CR4.2 | Permafrost dynamics, interactions, feedbacks, disturbances and GHG's across scales: perspectives from observation to modelling
EDI
Permafrost dynamics, interactions, feedbacks, disturbances and GHG's across scales: perspectives from observation to modelling
Co-organized by BG1
Convener: Helena BergstedtECSECS | Co-conveners: In-Won KimECSECS, Martijn PallandtECSECS, Louise Farquharson, David Wårlind, Annett Bartsch, Rebecca ScholtenECSECS
Orals
| Fri, 19 Apr, 14:00–15:45 (CEST), 16:15–18:00 (CEST)
 
Room L3
Posters on site
| Attendance Thu, 18 Apr, 10:45–12:30 (CEST) | Display Thu, 18 Apr, 08:30–12:30
 
Hall X4
Posters virtual
| Attendance Thu, 18 Apr, 14:00–15:45 (CEST) | Display Thu, 18 Apr, 08:30–18:00
 
vHall X4
Orals |
Fri, 14:00
Thu, 10:45
Thu, 14:00
This session is a merger of three sessions from Cryospheric Sciences (CR) and Biogeosciences (BG).

The original sessions were:
- Disturbance processes in permafrost regions
- Permafrost dynamics, interactions, and feedbacks: past, present, and future
- High latitude biogeochemistry: Addressing challenges in GHG, from in situ to remote sensing

This merged session collects abstracts focussing on permafrost regions and other high latitude landscapes which have experienced the highest levels of warming in the world. Permafrost shapes Arctic ecosystems and interacts with the global climate system in manifold ways. It affects the cycling of water, energy, and carbon in high latitudes and impacts climate patterns at local to global scales. Furthermore, anthropogenic activities such as the construction of roads, mining, oil and gas extraction, and agricultural expansion are increasing in these regions. Permafrost regions are highly sensitive to disturbance due to their dependence on a thermal threshold for stability and as a result they are impacted by a wide range of disturbances including wildfire, infrastructure development, the arrival of invasive species, and ongoing atmospheric warming. This can result in a myriad of geomorphological processes including thermokarst formation, mass-movement initiation, coastal erosion, and lake drainage events; all of which impact a wide range of ecosystem processes, as well as the built environment. The interplay of atmospheric warming and anthropogenic activities have likely increased the frequency and magnitude of these disturbances and altered their spatiotemporal occurrence.

This session is a forum for scientists involved in the state-of-the-art research on permafrost dynamics, disturbance processes and impacts in permafrost environments, and the mechanisms and changes in greenhouse gas cycles in these highly dynamic regions.

This session covers observations and modelling of permafrost dynamics, interactions, and feedbacks with the hydrological cycle, seasonal snow cover, biogeochemical and biogeophysical processes, and landscape processes (e.g. thermokarst, wildfires) across spatial scales.

Orals: Fri, 19 Apr | Room L3

Chairpersons: Helena Bergstedt, Annett Bartsch, David Wårlind
14:00–14:05
14:05–14:25
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EGU24-21829
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solicited
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On-site presentation
Torsten Sachs and the the MOMENT project team

Estimates of the future methane (CH4) budget of northern permafrost landscapes remain highly uncertain with projections ranging from negligible to major CH4 releases to the atmosphere.

The German collaborative MOMENT project aims to address important gaps in process understanding of the high-latitude methane cycle using multi-scale methane flux observations in western Greenland linked to microbiological and biogeochemical laboratory studies. Through an innovative model-data integration framework, these novel datasets will be used to develop and evaluate land surface schemes of German Earth System Models (ESM) across terrestrial systems and multiple scales with the overarching goal to reduce uncertainties in future greenhouse gas projections.

We will introduce the overall project along with the innovations in experimental and observational techniques that facilitate observations at remote Arctic locations as well as in the lab. New remote sensing products allow for wall-to-wall mapping of structures on the finest scale across the Arctic, while novel computational infrastructure and modelling frameworks help with integration of all this information into next generation ESMs.

Selected preliminary results of the first field season and lab experiments will be highlighted.

How to cite: Sachs, T. and the the MOMENT project team: The MOMENT Project - Permafrost Research Towards Integrated Observation and Modelling of the Methane Budget of Ecosystems, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-21829, https://doi.org/10.5194/egusphere-egu24-21829, 2024.

14:25–14:35
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EGU24-19342
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On-site presentation
Emissions and atmospheric distribution of methane in Scandinavia: Results and lessons learned from the MAGIC2021 international campaign
(withdrawn)
Cyril Crevoisier and Caroline Bès
14:35–14:45
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EGU24-20159
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On-site presentation
Johanna Tamminen and the MethaneCAMP project team

The ESA funded MethaneCAMP project has focused on assessing, improving, and analysing satellite observations of methane (CH4) in the Arctic in support of the collaborative ESA-NASA Arctic Methane and Permafrost Challenge (AMPAC) initiative. 

Traditionally, the high latitude conditions have received minor attention when the satellite retrievals for methane have been optimised for global purposes as there has been known challenges caused by high solar zenith angles, low reflectivity over snow and ice, frequent cloudiness, varying polar vortex conditions and limited number of validation data sets. Now when the two-year MethaneCAMP project is finishing, we will demonstrate the recent improvements in the observation capacity over the polar regions by assessing and optimising methane SWIR and TIR retrievals at high northern latitudes. Moreover, the importance of AirCore reference observations of methane profiles in the varying polar vortex conditions will be highlighted.

We will analyse the long-term methane trends in the northern high latitudes and permafrost regions by using satellite observations and inverse modelling. We aim to demonstrate the potential of using satellite observations of methane together with modelling and surface observations in analysing spatial and temporal changes of the Arctic methane. Detection of methane hot spots will also be mentioned.

In MethaneCAMP project our focus has been on Sentinel 5P/TROPMI, GOSAT, GOSAT-2 and IASI XCH4 observations and GHGSat emission estimates. In this presentation we summarise the results of the project and discuss how the outcomes can be utilised in the AMPAC working group activities.

How to cite: Tamminen, J. and the MethaneCAMP project team: MethaneCAMP project – overview of results, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20159, https://doi.org/10.5194/egusphere-egu24-20159, 2024.

14:45–14:55
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EGU24-14659
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On-site presentation
Mathias Göckede, Victor Brovkin, Annett Bartsch, and Martin Heimann and the Q-Arctic Team

Arctic permafrost has been identified as a critical element in the global climate system, since it stores a vast amount of carbon that is at high risk of being released under climate change. The feedbacks between permafrost carbon and climate change are moderated by complex interactions between physical, hydrological, biogeochemical, and ecological processes. Many of these are not well understood to date, and therefore also only rudimentarily represented in current Earth System Models (ESMs). A particular problem in this context is a scaling gap between processes and model grid.

The Q-ARCTIC project funded by the European Research Council (ERC) follows a synergetic approach by combining remote sensing and local-scale observations with modeling on scales from a few meters to hundreds of kilometers. The primary objective of Q-ARCTIC is to close the gap between process scales and the much coarser grid resolution of Earth System Models (ESMs), with a particular focus on the net effect of disturbance processes and associated changes in hydrology on the pan-Arctic scale. To close this gap, we developed new ESM modules representing subgrid through stochastic parameterizations, trained and evaluated with high-resolution remote sensing data and site-level observations.

We will present novel results based on in-situ observations that characterize prominent Arctic disturbance features, and satellite remote sensing products investigating fine scale (few meters) patterns in Arctic landscapes that are undergoing modifications linked to climate change. Targets investigated include for example sinking surfaces, wetness gradients in heterogeneous landscapes, or drained lake basins. Assimilation of these new datasets supported the development of new ESM model components that successfully capture the statistics of small-scale features, e.g. depressions linked to sinking surfaces, or surface water bodies that form when soil ice melts. Our results demonstrate that the ability to project the response of the high-latitude water, energy and carbon cycles to rising global temperatures may strongly depend on the ability to adequately represent the soil hydrology in permafrost affected regions.

How to cite: Göckede, M., Brovkin, V., Bartsch, A., and Heimann, M. and the Q-Arctic Team: Q-Arctic: A synergetic approach to observe and model pan-Arctic interactions between hydrology and carbon, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-14659, https://doi.org/10.5194/egusphere-egu24-14659, 2024.

14:55–15:05
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EGU24-9594
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ECS
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On-site presentation
Mark Schlutow and Mathias Göckede

The vulnerability of Arctic permafrost to climate change is evident, with anticipated widespread enhanced thawing under climate warming. This process may release substantial amounts of organic carbon. The positive feedback mechanism resulting from accelerated thaw and increased carbon emission is suspected to be a potential tipping element, possibly occurring within the 1.5 °C global warming range of the Paris Agreement. The consequences of Arctic permafrost thaw extend beyond carbon release, with the capability to drastically alter Earth's surface in Northern high latitudes.

This study employs high-resolution Large Eddy Simulations to investigate the impact of changing surfaces in the Arctic region on the neutrally stratified Atmospheric Boundary Layer. Utilizing a stochastic land cover model based on Gaussian Random Fields, representative permafrost landscapes are classified by distinct surface features. Experiments varying the areal fraction and surface correlation length of these surface features reveal significant insights into the sensitivity of the boundary layer to surface heterogeneity.

Key findings include a substantial impact of areal fraction of open water bodies on aggregated sensible heat flux at the blending height, suggesting a potential feedback mechanism: The smaller the areal fraction of open water bodies, the greater the sensible heat flux, the warmer the surface. Additionally, the blending height is significantly influenced by the correlation length of surface features. A longer surface correlation length leads to an increased blending height, highlighting the relevance of this metric for land surface models focused on Arctic permafrost.

How to cite: Schlutow, M. and Göckede, M.: Interaction of the Atmospheric Boundary Layer with degrading Arctic permafrost: A numerical study, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-9594, https://doi.org/10.5194/egusphere-egu24-9594, 2024.

15:05–15:15
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EGU24-2682
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On-site presentation
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Paul Glover

Thawing of permafrost due to climate change is known to release gases such as the climate drivers carbon dioxide and methane, as well as the carcinogen radon. Radon is a natural radioactive gas responsible for about 10% of lung cancer deaths globally, and substantially greater rates in sub-Arctic communities. Gas transport is significantly reduced in permafrost, but now that permafrost is thawing due to climate change, the effect on the release of CO2 and CH4, and on domestic radon exposure is unknown.

Measurement: Few experimental measurements have shown the gas permeability of permafrost to be very small (order of 10-16 m2). Here we present the initial measurements of the changes in porosity and gas permeability during the thawing of synthetic permafrost using a pyknopermeameter that we are developing. The results show increases in gas permeability by many orders of magnitude, that remain during freeze-thaw cycles providing the thawed water does not drain from the sample. Draining the thawed water leads to compaction which decreases the effects of subsequent thawing on the matrix gas permeability, but can cause fracturing which provide high permeability pathways for gas flow.

Modelling: Results from radon transport modelling through soil, permafrost, and model buildings either with basements or built on piles show that permafrost acts as an effective radon barrier, reducing radiation exposure to a tenth of the background level in dwellings while producing a ten-fold increase in the radon activity below the permafrost. When we model thawing of the permafrost barrier, we find no increase in radon to the background level for buildings on piles.  However, for buildings with basements, the level of radioactivity due to the radon increases to over one hundred times its initial value and can remain above the 200 Bq/m3 threshold for up to 7 years depending on the depth of the permafrost and the speed of thawing. When thawing speed is taken into account, radiations remain higher than the threshold for all scenarios where 40% thawing occurs within 15 years. This new information suggests that the sub-Arctic population could be exposed to dangerous radon levels as a result of climate change.

How to cite: Glover, P.: Modelling and Measurement of Radon and CO2 Release from Thawing Permafrost Caused by Climate Change, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2682, https://doi.org/10.5194/egusphere-egu24-2682, 2024.

15:15–15:25
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EGU24-2979
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On-site presentation
Yuanhe Yang, Guanqing Wang, and Yunfeng Peng

As global temperatures continue to rise, a key uncertainty of terrestrial carbon (C) climate feedback is the rates of C loss upon abrupt permafrost thaw. This type of thawing - termed thermokarst - may in turn accelerate or dampen the response of microbial degradation of soil organic matter and carbon dioxide (CO2) release to climate warming. However, such impacts have not yet been explored in experimental studies. Here, by experimentally warming three thermo-erosion gullies in an upland thermokarst site combined with incubating soils from another five thermokarst-impacted sites on the Tibetan Plateau, we investigate whether and how abrupt permafrost thaw would influence the responses of soil CO2 release to climate warming. Our results show that warming-induced increase in soil CO2 release is higher in thermokarst features than the adjacent non-thermokarst landforms. This larger warming response is mainly attributed to the lower substrate quality and higher abundance of microbial functional genes for recalcitrant C degradation in thermokarst-affected soils. Taken together, our study provides experimental evidence that abrupt permafrost thaw aggravates the warming-associated soil CO2 loss, which will exacerbate the positive soil C-climate feedback in permafrost-affected regions under future warming scenarios.

How to cite: Yang, Y., Wang, G., and Peng, Y.: Intensified warming effects on soil respiration upon thermokarst formation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2979, https://doi.org/10.5194/egusphere-egu24-2979, 2024.

15:25–15:35
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EGU24-8527
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ECS
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On-site presentation
Friedrich Röseler, Claire Treat, and Gerard Heuvelink

The northern circumpolar permafrost region contains up to half of the global soil carbon pool and twice as much carbon as currently is in the atmosphere. At the same time, the Arctic is rapidly warming due to climate change, causing the permafrost to thaw. There is a risk that substantial amounts of soil organic carbon (SOC) may be released into the atmosphere as greenhouse gases during this process. This makes permafrost carbon a potentially strong climate feedback that could further amplify global warming.

Currently, only a few studies attempted to quantify this permafrost carbon on a global scale. Despite the advances in estimating how much SOC is stored in the northern circumpolar permafrost region, there are still large uncertainties. Modelling permafrost carbon is particularly challenging due to the scarce availability of reference datasets on SOC content and great subsurface variability in the Arctic environment caused by cryoturbation. The high lateral (i.e. horizontal) and vertical (i.e. along the soil profile) variability results in several obstacles when mapping SOC in permafrost regions.

While previous studies on modelling permafrost carbon focused on quantifying its spatial heterogeneity, they lacked in capturing the complex (vertical) distribution of SOC as a function of depth. Furthermore, they often rely on discrete models to estimate the spatial variation. In this work, we focus on providing more accurate high-resolution, continuous global maps of permafrost SOC density using a 3D digital soil mapping approach. Digital soil mapping has shown to be a valuable tool in mapping SOC, as it can better capture the continuous variation of soil properties. Here, we used a random forest machine learning model to predict SOC based on a number of spatial variables representing soil forming factors (such as topographic attributes, climate, carbon age and land cover). The reference dataset that we used to train the model consists of soil profile observations from the permafrost region of the Northern Hemisphere, excluding alpine permafrost. We harmonised this dataset from existing databases and recent studies that provide information on carbon content from soil core measurements. Information on the bulk density was needed to calculate the SOC density and estimated for missing observations using pedotransfer functions. Results indicate that 3D modelling of permafrost carbon produces substantially different results than conventional 2D approaches. Furthermore, accounting for the vertical variation in SOC improves the prediction accuracy.

How to cite: Röseler, F., Treat, C., and Heuvelink, G.: Geospatial modelling of soil organic carbon density in 3D across the northern circumpolar permafrost region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8527, https://doi.org/10.5194/egusphere-egu24-8527, 2024.

15:35–15:45
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EGU24-2291
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ECS
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On-site presentation
Xingru Zhu, Gensuo Jia, and Xiyan Xu

Wildfires over permafrost put perennially frozen carbon at risk. However, burned area and wildfire carbon emissions from biomass burning over the diverse range of permafrost regions have not been revealed. Here, we show that continuous permafrost was a major contribution to wildfire expansion and carbon emission in the pan-Arctic over the last two decades. Burned area and wildfire carbon emissions dramatically increased over continuous permafrost during the last two decades, but decreased in other permafrost regions. Accelerating wildfire emission from continuous permafrost region is the single largest contribution to the increased emissions in northern permafrost regions. The share of permafrost in global wildfire CO2 emissions grew from 2.42% in 1997 to 20.86% in 2021. Wildfire expansion is closely linked to an increased soil moisture deficit, considering wildfires there combust more than 90% of belowground fuel. Continuous permafrost experiences more severe fire-induced degradation. Active layer thickening following wildfires over continuous permafrost lasts more than three decades to reach a maximum of more than triple the pre-fire thickness. These findings highlight expansion of wildfires and acceleration of fire-induced carbon emission from continuous permafrost region, which disturbs organic carbon stock, accelerates the positive feedback between permafrost degradation and climate warming.

 

How to cite: Zhu, X., Jia, G., and Xu, X.: Expansion of wildfires and their impact on carbon emissions over pan-Arctic permafrost, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2291, https://doi.org/10.5194/egusphere-egu24-2291, 2024.

Coffee break
Chairpersons: In-Won Kim, Louise Farquharson, Martijn Pallandt
16:15–16:20
16:20–16:30
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EGU24-2165
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ECS
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On-site presentation
Nina Nesterova, Ilya Tarasevich, Marina Leibman, Aleksander Kizyakov, Ingmar Nitze, and Guido Grosse

Regressive thaw slumps (RTSs) are permafrost landforms formed by the thawing of ice-rich permafrost or the melting of massive ground ice. The West Siberian Arctic (Yamal and Gydan peninsulas) is an area with widespread distribution of RTSs due to continuous permafrost and massive tabular ground ice close to the surface. The initiation of RTS in the region strongly affects the environment by altering vegetation and topography and releasing carbon. Roads and railways are also affected by RTS occurrence.  

There is still no complete understanding of the true RTS distribution and its environmental controls in the West Siberian Arctic because of the remote location of the region. A remote sensing technique can be used to enhance our understanding of the characteristics of RTS over a large area. However, automated mapping of RTSs has certain limitations, including the lack of ground truth data, the large number of false-positive detections, and the ambiguity in interpretation. Moreover, the polycyclic nature of RTS development leads to a very complex spatial aggradation with numerous overlapping or nested RTSs. This poses additional challenges for mapping.

Based on theoretical and field studies, we developed a classification to capture the main morphological and environmental parameters of RTS nature visible on satellite imagery. To minimize false-positive detections we performed in-detail manual mapping of the RTSs in West Siberia using multiple sources including the ESRI satellite base map, Google Earth satellite base map, and Yandex Maps satellite base map. Each point was classified by several parameters: morphology, spatial aggradation, concurrent cryogenic processes, terrain position, and attachment to the base level. Field experience and data at the key sites, as well as a helicopter-based inventory, helped to perform verification and estimate accuracy.

We identified more than 4000 RTSs. The spatial distribution of identified RTSs demonstrates clusters over the western Yamal Peninsula and central-northern Gydan Peninsula. This research aims at a comprehensive analysis of the spatial distribution of classified RTS concerning regional geological, climate, and other available environmental data. Our results are valuable for understanding the nature of this widespread phenomenon in the Arctic.

How to cite: Nesterova, N., Tarasevich, I., Leibman, M., Kizyakov, A., Nitze, I., and Grosse, G.: Modern spatial distribution of diverse retrogressive thaw slumps in West Siberia, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2165, https://doi.org/10.5194/egusphere-egu24-2165, 2024.

16:30–16:40
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EGU24-17224
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ECS
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On-site presentation
Zhijun Liu, Barbara Widhalm, Annett Bartsch, Thomas Kleinen, and Victor Brovkin

The northern high latitudes are warming much faster than the rest of the planet. While gradual thaw of permafrost is accounted for in the recent generation of the Earth System Models (ESMs), consequences of the abrupt thaw of permafrost and the subsequent greenhouse gas release are not yet taken into consideration. However, an abrupt thaw of very small fraction of the northern permafrost region can lead to significant carbon release and subsequent global warming (Turetsky et al. 2020).

An in-depth analysis of fine-scale permafrost subsidence processes is crucial for improved representation of abrupt thawing in simulations. Currently, permafrost subsidence is only taken into consideration in a few models, where subsidence is described in a deterministic process-based approach. This approach overlooks the high spatial heterogeneity in fine-scale permafrost processes.

Recent advancements in satellite technology allow the acquisition of Interferometric Synthetic Aperture Radar (InSAR) data on permafrost vertical displacement at meter-scale resolution. We conducted a case study on the Yamal Peninsula, Russia, where we compare permafrost subsidence data from Sentinel-1 with various potential driving factors, including climate forcing data from ERA5-Land and geomorphology data from MERIT Hydro. A statistical approach is taken to analyse the relationships between different factors and their contributions to permafrost subsidence. The results demonstrate the high heterogeneity of permafrost subsidence in the form of probability distribution functions at ESM-scale resolution. Eventually, our study aims to obtain a parameterization for pan-Arctic permafrost subsidence that can be implemented into the ICON-ESM in order to close the gap in permafrost modelling between process- and ESM-scale.

 

Reference: Turetsky, M.R., Abbott, B.W., Jones, M.C. et al. Carbon release through abrupt permafrost thaw. Nat. Geosci. 13, 138–143 (2020). https://doi.org/10.1038/s41561-019-0526-0

How to cite: Liu, Z., Widhalm, B., Bartsch, A., Kleinen, T., and Brovkin, V.: Statistical Modelling of Permafrost Subsidence Based on High-resolution InSAR Data, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17224, https://doi.org/10.5194/egusphere-egu24-17224, 2024.

16:40–16:50
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EGU24-559
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ECS
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On-site presentation
Maxime Thomas, Thomas Moenaert, Éléonore du Bois d’Aische, Maëlle Villani, Catherine Hirst, Erik Lundin, François Jonard, Sébastien Lambot, Kristof Van Oost, Veerle Vanacker, Reiner Giesler, Carl-Magnus Mörth, and Sophie Opfergelt

In situ field studies in thawing permafrost regions have shown that C emissions resulting from organic carbon (OC) decomposition depend among others on the variability in soil water content, which can be directly related to microtopography. A more precise assessment of the evolution of permafrost C emissions as a function of thermokarst development requires high-resolution quantification of thermokarst-affected areas, as lowland thermokarst development induces fine-scale spatial variability (~ 50 – 100 cm). Here, we investigate a gradient of lowland thermokarst development at Stordalen mire, Abisko, Sweden, from well-drained undisturbed palsas to inundated fens, which have undergone ground subsidence. We produced orthomosaics and digital elevation models from very-high resolution (10 cm) UAV photogrammetry as well as a spatially continuous map of soil electrical conductivity (EC) based on Electromagnetic Induction (EMI) measurements performed in September 2021. In conjunction, we measured in situ the soil water content from the different stages of thermokarst development at the same period. The soil EC values are contrasted along the gradient in line with contrasts observed in the landscape classification derived from the orthomosaics and digital elevation models: palsas are flat areas with low soil EC (drier), whereas fens are subsided areas with higher EC (water-saturated). Areas in the course of degradation (transition zones) are well identified based on their higher slope, and broad range of EC. Importantly, these transition zones are only detected using a very fine spatial scale (i.e., 10 cm) coupled to information on the microtopography. Compared to a set of previously collected orthomosaics and digital elevation models, our results show an acceleration of thermokarst development in this area with a rate of palsa decline 4 to 10 times greater in 2019-2021 than in 2000-2014.

How to cite: Thomas, M., Moenaert, T., du Bois d’Aische, É., Villani, M., Hirst, C., Lundin, E., Jonard, F., Lambot, S., Van Oost, K., Vanacker, V., Giesler, R., Mörth, C.-M., and Opfergelt, S.: Detecting lowland thermokarst development by UAV remote sensing in the Stordalen mire, Abisko, Sweden , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-559, https://doi.org/10.5194/egusphere-egu24-559, 2024.

16:50–17:00
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EGU24-17812
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ECS
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On-site presentation
Yi Xi, Chunjing Qiu, Yuan Zhang, Dan Zhu, Shushi Peng, Gustaf Hugelius, Jinfeng Chang, Elodie Salmon, and Philippe Ciais

The surface energy budget plays a critical role in terrestrial hydrologic and biogeochemical cycles. Nevertheless, its highly spatial heterogeneity across different vegetation types is still missing in the land surface model, ORCHIDEE-MICT (ORganizing Carbon and Hydrology in Dynamic EcosystEms–aMeliorated Interactions between Carbon and Temperature). In this study, we describe the representation of a multi-tiling energy budget in ORCHIDEE-MICT and assess its short and long-term impacts on energy, hydrology, and carbon processes. We found that: 1) With the specific values of surface properties for each vegetation type, the new version presents warmer surface and soil temperatures, wetter soil moisture, and increased soil organic carbon storage across the Northern Hemisphere. 2) Despite reproducing the absolute values and spatial gradients of surface and soil temperatures from satellite and in-situ observations, the considerable uncertainties in simulated soil organic carbon and hydrologic processes prevent an obvious improvement of temperature bias existing in the original ORCHIDEE-MICT. 3) The simulated continuous permafrost area (15.2 Mkm2) and non-continuous permafrost area (3.1 Mkm2) are comparative to observation-based datasets from Brown et al. (2002) (10.8 Mkm2 for continuous and 4.6 Mkm2 for non-continuous) and Obu et al. (2019) (11.5 Mkm2 for continuous and 5.3 Mkm2 for non-continuous). Consequently, the new version will facilitate various model-based permafrost studies in the future. 

How to cite: Xi, Y., Qiu, C., Zhang, Y., Zhu, D., Peng, S., Hugelius, G., Chang, J., Salmon, E., and Ciais, P.: Improving the simulation of permafrost extent by representing the multi-tiling energy budgets in ORCHIDEE-MICT model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17812, https://doi.org/10.5194/egusphere-egu24-17812, 2024.

17:00–17:10
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EGU24-4091
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ECS
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On-site presentation
Cengiz Akandil, Elena Plekhanova, Nils Rietze, Jacqueline Oehri, Miguel O. Roman, Zhuosen Wang, Volker Radeloff, and Gabriela Schaepman-Strub

Climate warming enables easier access and operation in the Arctic, fostering industrial and urban development. However, there is no comprehensive pan-Arctic overview of industrial and urban development, which is crucial for the planning of sustainable development of the region. In this study, we utilize satellite derived artificial light at night (ALAN) data to quantify the hotspots and the development of human activity across the Arctic from 1992 – 2013. We find that out of 16.4 million km2 analyzed a total area of 839,710 km2 (5.14%) is lit by human activity with an annual increase of 4.8%. The European Arctic and the oil and gas extraction regions in Russia and Alaska are hotspots of ALAN with up to a third of the land area lit, while the Canadian Arctic remains dark to a large extent. On average, only 15% of lit area in the Arctic contains human settlement, indicating that artificial light is largely attributable to industrial human activity. With this study, we provide a new, standardized approach to spatially assess human industrial activity across the Arctic, independent from economic data. Our results provide a crucial baseline for sustainable development and conservation planning across the highly vulnerable Arctic region.

 

How to cite: Akandil, C., Plekhanova, E., Rietze, N., Oehri, J., Roman, M. O., Wang, Z., Radeloff, V., and Schaepman-Strub, G.: Artificial light at night reveals hotspots and rapid development of industrial activity in the Arctic, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4091, https://doi.org/10.5194/egusphere-egu24-4091, 2024.

17:10–17:20
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EGU24-17398
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ECS
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On-site presentation
Joana Baptista, Gonçalo Vieira, Sebastian Westermann, and Hyoungseok Lee

The temperature dynamics of permafrost is crucial for ecosystem processes in the ice-free areas of the Antarctic Peninsula, where a strong long-term warming trend with an increase of 3.4 ºC in the mean annual air temperature since 1950 has been recorded (Turner et al., 2020). The consequences of this warming on past and future permafrost degradation are still not fully understood, mainly due to the sparse spatial coverage and short time span of borehole data, only available after the mid to late 2000’s (Vieira et al., 2010; Bockheim et al., 2013). The Cryogrid Community Model is an adaptable toolbox for simulating the ground thermal regime and the ice/water balance for permafrost (Westermann et al., 2017, 2022). The modular structure allows combinations of classes that represent the snow conditions and the subsurface materials. Here, permafrost temperatures from the 13 m depth King Sejong Station borehole (KSS), from Barton Peninsula, King George Island were used to assess the performance of Cryogrid and the quality of ERA5 forcing. For evaluating model performance, the setup was firstly used in its basic version with the GROUND_freeW_ubtf class, which considers a temperature boundary condition, for which air temperatures from KSS were used. Modifications to the stratigraphy and parameters were performed to achieve the strongest correlations and lower Mean Absolute Errors (MAE) between the simulated and observed ground temperature at nine depth levels. This approach allowed for the definition of the stratigraphy and parameters later used with the GROUND_freeW_seb_snow class, in which the surface energy balance scheme is included. The results show that ERA5 air temperature underestimates the records from KSS, especially during the summer, impacting the representation of surface warming. This deviation was corrected using linear regression corrected temperatures. The Cryogrid modelling results indicate an overestimation of the ground temperature during the thawing season and an underestimation during the freezing season, being the difference more pronounced at the surface. A strong correlation was shown between the simulated and measured ground temperatures in KSS down to 6 m depth (r>0.9) with MAE ranging from 0.4 to 0.9 ºC. Below 6 m the correlation weakens to 0.45 (13 m depth) due to differences in heat propagation and lack of temperature oscillation on the records when compared with the simulation. However, MAE values are residual, ranging from 0.1 to 0.2 ºC. The active layer thickness was overestimated in about 1 m. This research was funded by the project THAWIMPACT (FCT2022.06628.PTDC) and by CEG/IGOT (UIDP/00295/2020). Joana Baptista is funded by the FCT with a doctoral grant (2021.05119.BD).

How to cite: Baptista, J., Vieira, G., Westermann, S., and Lee, H.: Cryogrid modelling of permafrost temperature in the Maritime Antarctic (Barton Peninsula, King George Island), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-17398, https://doi.org/10.5194/egusphere-egu24-17398, 2024.

17:20–17:30
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EGU24-15989
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ECS
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On-site presentation
Rodrigue Tanguy, Annett Bartsch, Ingmar Nitze, Anna Irrgang, Pia Petzold, Barbara Widhalm, Clemens von Baeckmann, Julia Boike, Julia Martin, Aleksandra Efimova, Gonçalo Vieira, Birgit Heim, Mareike Wieczorek, Guido Grosse, and Dorothee Ehrich

This study assesses the escalating vulnerability of Arctic coastal communities due to the combined impacts of coastal erosion and permafrost warming. With the Arctic experiencing heightened temperatures, coastal permafrost areas face increased instability, endangering vital infrastructures. The study focuses on a pan-Arctic evaluation of settlements and infrastructures at risk, enhancing the existing Arctic coastal infrastructure dataset (SACHI) to include road types, airstrips, and artificial water reservoirs.

By analyzing coastline change rates from 2000 to 2020, alongside permafrost ground temperature and active layer thickness trends from the ESA Permafrost Climate Change Initiative datasets, the research identifies settlements at risk for the years 2030, 2050, and 2100. The accuracy of the dataset is rigorously evaluated. Results indicate that by 2100, 23% of coastal settlements will face the impacts of coastal erosion. Projections based on linear trends suggest an 8°C increase in coastal permafrost ground temperature and a 0.9-meter growth in active layer thickness by the same year.

Crucially, the study reveals that 65% of all infrastructures and settlements will be affected by permafrost warming within the range of 5-15°C, with 35% experiencing active layer thickening between 1-5 meters. This research marks the first regional-scale identification of settlements at risk from coastal erosion along Arctic and permafrost-dominated coasts in the northern hemisphere. The findings emphasize the urgency of adapting to current and future environmental changes to mitigate the deterioration of living conditions in permafrost coastal settlements. Immediate action is imperative to counteract these challenges and ensure the resilience of these vulnerable communities.

How to cite: Tanguy, R., Bartsch, A., Nitze, I., Irrgang, A., Petzold, P., Widhalm, B., von Baeckmann, C., Boike, J., Martin, J., Efimova, A., Vieira, G., Heim, B., Wieczorek, M., Grosse, G., and Ehrich, D.: Vulnerability assessment of Arctic coastal communities to the effects of coastal erosion and permafrost warming., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15989, https://doi.org/10.5194/egusphere-egu24-15989, 2024.

17:30–17:40
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EGU24-149
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ECS
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On-site presentation
Manuel Ruben, Jens Hefter, Torben Gentz, Florence Schubotz, Bingbing Wei, Bo Liu, Michael Fritz, Anna Maria Irrgang, Anabel von Jackowski, Walter Geibert, and Gesine Mollenhauer

Arctic permafrost is a critical global tipping element in a warming climate. Annually, the erosion of coastal permafrost discharges an estimated 5 to 14 Tg of organic carbon (OC) into the Arctic Ocean. Although this previously stored OC has the potential to be reintroduced into the atmosphere, thus accelerating human-induced climate change, little is known about the benthic remineralization processes of permafrost OC after erosion and redeposition on the ocean floor. Our research quantified fluxes of dissolved inorganic carbon (DIC) and analyzed its isotopic composition of nearshore sediments in the Canadian Beaufort Sea, specifically off Herschel Island. Our findings showed a DIC release of 0.217 mmo/m²/d, with an average signature of δ13C = -22.44 ± 72 ‰ and F14C = 0.548 ± 0.007. Utilizing a model that combines two carbon isotopes, we estimate that approximately 38 ± 10% of the released DIC is a result of subsurface degradation of redeposited permafrost OC, with an additional 15 ± 12% originating from redeposited active layer OC. Additionally, isotopic endmember analysis was utilized on bacterial membrane lipids from live sedimentary bacteria to determine the relative utilization of OC sources in bacterial communities within shallow subsurface sediment (<25 cm). Our results indicate that, on average, these communities obtain 73 ± 10% of their OC from recent marine primary production, 11 ± 6% from permafrost OC, and 16 ± 11% from active layer OC. This study is the first direct quantitative assessment of the release of permafrost OC into the active carbon cycle after it has been redeposited on the ocean floor, as far as we know. The data suggest that the redeposited permafrost OC is easily accessible and utilized by subsurface bacteria. Considering the immense size and vulnerability of the eroding coastal permafrost OC pool, 27 to 53% of it contributing to benthic DIC fluxes could have a prolonged effect on the world's climate, worsening the climate emergency.

How to cite: Ruben, M., Hefter, J., Gentz, T., Schubotz, F., Wei, B., Liu, B., Fritz, M., Irrgang, A. M., von Jackowski, A., Geibert, W., and Mollenhauer, G.: Quantifying permafrost organic carbon remineralization after redeposition on the ocean floor, using  δ13C and F14C., EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-149, https://doi.org/10.5194/egusphere-egu24-149, 2024.

17:40–17:50
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EGU24-19404
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ECS
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On-site presentation
Kirsi Keskitalo, Paul Mann, Tommaso Tesi, Bart van Dongen, Jannik Martens, Igor Semiletov, Oleg Dudarev, Örjan Gustafsson, and Jorien Vonk

Rapidly rising temperatures in the Arctic cause thaw of permafrost and increase coastal erosion that mobilizes permafrost-derived organic carbon (OC) into coastal waters. In the water column, permafrost-OC may either degrade and thus, enhance climate warming by adding greenhouse gases to the atmosphere or settle on the seabed and be buried in the sediments. In this study, we focused on the composition and degradation of particulate OC (POC) within the flocculation (nepheloid) layer - a turbulent layer close to seabed that holds a high amount of suspended sediments/particles and transports them across the vast Siberian Arctic shelves. More importantly, previous studies have shown that permafrost-OC, exported to the Arctic Ocean via coastal erosion, is largely carried in the POC fraction of the flocculation layer.

To study flocculation layer dynamics, sediment cores were collected using a multicorer device from the East Siberian Sea, Laptev Sea, and Kara Sea onboard R/V Akademik Mstistlav Keldysh in 2020. The overlying water of the sediment cores was stirred under controlled conditions to mimic sediment resuspension. The entrained suspended sediments were collected and incubated for two weeks (in the dark) to assess their susceptibility to degradation. During the incubation, dissolved O2, POC, dissolved OC (DOC), dissolved inorganic carbon and δ13C of each carbon pool were measured at set time points. Additionally, to better understand sediment entrainment and degradation, sediment physical properties, including grain size and mineral-specific surface area, and macromolecular composition were determined.

Our preliminary results show that stirring largely entrains the smallest sediment particles, while it seems not to influence sediment macromolecular composition suggesting that none of the compound classes such as polysaccharides or aromatic compounds are preferentially entrained. Our incubation data show losses in dissolved O2 suggesting microbial degradation, however, instead of decreases in the OC pools, especially POC shows increases combined with increases or decreases in DOC. These carbon dynamics likely result from interactions between different carbon pools such as adsorption of DOC to particles and/or leaching of POC to the DOC pool. With accelerated coastal erosion and increase in storminess in the Arctic Ocean due to sea ice loss, understanding dynamics of the flocculation layer and degradation of permafrost-OC on the Arctic sea shelves is becoming even more important to better constrain their potential climate impact.  

How to cite: Keskitalo, K., Mann, P., Tesi, T., van Dongen, B., Martens, J., Semiletov, I., Dudarev, O., Gustafsson, Ö., and Vonk, J.: Degradation and composition of organic carbon in the flocculation layer on the Laptev, East Siberian, and Kara seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19404, https://doi.org/10.5194/egusphere-egu24-19404, 2024.

17:50–18:00
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EGU24-5198
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On-site presentation
Young Keun Jin, Seung-Goo Kang, Yeonjin Choi, Sumin Kim, and Jong Kuk Hong

The stability and spatial distribution of subsea permafrost across the Arctic continental shelves play a pivotal role in our understanding of global warming. Serving as a significant carbon store, this permafrost has the potential to release greenhouse gases when it thaws, significantly influencing the global climate. This study is dedicated to a comprehensive investigation of the extent and state of submarine permafrost within the Arctic, with a particular focus on the comparative analysis of subsea permafrost development along the continental shelves of the Beaufort and East Siberian Seas. This research enhances our grasp of Arctic subsea permafrost's current variability and its role in global warming processes. To map the extent of subsea permafrost, we utilized multichannel seismic data from the Beaufort Sea (2014) and East Siberian Sea (2016, 2019), collected by the IBRV Araon. Employing a full waveform inversion approach, we precisely determined the seafloor permafrost's velocity structure, offering insights into its depth and state. The research reveals pronounced regional variations in the development of subsea permafrost on Arctic continental shelves. In particular, the continental shelf of the Beaufort Sea is characterized by a densely concentrated distribution of subsea permafrost extending to depths of up to 600 meters. In contrast, the continental shelf of the East Siberian Sea is dominated by permafrost that has thawed significantly, reaching depths of around 400 meters. These different regional patterns may be influenced by a number of factors, including the proximity of the shelf to the coast, the influence of ocean currents, the geological composition of the seabed and the prevailing thermal conditions. These findings suggest that the highly variable nature of submarine permafrost across the Arctic shelf is crucial to understanding warming induced changes in Arctic submarine permafrost and the potential for greenhouse gas release through permafrost dissociation.

How to cite: Jin, Y. K., Kang, S.-G., Choi, Y., Kim, S., and Hong, J. K.: Regional Variations of Subsea Permafrost Development on the Arctic Continental Shelves: A comparative analysis of the Beaufort and East Siberian Seas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5198, https://doi.org/10.5194/egusphere-egu24-5198, 2024.

Posters on site: Thu, 18 Apr, 10:45–12:30 | Hall X4

Display time: Thu, 18 Apr 08:30–Thu, 18 Apr 12:30
Chairpersons: Annett Bartsch, Rebecca Scholten, David Wårlind
X4.1
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EGU24-7215
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ECS
In-Won Kim, Axel Timmermann, Ji-Eun Kim, Keith Rodgers, Sun-Seon Lee, Hanna Lee, and William Wieder

Greenhouse warming is accelerating permafrost thaw and the risk of wildfires in the northern high latitudes. However, the impact of permafrost thaw on Arctic-Subarctic wildfires and the associated release of greenhouse gases and aerosols is less well understood. Here we investigate the effect of future permafrost thaw on Arctic-Subarctic wildfires using the CESM2 large ensemble simulations forced by the SSP3-7.0 greenhouse gas emission scenario. We find that an increase in soil permeability induced by rapid permafrost thawing leads to an abrupt increase in sub-surface runoff and a decrease in soil moisture over the Arctic-Subarctic region. This sudden soil drying causes a significant increase in surface air temperature and a decrease in relative humidity during summer. The resulting soil drying and atmospheric dryness lead to a rapid intensification of wildfires in western Siberia and Canada in the mid-to-late 21st century.

How to cite: Kim, I.-W., Timmermann, A., Kim, J.-E., Rodgers, K., Lee, S.-S., Lee, H., and Wieder, W.: Abrupt increase in Arctic-Subarctic wildfires following permafrost thawing in a warmer climate, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7215, https://doi.org/10.5194/egusphere-egu24-7215, 2024.

X4.2
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EGU24-20267
Louise Farquharson, Dmitry Nicolsky, Monika Calif, Jennifer Schmidt, Vladimir Romanovsky, and Thomas Douglas

Permafrost thaw, ground-ice melt, and associated ground settlement pose significant hazards to northern communities and industry. Thaw of permafrost affected soils can decrease bearing capacity while settlement due to ground ice melt can cause ground collapse (thermokarst) and localized flooding. Here, explore ground ice distribution and potential for thaw induced settlement in the Fairbanks North Star Borough (FNSB), located in an area of discontinuous permafrost in Interior Alaska, USA. Pleistocene-Holocene sediment deposition, ice wedge development, and subsequent reworking due to thaw and hillslope processes have left a complex mosaic of cryolithological conditions that make thaw-related hazards a challenge to predict. The Borough is home to critical infrastructure including two military bases, a university, several gold mines, and the Trans Alaska Pipeline.

 

We created a permafrost hazard map by combining modelled ground ice distribution with projections of ground temperature through to 2090 using the GIPL 2.0 model for key ecotypes in the area. From this we were able to infer temperature dynamics, active layer deepening, talik development, and the potential for thermokarst degradation for IPCC Representative Concentration Pathway scenarios 4.5 and 8.5 through to 2090. We established ground ice distribution through a combination of existing geologic maps, numerical modeling, lidar derived thaw feature maps, and industry bore holes.  To extrapolate ground ice values from the representative sub-sample of ~ 2000km2 to the entire Borough we utilized a gradient-boosted decision tree aggregate model.

 

 Across the FNSB 23 % of the terrain is underlain by the high ground ice class, 10% medium, 4% low, 44% negligible, and 17% of the region is unaffected. High ground ice content underlines 23 % powerlines, 21% of roads and 4% of critical infrastructure (schools, hospitals, power plants etc.). Future projections of subsidence in areas of black spruce forest under RCP4.5 and 8.5 for areas respectively show that areas of high ice content could see subsidence of up to 5 and 10 meters respectively by 2090. Subsidence values for a range of topographic locations were calculated. Results from this study may help the FNSB, land managers, and homeowners best prepare and plan for the impacts of climate change in the Fairbanks region and potentially provide a hazard mitigation and climate change adaptation guides for other sub-Arctic communities.

How to cite: Farquharson, L., Nicolsky, D., Calif, M., Schmidt, J., Romanovsky, V., and Douglas, T.: Projecting future permafrost thaw and subsidence driven infrastructure damage in the discontinuous permafrost zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-20267, https://doi.org/10.5194/egusphere-egu24-20267, 2024.

X4.3
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EGU24-5562
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ECS
Agnieszka Halaś, Mariusz Lamentowicz, Milena Obremska, Dominika Łuców, and Michał Słowiński

Western Siberian peatlands are one of the biggest peatland complexes in the world. Despite playing an essential role in regulating global climate, these ecosystems still remain understudied. A lack of long-term multi-proxy studies comprehensively examining the dynamics between permafrost thaw and peatland ecosystems in Siberia makes it difficult to determine how these areas will be affected by future climate change. Our research covers the history of the Khanymei peatlands (63°43’N, 75°57’E), located in the discontinuous permafrost zone in the last 200 years (from the end of the Little Ice Age to modern times). In this study, we applied multi-proxy analysis (testate amoebae, plant macrofossil, pollen, micro and macro charcoal, LOI and XRF) on two cores from a transect between a peat mound and a thermokarst lake. A newly developed by Halaś et al. (2023) testate amoebae calibration data set based on samples from the Khanymei peatlands complex was used to reconstruct past changes in peatland hydrology. In the last 200 years, we observed constant drying of studied peatlands with events of wetting caused by thawing permafrost. Reconstructed changes in peatland vegetation indicate that lichens (genus Cladonia) dominate during stable permafrost phases. We discovered that peatland drying in recent decades caused the expansion of shrubs onto Khanymei peatlands, which is also widely observed in other parts of Arctic tundra. The increase in peatland moisture after thawing is noted only in the initial period and in a limited area. Thawing led to high Sphagnum growth and change in the structure of testate amoebae communities, with an increase of mixotrophic species like Placocista spinosa. Species with organic and idiosomic tests started to dominate in the community replacing species with agglutinated shells. We discovered that permafrost thawing resulted in a short-term increase of peat accumulation and carbon sequestration, increased abundance of fungal communities, and promotion of oxic conditions. Initially, positive effects of thawing (like carbon accumulation) quickly weakened as favorable moisture conditions disappeared.
As permafrost continues to thaw, these processes will occur on an increasingly larger scale. According to climate change predictions, this region in Western Siberia may become unsuitable for the functioning of permafrost peatlands in their current form.

References:

Halaś, A., Lamentowicz, M., Łuców, D., & Słowiński, M. (2023). Developing a new testate amoeba hydrological transfer function for permafrost peatlands of NW Siberia. Quaternary Science Reviews, 308, 108067. https://doi.org/10.1016/j.quascirev.2023.108067

The study was supported by the National Science Center (Grant no. 2019/35/O/ST10/0290 and 2021/41/B/ST10/00060) and INTERACT No. 730938.

How to cite: Halaś, A., Lamentowicz, M., Obremska, M., Łuców, D., and Słowiński, M.: Dynamics of permafrost thaw in Western Siberia - a 200 years multi-proxy and high-resolution reconstruction from Khanymei peatlands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5562, https://doi.org/10.5194/egusphere-egu24-5562, 2024.

X4.4
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EGU24-15078
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ECS
Helena Bergstedt, Annett Bartsch, Clemens von Baeckmann, Benjamin Jones, Amy Breen, Juliane Wolter, Louise Farquharson, Guido Grosse, and Mikhail Kanevskiy

Lakes and drained lake basins (DLB) are common landforms in permafrost lowland regions in the Arctic and widely cover 50% to 75% of the landscape in parts of Alaska, Siberia, and Canada. Lakes and DLBs create a heterogeneous and dynamic mosaic of terrain units, providing unique habitats for flora and fauna. Lakes and drained lake basins in permafrost regions play a crucial role in the regions landscape and ecosystem processes, influencing permafrost dynamics, biogeochemical processes, the hydrologic regime, as well as carbon cycling and greenhouse gas emissions. Depending on time passed since drainage of a given DLB, characteristics like surface roughness, vegetation, moisture, and abundance of ponds may vary between basins. Spatial heterogeneity within a single basin also varies between basins of different age. The mosaic of vegetative and geomorphic succession within DLBs and the distinct differences between DLBs and surrounding areas can be discriminated with remote sensing and used to derive a landscape-scale classification. In situ observations of these surface characteristics of DLBs are crucial for a better understanding of these features but can only describe a small percentage of existing DLBs.

In this study, we use a novel pan-Arctic assessment on DLB occurrence and the ESA Permafrost_cci circumpolar landcover unit data set based on Sentinel-1 and Sentinel-2 satellite imagery to assess the inter and intra-DLB spatial heterogeneity of surface characteristics. Building on existing research, we sort DLBs into distinct groups corresponding to previously published DLB age classification schemes (young, medium, old and ancient DLBs). DLB groupings show different landcover distribution within the basins, allowing for assumptions about the relative time passed since a drainage event occurred. To compliment and verify our remote sensing-based approach, a wide array of field data was collected at multiple sites across the Arctic, including on the Alaska North Slope. First results show distinct differences between DLBs within the study area, based on the landcover occurring within basins and other surface properties. Comprehensive mapping and characterizing of DLBs on a circumpolar scale will allow for improved parametrization of regional to pan-Arctic modeling efforts and improve our understanding of DLBs as a crucial landform in Arctic permafrost landscapes.  

How to cite: Bergstedt, H., Bartsch, A., von Baeckmann, C., Jones, B., Breen, A., Wolter, J., Farquharson, L., Grosse, G., and Kanevskiy, M.: Characterizing drained lake basins across the Arctic , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15078, https://doi.org/10.5194/egusphere-egu24-15078, 2024.

X4.5
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EGU24-15688
Barbara Widhalm, Annett Bartsch, Helena Bergstedt, Clemens von Baeckmann, and Tazio Strozzi

Arctic permafrost regions are subject to rapid changes due to climate warming affecting hydrology, topography and ecology. Soil wetness is of great importance in these regions facilitating for example upscaling of carbon fluxes. In this study we therefore investigate the Topographic Wetness Index (TWI) as often used in land surface modelling, focusing on study regions in the Siberian and Canadian Arctic. We analyse the influence of the used Digital Elevation Model (DEM) by comparing results of the openly available ArcticDEM (2m resolution) and Copernicus DEM (30m resolution). Results are being validated against near-surface soil moisture in-situ measurements. Further comparisons are being made to other wetness indices such as the Tasselled Cap Wetness index or the Normalized Differential Moisture Index derived from Landsat 8. The relationship to InSAR derived surface displacements as an indicator of soil wetness is explored, as well as additional parameters such as the Topographic Position Index and correlations to other moisture indicators including land cover products.

How to cite: Widhalm, B., Bartsch, A., Bergstedt, H., von Baeckmann, C., and Strozzi, T.: Assessment of the Topographic Wetness Index in Permafrost landscapes , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15688, https://doi.org/10.5194/egusphere-egu24-15688, 2024.

X4.6
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EGU24-16785
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ECS
Rustam Khairullin, Clemens von Baeckmann, Annett Bartsch, Helena Bergstedt, Barbara Widhalm, Aleksandra Efimova, Xaver Muri, Ksenia Ermokhina, and Birgit Heim

The Circumpolar Landcover unit database provides landcover information in high detail, spatially (10m) and thematically (23 units). Such detail is needed for a wide range of applications targeting climate change impacts and ecological research questions. The landcover unit retrieval scheme used provides unprecedented detail. The landcover units have been derived by fusion of satellite data using Sentinel-1 (synthetic aperture radar) and Sentinel-2 (multispectral). The units reflect gradients of moisture as well as vegetation physiognomy.

 

The original database covered the Arctic north of the tree line. It has been extended towards south, providing additional detail within the tundra-taiga transition zone in permafrost regions. The available spatial detail provides the means to assess the complexity of this zone in addition to information on recent disturbance related to for example wildfire and thermokarst lake change.

 

Bartsch, A., Efimova, A., Widhalm, B., Muri, X., von Baeckmann, C., Bergstedt, H., Ermokhina, K., Hugelius, G., Heim, B., & Leibmann, M. (2023). Circumpolar Landcover Units (1.0) [Data set]. Zenodo. https://doi.org/10.5281/zenodo.8399018

How to cite: Khairullin, R., von Baeckmann, C., Bartsch, A., Bergstedt, H., Widhalm, B., Efimova, A., Muri, X., Ermokhina, K., and Heim, B.: Status of the Circumpolar Landcover Unit database, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16785, https://doi.org/10.5194/egusphere-egu24-16785, 2024.

X4.7
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EGU24-4769
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ECS
Félix García-Pereira, Jesús Fidel González-Rouco, Nagore Meabe-Yanguas, Norman Julius Steinert, Johann Jungclaus, Philip de Vrese, and Stephan Lorenz

Soil warming is particularly sensitive in Arctic regions, underlain by permafrost. Permafrost degradation with warming enhances the release of substantial amounts of carbon into the atmosphere, which acts as a positive radiative feedback. However, the increasing temperature is not the only factor affecting permafrost degradation. Water availability changes affecting the Arctic, induced by changes in the atmospheric general circulation considerably affect the soil moisture and ice presence and subsequently thermal structure in permafrost regions. The interaction between soil hydrology and thermodynamics is still poorly represented by most of the CMIP6 land surface models (LSMs), mainly in terms of the soil depth, vertical resolution, and coupling between hydrology and thermodynamics.

This work explores the response of the Max Planck Institute Earth System Model (MPI-ESM) in historical and scenario simulations to changes in the hydrological and thermodynamic features of its LSM, JSBACH, in permafrost-affected regions. An ensemble of experiments was performed with varying soil depth and vertical resolution under two configurations of the hydro-thermodynamical coupling, which generate comparatively drier or wetter conditions over permafrost areas. Results show that deepening JSBACH reduces the intensity of near-surface warming, reducing the deep permafrost degradation area by ca. 2 million km2 and constraining the active layer thickness deepening by the end of the 21st century in high radiative forcing scenarios. Nevertheless, the largest impacts on permafrost extent and active layer thickness are produced by the dry and wet settings, which yield diverging soil moisture and warming conditions during the 21st century. These two configurations show differences in near-surface and deep permafrost extent of up to 5 million km2 by the end of the 21st century.

How to cite: García-Pereira, F., González-Rouco, J. F., Meabe-Yanguas, N., Steinert, N. J., Jungclaus, J., de Vrese, P., and Lorenz, S.: Permafrost thermal response to improved soil hydro-thermodynamics in historical and scenario simulations with a modified version of the MPI-ESM , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-4769, https://doi.org/10.5194/egusphere-egu24-4769, 2024.

X4.8
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EGU24-630
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ECS
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Cas Renette, Sofia Thorson, Mats Olvmo, Björn Holmer, and Heather Reese

In the context of the accelerating impacts of climate change on permafrost landscapes, this study employs UAV (Unmanned Aerial Vehicle) LiDAR technology to investigate seasonal terrain changes in palsas – mounds of frozen peat – since traditional remote sensing methods have struggled to capture the full dynamics of these landforms. We investigated two tall (4–5 m tall) palsas in Sweden's largest palsa mire complex, where we performed five field campaigns between September 2022 and September 2023 to track intra-annual frost heave and thaw subsidence. Our approach allowed us to create digital terrain models (DTMs) from high density point clouds (>1,000 points/m²) and analyze elevation changes over time. We found that both palsas heaved 0.15 m from September to April and subsided back to their height from the previous year, or slightly below, over the course of the following summer. At one of the palsas, we observed notable lateral degradation over the study period in a 300 m2 area, with 0.5–2.0 m height loss, likely initiated during the preceding warm and wet summer months. Part of this degradation occurred between September 2022 and April 2023, suggesting that the degradation of these palsas is not limited to the summer months. Our study shows the value of using UAV LiDAR for understanding how permafrost areas are changing. It helps in tracking the ongoing effects of climate change and highlights palsa dynamics that would not be captured by annual measurements only.

How to cite: Renette, C., Thorson, S., Olvmo, M., Holmer, B., and Reese, H.: Multitemporal UAV LiDAR detects seasonal heave and subsidence on palsas, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-630, https://doi.org/10.5194/egusphere-egu24-630, 2024.

X4.9
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EGU24-13717
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ECS
Zhicheng Luo, Bodo Ahrens, Danny Risto, and Mittal Parmar

The performance of a climate model to reproduce frozen soil depends on the modeled atmospheric forcing and the parameterizations in the land surface. Due to the complex land-air interactions caused by snow and soil freezing and thawing, biased simulations of climate models may be compensated or amplified by errors in land surface models. This may lead to a misjudgment of the simulation capabilities of the land surface model itself, especially when we are trying to improve the overall performance of the climate model without being able to balance the results in frozen soil. In order to separately investigate the simulation performance of the land surface model in the frozen soil region, we conduct simulations using the stand-alone land surface models CLM5, TERRA, and JSBACH at representative sites in Siberia, Alaska, and the Tibetan Plateau and explore the performance of the models from daily to interannual scales using the same atmospheric forcing and initial conditions.

The main evaluation objects will be the insulating effect of snow, soil energy balance, and soil moisture transportation to a depth of 3 meters below the ground surface. We look forward to the offline simulation experiments to evaluate the accuracy of different land surface model simulations, the optimal soil hydrothermal parameterization scheme, and important physical processes that may be neglected by the models’ prediction of frozen soil in daily and monthly time scales.

How to cite: Luo, Z., Ahrens, B., Risto, D., and Parmar, M.: Evaluation of Standalone In-situ Simulations of Frozen Soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-13717, https://doi.org/10.5194/egusphere-egu24-13717, 2024.

X4.10
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EGU24-2589
Impact of Initial Soil Conditions on Soil Hydrothermal and Surface Energy Fluxes in the Permafrost Region of the Tibetan Plateau
(withdrawn after no-show)
Siqiong Luo and Zihang Chen
X4.11
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EGU24-8248
Melanie A. Thurner, Xavier Rodriguez-Lloveras, and Christian Beer

Soils and landscapes vary within centimeters to decameters, which is not captured by state-of-the-art land-surface models that operate on kilometer scale. This leads to potential mismatches when simulating the exchange of energy, water and gasses between land and atmosphere, which are summarized under the term “aggregation error”, and is a major source of uncertainty. To overcome this issue and account for subgrid-scale heterogeneity so-called tiling approaches are used, which separate grid cells internally into different tiles that interact with each other. Although this is a valid approach, it remains unclear, if and to what extend tiling reduces the aggregation error and consequently, if tiling is sufficient to account for subgrid-scale heterogeneity.

Permafrost soils are especially heterogeneous and the aggregation error when simulating permafrost landscapes is especially problematic, because it can make the differences between frozen and unfrozen, as well as waterlogged and unsaturated areas. This affects the presence of permafrost itself, the build of soil ice and resulting frost heave, and determines pond locations as well as the duration and thickness of the seasonal snow cover, which all together influence vegetation and thus ecosystem dynamics.

To address the sufficiency of tiling at permafrost landscapes, we apply the two-dimensional pedon-scale soil model DynSoM at a non-sorted circle site. We run DynSoM with four different horizontal resolutions: (i) with an explicit resolution of 10cm, (ii) with three tiles, representing center, rim, and interface area, (iii) with two tiles, representing center and rim, and (iv) without tiling, representing a typical state-of-the-art land surface model. By comparing mean simulations, we assess the benefits, but also the shortcomings and limitations of the different tiling set-ups, and discuss implications for tiling within kilometer-scale land-surface models.

How to cite: Thurner, M. A., Rodriguez-Lloveras, X., and Beer, C.: To tile or not to tile?, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8248, https://doi.org/10.5194/egusphere-egu24-8248, 2024.

X4.12
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EGU24-16738
Thomas Kleinen, Philipp de Vrese, Tobias Stacke, and Victor Brovkin

When considering high latitude regions, one of the striking characteristics is the abundance of surface water in comparison to lower latitudes. This difference is not just limited to the total area covered by surface water, but it also extends to the size distribution of water bodies: While surface water in lower latitudes most often occurs in the form of larger lakes or rivers, high latitude regions often display a wide variety of surface water features, ranging from small puddles to huge lakes. Considering the climatic and carbon cycle consequences of lower latitude large water bodies in land models is relatively straightforward – they can be considered static, be prescribed from observations, and described using dedicated submodels. However, considering surface water in the high latitudes comprehensively is substantially more challenging, as a much larger range of sizes needs to be considered, parts of which will not be available from observations. Furthermore, due to the dynamics of permafrost, these cannot be considered static any more and need to be treated dynamically.

To better represent high latitude regions in the ICON-Land land surface model, part of the ICON-ESM Earth System Modelling framework, we are developing a representation of multiple scales of water bodies, ranging from large lakes to small puddles, as well as areas of water-saturated soil. The smaller-scale features are of particular interest, as they do not just affect the exchange of water and energy between surface and atmosphere, but also have large impacts on the carbon cycle and methane emissions. To do this, we employ a statistical distribution function of water body sizes, allowing us to obtain energy, water, carbon and methane fluxes for water features of all sizes.

We will present our novel modelling framework and show first results covering selected Arctic locations.

How to cite: Kleinen, T., de Vrese, P., Stacke, T., and Brovkin, V.: Modelling heterogeneity of land surface waters in the permafrost region, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-16738, https://doi.org/10.5194/egusphere-egu24-16738, 2024.

X4.13
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EGU24-19799
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ECS
Michael Angelopoulos, Pier Paul Overduin, Frederieke Miesner, Julia Boike, Michael Krautblatter, and Sebastian Westermann

Saline permafrost is primarily found in marine deposits beneath shallow shelf seas and can often extend several kilometres inland from present Arctic coastlines. On land, saline permafrost forms when previously submerged marine sediments are exposed to the atmosphere, either through a sea level regression or post-glacial rebound. Cryopegs are perennially cryotic layers or pockets within permafrost that remain unfrozen due to their high salt content. While heat and salt flow models have been applied to study subsea permafrost degradation, adapting these models to terrestrial saline permafrost remains a significant gap in model development. We utilize a version of the CryoGrid modelling suite that couples heat and salt diffusion. This enables us to simulate the formation of saline permafrost and the development of cryopegs during transitions from sub-aquatic to sub-aerial conditions. As the freezing front descends, ice forms in the sediment matrix, expulsing salts into the remaining unfrozen liquid water at sub-zero temperatures. The increased unfrozen porewater salt concentration gradient increases the rate at which salt diffuses downwards into the sediment column. Over time the thermal gradient weakens, potentially allowing a more effective salt build-up ahead of the freezing front.

How to cite: Angelopoulos, M., Overduin, P. P., Miesner, F., Boike, J., Krautblatter, M., and Westermann, S.: Simulating Saline Permafrost and Cryopeg Evolution Using a Coupled Heat and Salt Diffusion Model, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-19799, https://doi.org/10.5194/egusphere-egu24-19799, 2024.

X4.14
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EGU24-5063
Jong Kuk Hong, Seung-Goo Kang, Yeonjin Choi, Tae Siek Rhee, Sookwan Kim, Younggyun Kim, and Young Keun Jin

The Eastern Siberian Sea is known for the presence of subsurface permafrost and for emitting significant amounts of methane close to the coastline. The thawing of permafrost accelerates the release of methane and carbon dioxide, contributing to increased greenhouse gas concentrations in the atmosphere. In 2021 and 2023, a multidisciplinary survey aboard the Korean icebreaker Araon was conducted on the continental shelf of the East Siberian Sea. The survey area lies more than 500 km away from the nearest coastline and falls within international waters. During the survey, areas with high methane concentration were identified on the shallow continental shelf, at depths ranging from 50 to 70 meters, utilizing underway CH4 measurements. These zones extend in a northwest-southeast direction. Multiple surveys were conducted to pinpoint gas seepage zones and delineate subsurface structures. The EK80 scientific echosounder proved instrumental in locating the gas vents, as it displayed methane gas eruptions clearly, resembling pillars in the imaging. The shallow sedimentrary structure of the lower part of the gas vent, observed  by the SBP survey, revealed high-amplitude reflections at a shallow depth (~5 m) below the seafloor. At the gas expulsion sites, seismic profiles show numerous vertical faults within the shallow sedimentary layers and scatterings in the water column caused by the methane emission from the seafloor. Backscattered images from the side-scan sonar clearly depict gases emitting from the vents and moving upward in the water column. These gas vents were found to have about 10 meters in diameter.

How to cite: Hong, J. K., Kang, S.-G., Choi, Y., Rhee, T. S., Kim, S., Kim, Y., and Jin, Y. K.: Geological features of methane vents in the East Siberian Sea, the Arctic Ocean, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-5063, https://doi.org/10.5194/egusphere-egu24-5063, 2024.

X4.15
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EGU24-3674
Charles K. Paull, Jong Kuk Hong, David W. Caress, Roberto Gwiazda, Ji-Hoon Kim, Mathieu J. Duchesne, Eve Lundsten, Jennifer B. Paduan, Tae Siek Rhee, Young Keun Jin, Virginia Brake, Jeffrey Obelcz, and Maureen Walton

Substantial morphological changes are rapidly occurring along the Canadian Arctic shelf edge (Paull et al., 2022, PNAS). During a 2022 IBRV Araon cruise, autonomous underwater vehicle mapping surveys identified several new craters that formed between 2019 and 2022. Five multibeam bathymetric mapping surveys, each partially covering a 15 km2 study area between 120 and 200 mwd have now been conducted over a 12-year time period. These repeat surveys reveal 65 new depressions developed averaging 6.5 m deep and reaching up to 30 m deep. Remotely operated vehicle investigations also discovered outcrops of massive ice exposed on the flanks of the newest craters. This ice is not believed to be relic permafrost formed during Pleistocene sea-level low-stands because the host sediments were deposited in a submarine setting. The low porewater salinity and light isotopic compositions in the meltwater of ice samples from sediment cores indicate brackish waters reflecting a meteoric source are discharging and freezing in this area. The ascending brackish groundwater is likely derived from melting relict permafrost under the shelf. The ~ -1.4°C bottom water temperatures provide conditions appropriate for freezing brackish porewaters within the near seafloor sediments. Conditions appropriate for the melting of ice also exist nearby where ice is in contact with seawater or warmed by ascending groundwater. Small variations in either temperature or salinity, over time, can shift equilibrium conditions of ice formation and degradation, which leads to repetitive freezing and thawing of ascending brackish groundwater and the development of wide-spread ice layers in the near seafloor sediments. These conditions have produced a dramatic submarine thermokarst morphology riddled with multi-aged depressions captured in the repeat mapping surveys. These findings suggest that the distribution of submarine permafrost ice should be reassessed as it may include extensive areas where ice formed during the Holocene where groundwaters discharge at sub-zero temperatures, in addition to relict Pleistocene permafrost.

How to cite: Paull, C. K., Hong, J. K., Caress, D. W., Gwiazda, R., Kim, J.-H., Duchesne, M. J., Lundsten, E., Paduan, J. B., Rhee, T. S., Jin, Y. K., Brake, V., Obelcz, J., and Walton, M.: Rapidly forming submarine craters and massive ice outcrops along the Arctic shelf edge: by-products of subsea permafrost degradation, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3674, https://doi.org/10.5194/egusphere-egu24-3674, 2024.

Posters virtual: Thu, 18 Apr, 14:00–15:45 | vHall X4

Display time: Thu, 18 Apr 08:30–Thu, 18 Apr 18:00
Chairperson: Helena Bergstedt
vX4.3
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EGU24-17287
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ECS
Detecting methane from thawing yedoma: an OSSE evaluating tall towers, TROPOMI, and MERLIN’s capabilities.  
(withdrawn)
Martijn Pallandt, Abhishek Chatterjee, Lesley Ott, julia Marshall, and Mathias Göckede