-Arctic scale effort is needed to better understand the importance of DLBs in circumpolar permafrost-regions. Here we present an update of ongoing work within the Action Group on DLBs supported by the International Permafrost Association (IPA), an effort by the community to develop a first pan-Arctic drained lake basin data product. Comprehensive mapping of DLB areas across the circumpolar permafrost landscape will allow for future utilization of these data in pan-Arctic models and greatly enhance our understanding of DLBs in the context of permafrost landscapes. Utilizing remote sensing imagery (Landsat-8) and freely available DEM data sets (e.g. ArcticDEM) allows us to implement our mapping approach on a circumpolar scale. A previously published prototype of this data product covering the North Slope of Alaska forms the basis of this large-scale mapping effort. Here we present first result working towards a pan-Arctic remote sensing-based DLB data product focussing on selected areas in Canada and Siberia, Russia. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-9681

2022046695 Bröder, Lisa (Swiss Federal Institute of Technology, Department of Earth Sciences, Zurich, Switzerland); Lattaud, Julie; Juhls, Bennet; Eulenburg, Antje; Priest, Taylor; Fritz, Michael; Matsuoka, Atsushi; Pellerin, André; Bossé-Demers, Thomas; Rudbäck, Daniel; O'Regan, Matt; Whalen, Dustin; Haghipour, Negar; Eglinton, Timothy; Overduin, Paul and Vonk, Jorien. Tracing the footprint of permafrost carbon supply to the Canadian Beaufort Sea [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8694, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Canadian Beaufort Sea receives large quantities of sediment, organic carbon and nutrients from rapid coastal erosion and permafrost degradation. In addition, the Mackenzie River, the largest North American Arctic river, discharges great amounts of freshwater, dissolved solids and suspended sediments to the Beaufort Sea. Current changes in these fluxes in response to the warming climate have uncertain consequences for the carbon budget on the shelf and in the deep ocean. To investigate the movement and transformation of organic matter along the land-ocean continuum, we collected water and surface sediment samples along five major transects across the Beaufort Sea during the 2021 expedition of the Canadian Coast Guard Ship Amundsen. Sampling locations span from shallow, coastal, sites with water depths ≤&eq;20 m, to shelf-break and deep-water settings on the continental slope (water depths of >&eq;1000 m). For this study, we use stable and radiocarbon isotopic (d13C and 14C) analyses of dissolved inorganic (DIC), dissolved organic (DOC) and particulate organic carbon (POC) for surface and bottom waters, as well as surface sediments, in order to compare, contrast and constrain the relative source contributions and ages of these different forms of carbon. Our results will help to better understand the fate of permafrost organic matter in the marine environment and to ultimately improve assessments of the Canadian Beaufort Sea shelf as a carbon source or sink and its potential trajectory with ongoing environmental changes. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8694

2022046696 Churakova, Olga V. (Siberian Federal University, Institute of Ecology and Geography, Krasnoyarsk, Russian Federation); Zharkov, Mikhail S.; Fonti, Marina V.; Trushkina, Tatyana V.; Barinov, Valentin V.; Taynik, Anna V.; Porter, Trevor J.; Kirdyanov, Alexander V.; Arzac, Alberto and Saurer, Matthias. Tree-ring oxygen isotope patterns from Siberian and Canadian subarctic to test usability of local versus gridded climate data [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8756, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Rapid temperature and vapor pressure deficit (VPD) increase along with precipitation decrease over the past decades lead to massive wildfires and permafrost degradation in boreal forests. Conifer trees growing in subarctic regions are highly sensitive to these climatic changes due to their location at the high latitudes, where air temperature is the limiting factor, but also water relations have a strong impact on tree growth. In this study, we aimed (i) to assess the usability of local vs. gridded climate data; (ii) to reveal how conifer trees capture temperature and moisture signals based on the local weather station data vs. gridded data from the two Siberian sites in northeastern Yakutia and eastern Taimyr, and one site from northwestern Canada in Mackenzie Delta; (iii) to perform trend analysis of climatic data and d18O in tree-ring cellulose; and (iv) to carry out spatial correlation analysis of oxygen isotope patterns and determine the distribution of climatic signal over broad geographical scales in the Siberian and Canadian subarctic. Comparative analysis of the local and gridded climatic data (air temperature, precipitation and VPD) for the three study sites showed that mainly temperatures are highly correlated between each other. Subarctic trees grow in a temperature-limited environment; therefore, the large spatial coherence of temperature signals is not surprising. Conversely, insignificant correlations between local and gridded for precipitation and rather low correlations for VPD is attributed to the more heterogeneous nature of moisture variables at larger spatial scales. Therefore, analyzing moisture changes in the subarctic using local weather station data is advantageous compared to gridded data. Trend analysis of the climate data showed that drastic changes in climate variability occurred from the 1980s in the investigated subarctic regions and were even more pronounced from 2000 to 2021. Recent warming and development of drought conditions were stronger in the Canadian subarctic than the Siberian subarctic sites. Drastic precipitation changes, temperature and VPD increase mainly occurred during winter, spring and autumn in the studied subarctic regions. New updated stable isotope chronologies from remote subarctic regions allowed us to accurately reconstruct moisture changes using precipitation and VPD data from the local weather stations while reconstructing air temperature using gridded data. This research was funded by the Russian Science Foundation (RSF) grant number 21-17-00006. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8756

2022046681 Cusicanqui, Diego (Université Grenoble Alpes, Institut de Géosciences de l'Environnement, Grenoble, France); Bodin, Xavier; Rabatel, Antoine; Duvillard, Pierre Allain; Revil, Andre; Schoeniech, Philippe and Berthet, Johan. Glacier-permafrost interactions and GLOF's; insights from 7 decades of kinematics and elevation changes in the southern French Alps [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7659, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The mountain cryosphere is currently undergoing substantial modifications in an unprecedented short period of time. As effects of climate change becomes important, understanding the glacier and periglacial dynamics that lead to complex and delayed responses is timely. The spatial and functional interactions between landforms within these environments may strongly influence their processes (e.g., ablation, accumulation), usually studied in two separate research paths (i.e., glaciology and geomorphology). Very little research has focused on glacial and periglacial systems, where several perennial cryospheric elements (debris-covered glaciers, rock glaciers) are intertwined. Here, a multidisciplinary approach is proposed combining (i) Structure from Motion on historical, modern aerial images and spaceborne images, (ii) geophysical with Electrical Resistivity Tomograms, and (iii) geomorphological surveys. The purpose is to quantify and describe morphometric changes over seven decades (1940-2020) at the Chauvet glacial and periglacial system (Southern French Alps, 44.85°N, 6.84°E). This study site is critical in terms of natural hazards because at least six Glacier Lake Outburst Floods were recorded during the 20th and 21th centuries, likely related to the permafrost degradation, the presence of a thermokarstic lake and an englacial conduit within the ice. Complex spatio-temporal patterns and functional interactions between different landforms were evidenced. In the upper part of the valley, a small debris-free glacier turns downvalley into a debris-covered glacier occupying most of the central part of the valley. Further downslope, a rock glacier developed. The contrasting developments and landform responses are documented with multi-temporal DEMs and ortho-images. Very low thinning rates and surface velocities (<0.5 m a-1) were observed on the rock glacier, whereas the adjacent debris-covered glacier presents intermediate thickness losses (>1 m a-1) and higher surface velocities. However, the contact zone between the dead debris-covered and the rock glacier shows clear signs of mass down-wasting and complex interplay of phenomena such as thermokarst melting of massive ice and the flow towards the topographic depression. An important speed-up of the horizontal displacements since the 1990s and an important surface lowering have most probably conditioned the dynamics of the observed outburst-floods. Those seem to be a complex combination of several processes affecting the different cryospheric elements. (i) the well-developed thermokarst lake over debris-covered area, on the topographic depression (i.e., bucket shape with barriers damming the lake) which is mainly controlled by the bedrock morphology and evolution of the surface topography. The current capacity of this depression has been estimated to 180,000±350 m3. (ii) the specific glacio-geomorphological dynamics of debris-covered and the rock glacier units, which dynamics influence the opening/enlargement and closure of the englacial conduit. (iii) the hydro-meteorological conditions (e.g., enhanced snow melt in late spring) probably impacts the hydrology, water filling and the lake outflow. The findings of this study highlight the relationships between glacial and periglacial features and their long-term evolution. The systemic study of GLOF formation processes would lead to a better identification of sites at risk and to the implementation of more robust prevention procedures in order to face the environmental and societal challenges of climate change. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7659

2022046741 Dannenmann, Michael (Karlsruhe Institute of Technology, Biosphere-Atmosphere interactions under Global Change, Garmisch- Partenkirchen, Germany); Ramm, Elisabeth; Liu Chunyan; Ambus, Per; Butterbach-Bahl, Klaus; Hu Bin; Martikainen, Pertti J.; Marushchak, Maija E.; Mueller, Carsten W.; Rennenberg, Heinz; Schloter, Michael; Siljanen, Henri M. P.; Voigt, Carolina; Werner, Christian and Biasi, Christina. A review of the importance of mineral nitrogen cycling in the plant-soil-microbe system of permafrost-affected soils; changing the paradigm [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-11621, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The paradigm that permafrost-affected soils show restricted mineral nitrogen (N) cycling in favor of organic N compounds is based on the observation that net N mineralization rates in these cold climates are negligible. However, we find here that this perception is wrong. By synthesizing published data on N cycling in the plant-soil-microbe system of permafrost ecosystems we show that gross ammonification and nitrification rates in active layers were of similar magnitude and showed a similar dependence on soil organic carbon (C) and total N concentrations as observed in temperate and tropical systems. Moreover, high protein depolymerization rates and only marginal effects of C:N stoichiometry on gross N turnover provided little evidence for N limitation. Instead, the rather short period when soils are not frozen is the single main factor limiting N turnover. High gross rates of mineral N cycling are thus facilitated by released protection of organic matter in active layers with nitrification gaining particular importance in N-rich soils, such as organic soils without vegetation. Our finding that permafrost-affected soils show vigorous N cycling activity is confirmed by the rich functional microbial community which can be found both in active and permafrost layers. The high rates of N cycling and soil N availability are supported by biological N fixation, while atmospheric N deposition in the Arctic still is marginal except for fire-affected areas. In line with high soil mineral N production, recent plant physiological research indicates a higher importance of mineral plant N nutrition than previously thought. Our synthesis shows that mineral N production and turnover rates in active layers of permafrost-affected soils do not generally differ from those observed in temperate or tropical soils. We therefore suggest to adjust the permafrost N cycle paradigm, assigning a generally important role to mineral N cycling. This new paradigm suggests larger permafrost N climate feedbacks than assumed previously. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-11621

2022046763 de Bruin, Jelte (Universiteit Wageningen, Environmental Sciences Group, Wageningen, Netherlands); Bense, Victor and van der Ploeg, Martine. Inferring permafrost thermal properties from freeze-thaw column experiments and numerical modelling [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12968, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Cold-regions contain a vast pool of organic carbon in permafrost, which is currently immobilized. As the global air temperatures rise, permafrost active layer depths are increasing. The deepening of the active layer reactivates groundwater transport processes, leading to the release of solutes such as dissolved carbon to streams and the atmosphere. In order to make predictions of the rates of permafrost thaw based upon numerical modeling, we need accurate data on active layer thermal properties. Active layer thermal properties, thermal conductivity and heat capacity, are strongly coupled to geological properties such as water content, and organic matter content and are therefore highly heterogenous in natural systems. Furthermore, the effective thermal properties vary as a function of temperature through ice-content, especially across the freeze-thaw interval near 0°C. Direct in-situ observations of active-layer thermal properties are rare because in-situ measurements involves sampling of frozen samples and analysis in a laboratory. This study uses soil column (1 m high´0.31 m diameter) experiments to investigate the relation between soil physical properties and thermal properties. A total of nine samples were synthesized using a range of grain sizes and organic matter contents, and were fully saturated with water. The columns were insulated on the sides and top, aiming to create a fully 1D thermal system allowing only vertical heat transport. The columns are subjected to one freeze-thaw cycle, lasting about 20 weeks. Resulting temperature observations were analyzed using a numerical heat transfer model. By fitting the temperature observations to the heat transfer model, thermal properties can be inferred. Initial data shows differences in heat propagation through the soil column, indicating differences in thermal conductivity and heat capacity as a result of varying soil grain size and organic matter content. This research will help to link permafrost soil physical properties to thermal properties, and increase understanding at the dynamic freeze-thaw interval. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12968

2022046759 Diak, Magdalena (Polish Academy of Sciences, Institute of Oceanology, Sopot, Poland); Borecka, Marta; Böttcher, Michael E.; Hong, Wei-Li; Knies, Jochen; Kotwicki, Lech; Kulinski, Karol; Lepland, Aivo; Koziorowska-Makuch, Katarzyna; Sen, Arunima; von Ahn, Catia M. E.; Winogradow, Aleksandra and Szymczycha, Beata. Permafrost and groundwater interaction [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12719, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost is defined as perennially frozen ground (soil or rock and included ice and organic material) with a temperature near or below 0°C that remains for at least two consecutive years. Permafrost occurs mainly in high latitudes of the Southern and Northern Hemispheres, but significant area can also be found in the middle- and low-latitude regions. In these areas, the groundwater cycle is mainly controlled by the permafrost layer that may act as an aquiclude and hence block or retard the groundwater flow. However, rapid climate changes which are observed during the last decades, markedly contribute to permafrost degradation. New connections between permafrost and groundwater are expected to form during the permafrost thawing process. This will contribute to enhance permafrost and groundwater interaction and reinforce groundwater discharge. In general, groundwater discharge is a groundwater movement from the saturated ground to the surface water bodies or submarine groundwater inflow into the sea. Increased groundwater discharge may transport a significant amount of nutrients, metals, and gases to land and ocean waters and hence may change their physicochemical parameters. Unfortunately, due to the limited number of studies, understanding the significance of groundwater discharge in the Arctic regions is limited. The study aims to provide a comprehensive review of the present literature data that contribute to better understanding interaction between permafrost and groundwater in the Arctic regions, which are particularly vulnerable to climate changes. This review is focused on permafrost thawing, groundwater discharge, and recharge processes and their implication on the environment. We attempt to answer the following questions: How does permafrost affect groundwater discharge and recharge? Does permafrost act as a hindrance for groundwater? How does progressive global warming and thereby permafrost thawing impact the groundwater discharge? How significant is groundwater discharge? How important is the transport of different solutes to the environment by groundwater discharge? Based on the literature, we can conclude that the degradation of permafrost greatly influences hydrological systems in cold zones. Permafrost has a strong impact on fluid dynamics caused by negligible hydraulic conductivity. This relationship, beyond all physical, chemical, and biogeochemical responses, contributes to the formation of complex permafrost-groundwater interactions. Permafrost degradation strongly affects the ecosystem through direct and indirect impacts on the transport and cycles of different compounds, elements, and ions. Moreover, all processes are dependent on topography, geomorphology, tectonics, and surface hydrology. Research conducted in other than Arctic permafrost areas also indicated that permafrost thawing is the cause of enhanced groundwater recharge and discharge rates, which resulted in deeper water tables and groundwater flow paths. However, comprehensible and systematic studies are still needed for global assessment also in terms of searching for interdependencies between different regions. This belongs to Project No. 2019/34/H/ST10/00645 "Submarine Groundwater Discharge in a Changing Arctic Region: Scale and Biogeochemical impact", which is supported by the Norwegian Financial Mechanism and Polish national Basic Research Program. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12719

2022046734 Dorodnikov, Maxim (Georg-August-Universität Göttingen, Büsgen-Institute, Gottingen, Germany); Manasypov, Rinat; Fan, Lichao; Pokrovsky, Oleg; Dippold, Michaela A. and Kuzyakov, Yakov. The size matters; aerobic methane oxidation in thermokarst lake sediments in western Siberia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-11190, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Thermokarst lakes of permafrost peatlands in Western Siberia are among the most important sources of greenhouse gases (GHG) such as CO2 and CH4 because of current permafrost thawing due to climate change. Field measurements demonstrated the increase of dissolved GHG concentrations with the decreasing lake size due to higher concentration of coastal-derived organic C in water of small lakes. However, the size-dependent mechanisms of the GHG production and consumption (e.g. CH4 oxidation) in the sediments of these lakes remain poorly known. We estimated aerobic CO2 production and CH4 oxidation potentials based on natural 13C abundance and 13C labeling in two layers of upper 20 cm sediments of three thermokarst lakes: small (~300 m2), medium (~3000 m2) and large (~1 km2). We hypothesized that i) specific CO2 production (per gram of sediment) decreases with increasing lake size, but CH4 oxidation increases, and ii) both processes are more intensive in the upper 10 cm of sediments than in deeper 10-20 cm, due to naturally occurring O2 gradients and the available C. As expected, CO2 production in the upper layer was 1.4-3.5 times higher than in the deeper layer and the rate of production increased from large (170 nmol CO2 g-1 d.w. h-1) to medium (182) and small (234) lakes. In contrast to CO2, CH4 oxidation in the uppermost sediment layer was similar between lakes, while the deeper layer in the large lakes had 12- and 73-fold higher oxidation rates (5.1 nmol CH4-derived CO2 g-1 d.w. h-1) than in small and medium lakes, respectively. This was attributed to the fact that the O2 concentration in the water of large lakes is higher than in smaller lakes due to the intense turbulence caused by wind and waves. Due to the ongoing and future thawing of permafrost, smaller lakes will increase in size, so that a large part of the CH4 produced in the sediments will be oxidized. However, this process can be (over)compensated by the increased formation of new small lakes. From an ecological perspective, the sediments of shallow thermokarst lakes in the discontinuous permafrost zone of Western Siberia could oxidize up to 0.48 Tg C as CH4 in the summer period, with the largest contribution coming from the large lakes. This confirms the key role of the thermokarst lake ecosystems as a global hotspot of GHG turnover. Acknowledgement. This work was supported by RSF grant No. 21-77-10067 and the German Academic Exchange Service (DAAD). [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-11190

2022046687 Eberle, Anne (University of Bristol, School of Earth Sciences, Bristol, United Kingdom); Gallego-Sala, Angela; Kappler, Andreas; Pancost, Richard D. and Bryce, Casey. Variability of mineral protection of organic matter in thawing permafrost peatlands [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8158, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost preserves huge amounts of carbon in Arctic soils including peatlands, which are common in high latitudes. The potential for carbon release from these peatlands upon permafrost thaw is still a big uncertainty for climate predictions. Protection of organic matter against microbial degradation by association with minerals such as iron minerals has been identified as an important stabilization mechanism for organic carbon in soils. In a permafrost peatland in northern Sweden (Stordalen mire) up to 20% of organic carbon was found associated with iron minerals in oxic peat layers. However, upon thaw and collapse of frozen peat, reducing conditions cause microbial iron reduction and dissolution of minerals, therefore releasing associated carbon. Despite the prevalence of peatlands in the permafrost zone, little is known about the variability and overall importance of mineral protection in permafrost peatlands, and it is still uncertain how this will change upon collapse of palsas (frozen peat mounds). Following optimization of a protocol for Fe-OC quantification from peat, we sampled peat cores and pore water from different thawing palsas in the Tornetrask area of northern Sweden to quantify iron-carbon associations across different sites and estimate the changes in geochemistry upon permafrost thaw. Understanding these changes and differences between peatlands will help to predict the role of permafrost peatlands for carbon emissions triggered by permafrost thaw across larger geographical areas. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8158

2022046721 Frey, Holger (Universität Zürich, Department of Geography, Zurich, Switzerland); Allen, Simon; Huggel, Christian and Sharma, Divya Kashyap. Glacier and permafrost hazard and risk management; from science to policy and implementation [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10234, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Glacier and permafrost hazards in cold mountain regions encompass various flood and mass movement processes that are strongly affected by climate change. Rising temperatures cause glacier retreat, permafrost thawing and degradation, with underground warming continuously propagating at greater depths. These cumulative changes, happening at different time scales, generally exacerbate slope stability and increase the probability for destructive mass movement events. Outbursts of glacial lakes, which are newly forming and growing with glacier retreat, are destructive processes with potential reaches of several hundreds of kilometers. These events often involve chains of cascading and interacting mass movement processes, threatening mountain communities which are typically highly vulnerable, but also putting at risk critical infrastructure such as roads, buildings, agricultural land and hydropower installations. Here we present a series of research and cooperation projects, funded by the Global Programme Climate Change and Environment of the Swiss Agency for Development and Cooperation (SDC). These projects supported the development of guidelines for hazard assessment, contributed substantially to the elaboration of risk management guidelines for Glacial Lake Outburst Floods (GLOFs) for India, and eventually led to supporting the design and implementation of a GLOF Early Warning System (EWS) in Sikkim, India. From 2016 to 2017, a large consortium of international experts from the Standing Group on Glacier and Permafrost Hazards (GAPHAZ) of the International Association of Cryospheric Sciences and International Permafrost Association (IACS/IPA), elaborated a technical guidance document on the assessment of glacier and permafrost hazards in mountain regions. This guidance document reflects the current state-of-the-art of future oriented, scenario based hazard assessment and mapping, supported by physically based, numerical models. Building on that, scientists involved in the elaboration of this document have been invited as international experts in the elaboration of Guidelines for the Management of Glacial Lake Outburst Floods for India, led by the National Disaster Management Authority (NDMA) of the Indian Government. This document builds on the concepts in the GAPHAZ guidelines, but beyond hazard assessment includes also relevant aspects of risk management and DRR, while being specifically tailored to the situation of Indian Himalayan States. Currently efforts are ongoing to implement a multi-lake EWS in the Teesta River Basin in Sikkim, India with the support of NDMA. This project, which also involves the government of Sikkim, local stakeholders, Swiss universities and companies and SDC, is considered by NDMA as a pilot study for the implementation of the new GLOF management guidelines described above. These continued long-term efforts provide invaluable learnings on collaborative scientific efforts, transdisciplinary work at the science-policy interface, and joint efforts of the academia, public and private sector towards real world applications of disaster risk management under challenging conditions. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10234

2022046686 Gartler, Susanna (Universität Wien, Department of Social and Cultural Anthropology, Vienna, Austria); Larsen, Joan Nymand; Ingimundarson, Jon Haukur; Schweitzer, Peter; Povoroznyuk, Olga and Meyer, Alexandra. A risk analysis framework; key risks from permafrost thaw in Arctic coastal areas [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7937, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

This paper presents the results from fieldwork conducted in three focal areas of the "Nunataryuk" EU H2020 permafrost project: the Nordic Area (Greenland and Svalbard), the Beaufort Sea Area in Canada (Northwest Territories/Inuvialuit Settlement Region and Gwich'in First Nation Traditional Territory) and Northeastern Siberia in Russia. The paper analyzes the entanglement between social and environmental change and presents a risk analysis framework, including the interconnected geo-physical & socio-cultural risks, with the aim to improve adaptation and mitigation strategies of local communities. Guided by a mixed-methods approach, the research outcomes are the result of field-based research, including focus groups, qualitative interviews, participant observation, community workshops--as well as a quantitative survey in three settlements (Qeqertarsuaq in Greenland, Aklavik in Canada and Longyearbyen on Svalbard). [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7937

2022046703 Grau, Oriol (University of Antwerp, Plants and Ecosystems, Wilrijk, Belgium); Margalef, Olga; Joosten, Hans; Richter, Andreas; Canarini, Alberto; Dorrepaal, Ellen; Keuper, Frida; Sardans, Jordi; Peñuelas, Josep and Janssens, Ivan. Biogeochemical responses of plants, soils and microbes to permafrost degradation in a subarctic peatland [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9369, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost peatlands are particularly sensitive to climate warming. The thawing of permafrost in these ecosystems accelerates the decomposition of old organic matter in deep soil layers and reactivates the cycling of carbon (C) and nutrients. Several studies showed that the thawing of permafrost in subarctic peatlands increases nitrogen (N) availability, ecosystem productivity as well as methane (CH4) and C dioxide (CO2) emissions. The mobilisation of other nutrients like phosphorus (P) or potassium (K) and the stoichiometric changes occurring in plants, soils and microbes in these fragile ecosystems are nevertheless poorly understood. In June 2018 we collected plant and soil samples across several permafrost thaw gradients in a palsa mire complex at Stordalen (Abisko, 68°N, Sweden). We selected three contrasting situations across the gradients: a) peat mounds with an intact permafrost core ('palsa' areas), b) semi-degraded palsas ('transition' area), and c) completely degraded palsas with no permafrost ('collapsed' area). For each situation we collected samples of the aboveground vegetation and soil samples at 5-10, 40-45, 70-75 and 95-100 cm (layers A-D), encompassing peat (A and B) and mineral soil layers (C and D). We determined total C, N, P and K, extractable organic C (EOC), total extractable N (TEN), extractable organic N (EON), ammonium (NH4+), nitrate (NO3-), extractable organic and inorganic P (EOP and EIP), microbial enzymatic activity, microbial C, N and P and pH in soil samples at each of the four depths across the gradient. We also determined total C, N, P and K in aboveground vegetation samples. The uppermost soil layer A showed the most statistically significant changes across the gradient of permafrost thaw, namely a 2-fold increase of total N and total P, 3- fold increase of EIP, 4-fold increase of EOP and 5-fold increase of NH4+, along with an increase of potential extracellular enzymatic activity. The fraction of total P immobilised by microbes was highest in the uppermost soil layer of palsas, where microbial P reached 33% of total P. In layer B, there were also several significant changes, such as a 4-fold increase of EOC and TEN and 12-fold increase of NH4+ in transition areas, and a 4-fold increase of EOP in collapsed areas. In addition, foliar chemistry changed significatively across the gradient of permafrost thaw, with a generalised increase of N, P and K, and a decrease of the CN and NP ratios. Along with these changes in foliar chemistry there was an increase of the stocks of N, P and K in biomass across the gradient. The biogeochemical and stoichiometric changes observed in plants, soil and microbes at different soil layers and across the gradient of permafrost thaw evidence that ongoing and future environmental changes will have a major impact on the functioning of these fragile ecosystems in the Subarctic. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-9369

2022046693 Grob, Henrik (Christian-Albrechts-Universität zu Kiel, Kiel, Germany); Riedel, Michael; Duchesne, Mathieu J.; Krastel, Sebastian; Restrepo, Jefferson Bustamante; Fabien-Ouellet, Gabriel; Kläschen, Dirk; Preine, Jonas; Jin, Young Keun and Hong, Jong Kuk. Using different seismic approaches to detect submarine permafrost and gas hydrates on the continental Beaufort Shelf of the Canadian Arctic [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8555, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

In the Canadian Arctic, permafrost and permafrost-associated gas hydrates formed extensively during the last 1 Ma. After the last glaciation, a marine transgression followed and former terrestrially exposed shelf areas became submerged. Subaerial mean annual temperatures of -20°C or even less changed to present submarine bottom water temperatures near -1°C. The relict submarine permafrost and gas hydrates present in the Beaufort Sea still react to this ongoing thermal change which results in their continued degradation. Thawing permafrost and destabilisation of permafrost-associated gas hydrates may release previously trapped greenhouse gases and can lead to even further gas hydrate dissociation. Moreover, thawing permafrost poses a geohazard in form of landslides and ground collapses. Yet, both the extent of the submarine permafrost and the permafrost-associated gas hydrates are still not well known. Here, we present three different approaches using marine 2D multichannel seismic data to improve the current knowledge of the distribution of offshore permafrost and gas hydrates occurrences in the southern Canadian Beaufort Sea. The acoustic properties of permafrost are determined by the content of ice and unfrozen pore fluids. Changing permafrost conditions affect the elasticity of the medium making seismic methods appropriate for permafrost detection. First, we identify direct and indirect seismic reflection indicators from permafrost and gas hydrates by the presence of cross-cutting, polarity-reversed, and upward-bend reflections as well as velocity pull-ups and shallow pronounced high-amplitude reflections. Second, using diving-wave tomography provides insights into the near-surface permafrost structure by imaging the velocity structure in greater detail than achievable by standard velocity analyses. And third, diffractions separated from the reflected wavefield yield insights into the sub-wavelength architecture of the permafrost realm on the southern Canadian Beaufort Shelf that may add information about weak phase-boundaries and small-scale heterogeneities. All methods are applied to seismic lines crossing the outer continental margin, where a maximum thermal effect of the transgression is expected, and thus a maximum lateral variation in permafrost and permafrost-associated gas hydrate phase boundaries is expected to be present. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8555

2022046724 Groenke, Brian (Alfred Wegener Institute, Potsdam, Germany); Langer, Moritz; Gallego, Guillermo and Boike, Julia. A probabilistic analysis of permafrost temperature trends with ensemble modeling of heat transfer [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10509, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Over the past few decades, polar research teams around the world have deployed long-term measurement sites to monitor changes in permafrost environments. Many of these sites include borehole sensor arrays which provide measurements of ground temperature as deep as 50 meters or more below the surface. Recent studies have attempted to leverage these borehole data from the Global Terrestrial Network of Permafrost to quantify changes in permafrost temperatures at a global scale. However, temperature measurements provide an incomplete picture of the Earth's subsurface thermal regime. It is well known that regions with warmer permafrost, i.e. where mean annual ground temperatures are close to zero, often show little to no long-term change in ground temperature due to the latent heat effect. Thus, regions where the least warming is observed may also be the most vulnerable to rapid permafrost thaw. Since direct measurements of soil moisture in the permafrost layer are not widely available, thermal modeling of the subsurface plays a crucial role in understanding how permafrost responds to changes in the local energy balance. In this work, we explore a new probabilistic method to link observed annual temperatures in boreholes to permafrost thaw via Bayesian parameter estimation and Monte Carlo simulation with a transient heat model. We apply our approach to several sites across the Arctic and demonstrate the impact of local landscape variability on the relationship between long term changes in temperature and latent heat. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10509

2022046685 Hendrickx, Hanne (Universiteit Ghent, Department of Geography, Ghent, Belgium); Delaloye, Reynald; Nyssen, Jan and Frankl, Amaury. Geomorphic responses at the permafrost margins; observations from the Swiss Alps [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7928, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The warming and thawing of permafrost creates a multitude of geomorphic responses. Warm permafrost areas, with temperatures between -2° and 0°C, are especially affected because of the occurrence of pressurized water at the bounding of the ice/rock contact, which is very sensitive to any temperature change. In mountain permafrost regions, this implies that geomorphic response will first be observed at lower elevations, close to the permafrost margins, before shifting upwards as the climate changes. In addition, an increased surface summer runoff related to the rising elevation of rain precipitation, more severe rainfall events and a reduced extent of snow patches can be observed. Therefore, there is a need for a detailed monitoring of these critical areas, where climate change induced processes will first occur, to improve our understanding of the landscape evolution in mountainous regions. For this purpose, four common mountainous periglacial landforms, a rock wall, a debris flow affected talus slope, a rock glacier and a rockslide are monitored in high temporal and spatial resolutions. These landforms are important steps in the alpine sediment cascade, potentially acting as a sediment source or sink depending on their connectivity within the landscape. Several close range sensing techniques were combined (GNSS data, archival aerial photographs, uncrewed aerial vehicles, terrestrial laser scanning, time-lapse photography and seismic data), providing multiple lines of evidence. Limitations related to the sensor and monitoring intervals were overcome by the integration of the different datasets. Especially in the European Alps, where monitoring activities have been ongoing for decades with an increased instrumentation, this approach unlocks interesting research paths. All four studied landforms show a clear response to the present-day climate change. We observed a 2-year rock wall destabilisation with an unprecedented level of detail, including a precursory deformation of the rock wall, a process already ongoing before the start of the monitoring. The deep permafrost bedrock that was exposed after large cliff falls (104-106 m3) has already been out of equilibrium with the surface temperature for three decades. On the studied talus slope, a high magnitude debris flow event (3´104 m3, various surges) was recorded in summer 2019 as a result of several convective thunderstorms, exceeding all historical debris flow events since 1946. Rock glacier acceleration (up to 15 m yr-1) and destabilisation has been observed, in this case delivering a considerable volume of debris to steep torrential gullies where it can be mobilised again in the form of debris flows. The Grabengufer rockslide, one of the only permafrost-affected active rock slide accurately monitored in the Alps, is continuously accelerating (from 0.3 to >1 m y-1 in a bit more than a decade). Although all our observations are study area specific, similar observations have been made elsewhere in the European Alps. Therefore, the high resolution spatial and temporal data collected in this study deepens the insight in processes increasingly occurring throughout the Alps. By doing so, this research contributes to the understanding of high mountain geomorphology in a changing climate. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7928

2022046730 Hu Yufeng (Chang'an University, College of Geological Engineering and Geomatics, Xi'an, China) and Wang Jiatong. Simultaneous estimation of snow depth and freezing-ground uplift by GPS interferometric reflectometry over a permafrost area [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10858, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Ground surface movements and snow cover during freeze/thaw cycles of permafrost are important variables for studying climate change. GPS-IR has emerged as an effective technique to estimate the relative elevation changes of ground surface such as the thaw subsidence of frozen ground and snow depth variations. In permafrost areas, the freezing process of the ground is always accompanied by the snow accumulations, making it hard for GPS-IR to separate these two distinct signals from the estimated elevation changes. In this study, using the Signal to Noise Ratio (SNR) collected by a permafrost GPS site SG27 (Northern Alaska) in 2018, we proposed a physical model-based method to simultaneously estimate the daily snow depths and freezing-ground uplifts with GPS-IR. First, we applied GPS-IR to the SNR data to obtain the daily elevation changes of the ground surface from September 1 in 2018 to August 31 in 2019. The elevation change measurements indicate the onset of snow season on October 18 in 2018 and the end of snow-cover on June 15 in 2019. Second, we used the thermal index Accumulated Degree Days of Freezing (ADDF) calculated from the temperature records to determine the onset of the permafrost freezing season as of September 17 in 2018. Third, we fitted the Stefan function to the estimated elevation changes (i.e. freezing-ground uplifts) from September 17 to October 18 in 2018. The Stefan model agrees with the freezing uplifts with an R2 of 0.65. Forth, we extended the fitted model to the time when the ground was completely frozen (November 1) to estimate daily freezing-ground uplifts up to 1.75 cm under the snowpack. Last, we extracted the snow depths from the estimated elevation changes by subtracting the corresponding freezing-ground uplifts. Our study is the first attempt to simultaneously estimate the daily freezing-ground uplifts and snow depths over the permafrost area with GPS-IR, providing the measurements to understand the coupling effects of the permafrost and snow cover. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10858

2022046692 Jongejans, Loeka (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research Potsdam, Permafrost Research Section, Potsdam, Germany); Mangelsdorf, Kai; Liebner, Susanne; Grosse, Guido; Grigoriev, Mikhail; Fedorov, Alexander and Strauss, Jens. Molecular biomarkers and carbon turnover data in ice-rich permafrost in Yakutia [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8348, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

With ongoing climate warming, ice-rich permafrost, such as late Pleistocene Yedoma permafrost, is especially vulnerable to rapid and deep thaw processes. Such permafrost sediments contain a large organic matter storage that becomes increasingly accessible to microbes upon thaw. Only a few studies analysed organic matter in deep (>10 m) permafrost and thawed permafrost sediments. We studied Yedoma sediments from four sites in Yakutia in the Russian Federation: at the Arctic Ocean (Bykovsky Peninsula), inside the Lena Delta (Sobo-Sise Cliff), close to the northern hemisphere's cold pole (Batagay) and in central Yakutia (Yukechi Alas). We measured biomarker concentrations of sediment cores taken from below thermokarst lakes and sediment samples taken from the headwall of a coastal bluff and a retrogressive thaw slump. In addition, we carried out incubation experiments to quantify greenhouse gas production in thawing permafrost. Here, we present the first molecular biomarker distributions (alkanes and fatty acids) and organic carbon turnover (anaerobic CO2 and CH4 production) data as well as insights in organic matter decomposition processes in deep frozen and thawed Yedoma sediments. We show that biomarker proxies are useful to assess the source and degree of degradation of permafrost organic matter. Furthermore, the organic matter in frozen Pleistocene Yedoma sediments was better preserved than in thawed Holocene sediments. These findings show the relevance of studying organic matter in deep permafrost sediments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8348

2022046743 Jung, Yoon Taek (Sejong University, Department of Geoinformation Engineering, Seoul, South Korea); Lee, Yeji and Park, Sang-Eun. Monitoring frost heave and thaw settlement of permafrost using timeseries InSAR measurements [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-11674, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Due to large temperature variations between the summer and winter seasons the active layer of permafrost undergoes repetitive thawing and freezing, and the increase of global temperature has accelerated permafrost degradation related to surface deformation seasonally and annually. Repeated freezing and thawing causes frost heave and thaw settlement, which results in displacement in the activity layer of permafrost. This surface displacement is also associated with ground ice and soil moisture content, and these factors in permafrost region could be observed through timely-dense SAR data. In particular, since the revisit time of Sentinel-1 (C-band) is relatively dense, timeseries SAR interferometry could be useful tools for monitoring and mapping subsurface soil properties over such a wide area. In this study, since the degree of freezing and thawing is very different spatially and temporally, we propose the method to indirectly estimate the ground ice content of the freezing period and the moisture content of the thawing period by quantifying the displacement using timeseries InSAR measurements in the Lena-river floodplain, Siberia. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-11674

2022046678 Kaiser, Lara Sophia (University of Hamburg, Department of Earth System Science, Hamburg, Germany); Knoblauch, Christian and Beer, Christian. Who dealt it? Mechanistic modeling of microbial functional types in anaerobic permafrost soils [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7559, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The release of CH4 and CO2 from thawing permafrost soils will substantially impact the global carbon budget. During anaerobic conditions, these emissions are caused by a complex web of microbes. Depending on their interactions, differing ratios of CH4 to CO2 are produced. In order to predict these emissions, mechanistic modeling of microbial processes is essential but is largely omitted in current climate models. We present a new, process-based model for CH4 and CO2 production in anaerobic permafrost soils after thaw, incorporating key microbial functional types. Each microbial functional type is represented by a specific chemical pathway, allowing the calculation of substance utilization and production stoichiometrically for each time step. To the best of our knowledge, this is the first model incorporating a microbial type utilizing alternative electron acceptors, specifically Fe3+. These microbes out-compete acetoclastic methanogens for acetate as long as Fe3+ is sufficiently abundant, thereby suppressing CH4 production via this pathway. In addition, fermentation can be inhibited by the accumulation of its end product acetate, as has been observed in experiments. We optimize the model parameters against data from an anaerobic permafrost soil incubation experiment over seven years. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7559

2022046704 Knutson, Jacqueline (Norwegian Institute for Water Research, Oslo, Norway); Clayer, François; Dörsch, Peter; Westermann, Sebastian and de Wit, Heleen A. Investigating hydrology and carbon cycling connections in peatland permafrost, Northern Norway [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9445, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost in northern Norway is characterized by peat plateaus and palsas and is among the fastest degrading permafrost areas in the world. Changes in these ecosystems with sporadic permafrost can be viewed as possible future states for currently stable permafrost regions. The thawing of permafrost at large scale has the potential to release stored carbon into atmospheric cycling and becomes a source of greenhouse gases. Lateral export of dissolved organic matter (DOM) from thawing permafrost could be an important pathway for loss of formerly stable organic matter (OM), and is controlled by temperature, soil moisture and local hydrology. We aim to study thermokarst ponds and the lateral flux of water, heat, organic carbon and greenhouse gases from a rapidly thawing permafrost peat plateau using high-frequency sensors, floating chambers, measurements of dissolved gases and water chemistry, and assessment of DOM. We analyzed water chemistry and extracted gas samples on 5 sampling campaigns of the Iskoras peat plateau located in the Finnmarksvidda in northern Norway between Sept 2020 and Oct 2021. We investigated production and consumption rates of gases at 3 campaigns by dark incubations between 36-50 hours. We present early data of the peat plateau and the hydrologically connected adjacent wetland. We explore three hypotheses to better understand the role of hydrology and biogeochemistry in lateral transport of organic matter from the active peat plateau area to the larger catchment. First, there is seasonal changes in the lability of DOM in thermokarst ponds. Second, there is seasonal connection and transport of OM from the peat plateau to the wetland stream that connects to the catchment. Finally, we focus on identifying the areas in the landscape that are hotspots for greenhouse gas production and transport. The thermokarst ponds were very acidic and high in dissolved gases and TOC compared with the wetland stream system. High emissions from the thermokarst ponds are a key source of CO2 and CH4. Aquatic processing of DOM and turbulence in streams both affect level of GHG emissions. There are also differences in parameters such as CO2 evasion and DIC concentration when there is connection of the wetland stream to the peat plateau. The early data indicate high rates of DOM processing and GHG production in the thermokarst ponds and high variability in DOM export from the peat plateau. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-9445

2022046749 Koenig, Cassandra (Université de Fribourg, Fribourg, Switzerland); Hauck, Christian; Arenson, Lukas and Hilbich, Christin. Effects of geologic heterogeneity on permafrost distribution and catchment hydrology in mountain environments [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12146, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Changes in surface runoff from permafrost thaw in mountain catchments can be estimated using numerical cryo-hydrogeology models. However, such models can be complex from a numerical standpoint due to the need to simulate transient thermo-hydrologic feedbacks in highly heterogenous geological settings. Models that also seek to quantify water movement and water-budget contributions from ground-ice thaw must further account for changes in water/ice saturation to continually estimate and update the physical properties that control heat and water transfer in the ground (i.e., thermal and hydraulic conductivity) during the model execution. This has important implications for permafrost hydrology modelling efforts in arid mountain watersheds like the High Andes, where water security is threatened by climate change and the role of permafrost in the hydrologic cycle is unclear. In this contribution the coupled finite element codes TEMP/W and SEEP/W are used to illustrate ground thermal and hydrologic dynamics for different geological scenarios within a hypothetical mountain slope, characteristic of the High Andes at an altitude of up to 6000 m. The 3 km-long, two dimensional cross-sectional model was developed based on a simplified topography, and ground temperatures and climate data collected within the region. In the first scenario, a uniform hydraulic conductivity is applied to the full model domain. A second scenario simulates a case where the hydraulic conductivity of the ground in the upper 200 m is an order of magnitude higher than for the rest of the model (i.e., as in fractured bedrock or unconsolidated sediment). The scenarios were subjected to a 1,000-yr seasonally cyclic climate forcing, followed by 1,000 years of warming superimposed on inter-annual variability at an average warming rate of 4 deg/100 year. Model experiments show that the applied variations in hydraulic conductivity support vastly different permafrost and ground ice-content distributions under identical climate forcing. Compared to the uniform hydraulic conductivity case, the scenario with high hydraulic conductivity upper layer produces an increase in the heterogeneity of ice-rich permafrost under the stable climate forcing, and a slightly accelerated rate of permafrost thaw under climate warming. Higher recharge and discharge fluxes across the model surface are also predicted for the high hydraulic conductivity scenario. The divergence in the results is attributed to preferential flow paths that develop near the model surface in the higher hydraulic conductivity case, which in turn leads to increased spatial complexity in advective heat transfer. This can have profound effects on predictive models aiming to estimate rates of permafrost thaw and discharge behaviour under climate warming, and highlights the need for awareness of uncertainties associated with estimated or assumed thermal and hydrologic properties in modelling large mountain catchments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12146

2022046682 Lacroix, Fabrice (Max-Planck-Institute for Biogeochemistry, Jena, Germany); Zaehle, Sönke; Caldararu, Silvia; Schaller, Jörg; Stimmler, Peter and Goeckede, Mathias. Temporal disconnect of seasonal plant nutrient demand and thaw depth implies an increasing source of N2O in high-latitude permafrost ecosystems [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7693, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Thawing and degradation of permafrost in high latitudes could have an important effect on the Earth's greenhouse budget. Implications of increased nutrient availability resulting from thawing of nutrient-rich permafrost, however, remain poorly assessed, despite nutrients having being identified as a strong present-day constraint for plant growth and microbial activity in the high latitudes. In our pan-arctic scale study, we extend the terrestrial ecosystem model QUINCY, which already couples C-N-P cycles in soil and vegetation, for a better representation of high-latitude processes. With this model version, we perform historical simulations at the site-level over 1960-2019. Averaged over high-latitude grassland sites, our simulations show an average increase in the soil active layer depth of 0.1 m and an increased gradient of biologically-available P and N at the permafrost front. In spite of this, only 11% of the simulated increase over the GPP (+34%) is a result of increased nutrient supply from permafrost organic matter degradation. This owes to spatial and temporal decoupling of the simulated vegetation growth peak (mid-to-late-July), the time period where plant nutrient demand is the highest, and the maximum of the seasonal thaw depth (mid-to-late August), the time period in which nutrients in the deep active layer would potentially be available for uptake. As a result, increased nitrogen at the permafrost front and alternating aerobic-anaerobic conditions contribute to enhancing nitrification and denitrification in the model, causing a weak source of N2O to the atmosphere of 0.7 kg N ha-1 yr-1, which undergoes a considerable upward trend of up to 0.1 kg N ha-1 decade-1, locally,over the simulation time frame. Considering the vastness of the permafrost domain, and that N2O emissions from these regions have been largely neglected in the past, these results imply that high latitudes could be a considerable and growing contributor to the global atmospheric N2O budget. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7693

2022046690 Lindner, Fabian (Ludwig Maximilian University Munich, Geophysical Observatory, Munich, Germany); Smolinski, Krystyna; Igel, Jonas; Bowden, Daniel; Fichtner, Andreas and Wassermann, Joachim. A passive seismic approach including fiber-optic sensing for permafrost monitoring on Mt. Zugspitze (Germany) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8245, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

As observed elsewhere on a global scale, permafrost at Mt. Zugspitze (German/Austrian Alps) is warming in response to climate change. To monitor permafrost warming and thawing, which affect the rock slope stability and thus the hazard potential, borehole temperature logging and electrical resistivity tomography (ERT) have been employed at Mt. Zugspitze for more than a decade. Furthermore, a recent study shows that the ambient seismic noise recordings of a single seismometer at the same site can be utilized to track permafrost changes over the past 15 years. This passive seismic approach is non-invasive, labour- and cost-effective and provides high temporal resolution. Together with recent advances in instrumentation allowing the measurement of seismic vibrations on a meter scale along a fiber-optic cable (known as distributed acoustic sensing), passive seismology provides unprecedented spatio-temporal resolution for monitoring applications. Starting in July 2021, we extended the single-station deployment on Mt. Zugspitze with three small seismic arrays (six stations each, aperture ~25 m) along the permafrost-affected ridge. The stations are partly installed in a tunnel beneath the surface, which intersects a permafrost body, thus allowing in-situ observations of the frozen rock. We equipped the tunnel facilities with a fiber-optic cable, which we will interrogate on a regular basis, about once per quarter year, to resolve seasonal permafrost dynamics. A first 10-day data set of this monitoring element with seismic channel spacing of 2 m along a cable exceeding 1 km in length is already available and shows that artificial avalanche triggering explosions were successfully recorded. We present data and first results dedicated to permafrost monitoring along the fiber-optic cable and between pairs of seismic stations through cross-correlation of ambient seismic noise. In addition, the seismic arrays are designed to derive rotational ground motions, which we expect to be more sensitive to local subsurface/permafrost changes compared to the classical translational motion measurements. The experiment aims to explore the permafrost monitoring capabilities of passive seismology compared to more classical and established methods as ERT. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8245

2022046732 Mack, Mikhail (Wilfrid Laurier University, Geography and Environmental Studies, Waterloo, ON, Canada); Quinton, William; McLaughlin, James and Hopkinson, Christopher. Vulnerability of peatland complexes in the Hudson Plains, Canada to permafrost-thaw-driven hydrological change [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10949, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Thawing discontinuous permafrost in subarctic peatland-dominated landscapes is increasingly recognized as an indicator of a warming climate and potentially shifting these landscapes from atmospheric carbon store to source. Furthermore, in certain discontinuous permafrost landscapes (e.g., northwest Canada) the thaw of permafrost peatlands leads to a reorganization of near-surface flow paths as permafrost-free peatlands expand, connect, merge, and drain. Collectively, these permafrost-thaw-driven landcover and hydrological changes have increased runoff and altered biogeochemical cycles threatening natural resources and critical infrastructure in Indigenous peoples' traditional territories along with aquatic and terrestrial wildlife habitat. Owing to the region's remote position and vast scale, comparatively less is known about the landcover and hydrological impacts of permafrost thaw in the Hudson Plains, the world's third largest peatland region (370,000 km2) and southern most extent continental permafrost. For this study, we assign specific hydrological functions to individual peatland types based on their form, to then infer hydrological flux and storage processes within and between peatlands and a circuitry analog, at the scale of the peatland complexes and peatland complex regions. We analyze several remotely sensed data, including high-resolution lidar, historical air photographs, and recent panchromatic and multispectral satellite imagery along a latitudinal transect to evaluate peatland form, complex, and regional patterns. We then summarise these results and interpretation to present an initial vulnerability map of peatland complexes in the Hudson Plains to permafrost-thaw-driven hydrological change. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10949

2022046753 Margalef, Olga (Universitat de Barcelona, Department of Earth and Ocean Dynamics, Barcelona, Spain); Grau, Oriol; Joosten, Hans; Haase, Aaron Pérez; Rabes, Sergi Pla; Fernández, Pere Roc; Giralt, Santiago; Sánchez, Marc; Obiol, Ramon Pérez; Soriano, Joan Manuel; Pèlachs, Albert; Campderrós, Sara; Alarcón, Cristina Fernández and Peñuelas, Josep. Late Holocene permafrost development triggers hydrological and geochemical changes in subarctic peatlands (Abisko, 68°N) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12387, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Palsa mires are a common feature in the Subarctic zone of discontinuous permafrost. In these peatlands, the patchy distribution of frozen soil constrains relief, water regime and vegetation distribution. Because they lie at the edge of permafrost distribution, palsa mires are very sensitive to climate changes and become extremely valuable high-latitude terrestrial records. However, both (1) their origin, including their rapid development towards ombrotrophy because of uplift by ice accretion and (2) the irreversible geochemical effects of collapse and permafrost thaw make them challenging environmental archives. Understanding the Late Holocene evolution of these systems becomes a key framework to decipher potential consequences of the permafrost disappearance observed during the last decades. A 120 cm peat record was recovered on the Storflaket Palsa plateau (Abisko, Sweden, 68°N) on June 2018. This register contains more than 9000 years of paleoenvironmental information and was entirely made of peat, with two centimetric layers of volcanic ash interbedded at 74-77 and 46-47 cm depth. A multidisciplinary approach using chemical (stoichiometry, stable isotopy and elemental composition) and biological proxies (macrofossil and pollen determination) was used to reconstruct the environmental evolution of the site. Bottom most layers (50-120 cm) were characterized by peat made of different types of brown mosses and abundant aquatic fauna indicating that the area was covered by a high and stable water table that promoted organic matter accumulation in a percolation mire system. The very high accumulation rates and the extremely good preservation of macrofossil remains suggest a permafrost free area around 8000 cal yr BP. From 50 to 9 cm the peat is made of highly degraded brown moss, with increasing degradation towards the top. Chemical and macrofossil analyses indicate a strong oxidation processes due to peat exposition. The top layer (9 to 0 cm) is characterized by dry palsa peat and depicts very low accumulation rates, suggesting that this record is capturing the uplift movement of the peat mound by ice accretion and a shift from a minerotrophic and waterlogged mire system towards the development of a palsa plateau. Chemical and biological signals allow us to date the age of permafrost establishment later than 3000 cal. yr BP. The deposition of ash layers is linked to sudden inputs of phosphorus and metals leading to stoichiometric changes in peat composition. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12387

2022046725 Mollaret, Coline (Université de Fribourg, Fribourg, Switzerland); Hilbich, Christin; Herring, Teddi; Farzamian, Mohammad; Buckel, Johannes; Dafflon, Baptiste; Draebing, Daniel; Fossaert, Hannelore; Gugerli, Rebecca; Hauck, Christian; Kunz, Julius; Lewkowicz, Antoni; Limbrock, Jonas K.; Maierhofer, Theresa; Magnin, Florence; Pellet, Cécile; Pfaehler, Sebastian; Scandroglio, Riccardo; Uhlemann, Sebastian; Etzelmüller, Bernd; Orozco, Adrian Flores; Hördt, Andreas; Kemna, Andreas; Kneisel, Christof; Lambiel, Christophe and Onaca, Alexandru. Initiation of an International Database of Geoelectrical Surveys on Permafrost to promote data sharing, survey repetition and standardized data reprocessing [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10565, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Geoelectrical methods are widely used for permafrost investigations by research groups, government agencies and industry. Electrical Resistivity Tomography (ERT) surveys are typically performed only once to detect the presence or absence of permafrost. Exchange of data and expertise among users is limited and usually occurs bilaterally. Neither complete information about the existence of geophysical surveys on permafrost nor the data itself is available on a global scale. Given the potential gain for identifying permafrost evidence and their spatio-temporal changes, there is a strong need for coordinated efforts regarding data, metadata, guidelines, and expertise exchange. Repetition of ERT surveys is rare, even though it could provide a quantitative spatio-temporal measure of permafrost evolution, helping to quantify the effects of climate change at local (where the ERT survey takes place) and global scales (due to the inventory). Our International Permafrost Association (IPA) action group (2021-2023) has the main objective of bringing together the international community interested in geoelectrical measurements on permafrost and laying the foundations for an operational International Database of Geoelectrical Surveys on Permafrost (IDGSP). Our contribution presents a new international database of electrical resistivity datasets on permafrost. The core members of our action group represent more than 10 research groups, who have already contributed their own metadata (currently > 200 profiles covering 15 countries). These metadata will be fully publicly accessible in the near future whereas access to the resistivity data may be either public or restricted. Thanks to this open-access policy, we aim at increasing the level of transparency, encouraging further data providers and fostering survey repetitions by new users. The database is set up on a virtual machine hosted by the University of Fribourg. The advanced open-source relational database system PostgreSQL is used to program the database. Homogenization and standardization of a large number of data and metadata are among the greatest challenges, yet are essential to a structured relational database. In this contribution, we present the structure of the database, statistics of the metadata uploaded, as well as first results of repetitions from legacy geoelectrical measurements on permafrost. Guidelines and strategies are developed to handle repetition challenges such as changing survey configuration, changing geometry or inaccurate/missing metadata. First steps toward transparent and reproducible automated filtering and inversion of a great number of datasets will also be presented. By archiving geoelectrical data on permafrost, the ambition of this project is the reanalysis of the full database and its climatic interpretation. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10565

2022046694 Moser, Clemens (Technical University of Vienna, Department of Geodesy and Geoinformation, Vienna, Austria); Maierhofer, Theresa; Drigo, Elisabetta; Di Cella, Umberto Morra; Hauck, Christian and Orozco, Adrian Flores. 3D spectral induced polarization survey to evaluate a thawing permafrost endangered hut in the Italian Alps [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8588, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Due to generally rising air temperatures in the European Alps in context of climate change, large areas of mountain permafrost are thawing, and subsurface pore ice is melting. Consequently, the cohesion of rock masses decreases which can constitute a threat for infrastructure like mountain huts in alpine areas. One directly affected building is the Guide Val d'Ayas al Lambronecca, a hut on a rock ledge in the Italian Alps at 3400 m above sea level. During the last decade the ground directly underneath the hut sank of about 2 m, probably due to the melting of pore ice in the subsurface below the hut. In this study, we investigate the subsurface properties beneath the hut using a 3D geophysical survey. In particular, we deploy the spectral induced polarization (SIP) method, which has emerged as a promising tool to discriminate between ice-rich and ice-poor regions in the subsurface. Our investigation is built on the hypothesis that ice can be identified in electrical images due to its high electrical resistivity and polarization (i.e., capacitive) properties at frequencies above 10 Hz. In our survey, we conducted 2D SIP measurements in summer 2020 (between 0.5 and 225 Hz) along three profiles near the hut, while real 3D SIP measurements (in the range between 1 and 240 Hz) were conducted in summer 2021. For the 3D measurements, we deployed two parallel lines, one on the southern and one on the northern rock wall of the summit where the hut is located. To improve the data quality, we used coaxial cables for the 2D measurements in 2020, while data collected in 2021 were based on the actual separation of the transmitter and receiver (i.e., instrument and cables) to reduce the contamination of the data due to parasitic electromagnetic fields. Processing of the data was based on the statistical analysis of normal and reciprocal misfits. Inversion of the data was performed in 3D using ResIPy which uses complex calculus to simultaneously resolve for the conductive and capacitive properties. Our imaging results evidence a core of ice-filled pores corresponding to high resistivity values (>10 kOm) directly underneath the hut, this structure is overlain by lower values (<1 kWm) in near-surface areas representing the active layer. Images of the polarization effect confirm an anomaly due to high values at frequencies above 10 Hz in the center of the rock ledge. Our study demonstrates that 3D SIP measurements can be used to differentiate between ice-rich and ice-poor areas in high mountain permafrost sites with complex topography. Moreover, 3D SIP approaches enable a detection of electrical anomalies in all three dimensions and not only along one certain direction in the case of 2D profiles. This information can be used to assess the impact of permafrost degradation on infrastructure stability in mountain regions and to support restoration actions. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8588

2022046756 Offer, Maike (Technische Universität München, Munich, Germany); Scandroglio, Riccardo; Mamot, Philipp; Keuschnig, Markus and Krautblatter, Michael. Using combined quantitative geophysical methods to delimit physical properties of low porosity permafrost bedrocks [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12546, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Degradation of mountain permafrost poses an increasing hazard to the stability of high-alpine infrastructures, which are predominantly located in low porosity bedrocks. Considering the dramatic climate change-induced temperature increase and the recent tourism expansion in these regions, safe long-lasting constructions and maintenance of infrastructures at high altitudes requires a complete process understanding of these permafrost systems. Non-invasive, geophysical measurements such as Electrical Resistivity Tomography (ERT) and Seismic Refraction Tomography (SRT) are the state of the art today in permafrost research due to their capability to distinguish between frozen and unfrozen medium. Thanks to their complementary sensitive records, it is common to combine electrical and seismic data sets by using petrophysical relations. Several multimethod approaches were already successfully applied in ice-rich conditions, however quantitative studies in ice-poor bedrock characterized by different physical properties are rarely investigated. In this study, we present a quantitative multimethod approach for long-term monitoring of low porosity permafrost bedrock. ERT and SRT data sets were recorded between 2010 and 2021 at the Zugspitze crest (Germany, 2.885 m asl) and in the Hanna-Stollen at the Kitzsteinhorn (Austria, 3.029 m asl). Both locations are visited every day by thousands of tourists, present infrastructure founded in bedrock with porosity of 0.2 to 5.0% and are affected by degrading permafrost, although showing different lithologies. A combined analysis of resistivities and p-wave velocities, supported by their laboratory temperature calibrations with water-saturated samples from the field, allowed us to quantitatively estimate site-specific permafrost changes. The preliminary results show a clear warming of the permafrost core and a thickening of the active layer, well in agreement with other long-term permafrost observation at the Zugspitze summit and at further alpine sites (e.g. Scandroglio et. al., 2021). In summary, our quantitative multimethod analysis for ice-poor bedrock provides fundamental contributions for planning and maintenance of permafrost-founded infrastructure under the influence of climate change. In the future, we aim at developing a new benchmark approach for hazard potential assessment of high-alpine infrastructures with foundations and anchoring in thawing permafrost. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12546

2022046729 Palucis, Marisa (Dartmouth College, Department of Earth Sciences, Hanover, NH); Marshall, Jill and Strauss, Justin. Sediment production and transport processes in an Arctic watershed undergoing climate change [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10812, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Arctic landscapes are among the most vulnerable on Earth to climate change, largely due to the degradation and thawing of permafrost. In steeper bedrock-dominated terrains, slope instability from warming permafrost leads to larger and more frequent rockfall and frost cracking events, which in turn increases the production and delivery of sediment to hillslopes and channel networks by debris flow and fluvial processes. However, there is a fundamental lack of data on past and current rates of sediment production and transport in Arctic watersheds. Without an understanding of these phenomena, it is impossible to predict the transient responses, rates, and directions of periglacial processes in response to future climate change. To begin to address this knowledge gap, we conducted a field-based study of the Black Mountain catchment in the Aklavik Range (Northwest Territories, Canada). This site was chosen due to its position within a zone of continuous permafrost and the presence of an alluvial fan at the base of the catchment, providing a closed system. In the summer of 2019, after a summer storm event, we observed several debris flows that initiated from ice-filled gullies, as well as fluvial sediment transport from snowmelt. We documented flow and sediment transport conditions on the fan, yielding modern-day fluvial transport rates of 0.2-2 m3/hr for water runoff rates of 0.01-0.2 mm/hr. However, less-frequent mass flow events can rapidly deposit large amounts of sediment. For example, we estimate that a mass flow event that occurred in 2016 delivered ~1.5*105 m3 of sediment to the fan-equivalent to ~8-85 years of continuous fluvial sediment transport. Based on our surficial and sedimentological mapping, the fan has likely been forming under a periglacial climate over the last ~13,000 years from a combination of mass flow and fluvial processes. Most of the fan (~67%) was deposited fluvially, but the upper, steeper portion of the fan was deposited by coarse granular debris flows. We hypothesize that accelerated warming has increased sediment supply due to frost cracking, leading to aggradation, increased debris flow activity, and upper fan steepening. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10812

2022046731 Park, Sowon (Pohang University of Science and Technology, Division of Environmental Science and Engineering, Pohang, South Korea) and Kug, Jong-Seong. Hysteresis of terrestrial carbon cycle to CO2 ramp-up and -down forcing [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10878, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

To prevent excessive global warming, we have faced a situation to reduce the net carbon dioxide (CO2) emission. However, how the Earth's terrestrial biosphere behaves under negative emission is highly uncertain. Here we show that there is a strong hysteresis in terrestrial carbon cycle in response to CO2 ramp-up and -down forcing. Due to this strong hysteresis lag, terrestrial biosphere stores more carbon at the end of simulation than its initial state, lessening the burden on the net negative emission. This hysteresis is latitudinally-dependent, showing a longer timescale of reversibility in high-latitudes and particularly carbon in boreal forests can be stored for a long time. However, the hysteresis of the carbon cycle in the pan-Arctic region strongly depends on the presence of permafrost processes. That is, an unexpected irreversible carbon emission might occur in permafrost even after achieving net-zero emission, which implies the importance of the permafrost processes, highly uncertain in our current knowledge. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10878

2022046718 Pika, Philip (Vrije Universiteit Amsterdam, Amsterdam, Netherlands); Tanski, George; Ulrich, Mathias; Roy, Louis-Philippe; Calmels, Fabrice; Lantuit, Hugues; Fortier, Daniel; Fritz, Michael and Vonk, Jorien. Landscape-related ground ice variability on the Yukon coastal plain inferred from computed tomography and remote sensing [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10196, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Warming in the Arctic causes strong environmental changes with degradation of permafrost (permanently frozen ground). Active layer deepening (gradual thaw) and permafrost erosion (abrupt thaw) results in the mobilization and lateral transport of organic carbon, altering current carbon cycling in the Arctic. Ground ice content is a crucial factor limiting our understanding and ability to determine the rates and dynamics of permafrost thaw and its impact on potential thaw subsidence rates, changes in lateral hydrological pathways and its driving mechanisms on a landscape scale. In this study we investigate ground ice content and its characteristics across the most dominant landscape units of the Yukon coastal plain (Canadian Arctic), using two spatially and technically contrasting approaches. In our bottom-up approach, twelve permafrost cores were collected from moraine, lacustrine, fluvial and glaciofluvial deposits using a SIPRE corer (mean drilling depth of 2 m) in spring of 2019. Ground ice and sediment contents within polygon centers were analyzed and classified using computed tomography and image recognition software (k-means). Our top-down approach quantified ice-wedge volumes from remote sensing imagery tracing the circumference of polygon troughs over the same area. Preliminary results -- extrapolated to the entire coastal plain -- show that the ground-ice content in polygon centers vary significantly from massive ice in the polygon troughs (wedge-ice). Total ice volume was estimated around 80.2 vol.-%, of which 68.2±18.1 vol.-% was attributed to ground ice in polygon centers, and 12±3.1 vol.-% of the landscape is massive ice in wedge-ice along polygon troughs. Additionally, differences among and between landscape units are also substantial, with highest ice volume contents in moraines landscapes, where polygon centers contain 58.8 vol.-% ground ice and wedge-ice volume is 16.2 vol.-%), while the lowest ice contents are found in glacio-fluvial deposits (22.1 vol.-% resp. 9.1 vol.-%). Our results reveal a higher average and a larger variability in ground ice contents than previously found, suggesting a need of both ground-based measurements and remote sensing imagery to further our understanding of the future landscape subsidence, but also to avoid a likely under- or overestimation associated with the chosen approach. We conclude that due to the high ground ice contents on the Yukon coastal plain, substantial changes of the permafrost landscape will occur under current warming trends. These will include subsidence, abrupt erosion, changes in hydrology and organic carbon mobilization, degradation and export processes, which will differ between landscape units. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10196

2022046748 Poltavskaya, Natalina (Tomsk Polytechnic University, Tomsk, Russian Federation); Gershelis, Elena; Grinko, Andrey; Charkin, Alexander; Guseva, Natalia; Yaroshchuk, Elena and Semiletov, Igor. Composition of organic carbon in surface sediments of Chaun Bay (East Siberian Sea) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12051, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The East Siberian Arctic Shelf (ESAS), the world's widest and shallow continental shelf, plays a crucial role in the climate system of our planet holding huge amounts of organic carbon (OC) in the permafrost deposits which are remobilized upon accelerating permafrost thaw. To get more detailed insights into the sources of OC and compare the mechanisms of its transformation in the different ESAS zones, we investigate a scarcely studied coastal area of the East Siberian Sea - Chaun Bay (CB), a semi-closed accumulative area, where the influence of river discharge is limited and the coastline deposits are composed mainly of the rocky formations, which is contrasting to the permafrost-dominated Arctic bays. In this study, we analyzed 25 surface sediments collected along the profile from the coastal zone of CB to the midshelf of East Siberian Sea. To characterize the OC composition, we used Rock-Eval indicators along with traditional molecular markers (n-alkanes; n-alkanoic acids). Detailed grain size composition was also performed in order to assess the sedimentation environment operating in the study area. Sediments are mostly represented by sortable silt (7.61-62.48% on average 43.5%), fine silt (1.98-60.9% on average 34.63%) with a certain proportion of clay (average 11.13%) predominantly in the inner shelf areas, and sand (average 10.73%) deposited in the eastern, southern, and western (Aion Island) parts of the CB. OC content along the studied profile ranged from 0.49 to 1.76%. Hydrogen index along the studied profile ranged from 111 to 232 mg/g, Oxygen index varied from 134 to 239 mg/g. The relationship between HI and OI indicated roughly equal contributions of terrestrial and marine sources to the OC composition. Meanwhile, variable distribution of n-alkanes is observed with a pronounced presence of high-molecular-weight n-alkanes, which are recognized as higher terrestrial vegetation markers. These data will be further combined with more detailed biomarker analysis to reveal the OM sources proportions in the CB sediments and to understand the dominating mechanisms of OC transformation within this area. This analytical studies were financially supported by RSF (Project -77-00075). [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12051

2022046711 Ramm, Elisabeth (Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research, Garmisch-Partenkirchen, Germany); Liu Chunyan; Mueller, Carsten W.; Gschwendtner, Silvia; Yue Hongyu; Wang Xianwei; Bachmann, Juliane; Bohnhoff, Joost A.; Ostler, Ulrike; Schloter, Michael; Rennenberg, Heinz and Dannenmann, Michael. Alder-induced stimulation of soil gross nitrogen turnover in permafrost-affected peatlands of northeast China [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9792, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Unlike carbon dynamics, nitrogen (N) dynamics in permafrost peatlands are not well-studied. For the prediction of permafrost N climate feedbacks, a better process-based understanding of the N cycle in permafrost peatlands is however urgently needed. Therefore, we characterized and quantified soil organic matter, soil gross microbial N turnover and soil-atmosphere exchange of nitrous oxide (N2O) on the southern edge of the Eurasian permafrost area in situ ( Specifically, we sampled a tree-free lowland peatland and a lowland peatland with an N2-fixing alder forest in Northeast China. Nuclear magnetic resonance spectroscopy revealed more recalcitrant organic matter at greater depth and more bioavailable organic matter substrates in upper peat horizons. In line with this result, gross ammonification and nitrification generally decreased with increasing sampling depth. Gross rates of mineral N turnover in the active layers of the tree-free peatland were comparable to those of temperate ecosystems. Despite substantial gross ammonification, the low nitrification:ammonification ratios and negligible soil N2O emissions still depicted a closed N cycle characterized by N limitation in the tree-free peatland. In strong contrast, the peatland underneath the alder forest showed an accelerated N turnover with very high gross rates of ammonification (3.1 g N m-2 d-1) and nitrification (0.6 g N m-2 d-1), exceeding those of the alder-free peatland by an order of magnitude. This was accompanied by substantial N2O emissions. The increase in gross N turnover was most pronounced in the rooted soil layer, where N inputs from biological N fixation almost doubled total N concentrations and halved the ratios of soil organic carbon to total N. The frozen ground underneath alder trees contained strongly increased ammonium concentrations prone to be released upon thaw. This study shows that alder forests that further expand on permafrost-affected peatlands with global change create hot spots of soil mineral N turnover, thereby potentially enhancing permafrost N climate feedbacks. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-9792

2022046713 Rottensteiner, Cornelia (University of Vienna, Center of Microbiology and Environmental System Science, Vienna, Austria); Martin, Victoria; Schmidt, Hannes; Hadziabdic, Leila; Horak, Julia; Mohrlok, Moritz; Malo, Carolina Urbina; Wagner, Julia; A'Campo, Willeke; Durstewitz, Luca; Lodi, Rachele; Speetjens, Niek Jesse; Tanski, George; Fritz, Michael; Lantuit, Hugues; Hugelius, Gustaf and Richter, Andreas. Spatial variability shapes microbial communities of permafrost soils and their reaction to warming [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-9891, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Climate change threatens the Earth's biggest terrestrial organic carbon reservoir: permafrost soils. With climate warming, frozen soil organic matter may thaw and become available for microbial decomposition and subsequent greenhouse gas emissions. Permafrost soils are extremely heterogenous within the soil profile and between landforms. This heterogeneity in environmental conditions, carbon content and soil organic matter composition, potentially leads to different microbial communities with different responses to warming. The aim of the present study is to (1) elucidate these differences in microbial community compositions and (2) investigate how these communities react to warming. We performed short-term warming experiments with permafrost soil organic matter from northwestern Canada. We compared two sites characterized by different glacial histories (Laurentide Ice Sheet cover during LGM and without glaciation), three landscape types (low-center, flat-center, high-center polygons) and four different soil horizons (organic topsoil layer, mineral topsoil layer, cryoturbated soil layer, and the upper permanently frozen soil layer). We incubated aliquots of all soil samples at 4°C and at 14°C for 8 weeks and analyzed microbial community compositions (amplicon sequencing of 16S rRNA gene and ITS1 region) before and after the incubation, comparing them to microbial growth, microbial respiration, microbial biomass and soil organic matter composition. We found distinct bacterial, archaeal and fungal communities for soils of different glaciation history, polygon types and for different soil layers. Communities of low-center polygons differ from high-center and flat-center polygons in bacterial, archaeal and fungal community compositions, while communities of organic soil layers are significantly different from all other horizons. Interestingly, permanently frozen soil layers differ from all other horizons in bacterial and archaeal, but not fungal community composition. The 8-week incubations led to minor shifts in bacterial and archaeal community composition between initial soils and those subjected to 14°C warming. We also found a strong warming effect on the community compositions in some of the extreme habitats: microbial community compositions of (i) the upper permanently frozen layer and of (ii) low-center polygons differ significantly for incubations at 4°C and 14°C. Yet, the lack of a community change in horizons of the active layer suggests that microbes are adapted to fluctuating temperatures due to seasonal thaw events. Our results suggest that warming responses of permafrost soil organic matter, if not frozen or water-saturated, may be predictable by current models. Process changes induced by short-term warming can be rather attributed to changes in microbial physiology than community composition. This work is part of the EU H2020 project "Nunataryuk". [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-9891

2022046754 Sanders, Tina (Institute für Küstenforschung, Helmholtz-Zentrum Hereon, Geesthacht, Germany); Fiencke, Claudia; Juhls, Bennet; Ogneva, Olga; Strauss, Jens; Tuerena, Robyn and Dähnke, Kirstin. Nitrogen isotopic inventory of the Lena River delta [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-12454, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost-affected soils around the Arctic Ocean contain a large reservoir of organic matter including nitrogen, which partly reach the river after thawing, degradation and erosion of permafrost. After mobilization, reactive remineralised nitrogen is either used for primary production, microbial processing or is simply transported to coastal waters. With analyzing the natural abundance of the stable isotope composition in different form of nitrogen components, we aim to unravel the balance of transport and biological nitrogen turnover processes like remineralization or nitrification and in consequent the fate of the nitrogen. We have analyzed soil, suspended matter and dissolved inorganic and organic nitrogen for their contents and 15N stable isotope composition to create a baseline for a nitrogen inventory of the Lena River Delta in 2019/2020. We used samples from two transect cruises through the delta in March and August 2019, a monitoring program at Samoylov Island in the central delta (2019/2020), and different soil type samples from Samoylov and Kurunghak Island. Our aim was to determine nitrogen sources, sinks and transformation processes during transport in river and delta. Our data shows that in winter the nitrogen transported from the delta to the Laptev Sea were dominated by dissolved organic nitrogen (DON) and nitrate, which occur in similar amounts of approx. 10 mmol/L. The load of nitrate, during the transect cruise, increased slightly in the delta, while we observed no changes to the isotope values of DON and nitrate indicating a lack of biological activity in the winter season and the lateral transport from soils was the likely source. In summer, nitrogen was mainly transported as DON and particulate nitrogen in the suspended matter and nitrate was mainly below 1mmol/L. The nitrogen stable isotope values of the different nitrogen components ranges between 0.5 and 4.5 ppm, and were subsequently enriched from the soils via suspended particulate matter (SPM)/sediment and DON to nitrate. These light values indicate soil nitrogen mainly originates from atmospheric nitrogen fixation. During transport and remineralization, biogeochemical recycling via nitrification and assimilation by phytoplankton led to an isotopic enrichment in summer. In the coastal waters of the Laptev Sea, the exported river waters are slowly mixed with marine nitrate containing waters from the Arctic Ocean, and a part of the riverine organic nitrogen is buried in the sediments. Our data provides a baseline for isoscape analysis and can be used as an endmember signal for modeling approaches. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-12454

2022046716 Sanderson, Nicole (Université du Québec à Montréal, Montreal, QC, Canada); Aquino-López, Marco and Garneau, Michelle. Assessing shifts in 20th century carbon stocks in NE Canadian permafrost peatlands [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-10094, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Recent and rapid changes in climate and permafrost thaw are affecting carbon dynamics in high-latitude peatlands. There is growing interest in evaluating the C sink potential of peatlands for conservation as nature-based climate solutions. However, rapid decadal-to centennial-scale changes are poorly understood, in part due to poor dating resolution in surface peat. Here, we evaluate the timing of vegetation shifts and rates of carbon accumulation for the past ~200 years peatlands for 100 cores from boreal and subarctic regions in Quebec and Labrador (Eastern Canada). We used classical (Constant Rate of Supply - CRS) and Bayesian (Plum) approaches to model age-depth relationships from lead-210 (210Pb) and radiocarbon (14C) dates. Results highlight the important role of permafrost thaw in altering local peatland hydrological conditions, favouring Sphagnum growth and new peat addition in subarctic regions. While both models provide similar ages for the last century in complete cores, the CRS model tends to overestimate peat ages compared to Plum prior to ~1900CE. We recommend using Plum when constructing combined age-depth models, and importantly when if cores are incomplete. While 210Pb activity profiles are a clear indicator of disturbance in the peat column from permafrost thaw, the addition of independent dating markers (e.g. postbomb 14C dates) is especially important to validate age-depth models. The choice of age-depth model and user decisions can have important knock-on effects for interpreting timings of environmental shifts, as well as estimating the order of magnitude of C stocks for policy and conservation purposes. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-10094

2022046746 Scandroglio, Riccardo (Technische Universität München, Chair of Landslide Research, Munich, Germany); Heinze, Markus; Rehm, Till; Pail, Roland and Krautblatter, Michael. Hydrological changes in high alpine environments detected with relative gravimetry [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-11950, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Here we present the first long-time mass monitoring in periglacial environment with spring gravimetry and correlate it with external weather conditions (rainfall, snow melt) and cleft water discharge to understand water dynamics inside the bedrock. Water is widely recognized as a preparing and triggering factor in unstable slopes. Pressurized water is documented coincident to alpine rock slope failures, but the quantification of water and of effective destabilizing pressures inside the slope remains unresolved. Gravimetry allows to monitor water mass changes at different resolutions: satellite based gravimetry can detect hydrological changes with kilometer scale, while ground based absolute and relative superconducting gravimeters provide promising results at sub-basins scale. However, only relative spring gravimeters are light and handy enough for extended measurements in high-alpine environments, but example of this use are missing in the literature. We conducted monthly relative measurements with a spring gravimeter Scintrex CG-5 at 20 stations located at different altitude and slope expositions inside the permafrost affected Kammstollen tunnel (Mount Zugspitze, 2962 m asl, Germany) from 2015 to 2021. Additionally, monitoring with temperature loggers and electrical resistivity detected permafrost degradation, geological mapping provided cleft structure and snowpack simulations quantified water from snowmelt. Due to the low porosity of the local lithology (Wetterstein Limestone with 4-5% effective porosity), we expect perched water to accumulate in single fractures, especially when they are sealed by permafrost. A clear seasonal trend results from gravimetry, resistivity and temperature measurements, mainly attributable to the hydrological summer-winter cycle. Correlation with the water flow in clefts is also evident, as well with the snowmelt from the models. Uncertainties due to internal drifts of the instrument can be corrected but also show the limitations of this highly sensitive instrument. Although measuring hydrostatic pressures in single clefts remains an open challenge, this feasibility study is a benchmark showing that relative gravimetry can provide quantitative data on fluid flow and hydrostatic pressure in fractures even in periglacial and mountainous environments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-11950

2022046684 Schröer, Cosima (Universität Hamburg, Insitute for Soil Science, Hamburg, Germany); Knoblauch, Christian and Beer, Christian. Stabilization in the fate of destabilization; improving the representation of C stabilization when modeling C decomposition in permafrost-affected soils [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7837, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Permafrost thaw may stimulate microbial degradation of large soil organic carbon (SOC) stocks, releasing greenhouse gases into the atmosphere. Projecting this feedback to the global carbon (C) balance is urgent, but remains highly uncertain, because complex interactions between soil and microbes make it difficult to capture C dynamics accurately in models. How much CO2 will be respired is to a high degree dependent on C stabilization and persistence in the soil. SOC may be adsorbed to minerals and thereby unavailable to microbes. Common land surface models ignore this process, potentially overestimating C release from thawing permafrost. This study investigates the effect of this stabilization mechanism on the decomposition process by applying a process-orientated model approach. We fit a microbial-explicit model, which includes mineral adsorption, to a four-year dataset of aerobic incubations of soils from the Lena River Delta, Siberia. We compare this model to a more conceptual first-order decay model, and to a version without mineral adsorption. Preliminary results suggest that the mechanistic representation of mineral adsorption is crucial for extrapolations into the future, to avoid depletion of organic C pools or the introduction of artificially long C residence times. We further emphasize the importance of long-term incubation studies. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7837

2022046697 Schulze, Christopher (Université de Montréal, Département de géographie & Centre d'études nordiques, Montreal, QC, Canada); Olefeldt, David; Emmerton, Craig; Harris, Lorna; Kljun, Natascha; Chasmer, Laura; Hopkinson, Christopher; Detto, Matteo; Helbig, Manuel; Gosselin, Gabriel Hould and Sonnentag, Oliver. Effects of warming, wildfire, and permafrost thaw on carbon dioxide fluxes from boreal peat landscapes in northwestern Canada [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8978, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Taiga Plains ecozone in northwestern Canada is characterized by vast peat landscapes consisting of both mostly tree-less, permafrost-free and forested, permafrost-affected peat landscapes. In response to warming due to ongoing climate change, more frequent and severe wildfires and rapid permafrost thaw affect landscape composition, structure and functioning, whereas more and more ice-rich permafrost peat plateaus transform into water-saturated thermokarst wetlands or lakes. Collectively, these three agents of change, namely warming, wildfire, and thermokarst, could turn these boreal peat landscape from atmospheric carbon and nitrogen sinks into sources with potentially positive climate system feedbacks. We studied net ecosystem exchange (NEE) and its two component fluxes, i.e., gross primary productivity (GPP) and ecosystem respiration (ER), from three sites with five eddy covariance towers near the southern limit of permafrost in western Canada. Around the southernmost site Lutose, both footprint areas around the two towers have completely burned in wildfires in 2007 and 2019, respectively. We hypothesized that these two subsites would act as net CO2 sources, because of the recent disturbance history. This has been confirmed by preliminary results. The two other sites mainly differed in permafrost extent, ranging from sporadic (Scotty Creek) to discontinuous (Smith Creek), and in peat plateau-to-wetland ratio and corresponding forest cover (Scotty Creek < Smith Creek). Between the two sites Scotty Creek and Smith Creek, we hypothesized that the overall landscape GPP and ER will be higher at Scotty Creek compared to the northernmost site Smith Creek, due to both more abundant thermokarst wetlands and higher GPP and ER of the peat plateau areas at this more southern site. We further hypothesized that the effects of warming on GPP are greater than on ER and thus that the warmer Scotty Creek site is a greater net CO2 sink. Contrary to expectations, preliminary results have shown that there is no difference in NEE between Scotty Creek and Smith Creek, whereas both, the overall landscape GPP and ER, are actually higher at Smith Creek. To identify differences in the NEE, GPP, and ER between their peat plateaus and thermokarst wetlands, respectively, we move forward by applying footprint analyses for Smith Creek and Scotty Creek. Through these analyses we will be able to shed light on how each of the drivers, i.e., warming, wildfire, and thermokarst, alters magnitude and direction in greenhouse gas fluxes from rapidly thawing boreal peat landscapes. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8978

2022046683 Sirbu, Flavius (West University of Timisoara, Geography Department, Timisoara, Romania); Poncos, Valentin; Strozzi, Tazio; Onaca, Alexandru; Teleaga, Delia and Birtas, Dan. On the dynamics of rock glaciers in marginal mountain permafrost (Retezat Mountains, Romania) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7826, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Active rock glaciers (RG) are associated with mountain permafrost occurrence, and in the last years, remote sensing has been widely used to assess their dynamics. However, the use of remote sensing in determining the dynamics of slow-moving rock glaciers, from areas with patchy permafrost, controlled by site-specific conditions still remains a significant challenge. One such area is the central part of Retezat Mountains in the Southern Carpathians, Romania. Here we present and discuss the results obtained by using Persistent Scatterer Interferometry (PSI) on Sentinel-1 images between 15.5.2015 and 27.10.2020. The results were validated with 26 in situ measurements with a Topcon Hiper V Differential GPS connected to the ROMPOS network for real-time corrections and millimetric accuracy. Also, the spatial distribution of RG dynamics was compared with a predicted map of permafrost distribution. The results show that the displacement rates are low, at around 10 mm/year. Out of the 48 investigated RGs, only two have displacement rates between 10 and 20 mm/year, 14 show displacement of up to 10 mm/year, and 32 don't show any (measurable) displacement. However, the displacement rates are found to cover only part of the RGs, with stable areas being identified on all of them. When comparing the distribution pattern of the displacement rates, there is a good overall agreement with the modelled permafrost distribution, further suggesting that rock glacier dynamics are influenced by permafrost occurrence in marginal conditions. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7826

2022046688 Uxa, Tomas (Czech Acacademy of Sciences, Institute of Geophysics, Prague, Czech Republic); Krizek, Marek; Krause, David and Dlabackova, Tereza. Geometry of LGM polygonal sorted patterns analysed using high-resolution airborne data (Krkonose Mountains, Czech Republic) [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-8172, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Relict sorted patterns are valuable indicators of past permafrost and climate evolution, but their detailed terrain explorations are usually challenging due to high time requirements and poor pattern visibility. Here, we test the applicability of high-resolution airborne data to map and analyse the geometry of LGM polygonal sorted patterns at one site in the Krkonose Mts., Czech Republic. We delineated a total of 2000 sorted patterns using colour contrasts between their elevated centres and bordering troughs discernible on a LiDAR digital elevation model with a resolution of 0.5 m and on true-colour orthogonal aerial photographs with a resolution of 0.2 m. Since the patterns occupy an area of ~1.96 ha, the density of their network accounts for ~1019 cells per hectare. The patterns have a diameter of 3.59±0.95 m, a height of 0.30±0.11 m, and an estimated sorting depth of 1.00±0.26 m. The number of pattern sides ranges between three and ten, but 82% of the patterns are pentagonal to heptagonal, and their sides mostly meet at three-or four-way intersections at an angle of 120±24°. However, isometric patterns are rather rare as a length-to-width ratio attains 1.48±0.30. Generally, the remotely-sensed pattern attributes are consistent with ground-truth data previously collected at the study site, which proves the utility of high-resolution airborne data to rapidly map and complexly analyse the geometry of large sets of relict landforms over extensive areas that could not be done by conventional terrain surveys. The sorting depth indicates that permafrost superimposed by ~1 m thick active layer occurred at the study site during the LGM, which can be further used for past permafrost and climate modelling. The dataset can also have many other applications such as for validating automated pattern mapping/delineation tools and pattern growth models or for choosing an effective sample size for future surveys. The research is financially supported by the Czech Science Foundation, project number 21-23196S. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-8172

2022046737 van Crimpen, Fleur (Vrije Universiteit Amsterdam, Amsterdam, Netherlands); Madaj, Lina; Whalen, Dustin; Tesi, Tommaso and Vonk, Jorien. The hydrodynamic potential of eroding Arctic permafrost coasts; fractionation of permafrost parent material in the Canadian Arctic to determine its fate in the marine system [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-11429, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

The Canadian Beaufort Sea coastline consists of permafrost, permanently frozen soils, that store large amounts of organic carbon (OC). Rising temperatures in the Arctic will lead to thaw of these permafrost soils as well as enhanced coastal erosion. The trajectory of thawing coastal carbon upon thaw will determine the degree of breakdown and greenhouse gas emission, impacting climate warming. However, we still have a poor understanding of the marine fate of sediments and OC from eroding arctic coastlines. In order to obtain more insight into the fate of the eroding material, we will use hydrodynamic fractionation on a variety of actively eroding coastal cliffs (parent material). Hydrodynamic fractionation accounts for the sediment sorting of particles when exposed to different energy conditions such as waves. With this technique we will fractionate based on density and grainsize to mimic the route in the marine system. Current estimates of sediment and OC input from arctic coastal erosion are only based on bulk measurements. Samples were collected from eight sites (n=5 at each site) with a wide spatial and geological variation across the Canadian Beaufort Sea. These sites range from peaty and flat islands to muddy slumps and sandy locations. For all sites, parent material was collected onshore, fractionated and separated in five fractions based on density (cut-off 1.8 g/mL) and grainsize (cutoffs 38, 63, and 200 mm). All fractions will be analysed for geochemical properties (total OC, total nitrogen, d13C, and D14C, biomarkers and lipids) in order to determine the quantity and quality of the organic matter. Distribution of sediment fractions based on weight shows large variability between sites (e.g. low density fraction between 2-13% and high density between 9-50% with grainsize 63-200 mm) as well as within sites, depending on the characteristics of the coast. Using the spatial variability of these fractions in combination with coastal characteristics assessed with GIS techniques we will attempt to upscale for the Canadian Beaufort Coast. This will hopefully improve our insights on the type and composition of parent material which is released into the marine system as a source of carbon. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-11429

2022046733 Wegner, Rica (Universität Hamburg, Institute of Soil Science, Hamburg, Germany); Fiencke, Claudia; Knoblauch, Christian; Sauerland, Lewis and Beer, Christian. Rapid permafrost thaw removes nitrogen limitation rising the potential of N2O emissions [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-11181, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Previous research was addressed to carbon emissions after permafrost thaw, but less attention was paid to changes in nitrogen availability and N2O emissions and in particular data from the Russian Arctic are scarce. Rise in water temperature and sea-level contribute to coastal erosion accelerating thaw rates and the release of dissolved nitrogen. Already 78% of the coastal regions of the Laptev Sea are affected by rapid permafrost thaw. This study estimates whether eroded Arctic coasts are hotspots for N availability and N2O emissions and to further understand the impact of NO3- leaching. Therefore, we estimated N-transformation rates and greenhouse gas (GHG) production (CO2, CH4, N2O) by incubating non-vegetated and revegetated soil samples from a retrogressive thaw slump in the Lena River Delta, Siberia. Within the thaw slump we found at exposed thaw mounds a domination of DIN over DON and an accumulation of NO3- with up 110 mg N (g DW)-1 within the growing season and in the presence of vegetation. Those results are contracting to what is normally reported in Arctic regions. Our incubations indicate that thaw mounds are hotspots for N-mineralization and N2O release (up to 390 ng N2O-N (g DW)-1) via denitrification while at the slump floor denitrification was substrate limited. Substrate limitation is rather caused by soil moisture and pH value than by functional limitation, since in our incubation N-mineralization could proceed in all samples. Simulated NO3- leaching removed the substrate limitation of the denitrification and converted the slump floor to a significant N2O hotspot (410 ng N2O-N (g DW)-1). Our results emphasise that it is necessary to consider geomorphology and landscape processes to identify hotspots of gaseous and dissolved N loss. A higher availability of inorganic nitrogen in coastal zones will have effects on marine ecosystems and more in depth-studies are needed to characterise seasonality of nitrogen leaching by melt water and eroded sediments. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-11181

2022046677 Wild, Birgit (Stockholm University, Department of Environmental Science, Stockholm, Sweden); Ray, Nicholas; Lett, Céline; Davies, Amelia; Kirillova, Elena; Holmstrand, Henry; Klevantceva, Elizaveta; Osadchiev, Alexander; Gangnus, Ivan; Yakushev, Evgeniy; Kosmach, Denis; Dudarev, Oleg; Gustafsson, Orjan; Semiletov, Igor and Bruchert, Volker. Nitrous oxide dynamics on the Siberian Arctic Ocean shelves [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-7491, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

Nitrous oxide (N2O) is a strong greenhouse gas and a major ozone depleting agent. Almost a quarter of global N2O emissions stems from the ocean, but projections of future releases are uncertain due to scarce observations over large areas and limited understanding of the drivers behind. Here, we focus on the vast continental shelf seas north of Siberia, a hotspot area of global change that experiences rapid warming and high nitrogen input via rivers and coastal erosion; yet N2O measurements from this region are extremely scarce. We combine water column N2O measurements generated during two expeditions with on-board incubation of intact sediment cores to fill this observational gap, constrain N2O sources and assess the impact of land-derived nitrogen that is expected to increase with permafrost thaw. Our data show elevated nitrogen concentrations in the water column and sediments near the mouths of large rivers, suggesting that land-derived nitrogen might promote primary production, but also nitrification and denitrification in the region. However, N2O concentrations were only weakly influenced by elevated nitrogen availability near river mouths. Comparison with a range of environmental parameters suggests that N2O concentrations might be controlled by interactions of nitrogen availability with turbidity and possibly temperature. Surface water N2O concentrations were on average in equilibrium with the atmosphere, but high spatial variability indicates strong local N2O sources and sinks. Water column profiles of N2O concentrations and low sediment-water N2O fluxes do not support a dominant sedimentary source or sink, but point at production and consumption processes in the water column as main drivers of N2O dynamics in the Siberian shelf seas. The projected increases in water temperature and input of freshwater, nitrogen and suspended material from rivers and coastal erosion with land permafrost thaw have the potential to affect not only net N2O production rates, but also N2O solubility in the water, and increase N2O emissions from the Arctic Ocean. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-7491

2022046764 Zwinger, Thomas (CSC, IT Center for Science, Espoo, Finland); Cohen, Denis; Gladstone, Rupert and Raback, Peter. Modelling the thermal and mechanical interaction of an ice sheet with a partly frozen bedrock [abstr.]: in European Geosciences Union general assembly 2022, Geophysical Research Abstracts, 24, Abstract EGU22-13099, 2022. (Hybrid meeting). Meeting: European Geosciences Union general assembly 2022, May 23-27, 2022, Vienna, Austria.

In recent years, subglacial hydrological models as well as till deformation models have been coupled to ice-flow models in order to determine mechanical basal conditions underneath ice sheets and glaciers. These models, nevertheless, often ignore the thermo-dynamical aspects, in particular, not including the influence of permafrost in proximity to or underneath glaciers. Here we present a thermo-mechanically coupled ice-sheet bedrock model. The latter includes components of saturated aquifer water transport, soil deformation, salinity transport and - most important - energy balance including phase change of the solvent. Using synthetic flow-line setups we present studies of ice-sheet fronts, advancing either over existing permafrost or largely unfrozen soils. We investigate the heat- and meltwater-transfer between the ice-body and its substrate and discuss their impact on ice-dynamics. As the results suggest that in certain situations the water balance further demands the existence of a hydrological system between ice and bedrock, we currently work to include this third model component in form of a subglacial hydrological model. All model components are implemented in the Finite Element software Elmer, which renders their mutual coupling relatively easy, yet, numerically demanding. [Copyright Author(s) 2022. CC Attribution 4.0 License:]

DOI: 10.5194/egusphere-egu22-13099

2022043127 Kerr, Phil (Iowa Geological Survey, Iowa City, IA) and Heinzel, Chad. Evidence for late Pleistocene periglacial features in the Midwest United States [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. 12-9, 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.

Periglacial processes during the Late Pleistocene significantly impacted the modern landscape in the Midwest, especially in areas not covered by ice during the Late Wisconsin Episode. Recent mapping endeavors in eastern Iowa have discovered relict periglacial features on the Iowan Erosion Surface (IES). This landscape has a well-developed drainage network, unlike the recently glaciated region (formed by the Des Moines Lobe) to the west. Large areas of the IES are formed in thick (>100 m) clay-rich glacial diamicton while other regions have Paleozoic carbonate bedrock <2 m from the surface. Features such as involutions, ice wedge casts, and sand wedges (up to 4 m deep by 3 m wide) provide evidence that multiple periglacial processes occurred on the IES. Several hillslope coring transects show active layer detachment, indicative of the development of thermokarst terrain. These profiles suggest that most of the weathering profile and associated geosol were removed from the upland, and that the adjacent side slopes have preserved plug-like flow layers derived from parts of that missing stratigraphy. Furthermore, regressive thaw slumps are common in areas of shallow bedrock and/or valleys that carried glacial meltwater. Some thermocirques are >1 km2 and have linked to form thermokarst badlands >25 km2 in size. As a result, this thermokarst mass wasting caused a significant percentage of stream valleys on the IES to be underfit. Radiocarbon ages from plant material within these valley deposits suggest that periglacial erosion occurred 26-15 ka. Future efforts will seek to identify and describe additional periglacial features, improve the overall chronology using a combination of methods, and then integrate this data with a multi-proxy climate record. By doing so, this work on the IES may prove to be a useful analogue to modern permafrost thawing.

DOI: 10.1130/abs/2022NC-373939

2022047779 Prince, Karlee (State University of New York at Buffalo, Department of Geology, Buffalo, NY); Briner, Jason; Walcott, Caleb and Kozlowski, Andrew L. Evidence of extensive permafrost between deglaciation and 15,000 years ago in western New York, USA [abstr.]: in Geological Society of America, Northeastern Section, 57th annual meeting, Abstracts with Programs - Geological Society of America, 54(3), Abstract no. 33-2, March 2022. Meeting: Geological Society of America, Northeastern Section, 57th annual meeting, March 20-22, 2022, Lancaster, PA.

The chronology of the last deglaciation of the Laurentide Ice Sheet in western New York (WNY) is poorly constrained. To fill this spatial and temporal gap, we collected sediment cores from six bogs in the Kent (terminal) and Lake Escarpment (first major recessional) moraine systems in WNY to constrain moraine abandonment via radiocarbon dating of macrofossils from basal sediments. Unlike prior work, we collected mineral-rich sediments lower than Livingstone corer penetration using a percussion Geoprobe system. Generally, the cores capture a basal silty diamicton followed by gray and tan lacustrine silts. The lacustrine silt increases in organic matter before a transition to peat. The lowest ages from the gray lacustrine units from all six bogs range from ~15-14 cal kyr BP. Other radiocarbon ages from the same unit occasionally come back older than the lowest age, spanning from 15-19.5 cal kyr BP. The oldest age (19.5 cal kyr BP) appears to be from an organic-rich rip-up clast within the gray silt and suggests sediment re-working. Our working hypothesis is that the mixed ages are the result of persistent permafrost conditions that inhibited kettle basin formation until ~15 cal kyr BP. Between at least 19.5 and 15 cal kyr BP, large ice blocks likely survived in the moraines until 15-14 cal kyr BP. Once these ice blocks began to melt, organic material from thin, frozen organic deposits (dating back to at least 19.5 cal kyr BP) could have been re-worked into the kettle basins. According to our hypothesis, the ice sheet began retreating from its terminal position before 19.5 cal kyr BP, but permafrost conditions and later basin formation prohibited a typical post-glacial deposition sequence. As such, the oldest macrofossils found within minerogenic sections of sediment cores from moraines in WNY are the best minimum constraints on moraine abandonment, not necessarily the standard 'bog-bottom' ages. This model potentially reconciles recent work which proposed that ages from 13-14 cal kyr BP were the result of a re-occupation of WNY by the Laurentide Ice Sheet, which instead could be the result of delayed deposition from permafrost. The Laurentide Ice Sheet's proximal location over Lake Ontario until ~15 cal kyr BP and the Bolling/Allerod warming may have contributed to the extended cold conditions and eventual thawing of the landscape.

DOI: 10.1130/abs/2022NE-375207

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