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2022068391 Matsuoka, Atsushi (University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Durham, NH); Babin, Marcel and Vonk, Jorien E. Decadal trends in the release of terrigenous organic carbon to the Mackenzie Delta (Canadian Arctic) using satellite ocean color data (1998-2019): Remote Sensing of Environment, 283, Article 113322, illus. incl. 2 tables, sketch map, 80 ref., December 15, 2022.
Arctic rivers operate as integrators of northern high latitude regions, where large stocks of soil organic carbon (OC) are currently experiencing rapid warming. Here we show that tracking total OC in the Mackenzie Delta whose upstream catchment is underlain by permafrost soils is now possible using polar-orbiting satellite ocean color observations. A non-parametric trend analysis that is valid for hydrological data shows a significant increase in dissolved OC (DOC) as well as particulate OC (POC) concentrations in late summer (0.019 and 0.069 g m-3 year-1; p < 0.05 for both). Uncertainties of the satellite estimates of DOC and POC do not influence our results. These concentration increases are not related to changes in river discharge. Parallel increases of independent long-term (1979-2018) in situ measurements of thaw depth of the active layer, as well as meteorological and hydrological patterns suggest that these late summer increases can likely be explained by increasing inputs of permafrost OC. This study shows great promise for remote, large-scale detection of catchment-scale thaw impacts from space.
DOI: 10.1016/j.rse.2022.113322
2022068261 Wang Pan (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, State Key Laboratory of Frozen Soil Engineering, Lanzhou, China); Liu Enlong; Zhi Bin; Song Bingtang and Kang Jian. Creep characteristics and unified macro-meso creep model for saturated frozen soil under constant/variable temperature conditions: Acta Geotechnica (Berlin), 17(11), p. 5299-5319, illus. incl. 6 tables, 55 ref., November 2022.
In permafrost regions, under the interference of climate warming and human activities, the deformation stability of geological engineering with frozen soil as the medium is directly affected, and the typical ones are the creep characteristics under the influence of temperature and stress level. In order to reveal the internal mechanism of such characteristics, this paper carried out the creep tests of saturated frozen soil under constant/variable temperature conditions, and the following meaningful conclusions are drawn: an increase in temperature and deviatoric stress level leads to an increase in the effect of weakening mechanism on the meso-scale, which cause the creep mechanical behavior transition from a stable state to an unsteady state, and eventually reach a failure state; The creep strain and meso-scale broken law caused by temperature history are important features that affect the creep characteristics at subsequent temperature condition. Furthermore, with the breakage mechanics for geological materials and meso-mechanics theories, the strengthening and weakening mechanisms on the meso-scale under the influence of temperature and stress level (deviatoric stress and confining pressure) were defined and quantitatively described in the creep process, and then, an unified macro-meso creep constitutive model was proposed, which includes stress concentration tensor and breakage ratio. Finally, the creep deformation of saturated frozen soil under constant temperature and variable temperature condition was well predicted. The conclusion of the article can be used to evaluate and predict the long-term deformation stability of geological engineering in cold regions.
DOI: 10.1007/s11440-022-01586-6
2022065363 Sulman, Benjamin N. (Oak Ridge National Laboratory, Climate Change Science Institute and Environmental Sciences Division, Oak Ridge, TN); Yuan, Fengming; O'Meara, Teri; Gu, Baohua; Herndon, Elizabeth M.; Zheng, Jianqiu; Thornton, Peter E. and Graham, David E. Simulated hydrological dynamics and coupled iron redox cycling impact methane production in an Arctic soil: Journal of Geophysical Research: Biogeosciences, 127(10), Article e2021JG006662, illus. incl. 1 table, 55 ref., October 2022. Part of a special section entitled the Arctic; an AGU joint special collection.
The fate of organic carbon (C) in permafrost soils is important to the climate system due to the large global stocks of permafrost C. Thawing permafrost can be subject to dynamic hydrology, making redox processes an important factor controlling soil organic matter (SOM) decomposition rates and greenhouse gas production. In iron (Fe)-rich permafrost soils, Fe(III) can serve as a terminal electron acceptor, promoting anaerobic respiration of SOM and increasing pH. Current large-scale models of Arctic C cycling do not include Fe cycling or pH interactions. Here, a geochemical reaction model was developed by coupling Fe redox reactions and C cycling to simulate SOM decomposition, Fe(III) reduction, pH dynamics, and greenhouse gas production in permafrost soils subject to dynamic hydrology. We parameterized the model using measured CO2 and CH4 fluxes as well as changes in pH, Fe(II), and dissolved organic C concentrations from oxic and anoxic incubations of permafrost soils from polygonal permafrost sites in northern Alaska, United States. In simulations of repeated oxic-anoxic cycles, Fe(III) reduction during anoxic periods enhanced CO2 production, while the net effect of Fe(III) reduction on cumulative CH4 fluxes depended on substrate C availability. With lower substrate availability, Fe(III) reduction decreased total CH4 production by further limiting available substrate. With higher substrate availability, Fe(III) reduction enhanced CH4 production by increasing pH. Our results suggest that interactions among Fe-redox reactions, pH and methanogenesis are important factors in predicting CH4 and CO2 production as well as SOM decomposition rates in Fe-rich, frequently waterlogged Arctic soils. Abstract Copyright (2022), American Geophysical Union. All Rights Reserved.
DOI: 10.1029/2021JG006662
2022065276 Wang Hongwei (Chinese Academy of Sciences, Northwest Institute of Eco-Environment and Resources, Key Laboratory of Remote Sensing of Gansu Province, Lanzhou, China); Jin Huijun; Li Xiaoying; He Ruixia; Serban, Raul D.; Jin Xiaoying; Yang Xue; Serban, Mihaela; Yang Suiqiao and Wang Wenhui. Land use and cover change in northeast China and its impacts on the Xing'an permafrost in 1980s-2010s: Land Degradation & Development, 33(16), p. 3133-3149, illus. incl. 5 tables, sketch map, 76 ref., October 2022.
Boreal forest and wetland have important influences on the development and protection of the ecosystem-dominated Xing'an permafrost. However, the responses of different ecosystems to climate change and the impacts on the underlying permafrost are still unclear. Here, based on the multi-period land use/land cover (LULC) data and long-time series of air temperature, combined with the ordinary least squares (OLS) and ordinary kriging (OK) methods, the effects of land use and cover change (LUCC) on the distribution of mean annual air temperature (MAAT) and permafrost in Northeast China were analyzed. From 1980s to 2010s, MAAT showed an upward trend (0.025°C per yr) and extents of permafrost showed a decreasing trend (-3668 km2yr-1) in Northeast China. Permafrost degradation mainly occurred in forested land and grassland, with areal reductions of 4.0106 ´ 104 and 3.8754 ´ 104 km2, respectively. The transformation of LULC aggravates the degradation of permafrost. The conversions of forested land and grassland to cultivated land and forested land to grassland resulted in the shrinkage of permafrost extent by 6233 km2 from 1980s to 2010s. Our results confirm the significant impacts of LUCC on the Xing'an permafrost resulting in its degradation. Additionally, they can provide a scientific basis for ecological environment protection and restoration and sustainable development of boreal forest and wetland ecosystems in permafrost regions of Northeast China. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/ldr.4377
2022068002 Faki, Amro (McGill University, Department of Civil Engineering, Montreal, QC, Canada); Sushama, Laxmi and Doré, Guy. Regional-scale investigation of pile bearing capacity for Canadian permafrost regions in a warmer climate: Cold Regions Science and Technology, 201, Article no. 103624, 51 ref., September 2022. Based on Publisher-supplied data.
Climate change is being experienced particularly intensely in the Arctic and therefore adaptation of engineering systems for this region cannot be further delayed. However, one of the major barriers to studies focused on adapting northern engineering systems is the lack of information at the spatial and temporal scales required for engineering applications. This study investigates pile bearing capacity for selected pile configurations for the Canadian permafrost regions (Nunavut and Northwest Territories), for current and future climates, using the very first ultra-high resolution (4 km) climate change simulation developed for the region using the Global Environmental Multiscale (GEM) model, for a high emission scenario.Comparison of the ultra-high-resolution GEM simulation, driven by reanalysis, with available observations confirms the model's ability in representing near-surface permafrost and related climate variables. The estimated adfreeze contribution to the total bearing capacity, for current climate, informed by the reanalysis-driven GEM simulation, for a 5-m cement pile, is found to be of the order of 15% for regions with shallow bedrock and 80% for regions with deeper bedrock. Application of the GEM climate change simulation outputs, for RCP8.5 scenario, suggest decreases to adfreeze contribution in the 5-30% range by 2040, with the largest differences noted for regions with deeper bedrock. For steel piles of same configuration, although the adfreeze contributions are only about 70% of that for cement piles, the projected relative changes are of similar magnitude. Further downscaling to 250 m resolution using the land model of GEM for the Slave Geological-Grays Bay corridor, where future developments are planned, including an all-season road, enables better estimation of bearing capacity for realistic pile scenarios such as those for bridges (in thick layer of sediments) used for river crossings. Due to the wide variation of pile materials, lengths and installation methods, site specific information can be developed from the framework developed in this study. The results of this study, including the ultra-high resolution climate change information, will thus form the basis for additional detailed investigations on climate-infrastructure interactions and climate resiliency studies.
DOI: 10.1016/j.coldregions.2022.103624
2022067998 Han Fenglei (Chongqing Jiaotong University, Laboratory of Mountain Bridge and Tunnel Engineering, Chongqing, China); Qiu Kaichi; Chen Lin; Yu Wenbing; Gen Yongqi; Liu Zonghan and Lu Yan. Laboratory investigation on hydrothermal response of the open crushed-rock layer to rainfall infiltration in permafrost regions: Cold Regions Science and Technology, 201, Article no. 103609, 46 ref., September 2022. Based on Publisher-supplied data.
Under the condition of warming and wetting trend on Qinghai-Tibet Plateau due to climate change, summer rainfall infiltration alters the change of the hydrothermal state and may impact the cooling performance of crushed-rock interlayer embankment. Herein, two experimental models with the 1.4-m-thickness (M1) and 0.6-m-thickness (M2) crushed-rock layer (CRL) were conducted in an environmental simulator experiencing the freezing and thawing cycles. The hydrothermal response to rainfall events was investigated and quantified by analyzing the variations of measured soil temperatures, volumetric water contents, and heat fluxes. Thermal observations show that rainfall infiltration caused heat advection and resulted in step change of soil temperature at depth. Rainfall infiltration reduced the surface temperature of the CRL, but warmed the soil layer at depth by up to 2.13°C. The average temperature of the base soil layer under the action of concentrated rainfall basically showed an increasing trend. In particular, the CRL with a smaller thickness (M2) had a more significant thermal response to rainfall event. In addition, the moisture pulse, experiencing a step increase and following a gradual decrease caused by rainfall water infiltration, appeared several hours earlier than the temperature pulse. Moreover, infiltrated water produced an additional energy to warm the soil at depth, with maximum heat flux of 12.13 W/m2 and 79.90 W/m2 for the M1 and M2, respectively. The infiltrated water accumulated at the top of base soil significantly delayed the refreezing processes in cold period due to the latent heat effect. The net founding of this study provide an insight into improving the design crushed-rock embankment in permafrost regions.
DOI: 10.1016/j.coldregions.2022.103609
2022067994 Yang Linzhen (Northeast Forestry University, School of Civil Engineering, Institute of Cold Regions Science and Engineering, Harbin, China); Zhai Jinbang; Zhang Ze; Melnikov, Andrey and Jin Doudou. A test apparatus used to simulate the dual effects of freeze-thaw and dynamic load on subgrade in cold regions: Cold Regions Science and Technology, 201, Article no. 103586, 22 ref., September 2022. Based on Publisher-supplied data.
The highway and railway subgrade built in permafrost and seasonally frozen regions will not only be damaged by freezing and thawing, but also affected by dynamic load. However, there are little apparatus that have both freeze-thaw and dynamic loading functions. In order to study the stability of subgrade under dual effects, the apparatus that can apply freeze-thaw and dynamic load on subgrade has been developed. The verification test was carried out to verify the functional reliability of the apparatus. The test proved that the apparatus can simulate the dual effects of freeze-thaw and dynamic load, and on this basis, it can realize the monitoring functions of temperature, water, pore water pressure and deformation. Further, the apparatus runs stably and reliably, with accurate results and simple operation. It is considered to be a promising tool for studying the stability of subgrade in permafrost and seasonally frozen regions under the dual effects of freeze-thaw and dynamic load.
DOI: 10.1016/j.coldregions.2022.103586
2022067997 Zhang Yonggan (Hohai University, College of Water Conservancy and Hydropower Engineering, Nanjing, China); Lu Yang; Liu Sihong; Fang Binxin; Li Zhuo and Liu Kang. Volumetric behavior of an unsaturated clayey soil-rock mixture subjected to freeze-thaw cycles; a new insight: Cold Regions Science and Technology, 201, Article no. 103608, 42 ref., September 2022. Based on Publisher-supplied data.
The volumetric behavior of clayey soil-rock mixtures under freeze-thaw action is very important for the design of anti-frost heave in cold-region engineering. However, existing studies mainly focus on the effect of freeze-thaw cycles on the global volume change of fine-grained soils, and few attempts have focused on mixed soils with coarse particles such as clayey soil-rock mixtures. In this study, a series of laboratory freezing-thawing tests were conducted to investigate the effects of the freeze-thaw cycles and rock content on the global volume change, diameter change, and height change behaviors of cylindrical soil-rock mixture samples. The results demonstrate that: 1) the volumetric behavior of the samples under freeze-thaw cycles is closely related to the rock content, which is mainly because different rock contents dominate the different skeleton structures. 2) For samples with 0%, 10%, and 30% rock content, the global volume of compacted samples shows shrinkage upon freezing and expansion after thawing. However, the global volume of the sample with 50% rock content began to shrink after three freeze-thaw cycles. 3) Compared with the samples not subjected to freeze-thaw weathering, the height of samples with 0%, 10%, and 30% rock content shows shrinkage upon freezing and expansion after thawing no matter what the number of freeze-thaw cycles is. However, the diameter and height of the sample are always shrinking, regardless of whether they are frozen or thawed. 4) Upon freezing, the shrinkage of the sample's global volume and diameter tends to decrease linearly with the increase of rock content, but the shrinkage of the sample's height is not sensitive to the change of rock content. Upon thawing, the global volume and height of the sample exhibit a trend from expansion to contraction with increasing rock content, but the shrinkage of the diameter of the sample is nearly the same no matter what the rock content is. Furthermore, a computed tomography (CT)-based mesoscopic structural characteristic and two idealized schematic diagrams well illustrated the evolution mechanism of the volumetric behavior of an unsaturated clayey soil-rock mixture subjected to freeze-thaw cycles.
DOI: 10.1016/j.coldregions.2022.103608
2022066796 Zou Yiguang (Southern University of Science and Technology, School of Environmental Science and Engineering, Shenzhen, China); Kuang Xingxing; Feng Yuqing; Jiao, Jiu Jimmy; Liu Junguo; Wang Can; Fan Linfeng; Wang Qingjing; Chen Jianxin; Ji Fang; Yao Yingying and Zheng Chunmiao. Solid water melt dominates the increase of total groundwater storage in the Tibetan Plateau: Geophysical Research Letters, 49(18), Paper no. e2022GL100092, illus. incl. sketch maps, 170 ref., September 28, 2022.
Understanding how groundwater storage (GWS) responds to climate change is essential for water resources management and future water availability in the Tibetan Plateau (TP). However, the dominant factor controlling long-term GWS changes remains unclear and its responses to climate change are not well understood. Here we combined multi-source datasets including in-situ measurements, satellite observations, global models, and reanalysis products to reveal that GWS increased at 5.59 ± 1.44 Gt/yr during 2003-2016 while showing spatial heterogeneities with increasing trends in northern TP and glacial regions and declining trends in central and southern TP. The accelerated transformation from solid water (glaciers, snow, and permafrost; -17.72 ± 1.53 Gt/yr) into liquid water provide more recharge to groundwater, dominating the total GWS increase. This study contributes to a better understanding of the hydrological cycle under climate change and provides key information for projecting water availability under different future scenarios in the TP. Abstract Copyright (2022), American Geophysical Union. All Rights Reserved.
DOI: 10.1029/2022GL100092
2022066473 Daniels, William C. (University of Massachusetts at Amherst, Amherst, MA); Castañeda, Isla S.; Salacup, Jeffrey M.; Habicht, M. Helen; Lindberg, Kurt R. and Brigham-Grette, Julie. Archaeal lipids reveal climate-driven changes in microbial ecology at Lake El'gygytgyn (Far East Russia) during the Plio-Pleistocene: in Northern high latitude lakes; Quaternary evolution and climatic history (Melles, Martin, editor; et al.), JQS. Journal of Quaternary Science, 37(5), p. 900-914, illus. incl. sketch map, 122 ref., July 2022. NSF Grant EAR-1204087.
Isoprenoid glycerol dialkyl glycerol tetraethers (iGDGTs) are commonly preserved molecular biomarkers of archaea whose distributions can be used to reconstruct past temperature, and possibly, methane and nitrogen cycling. To date, iGDGT systematics have not been widely investigated in Arctic lacustrine environments. Here, we analyze iGDGTs in sediments of Lake El'gygytgyn, located in the Russian Arctic, to reconstruct the paleoenvironmental conditions from the Pliocene to today using TEX86 and other indices. The TEX86-inferred temperature history shows a long-term warming trend, in stark contrast to other Arctic records and other proxies from Lake El'gygytgyn, suggesting that non-temperature factors obfuscate the use of TEX86 at this site. Other GDGT-based indices including the BIT Index, DRing Index, Methane Index and the GDGT-0/crenarchaeol ratio suggest that TEX86 is strongly influenced by archaeal community changes. The most significant community shifts are observed c. 2.4 Ma and record an increase in Euryarchaeota production and/or a decrease in Thaumarchaeota production, which was driven by the establishment of permafrost and perennial lake ice during the early Pleistocene. Overall, this study demonstrates an important interpretative framework for iGDGTs in lacustrine systems and describes variations in Arctic climate and lake biogeochemistry over timescales of thousands to millions of years. Abstract Copyright (2022), John Wiley & Sons, Ltd.
DOI: 10.1002/jqs.3347
2022066422 Panek, Tomas (University of Ostrava, Department of Physical Geography and Geoecology, Ostrava, Czech Republic); Brezny, Michal; Harrison, Stephan; Schönfeldt, Elisabeth and Winocur, Diego. Large landslides cluster at the margin of deglaciated mountain belt: Scientific Reports, 12(5658), 13 p., illus. incl. geol. sketch map, 66 ref., April 5, 2022.
Landslides in deglaciated and deglaciating mountains represent a major hazard, but their distribution at the spatial scale of entire mountain belts has rarely been studied. Traditional models of landslide distribution assume that landslides are concentrated in the steepest, wettest, and most tectonically active parts of the orogens, where glaciers reached their greatest thickness. However, based on mapping large landslides (>0.9 km2) over an unprecedentedly large area of Southern Patagonia (~305,000 km2), we show that the distribution of landslides can have the opposite trend. We show that the largest landslides within the limits of the former Patagonian Ice Sheet (PIS) cluster along its eastern margins occupying lower, tectonically less active, and arid part of the Patagonian Andes. In contrast to the heavily glaciated, highest elevations of the mountain range, the peripheral regions have been glaciated only episodically, leaving a larger volume of unstable sedimentary and volcanic rocks that are subject to ongoing slope instability.
DOI: 10.1038/s41598-022-09357-9
2022067281 Gao Siqi (Chinese Academy of Sciences, Northeast Institute of Geography and Agroecology, Key Laboratory of Wetland Ecology and Environment, Changchun, China); Song Yanyu; Song Changchun; Wang Xianwei; Ma Xiuyan; Gao Jinli; Cheng Xiaofeng and Du Yu. Effects of temperature increase and nitrogen addition on the early litter decomposition in permafrost peatlands: Catena (Giessen), 209(part 1), Article 105801, February 2022. Based on Publisher-supplied data.
As one kind of the most important carbon (C) sink in the world, peatlands are sensitive to climate change. The decomposition of litter plays an important role in C fixation and nutrient utilization in peatlands. To reveal the mechanism of response of the litter decomposition to climate warming and the addition of nitrogen (N) in permafrost peatlands, we selected two typical plants, Eriophorum vaginatum and Sphagnum palustre, in the permafrost peatland of Da Hinggan Ling, China, as the research objects and conducted a 54-day litter decomposition experiment at 10°C and 20°C. Three N addition treatments (CK: 0 mg N g-1, N1: 2.5 mg N g-1, and N2: 5 mg N g-1) were established. Our results showed that the E. vaginatum litter decomposed more quickly than that of Sphagnum, and an increase in temperature significantly promoted the litter decomposition and CO2 emission of E. vaginatum and Sphagnum. The addition of N promoted the decomposition of E. vaginatum litter, whereas the decomposition of Sphagnum litter was promoted by the N1 treatment but was inhibited by the N2 treatment. The enzyme activity in both types of litter was inhibited with the increase in temperature. The abundances of bacteria and fungi positively correlated with the decomposition constant and mean CO2 release rate by E. vaginatum and Sphagnum litter, indicating that the effects of temperature and N addition on the decomposition of plant litter were primarily regulated by microorganisms. This study provides a theoretical basis to understand and predict the effects of global climate change on the decomposition of plant litter in boreal peatlands.
DOI: 10.1016/j.catena.2021.105801
2022067284 Pietruczuk, J. (Maria Curie-Sklodowska University, Institute of Earth and Environmental Sciences, Lublin, Poland); Dobrowolski, R.; Suchora, M.; Apolinarska, K.; Bieganowski, A.; Trembaczowski, A.; Polakowski, C. and Bober, A. From a periglacial lake to an alkaline fen; Late Glacial/Early Holocene evolution of Lublin Chalkland tracked in biogenic sediments of Bagno Staw (western Polesie Lowland, E Poland): Catena (Giessen), 209(part 1), Article 105813, February 2022. Based on Publisher-supplied data.
The paper presents records of lithofacial succession in the sediments of the Bagno Staw alkaline fen (Western Polesie Lowland, Eastern Poland), documenting the phase of rapid morphogenetic transformations during LG/H in the Lublin chalkland. Environmental conditions responsible for the morphogenesis and evolution of the site (from a shallow periglacial lake to an alkaline fen) were reconstructed. A detailed geological survey in combination with the analysis of Cladocera assemblages revealed the presence of numerous palaeodepressions under the plain covered today by the alkaline fen, which were initially small shallow lakes with a well-developed phytolittoral zone. Geochemical data and the analysis of stable O and C isotopes indicated that these lakes were supplied by ascending waters. Karstic phenomena under periglacial conditions, including subsidence at the bottom of biogenic accumulation basins, played an important role in the transformation of this site. These changes were largely determined by the chronology and dynamics of permafrost degradation.
DOI: 10.1016/j.catena.2021.105813
2022067278 Zhang Fei (Chinese Academy of Sciences, Institute of Earth Environment, State Key Laboratory of Loess and Quaternary Geology, Xi'an, China); Hu Yadan; Fan Xuanmei; Yu Wenlong; Liu Xingxing and Jin Zhangdong. Controls on seasonal erosion behavior and potential increase in sediment evacuation in the warming Tibetan Plateau: Catena (Giessen), 209(part 1), Article 105797, illus. incl. 2 tables, sketch map, 61 ref., February 2022.
Global warming and intensified climate variability have greatly affected Earth's surface processes and continental sediment evacuation. River suspended sediment is a sensitive indicator for tracing seasonal surface erosion, but details of the rates of sediment generation and evacuation, and their connections with nowadays warming climate are not entirely clear, particularly in Tibet and other high-altitude areas where field observations remain scarce. Here, we investigate daily to seasonal river sediment transport dynamics between the cold, permafrost-dominated northeastern Tibetan Plateau and warm, non-permafrost Sichuan and Taiwan regions. Our results show that at a given river water discharge, greater river suspended sediment was evacuated during the pre-monsoon season (April-Mid June) relative to other seasons in the cold NE Tibetan catchments. In contrast, no such phenomenon was observed in the warm, non-permafrost regions. These comparisons likely indicate a center role of freeze-thaw processes on loose sediment generation, which enhanced sediment output. Hydrometeorological records show up to ~2°C warming in the NE Tibetan Plateau since the past 30 years, coupled with an 8-fold increase in sediment transport. We suggest that continuous warming climate may further accelerate sediment and soil carbon release in the Tibetan Plateau and other global permafrost-dominated areas, which in turn influences climate feedback.
DOI: 10.1016/j.catena.2021.105797
2022067379 Bernhard, Philipp (ETH Zurich, Institute of Environmental Engineering, Zurich, Switzerland); Zwieback, Simon and Hajnsek, Irena. Accelerated mobilization of organic carbon from retrogressive thaw slumps on the northern Taymyr Peninsula: The Cryosphere, 16(7), p. 2819-2835, illus. incl. 2 tables, sketch map, 74 ref., 2022.
With climate change, Arctic hillslopes above ice-rich permafrost are vulnerable to enhanced mass wasting and organic carbon mobilization. In this study we use TanDEM-X-derived (TerraSAR-X add-on for Digital Elevation Measurement; synthetic-aperture radar) digital elevation models to document an approximately 43-fold increase in thaw slumping and concomitant 28-fold increase in carbon mobilization on the northern Taymyr Peninsula from 2010 to 2021. The available observations allowed us to compare two time periods, from 2010/11 to 2016/17 and from 2017/18 to 2020/21, and contrast retrogressive thaw slump (RTS) activity between these periods. We find that all quantities describing RTS activity increased in the observed period. The total volumetric change per year increased from about 0.17´106 to 7.4´106 m3 yr-1, a 43-fold increase. The observed surge in RTS activity is mainly driven by the initiation of new RTS, indicated by the 17-fold increase in active RTS numbers from 82 to 1404 and the relatively low average volumetric change rate per RTS increase of 2.3. In annual Sentinel-2 imagery, the number of detected RTSs in a subregion increased 10-fold in 2020. This coincides with a severe heatwave that occurred in northern Siberia in 2020. The area-to-volume scaling of the RTSs varied only slightly over time, despite the 2020 heatwave, indicating a robustness of the relationship to such an event. To estimate the slump-mobilized organic carbon, we intersected the elevation changes with a soil organic carbon (SOC) map, with contrasting assumptions about the deep carbon pool and massive-ice content. We estimated that the SOC mobilization rate increases 28-fold. The normalization of the SOC mobilization rate to our study region yields values of 11 gCyr-1m-2 with a confidence interval of 5 to 38 gCyr-1m-2. A comparison to an independent estimate of the net ecosystem exchange of 4.1±13.0 gCyr-1m-2 illustrates the importance of RTS activity to the carbon cycle. These results underscore that mass wasting is an important but commonly neglected component of the Arctic carbon cycle and particularly sensitive to extreme events.
DOI: 10.5194/tc-16-2819-2022
2022067377 Bertone, Aldo (University of Bologna, Department of Biological, Geological and Environmental Sciences, Bologna, Italy); Barboux, Chloé; Bodin, Xavier; Bolch, Tobias; Brardinoni, Francesco; Caduff, Rafael; Christiansen, Hanne H.; Darrow, Margaret M.; Delaloye, Reynald; Etzelmuller, Bernd; Humlum, Ole; Lambiel, Christophe; Lilleoren, Karianne S.; Mair, Volkmar; Pellegrinon, Gabriel; Rouyet, Line; Ruiz, Lucas and Strozzi, Tazio. Incorporating InSAR kinematics into rock glacier inventories; insights from 11 regions worldwide: The Cryosphere, 16(7), p. 2769-2792, illus. incl. 3 tables, sketch maps, 109 ref., 2022.
Rock glaciers are landforms related to permafrost creep that are sensitive to climate variability and change. Their spatial distribution and kinematic behaviour can be critical for managing water resources and geohazards in periglacial areas. Rock glaciers have been inventoried for decades worldwide, often without assessment of their kinematics. The availability of remote sensing data however makes the inclusion of kinematic information potentially feasible, but requires a common methodology in order to create homogeneous inventories. In this context, the International Permafrost Association (IPA) Action Group on rock glacier inventories and kinematics (2018-2023), with the support of the European Space Agency (ESA) Permafrost Climate Change Initiative (CCI) project, is defining standard guidelines for the inclusion of kinematic information within inventories. Here, we demonstrate the feasibility of applying common rules proposed by the Action Group in 11 regions worldwide. Spaceborne interferometric synthetic aperture radar (InSAR) was used to characterise identifiable moving areas related to rock glaciers, applying a manual and a semi-automated approach. Subsequently, these areas were used to assign kinematic information to rock glaciers in existing or newly compiled inventories. More than 5000 moving areas and more than 3600 rock glaciers were classified according to their kinematics. The method and the preliminary results were analysed. We identified drawbacks related to the intrinsic limitations of InSAR and to various applied strategies regarding the integration of non-moving rock glaciers in some investigated regions. This is the first internationally coordinated work that incorporates kinematic attributes within rock glacier inventories at a global scale. The results show the value of designing standardised inventorying procedures for periglacial geomorphology.
DOI: 10.5194/tc-16-2769-2022
2022067376 Cao Bin (Chinese Academy of Sciences, Institute of Tibetan Plateau Research, Beijing, China); Arduini, Gabriele and Zsoter, Ervin. Improving ERA5-land soil temperature in permafrost regions using an optimized multi-layer snow scheme: The Cryosphere, 16(7), p. 2701-2708, illus. incl. 2 tables, 31 ref., 2022.
We previously reported a notable warm bias in ERA5-Land soil temperature in permafrost regions that was supposedly being caused by an underestimation of snow density. In this study, we implemented and evaluated a new multi-layer snow scheme in the land surface scheme of ERA5-Land, i.e., HTESSEL, with revised snow densification parameterizations. We compared permafrost soil temperatures from the numerical experiments with observations and the original ERA5-Land with a single-layer snow scheme. The revised HTESSEL significantly improved the representation of soil temperature in permafrost regions compared to ERA5-Land. The daily warm bias in winter was reduced by about 0.6-3.0°C across the 522 observing stations in high-latitude permafrost regions, and the resulting modeled near-surface permafrost extent was improved (11.0-12.9´106 km2 during 2001-2018), comparing reasonably with observed estimates for continuous and discontinuous permafrost areas. We therefore suggest that a better-resolved snow scheme with a multi-layer snow profile should be included in next-generation reanalyses as a first step towards improving the representation of permafrost.
DOI: 10.5194/tc-16-2701-2022
2022068233 Clark, Jason A. (University of Alaska Fairbanks, Geophysical Institute, Fairbanks, AK); Jafarov, Elchin E.; Tape, Ken D.; Jones, Benjamin M. and Stepanenko, Victor. Thermal modeling of three lakes within the continuous permafrost zone in Alaska using the LAKE 2.0 model: Geoscientific Model Development (GMD), 15(19), p. 7421-7448, illus. incl. 2 tables, 65 ref., 2022. Includes 6 appendices.
Lakes in the Arctic are important reservoirs of heat with much lower albedo in summer and greater absorption of solar radiation than surrounding tundra vegetation. In the winter, lakes that do not freeze to their bed have a mean annual bed temperature >0°C in an otherwise frozen landscape. Under climate warming scenarios, we expect Arctic lakes to accelerate thawing of underlying permafrost due to warming water temperatures in the summer and winter. Previous studies of Arctic lakes have focused on ice cover and thickness, the ice decay process, catchment hydrology, lake water balance, and eddy covariance measurements, but little work has been done in the Arctic to model lake heat balance. We applied the LAKE 2.0 model to simulate water temperatures in three Arctic lakes in northern Alaska over several years and tested the sensitivity of the model to several perturbations of input meteorological variables (precipitation, shortwave radiation, and air temperature) and several model parameters (water vertical resolution, sediment vertical resolution, depth of soil column, and temporal resolution). The LAKE 2.0 model is a one-dimensional model that explicitly solves vertical profiles of water state variables on a grid. We used a combination of meteorological data from local and remote weather stations, as well as data derived from remote sensing, to drive the model. We validated modeled water temperatures with data of observed lake water temperatures at several depths over several years for each lake. Our validation of the LAKE 2.0 model is a necessary step toward modeling changes in Arctic lake ice regimes, lake heat balance, and thermal interactions with permafrost. The sensitivity analysis shows us that lake water temperature is not highly sensitive to small changes in air temperature or precipitation, while changes in shortwave radiation and large changes in precipitation produced larger effects. Snow depth and lake ice strongly affect water temperatures during the frozen season, which dominates the annual thermal regime of Arctic lakes. These findings suggest that reductions in lake ice thickness and duration could lead to more heat storage by lakes and enhanced permafrost degradation.
DOI: 10.5194/gmd-15-7421-2022
2022067380 Coulombe, Stéphanie (Polar Knowledge Canada, Cambridge Bay, NU, Canada); Fortier, Daniel; Bouchard, Frédéric; Paquette, Michel; Charbonneau, Simon; Lacelle, Denis; Laurion, Isabelle and Pienitz, Reinhard. Contrasted geomorphological and limnological properties of thermokarst lakes formed in buried glacier ice and ice-wedge polygon terrain: The Cryosphere, 16(7), p. 2837-2857, illus. incl. 1 table, sketch maps, 104 ref., 2022.
In formerly glaciated permafrost regions, extensive areas are still underlain by a considerable amount of glacier ice buried by glacigenic sediments. It is expected that large parts of glacier ice buried in the permafrost will melt in the near future, although the intensity and timing will depend on local terrain conditions and the magnitude and rate of future climate trends in different Arctic regions. The impact of these ice bodies on landscape evolution remains uncertain since the extent and volume of undisturbed relict glacier ice are unknown. These remnants of glacier ice buried and preserved in the permafrost contribute to the high spatial variability in ground ice condition of these landscapes, leading to the formation of lakes with diverse origins and morphometric and limnological properties. This study focuses on thermokarst lake initiation and development in response to varying ground ice conditions in a glacial valley on Bylot Island (Nunavut). We studied a lake-rich area using lake sediment cores, detailed bathymetric data, remotely sensed data and observations of buried glacier ice exposures. Our results suggest that initiation of thermokarst lakes in the valley was triggered from the melting of either buried glacier ice or intrasedimental ice and ice wedges. Over time, all lakes enlarged through thermal and mechanical shoreline erosion, as well as vertically through thaw consolidation and subsidence. Some of them coalesced with neighbouring water bodies to develop larger lakes. These glacial thermokarst lakes formed in buried glacier ice now evolve as "classic" thermokarst lakes that expand in area and volume as a result of the melting of intrasedimental ground ice in the surrounding material and the underlying glaciofluvial and till material. It is expected that the deepening of thaw bulbs (taliks) and the enlargement of Arctic lakes in response to global warming will reach undisturbed buried glacier ice where it is still present, which in turn will substantially alter lake bathymetry, geochemistry and greenhouse gas emissions from Arctic lowlands.
DOI: 10.5194/tc-16-2837-2022
2022067372 Mathys, Tamara (University of Fribourg, Department of Geosciences, Fribourg, Switzerland); Hilbich, Christin; Arenson, Lukas U.; Wainstein, Pablo A. and Hauck, Christian. Towards accurate quantification of ice content in permafrost of the central Andes; Part 2, An upscaling strategy of geophysical measurements to the catchment scale at two study sites: The Cryosphere, 16(6), p. 2595-2615, illus. incl. 2 tables, sketch map, 61 ref., 2022. Includes appendix.
With ongoing climate change, there is a pressing need to better understand how much water is stored as ground ice in areas with extensive permafrost occurrence, as well as how the regional water balance may alter in response to the potential generation of meltwater from permafrost degradation. However, field-based data on permafrost in remote and mountainous areas such as the South American Andes are scarce. Most current ground ice estimates are based on broadly generalized assumptions such as volume-area scaling and mean ground ice content estimates of rock glaciers. In addition, ground ice contents in permafrost areas outside of rock glaciers are usually not considered, resulting in a significant uncertainty regarding the volume of ground ice in the Andes and its hydrological role. In Part 1 of this contribution, Hilbich et al. (2022a) present an extensive geophysical data set based on electrical resistivity tomography and refraction seismic tomography surveys to detect and quantify ground ice of different landforms and surface types in several study regions in the semi-arid Andes of Chile and Argentina with the aim to contribute to the reduction of this data scarcity. In Part 2 we focus on the development of a strategy for the upscaling of geophysics-based ground ice quantification to an entire catchment to estimate the total ground ice volume (and its approximate water equivalent) in the study areas. In addition to the geophysical data, the upscaling approach is based on a permafrost distribution model and classifications of surface and landform types. In this paper, we introduce our upscaling strategy, and we demonstrate that the estimation of large-scale ground ice volumes can be improved by including (i) non-rock-glacier permafrost occurrences and (ii) field evidence through a large number of geophysical surveys and ground truthing information. The results of our study indicate that (i) conventional ground ice estimates for rock-glacier-dominated catchments without in situ data may significantly overestimate ground ice contents and (ii) substantial volumes of ground ice may also be present in catchments where rock glaciers are lacking.
DOI: 10.5194/tc-16-2595-2022
2022067953 Krautblatter, Michael (Technische Universität München, Fachgebiet Hangbewegungen, Munich, Germany); Schirrmeister, Lutz and Lenz, Josefine. Neue Fragestellungen, Methoden und Ergebnisse der Permafrostforschung in der letzten Dekade [New questions, methods and results of permafrost research in the last decade]: Polarforschung, 89(1), p. 69-71 (English sum.), 2021.
DOI: 10.5194/polf-89-69-2021
2022067252 Jones, Benjamin M. (University of Alaska Fairbanks, Institute of Northern Engineering, Fairbanks, AK); Tape, Ken D.; Clark, Jason A.; Nitze, Ingmar; Grosse, Guido and Disbrow, Jeff. Increase in beaver dams controls surface water and thermokarst dynamics in an Arctic tundra region, Baldwin Peninsula, northwestern Alaska: Environmental Research Letters, 15(7), Article no. 075005, illus. incl. 1 table, sketch maps, 61 ref., July 2020.
Beavers are starting to colonize low arctic tundra regions in Alaska and Canada, which has implications for surface water changes and ice-rich permafrost degradation. In this study, we assessed the spatial and temporal dynamics of beaver dam building in relation to surface water dynamics and thermokarst landforms using sub-meter resolution satellite imagery acquired between 2002 and 2019 for two tundra areas in northwestern Alaska. In a 100 km2 study area near Kotzebue, the number of dams increased markedly from 2 to 98 between 2002 and 2019. In a 430 km2 study area encompassing the entire northern Baldwin Peninsula, the number of dams increased from 94 to 409 between 2010 and 2019, indicating a regional trend. Correlating data on beaver dam numbers with surface water area mapped for 12 individual years between 2002 and 2019 for the Kotzebue study area showed a significant positive correlation (R2 = 0.61; p < .003). Beaver-influenced waterbodies accounted for two-thirds of the 8.3% increase in total surface water area in the Kotzebue study area during the 17 year period. Beavers specifically targeted thermokarst landforms in their dam building activities. Flooding of drained thermokarst lake basins accounted for 68% of beaver-influenced surface water increases, damming of lake outlets accounted for 26%, and damming of beaded streams accounted for 6%. Surface water increases resulting from beaver dam building likely exacerbated permafrost degradation in the region, but dam failure also factored into the drainage of several thermokarst lakes in the northern Baldwin Peninsula study region, which could promote local permafrost aggradation in freshly exposed lake sediments. Our findings highlight that beaver-driven ecosystem engineering must be carefully considered when accounting for changes occurring in some permafrost regions, and in particular, regional surface water dynamics in low Arctic and Boreal landscapes. Copyright 2020 The Author(s). Published by IOP Publishing Ltd
DOI: 10.1088/1748-9326/ab80f1
2022067251 Song, Chunlin (Chinese Academy of Sciences, Institute of Mountain Hazards and Environment, Sichuan, China); Wang, Genxu; Haghipour, Negar and Raymond, Peter A. Warming and monsoonal climate lead to large export of millennial-aged carbon from permafrost catchments of the Qinghai-Tibet Plateau: Environmental Research Letters, 15(7), Article no. 074012, illus. incl. 3 tables, sketch map, 76 ref., July 2020.
Permafrost carbon pool destabilization causes substantial fluvial export of soil carbon, yet the export patterns and magnitudes are not well understood. Here we investigated the radiocarbon (14C) in dissolved organic and inorganic carbon (DOC and DIC, respectively) exported from a mid-sized river in the central Qinghai-Tibet Plateau (QTP) permafrost region. We utilized the radiocarbon dating technique to reveal the ages of riverine dissolved carbon and a statistical model to partition the riverine carbon from different age categories. DOC and DIC showed bomb-depleted 14C signatures corresponding to millennial ages. Seasonally, 14C-depleted DOC and DIC ages were associated with active layer thaw and flow path deepening. Spatially, older DOC and DIC were found in the valley sites correlated with warmer permafrost and higher groundwater flow. Further, isotopic mixing models suggested that 83 ± 27% of riverine DOC was derived from active layer and permafrost layer aged carbon. DIC export was comprised of a smaller portion of aged carbon (47.3 ± 2.6%) but a much larger flux of aged carbon due to higher annual DIC export. Interestingly, approximately 56% of annual aged DOC and DIC were exported in the short summer season (July to September). The monsoon climate-induced overlap of high discharge and maximum active layer thaw depth in summer enhanced the remarkably rapid fluvial export of millennial-aged carbon. Annual aged carbon yields in YRSR (275 ± 90 and 1661 ± 91 kg km-2 yr-1 for DOC and DIC, respectively) are much larger than those of Kolyma River (160 ± 89 and 234 ± 105 kg km-2 yr-1 for DOC and DIC, respectively). These results suggest a unique old carbon loss pattern in the QTP permafrost region compared to higher latitude permafrost regions with a non-monsoonal climate. As climate warms, more old carbon export is expected, which may affect the permafrost carbon pool and the river biogeochemical processes. Copyright 2020 The Author(s). Published by IOP Publishing Ltd
DOI: 10.1088/1748-9326/ab83ac
2022067990 Wang Taihua (Tsinghua University, Department of Hydraulic Engineering, Beijing, China); Yang Dawen; Yang Yuting; Piao Shilong; Li Xin; Cheng Guodong and Fu Bojie. Permafrost thawing puts the frozen carbon at risk over the Tibetan Plateau: Science Advances, 6(19), Article no. eaaz3513, illus. incl. sketch maps, 50 ref., May 2020.
Soil organic carbon (SOC) stored in permafrost across the high-latitude/altitude Northern Hemisphere represents an important potential carbon source under future warming. Here, we provide a comprehensive investigation on the spatiotemporal dynamics of SOC over the high-altitude Tibetan Plateau (TP), which has received less attention compared with the circum-Arctic region. The permafrost region covers ~42% of the entire TP and contains ~37.21 Pg perennially frozen SOC at the baseline period (2006-2015). With continuous warming, the active layer is projected to further deepen, resulting in ~1.86±0.49 Pg and ~3.80±0.76 Pg permafrost carbon thawing by 2100 under moderate and high representative concentration pathways (RCP4.5 and RCP8.5), respectively. This could largely offset the regional carbon sink and even potentially turn the region into a net carbon source. Our findings also highlight the importance of deep permafrost thawing that is generally ignored in current Earth system models.
DOI: 10.1126/sciadv.aaz3513
2022067253 Huntzinger, D. N. (Northern Arizona University, School of Earth and Sustainability, Flagstaff, AZ); Schaefer, K.; Schwalm, C.; Fisher, J. B.; Hayes, D.; Stofferahn, E.; Carey, J.; Michalak, A. M.; Wei, Y.; Jain, A. K.; Kolus, H.; Mao, J.; Poulter, B.; Shi, X.; Tang, J. and Tian, H. Evaluation of simulated soil carbon dynamics in Arctic-boreal ecosystems: Environmental Research Letters, 15(2), Article 025005, illus. incl. 1 table, 75 ref., February 2020.
Given the magnitude of soil carbon stocks in northern ecosystems, and the vulnerability of these stocks to climate warming, land surface models must accurately represent soil carbon dynamics in these regions. We evaluate soil carbon stocks and turnover rates, and the relationship between soil carbon loss with soil temperature and moisture, from an ensemble of eleven global land surface models. We focus on the region of NASA's Arctic-Boreal vulnerability experiment (ABoVE) in North America to inform data collection and model development efforts. Models exhibit an order of magnitude difference in estimates of current total soil carbon stocks, generally under- or overestimating the size of current soil carbon stocks by greater than 50 PgC. We find that a model's soil carbon stock at steady-state in 1901 is the prime driver of its soil carbon stock a hundred years later-overwhelming the effect of environmental forcing factors like climate. The greatest divergence between modeled and observed soil carbon stocks is in regions dominated by peat and permafrost soils, suggesting that models are failing to capture the frozen soil carbon dynamics of permafrost regions. Using a set of functional benchmarks to test the simulated relationship of soil respiration to both soil temperature and moisture, we find that although models capture the observed shape of the soil moisture response of respiration, almost half of the models examined show temperature sensitivities, or Q10 values, that are half of observed. Significantly, models that perform better against observational constraints of respiration or carbon stock size do not necessarily perform well in terms of their functional response to key climatic factors like changing temperature. This suggests that models may be arriving at the right result, but for the wrong reason. The results of this work can help to bridge the gap between data and models by both pointing to the need to constrain initial carbon pool sizes, as well as highlighting the importance of incorporating functional benchmarks into ongoing, mechanistic modeling activities such as those included in ABoVE. Copyright 2020 The Author(s). Published by IOP Publishing Ltd
DOI: 10.1088/1748-9326/ab6784
2022066088 Tregubov, Oleg (Russian Academy of Sciences, North-East Interdisciplinary Scientific Research Institute, Far-East Branch, Anadyr, Russian Federation); Kraev, Gleb and Maslakov, Aleksey. Hazards of activation of cryogenic processes in the Arctic community; a geopenetrating radar study in Lorino, Chukotka, Russia: Geosciences (Basel), 10(2), Article 57, illus. incl. strat. col., 48 ref., February 2020.
The subsurface structure of permafrost is of high significance to forecast landscape dynamics and the engineering stability of infrastructure under human impacts and climate warming, which is a modern challenge for Arctic communities. Application of the non-destructive method of geo-penetrating radar (GPR) survey is a promising way to study it. The study program, which could be used for planning and monitoring of measures of adaptation of Arctic communities to environmental changes is provided in this paper. The main principle was to use etalons of coupled radargrams and archive geological data to interpret changes in the permafrost structure from a grid of 5-10 m deep GPR transects. Here, we show the application of GPR to reconstruct and predict hazards of activation of cryogenic processes from the spatial variability in the structure of permafrost. The cumulative effects of the village and climate change on permafrost were manifested in changes in the active layer thickness from 0.5-1.0 m to up to 3.5 m. Despite that the permafrost degradation has declined due to the improved maintenance of infrastructure and the effects of ground filling application, the hazards of heaving and thermokarst remain for the built-up area in Lorino.
DOI: 10.3390/geosciences10020057
2022067262 Zorn, Matija (Slovenian Academy of Sciences and Arts, Anton Melik Geographical Institute, Ljubljana, Slovenia); Komac, Blaz; Carrey, Anne; Hrvatin, Mauro; Ciglic, Rok and Lyons, Berry. The disappearing cryosphere in the southeastern Alps; introduction to special issue: in Special issue; the disappearing cryosphere in the southeastern Alps, Acta Geographica Slovenica, 60(2), p. 109-124 (Slovenian sum.), illus. incl. 1 table, 76 ref., 2020.
Various ice bodies are an important source of paleoenvironmental data, and their study improves the understanding of present and future environmental conditions. Their changes are an important indicator of climate change. This special issue of Acta geographica Slovenica draws attention to the changing and disappearing cryosphere across the globe, with an emphasis on the southeastern Alps, and the necessity to conduct research in this field before the ice disappears forever. This paper briefly summarizes the current body of knowledge on glaciers, permafrost, cave ice, lake and river ice, and snow in the southeastern Alps, and it presents the contribution of Acta geographica Slovenica to this research and the main highlights of all five papers included in this special issue.
DOI: 10.3986/AGS.9396
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The 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 
