February 2016 Permafrost Alert

The U.S. Permafrost Association, together with the American Geosciences Institute (AGI), is pleased to provide the following Permafrost Monthly Alerts (PMA). The AGI GeoRef service regularly scans the contents of over 3500 journals in 40 languages from the global geosciences literature, comprised of approximately 345 different sources. In addition to journals, special publications such as papers in proceedings and hard-to-find publications are provided. Each PMA represents a listing of the permafrost-related materials added to GeoRef during the previous month. Where available, a direct link to the publication is included, which provides access to the full document if you or your institution have a current online subscription.

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2016022561 Liu Wenjie (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Laboratory of Cryospheric Sciences, Lanzhou, China); Chen Shengyun; Zhao Qian; Sun Zhizhong; Ren Jiawen and Qin Dahe. Variation and control of soil organic carbon and other nutrients in permafrost regions on central Qinghai-Tibetan Plateau: Environmental Research Letters, 9(11), Paper no. 114013, illus. incl. 3 tables, sketch map, 47 ref., November 2014.

The variation and control of soil organic carbon (SOC) and other nutrients in permafrost regions are critical for studying the carbon cycle and its potential feedbacks to climate change; however, they are poorly understood. Soil nutrients samples at depths of 0-10, 10-20, 20-30, and 30-40 cm, were sampled eight times in 2009 in alpine swamp meadow, alpine meadow and alpine steppe in permafrost regions of the central Qinghai-Tibetan Plateau. SOC and total nitrogen (TN) in the alpine swamp meadow and meadow decreased with soil depth, whereas the highest SOC content in the alpine steppe was found at depths of 20-30 cm. The vertical profiles of total and available phosphorus (P) and potassium (K) were relatively uniform for all the three grassland types. Correlation and linear regression analyses showed that soil moisture (SM) was the most important parameter for the vertical variation of SOC and other soil nutrients, and that belowground biomass (BGB) was the main source of SOC and TN. The spatial variations (including seasonal variation) of SOC and TN at plot scale were large. The relative deviation of SOC ranged from 7.18 to 41.50 in the alpine swamp meadow, from 2.88 to 35.91 in the alpine meadow, and from 9.33 to 68.38 in the alpine steppe. The spatial variations in the other soil nutrients varied among different grassland types. The most important factors for spatial variations (including seasonal variation) of SOC, TN, total P, available P, and both total and available K were: SM, SM and temperature, SM, air temperature, and SM and BGB, respectively. The large variation in the three grassland types implies that spatial variation at plot scale should be considered when estimating SOC storage and its dynamics. Copyright (Copyright) 2014 IOP Publishing Ltd

2016019553 Wu Qingbai (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, State Key Laboratory of Frozen Soil Engineering, Lanzhou, China) and Niu Fujun. Permafrost changes and engineering stability in Qinghai-Xizang Plateau: Chinese Science Bulletin, 58(10), p. 1079-1094, illus. incl. sketch map, 126 ref., April 2013.

Climate change and engineering activities are the leading causes of permafrost temperature increase, active layer thickening, and ground-ice thaw, which trigger changes in the engineering stability of embankments. Based on the important research advances on permafrost changes and frozen soil engineering in Qinghai-Xizang Plateau, the changes in permafrost temperature and active layer thickness, their relationships with climate factors, the response process of engineering activities on permafrost, dynamic change of engineering stability of Qinghai-Xizang Railway, and the cooling mechanism and process of crushed-rock layers are discussed using the monitoring data of permafrost and embankment deformation. Finally, solutions to the key scientific problems of frozen soil engineering under climate change are proposed. Copyright 2012 The Author(s)

2016027659 Sherstyukov, A. B. (Russian Research Institute of Hydrometeorological Information, Global Data Center, Obninsk, Russian Federation) and Sherstyukov, B. G. Prostranstvennye osobennosti i novye tendentsii v izmeneniyakh termicheskogo sostoyaniya pochvogruntov i glubiny ikh sezonnogo protaivaniya v zone mnogoletney merzloty [Spatial variations, new tendencies in soil thermal regime and depth of seasonal thawing in the permafrost zone]: Meteorologiya i Gidrologiya, 2015(2), p. 5-12, sketch map, 20 ref., 2015.

2016020973 Dede, Volkan (Bilecik Seyh Edebali Universitesi, Fen-Edebiyat Fakultesi, Bilecik, Turkey); Cicek, Ihsan and Uncu, Levent. Karcal daglari'nda kaya buzulu olusumlari [Formation of rock glaciers in the Karcal Mountains]: Yerbilimleri, 36(2), p. 61-80 (English sum.), illus. incl. 2 tables, geol. sketch maps, 39 ref., August 2015.

Periglacial shapes form as a result of cold climatic conditions around glaciers. They are widely seen in high mountainous areas. Karcal Mountains are located in Artvin at the North-Eastern Anatolia. It has a mass structure separated from Eastern Black Sea Mountains with the Coruh River. The mountain chain is approximately 40 km away from the Black Sea. It has summits that partly exceed 3000 m above sea level. As a result of this characteristic, glaciers had the opportunity to developed in the summits in Karcal Mountains during the glacial times. Periglacial shapes were formed in the areas surrounding the glaciers. The most significant of the periglacial shapes encountered here are the Karcal rock glaciers. This study aims to present five rock glaciers that mapped in Karcal Mountains and assess them according to their geographic properties. These are Qamdali, Karcal, Sakiz, Yamukdiken and Ziyaret rock glaciers and cover 0.78 km2 and their minimum tongue elevation is 2.800 m. While Karcal and Ziyaret rock glaciers were formed as a result of permafrost effects and are non-active, Qamdali, Sakiz and Yamukdiken rock glaciers were formed as a result of glacier effect and are active.

2016022776 Langer, M. (Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung, Periglacial Research Section, Potsdam, Germany); Westermann, S.; Anthony, K. Walter; Wischnewski, K. and Boike, J. Frozen ponds; production and storage of methane during the Arctic winter in a lowland tundra landscape in northern Siberia, Lena River delta: Biogeosciences, 12(4), p. 977-990, illus. incl. sketch maps, 46 ref., 2015. Includes appendices.

Lakes and ponds play a key role in the carbon cycle of permafrost ecosystems, where they are considered to be hotspots of carbon dioxide CO2 and methane CH4 emission. The strength of these emissions is, however, controlled by a variety of physical and biogeochemical processes whose responses to a warming climate are complex and only poorly understood. Small waterbodies have been attracting an increasing amount of attention since recent studies demonstrated that ponds can make a significant contribution to the CO2 and CH4 emissions of tundra ecosystems. Waterbodies also have a marked effect on the thermal state of the surrounding permafrost; during the freezing period they prolong the period of time during which thawed soil material is available for microbial decomposition. This study presents net CH4 production rates during the freezing period from ponds within a typical lowland tundra landscape in northern Siberia. Rate estimations were based on CH4 concentrations measured in surface lake ice from a variety of waterbody types. Vertical profiles along ice blocks showed an exponential increase in CH4 concentration with depth. These CH4 profiles were reproduced by a 1-D mass balance model and the net CH4 production rates were then inferred through inverse modeling. Results revealed marked differences in early winter net CH4 production among various ponds. Ponds situated within intact polygonal ground structures yielded low net production rates, of the order of 10-11 to 10-10 mol m-2 s-1 (0.01 to 0.14 mgCH4 m-2 day-1). In contrast, ponds exhibiting clear signs of erosion yielded net CH4 production rates of the order of 10-7 mol m-2 s-1 (140 mgCH4 m-2 day-1). Our results therefore indicate that once a particular threshold in thermal erosion has been crossed, ponds can develop into major CH4 sources. This implies that any future warming of the climate may result in nonlinear CH4 emission behavior in tundra ecosystems.

URL: http://www.biogeosciences.net/12/977/2015/bg-12-977-2015.pdf

2016020479 Möller, Per (Lund University, Department of Geology, Lund, Sweden); Alexanderson, Helena; Funder, Svend and Hjort, Christian. The Taimyr Peninsula and the Severnaya Zemlya archipelago, Arctic Russia; a synthesis of glacial history and palaeo-environmental change during the last glacial cycle (MIS 5e-2): Quaternary Science Reviews, 107, p. 149-181, illus. incl. 2 tables, geol. sketch map, 88 ref., January 1, 2015.

We here suggest a glacial and climate history of the Taimyr Peninsula and Severnaya Zemlya archipelago in arctic Siberia for the last about 150 000 years (ka). Primarily it is based on results from seven field seasons between 1996 and 2012, to a large extent already published in papers referred to in the text - and on data presented by Russian workers from the 1930s to our days and by German colleagues working there since the 1990s. Although glaciations even up here often started in the local mountains, their culminations in this region invariably seems to have centered on the shallow Kara Sea continental shelf - most likely due to expanding marine ice-shelves grounding there, as a combined effect of thickening ice and eustatically lowered sea-levels. The most extensive glaciation so far identified in this region (named the Taz glaciation) took place during Marine Isotope Stage 6 (MIS 6), i.e. being an equivalent to the late Saale/Illinoian glaciations. It reached c. 400 km southeast of the Kara Sea coast, across and well beyond the Byrranga Mountain range and ended c. 130 ka. It was followed by the MIS 5e (Karginsky/Eemian) interglacial, with an extensive marine transgression to 140 m above present sea level - facilitated by strong isostatic downloading during the preceding glaciation. During the latest (Zyryankan/Weichselian/Wisconsinan) glacial cycle followed a series of major glacial advances. The earliest and most extensive, culminating c. 110-100 ka (MIS 5d-5e), also reached south of the Byrranga mountains and its post-glacial marine limit there was c. 100 m a.s.l. The later glacial phases (around 70-60 ka and 20 ka) terminated at the North Taimyr Ice Marginal Zone (NTZ), along or some distance inland from the present northwest coast of Taimyr. They dammed glacial lakes, which caused the Taimyr River to flow southwards where to-day it flows northwards into the Kara Sea. The c. 20 ka glacial phase, contemporary with the maximum (LGM) glaciation in NW Europe, was this glacial cycle's least extensive one up here - probably an effect of precipitation shadow caused by the major glaciations to the west. From the Kara Sea shelf this advance only reached c. 100 km inland, over some limited parts of NW Taimyr. The Severnaya Zemlya islands were only locally glaciated at this time. The lowlands south of the Byrranga Mountains have been a terrestrial "Mammoth steppe" environment during the last c. 50 ka and periglacial permafrosted sediments here have preserved excellent information on its megafauna and vegetation. The latter, according to new DNA-data, had considerably more (for grazing animals nourishing) flowering plants growing than earlier pollen-based (grass dominated) spectra have suggested. Abstract Copyright (2015) Elsevier, B.V.

2016020464 Sahling, H. (Universität Bremen, Zentrum für Marine Umweltwissenschaften, Bremen, Germany); Römer, M.; Pape, T.; Bergès, B.; dos Santos Fereirra, C.; Boelmann, J.; Geprägs, P.; Tomczyk, M.; Nowald, N.; Dimmler, W.; Schroedter, L.; Glockzin, M. and Bohrmann, G. Gas emissions at the continental margin west of Svalbard; mapping, sampling, and quantification: Biogeosciences, 11(21), p. 6029-6046, illus. incl. 7 tables, sketch maps, 36 ref., 2014.

We mapped, sampled, and quantified gas emissions at the continental margin west of Svalbard during R/V Heincke cruise He-387 in late summer 2012. Hydroacoustic mapping revealed that gas emissions were not limited to a zone just above 396 m water depth. Flares from this depth have gained significant attention in the scientific community in recent years because they may be caused by bottom-water warming-induced hydrate dissolution in the course of global warming and/or by recurring seasonal hydrate formation and decay. We found that gas emissions occurred widespread between about 80 and 415 m water depth, which indicates that hydrate dissolution might only be one of several triggers for active hydrocarbon seepage in that area. Gas emissions were remarkably intensive at the main ridge of the Forlandet moraine complex in 80 to 90 m water depths, and may be related to thawing permafrost. Focused seafloor investigations were performed with the remotely operated vehicle (ROV) "Cherokee". Geochemical analyses of gas bubbles sampled at about 240 m water depth as well as at the 396 m gas emission sites revealed that the vent gas is primarily composed of methane (> 99.70%) of microbial origin (average d13C = -55.7 per mil V-PDB). Estimates of the regional gas bubble flux from the seafloor to the water column in the area of possible hydrate decomposition were achieved by combining flare mapping using multibeam and single-beam echosounder data, bubble stream mapping using a ROV-mounted horizontally looking sonar, and quantification of individual bubble streams using ROV imagery and bubble counting. We estimated that about 53 ´ 106 mol methane were annually emitted at the two areas and allow for a large range of uncertainty due to our method (9 to 118 ´ 106 mol yr-1). First, these amounts show that gas emissions at the continental margin west of Svalbard were on the same order of magnitude as bubble emissions at other geological settings; second, they may be used to calibrate models predicting hydrate dissolution at present and in the future; and third, they may serve as a baseline (year 2012) estimate of the bubble flux that will potentially increase in the future due to ever-increasing global-warming-induced bottom water warming and hydrate dissociation.

URL: http://www.biogeosciences.net/11/6029/2014/bg-11-6029-2014.pdf

2016028190 Benkert, Bronwyn (Yukon College, Whitehorse, YT, Canada); Perrin, Alison and Calmels, Fabrice. Assessing hazard risk, cost of adaptation and traditional land use activities in the context of permafrost thaw in communities in Yukon and the Northwest Territories, Canada [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1218, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Together with its partners, the Northern Climate ExChange (NCE, part of the Yukon Research Centre at Yukon College) has been mapping permafrost-related hazard risk in northern communities since 2010. By integrating geoscience and climate project data, we have developed a series of community-scale hazard risk maps. The maps depict hazard risk in stoplight colours for easy interpretation, and support community-based, future-focused adaptation planning. Communities, First Nations, consultants and local regulatory agencies have used the hazard risk maps to site small-scale infrastructure projects, guide land planning processes, and assess suitability of land development applications. However, we know that assessing risk is only one step in integrating the implications of permafrost degradation in societal responses to environmental change. To build on our permafrost hazard risk maps, we are integrating economic principles and traditional land use elements. To assess economic implications of adaptation to permafrost change, we are working with geotechnical engineers to identify adaptation options (e.g., modified building techniques, permafrost thaw mitigation approaches) that suit the risks captured by our existing hazard risk maps. We layer this with an economic analysis of the costs associated with identified adaptation options, providing end-users with a more comprehensive basis upon which to make decisions related to infrastructure. NCE researchers have also integrated traditional land use activities in assessments of permafrost thaw risk, in a project led by Jean Marie River First Nation in the Northwest Territories. Here, the implications of permafrost degradation on food security and land use priorities were assessed by layering key game and gathering areas on permafrost thaw vulnerability maps. Results indicated that close to one quarter of big and small game habitats, and close to twenty percent of key furbearer and gathering areas within the First Nation's traditional territory, are situated on highly thaw sensitive permafrost. These projects demonstrate how physical and socio-economic factors can be integrated in assessments of permafrost vulnerability to thaw, thus providing tangible, useable results that reflect community priorities and support local decision making.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/74110

2016028150 Conrad, Mark E. (Lawrence Berkeley National Laboratory, Berkeley, CA); Curtis, John Bryan; Smith, Lydia J.; Bill, Markus and Torn, Margaret S. Fate and transport of methane formed in the active layer of Alaskan permafrost [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract B21D-0496, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Over the past 2 years a series of tracer tests designed to estimate rates of methane formation via acetoclastic methanogenesis in the active layer of permafrost soils were conducted at the Barrow Environmental Observatory (BEO) in northernmost Alaska. The tracer tests consisted of extracting 0.5 to 1.0 liters of soil water in gas-tight bags from different features of polygons at the BEO, followed by addition of a tracer cocktail including acetate with a 13C-labeled methyl group and D2O (as a conservative tracer) into the soil water and injection of the mixture back into the original extraction site. Samples were then taken at depths of 30 cm (just above the bottom of the active layer), 20 cm, 10 cm and surface flux to determine the fate of the 13C-labeled acetate. During 2014 (2015 results are pending) water, soil gas, and flux gas were sampled for 60 days following injection of the tracer solution. Those samples were analyzed for concentrations and isotopic compositions of CH4, DIC/CO2 and water. At one site (the trough of a low-centered polygon) the 13C acetate was completely converted to 13CH4 within the first 2 days. The signal persisted for throughout the entire monitoring period at the injection depth with little evidence of transport or oxidation in any of the other sampling depths. In the saturated center of the same polygon, the acetate was also rapidly converted to 13CH4, but water turnover caused the signal to rapidly dissipate. High d13C CO2 in flux samples from the polygon center indicate oxidation of the 13CH4 in near-surface waters. Conversely, CH4 production in the center of an unsaturated, flat-centered polygon was relatively small 13CH4 and dissipated rapidly without any evidence of either 13CH4 transport to shallower levels or oxidation. At another site in the edge of that polygon no 13CH4 was produced, but significant 13CO2/DIC was observed indicating direct aerobic oxidation of the acetate was occurring at this site. These results suggest that a longer thaw season resulting from a warming climate may increase the net CH4 flux from saturated polygonal features, but that effect may be minimized by increased drainage due to degradation of low-centered centered polygons.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/85533

2016028168 Edwards, Mary E. (University of Southampton, Southampton, United Kingdom); Grosse, Guido; McDowell, Patricia F. and Jones, Benjamin M. Evolution of a thermokarst landscape; a history of late-quaternary permafrost degradation and stabilization in interior Alaska illustrates the importance of multiple environmental controls [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-06, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The course of permafrost degradation depends on climate, vegetation, disturbance, and excess ground-ice content and distribution, which vary over time. Our understanding of possible future landscape trajectories under climate warming can be improved by observing past responses to changes in these critical drivers. Using a novel combination of lake-sediment records, field observations and LiDAR imagery, we reconstructed the late-Quaternary history of the marginal upland of the Yukon Flats, interior Alaska, a loess-mantled region with massive ground ice and numerous thermokarst lakes. Two lakes formed ~11,000-12,000 cal yr BP through inferred thermokarst processes. Charcoal in basal sediments indicates fire may have influenced lake initiation. In a third, older basin, major input of terrigenous silt occurred before or during this time. At all studied lakes, sedimentation has been stable through much of the Holocene. Meso-scale topographic features that are obscured by forest are revealed by LiDAR images to include widespread linear corrugations cutting across the uplands, deep gullies, and other features resembling lake drainage channels. These imply past dramatic surface-sediment mobilization. Lakes intersect the corrugations, indicating that the mobile phase occurred no later than the earliest Holocene. Several interacting factors may have been critical in first enhancing, then slowing, this activity. High summer insolation, increasing moisture, initially sparse vegetation, then development of woody cover and increase in fire disturbance likely combined to generate rapid and deep thaw of glacial-age permafrost. Initial lake lowering and generation of steep local topography favoring drying of uplands, a summer water deficit, and early-Holocene establishment of evergreen forest cover and consequent surface insulation likely combined to shift the system to a near-quiescent state (the system is not entirely inactive today: a partial lake drainage event was observed in 2103). The history and current state of this thermokarst-affected landscape differ from other regions. It has undergone non-linear shifts in process rates and developmental trajectory. Overall resilience to current and future environmental change here and in other regions may be equally individualistic.

2016028166 Fortier, Daniel (University of Montreal, Department of Geography, Montreal, QC, Canada); Godin, Etienne; Lévesque, Esther; Veillette, Audrey and Lamarque, Laurent. Thermal erosion of ice-wedge polygon terrains changes fluxes of energy and matter of permafrost geosystems [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-04, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Subsurface thermal erosion is triggered by convective heat transfers between flowing water and permafrost. Heat advection due to infiltration of run-off in the massive ice wedges and the ice-rich upper portion of permafrost creates sink holes and networks of interconnected tunnels in the permafrost. Mass movements such as collapse of tunnel's roof, retrogressive thaw-slumping and active layer detachment slides lead to the development of extensive gully networks in the landscape. These gullies drastically change the hydrology of ice-wedge polygon terrains and the fluxes of heat, water, sediment, nutrients and carbon within the geosystem. Exportation of sediments out of gullies are positive mechanical feed-back that keep channels active for decades. Along gully margins, drainage of disturbed polygons and ponds, slope drainage, soil consolidation, gully walls colonization by vegetation and wet to mesic plantsuccession change the thermal properties of the active layer and create negative feedback effects that stabilize active erosion processes and promote permafrost recovery in gully slopes and adjacent disturbed polygons. On Bylot Island (Nunavut), over 40 gullies were monitored to characterize gully geomorphology, thermal and mechanical processes of gully erosion, rates of gully erosion over time within different sedimentary deposits, total volume of eroded permafrost at the landscape scale and gully hydrology. We conducted field and laboratory experiments to quantify heat convection processes and speed of ice wedge ablation in order to derive empirical equations to develop model of permafrost thermal erosion. We used data, collected over 10 years, of geomorphological gully monitoring and regional climate scenarios to evaluate the potential response of ice-wedge polygon terrains to changes in snow, permafrost thermal regime and hydrological conditions over the coming decades and its implication for the short and long term dynamics of arctic permafrost geosystems.

2016028198 Gooseff, Michael N. (Institute of Arctic and Alpine Research, Boulder, CO) and Sudman, Zachary W. Impacts of permafrost degradation on stream geomorphology and sediment transport in Taylor Valley, Antarctica [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1226, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The McMurdo Dry Valleys (MDV) of Antarctica are a unique ice-free landscape that supports complex, microbially dominated ecosystems despite the harsh environment (<10 cm water equivalent/yr, -18°C mean air temperature). Recent observations suggest that this region is nearing a threshold of rapid landscape change. One such observation was the recent discovery of extensive thermokarst development (permafrost thaw features) along the banks of Crescent Stream in Taylor Valley. In 2012, a large stretch of the West Branch of Crescent Stream had significant bank failures, while the adjacent East Branch was unaffected. The objective of this study was to determine the rate of land surface change occurring on the stream bank, and the impacts of the sediment loading on the stream bed material. Three annually repeated terrestrial LiDAR scans were compared to determine the rates of ground surface change due to thermokarst degradation on the stream bank. The areal extent of the thermokarst was shown to be decreasing, however the average vertical erosion rate remained constant. Field measurements including, pebble counts, fine sediment counts, and sieve samples were collected and analyzed to determine the effects of the introduction of fine sediment on the stream bed material. The bed sediment of the thermokarst-impacted branch was consistently finer than the adjacent unaffected branch. The fine material introduced to the stream altered the bed material composition, which consequently increased the mobility of the of the bed material. These changes imposed on the stream have implications for stream morphology, endemic algal mat communities, and downstream aquatic systems.

2016028164 Herman-Mercer, Nicole Michelle (U. S. Geological Survey, Lakewood, CO); Elder, Kelly; Toohey, Ryan and Mutter, Edda Andrea. Observations and impacts of permafrost thaw in the lower Yukon River basin and Yukon delta region; the importance of local knowledge [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-02, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

In regions of the arctic and subarctic baseline measurements of permafrost dynamics are lacking and scientific research can be especially expensive when remote sensing techniques are utilized. This research demonstrated the importance of local observations, a powerful tool for understanding landscape change, such as permafrost dynamics. Fifty-five interviews were recently conducted with community members in four villages of the lower Yukon River Basin and Yukon Delta to understand local environmental and landscape changes and the impacts these changes may be having on the lives and livelihoods of these communities. The interviews were semi-structured and focused on many climate and landscape change factors including knowledge of permafrost in their community or the surrounding landscape. All positive respondents stated that they believe the permafrost is thawing. The research revealed that residents of the arctic and subarctic interact with permafrost in a variety of ways. Some people utilize permafrost to store food resources and have found that they have to dig deeper presently than in their youth in order to find ground cold enough. Others are involved in digging graves and report encountering easier excavation in recent years. Subsistence hunters and gatherers travel long distances by snowmobile and boat, and have noticed slumping ground, eroding river banks and coast lines, as well as land that seems to be rising. Finally, all residents of the arctic and subarctic interact with permafrost in terms of the stability of their homes and other infrastructure. Many interview participants complained of their houses leaning and needing more frequent adjustment than in the past. Indigenous residents of the arctic and subarctic have intimate relationships with their landscape owing to their subsistence lifestyle and are also connected to the landscape of the past through the teachings of their elders. Further, arctic and subarctic communities will sustain the majority of the impacts of permafrost degradation as the infrastructure of their communities is affected. Local residents have much to add to the study of permafrost in the arctic and subarctic. Ultimately, arctic and subarctic research will benefit most from the careful integration of local observations and physical science techniques.

2016028167 Iijima, Yoshihiro (Japan Agency for Marine-Earth Science and Technology (JAMSTEC), Yokosuka, Japan); Nakamura, Tetsu; Park, Hotaek and Fedorov, Alexander N. Climatological conditions of enhanced Arctic storm activity in relation to permafrost degradation in eastern Siberia [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-05, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The last decade (2000-2010) was the warmest on record at high northern latitudes. Surface air temperature anomalies and associated sea level pressure fields in Arctic exhibited different spatial patterns at the beginning of the 21st century than they did throughout the majority of the 20th century. In eastern Siberia, the abrupt soil warming within upper permafrost layer and deepening active layer thickness has observed in response to increasing in soil moisture under wet hydro-climatic conditions during the warming period of 2000s. According to climatological analyses, the large positive anomalies of both rainfall and snow accumulation in eastern Siberia are caused by strengthened cyclonic pattern in these years which induce more water vapor advection. These anomalies are more enhanced than those before 1990s and continuously appear after 2004. Long-term simulation of permafrost temperature and active layer thickness using a sophisticated land surface model (CHANGE) was carried out. The correlations between precipitation in late summer and soil temperature showed that the most regions exhibited either negative or not significant correlations between precipitation and soil temperature during the past period (1961-1980), whereas positive correlations were observed during the recent period (1991-2009). A region of significantly positive correlation was observed along the Siberian coast and in eastern Siberia and could have corresponded with areas of increased storm activity. The soil warming is thus due to not only increasing in snow accumulation which is well-known relationship by previous studies but also increasing in rainfall in late summer which furthermore accelerates the warming due to changes in hydro-thermal properties within the active layer. The precipitation increase in the last decade led to deepening active layer accompanying with remarkable increase in soil moisture. The perennially waterlogged conditions had exacerbated the boreal forest habitat; that is, larch trees had widely withered and died in eastern Siberia detected by field observation and satellite remote sensing analyses. The change in hydro-thermal regime could have important consequences on permafrost degradation with ecosystem and landscape changes in eastern Siberia.

2016028186 Kim, Young Gyun (Korea Polar Research Institute, Incheon, South Korea); Hong, Jong Kuk; Jin, Young Keun; Riedel, Michael; Melling, Humfrey; Kang, Seung Goo and Dallimore, Scott. Marine heat flow measurements across subsea permafrost limit in the eastern Mackenzie Trough, Canadian Beaufort Sea [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1214, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Marine heat flow measurements using a 5 m-long Ewing-type heat probe were made during Korean icebreaker R/V Araon's Arctic expeditions (ARA04C in 2013 and ARA05B in 2014) to better know the shallow subsurface thermal structure in the eastern slope of Mackenzie Trough, the Canadian Beaufort Sea, in which associative geological processes of permafrost degradation and gas hydrate dissociation occur because of long-term warming since the Last Glacial Maximum. Heat flow in the continental slope was collected for the first time and is rather higher than those from deep boreholes (up to a few km below the seafloor) in the continental shelf. However, the smaller geothermal gradient and thermal conductivity were observed from sites along a transect line across permafrost limit on the eastern slope of the trough. It is noted that geothermal gradients are relatively constant in the vicinity of permafrost limit but are much smaller (even minus) only at deeper depths with positive bottom water temperature. Reason for such distribution is unclear yet. Based on observed geothermal gradient and bottom water temperature, permafrost table shown in subbottom profile seems to be controlled not by temperature. On the other hand, our finding of permafrost evidence on the other subbottom profile located landward may support that permafrost limit in the trough is along with ~100 m isobath.

2016028163 Lamoureux, Scott F. (Queen's University, Kingston, ON, Canada) and Lafreniere, Melissa J. Impacts of permafrost change on landscape stability and water quality [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-01, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Communities and northern development depend on knowledge to support safe infrastructure design and to define appropriate environmental targets. Projected climate change is expected to have substantial impacts on permafrost through increased seasonal thaw. These changes will likely result in changing hydrological processes that will alter surface and subsurface water flow and quality. Similarly, in settings with ice-rich surficial materials, changing active layer depth and hydrological conditions can contribute to permafrost degradation and land instability. Predicting these impacts is an important need for sustainable development in permafrost regions. We have investigated these processes through a long term integrated watershed program at the Cape Bounty Arctic Watershed Observatory (CBAWO) in the Canadian Arctic. Surface water discharge and quality has been assessed since 2005 and in particular, through a period of record summer temperatures that resulted in substantial active layer perturbation and resulted in widespread localized disturbance. Research has documented the impact and recovery from these permafrost changes and demonstrate several key linkages between changing hydrological conditions, quality, and landscape sensitivity to disturbance. Deeper active layer thaw appears to alter subsurface flow paths, resulting sustained changes to water quality through increased solute fluxes and changes to nutrients. These effects are widespread across the landscape, while physical disturbance due to permafrost slope failures are dispersed and generate impacts ranging from minimal to locally-significant increases in downstream sediment and solute transport. We note that this strong spatial contrast between "thermal" and "physical" perturbation of the shallow permafrost system represents a key impact in these settings. Further, subsurface water pressurization appears to be localized but linked to physical disturbance. Hence, results indicate the benefit of an integrated approach to investigating impacts to the permafrost system through both hydrological and geomorphic perspectives.

2016028214 Marchenko, Sergey S. (University of Alaska Fairbanks, Fairbanks, AK); Streletskiy, Dmitry A.; Romanovsky, Vladimir E.; McGuire, David and Shiklomanov, Nikolay I. The permafrost condition from 1960 to 2300 based on simulations of the GIPL2 permafrost dynamics model across Eurasia; implications for soil carbon vulnerability, infrastructure and socio-economic impacts [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC31B-1179, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The impact of climate warming on permafrost and the potential of climate feedbacks resulting from permafrost thawing have recently received a great deal of attention. Most of the permafrost observatories in the Northern Eurasia show substantial warming of permafrost since the 1980s. The magnitude of warming has varied with location, but was typically from 0.5 to 3°C. The close proximity of the exceptionally ice-rich soil horizons to the ground surface, which is typical for the arctic tundra biome, makes tundra surfaces extremely sensitive to the natural and human-made changes that resulted in development of processes such as thermokarst, thermal erosion, and retrogressive thaw slumps that strongly affect the stability of ecosystems and infrastructure. The main aim of this study is to evaluate the vulnerability of permafrost under climate warming across the Permafrost Region of the Northern and High-altitude Eurasia in respect to ecosystems stability, infrastructure, socioeconomic impact, and to estimate the volume of newly thawed soils, which could be potential source or sink of additional amount of carbon in the Earth System. We applied the process-based permafrost dynamics model GIPL2 (Geophysical Institute Permafrost Lab), using a historical climate forcing CRU3.1 data set for retrospective (1960-2009) and CCSM4 RCP4.5 and RCP8.5 (2009-2300) for analysis of permafrost dynamics in the future. Our projections according to the CCSM4 RCP4.5 and RCP8.5 climate scenario indicate that the maximum unfrozen volume of soil within three upper meters could change between 12.8 and 20.8K cubic km during 2009-2300. If we assume a similar response (as modeled) of soil temperature and near-surface permafrost area shrinkage to warming in Eurasia, an additional 25% of the total volume of thawed soils could become biogeochemically active by the end of the current century and 60% by 2300.

2016028188 Sergeev, Dmitrii Olegovich (Sergeev Institute of Environmental Geoscience, Sait Petersburg, Russian Federation); Chesnokova, Irina Vasilievna and Morozova, Aleksandra V. Estimation of the past and future infrastructure damage due the permafrost evolution processes [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1216, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The geocryological processes such as thermokarst, frost heaving and fracturing, icing, thermal erosion are the source of immediate danger for the structures. The economic losses during the construction procedures in the permafrost area are linked also with the other geological processes that have the specific character in cold regions. These processes are swamping, desertification, deflation, flooding, mudflows and landslides. Linear transport structures are most vulnerable component of regional and national economy. Because the high length the transport structures have to cross the landscapes with different permafrost conditions that have the different reaction to climate change. The climate warming is favorable for thermokarst and the frost heaving is linked with climate cooling. In result the structure falls in the circumstances that are not predicted in the construction project. Local engineering problems of structure exploitation lead to global risks of sustainable development of regions. Authors developed the database of geocryological damage cases for the last twelve years at the Russian territory. Spatial data have the attributive table that was filled by the published information from various permafrost conference proceedings. The preliminary GIS-analysis of gathered data showed the widespread territorial distribution of the cases of negative consequences of geocryological processes activity. The information about maximum effect from geocryological processes was validated by detailed field investigation along the railways in Yamal and Transbaikalia Regions. Authors expect the expanding of database by similar data from other sectors of Arctic. It is important for analyzing the regional, time and industrial tendencies of geocryological risk evolution. Obtained information could be used in insurance procedures and in information systems of decisions support in different management levels. The investigation was completed with financial support by Russian Foundation of Basic Research (Project #13-05-00462).

2016028195 Strauss, Jens (Alfred Wegener Institute Helmholtz-Center for Polar and Marine Research Potsdam, Potsdam, Germany); Fedorov, Alexander N.; Fortier, Daniel; Froese, Duane G.; Fuchs, Matthias; Grosse, Guido; Günther, Frank; Harden, Jennifer W.; Hugelius, Gustaf; Kanevskiy, Mikhail Z.; Kholodov, Alexander L.; Kunitsky, Viktor; Laboor, Sebastian; Lapointe Elmrabti, Lyna; Rivkina, Elizaveta; Robinson, Joel E.; Schirrmeister, Lutz; Shmelev, Denis; Shur, Yuri; Spektor, Valentin; Ulrich, Mathias; Veremeeva, Alexandra; Walter Anthony, Katey M. and Zimov, Sergei. Ice-rich yedoma permafrost; a synthesis of Circum-Arctic distribution and thickness [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1223, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Vast portions of Arctic and sub-Arctic Siberia, Alaska and the Yukon Territory are covered by ice-rich silts that are penetrated by large ice wedges, resulting from syngenetic sedimentation and freezing. Accompanied by wedge-ice growth, the sedimentation process was driven by cold continental climatic and environmental conditions in unglaciated regions during the late Pleistocene, inducing the accumulation of the unique Yedoma permafrost deposits up to 50 meter thick. Because of fast incorporation of organic material into permafrost during formation, Yedoma deposits include low-decomposed organic matter. Moreover, ice-rich permafrost deposits like Yedoma are especially prone to degradation triggered by climate changes or human activity. When Yedoma deposits degrade, large amounts of sequestered organic carbon as well as other nutrients are released and become part of active biogeochemical cycling. This could be of global significance for the climate warming, as increased permafrost thaw is likely to cause a positive feedback loop. Therefore, a detailed assessment of the Yedoma deposit volume is of importance to estimate its potential future climate response. Moreover, as a step beyond the objectives of this synthesis study, our coverage (see figure for the Yedoma domain) and thickness estimation will provide critical data to refine the Yedoma permafrost organic carbon inventory, which is assumed to have freeze-locked between 83±12 and 129±30 gigatonnes (Gt) of organic carbon. Hence, we here synthesize data on the circum-Arctic and sub-Arctic distribution and thickness of Yedoma permafrost (see figure for the Yedoma domain) in the framework of an Action Group funded by the International Permafrost Association (IPA). The quantification of the Yedoma coverage is conducted by the digitization of geomorphological and Quaternary geological maps. Further data on Yedoma thickness is contributed from boreholes and exposures reported in the scientific literature.

2016028215 Streletskiy, Dmitry A. (George Washington University, Washington, DC); Davydova, Anna; Davydov, Sergei P.; Opel, Thomas; Shiklomanov, Alexander I.; Shiklomanov, Nikolay I.; Streletskaya, Irina D.; Tananaev, Nikita and Tokarev, Igor. Seasonal variations of stable isotope composition of river flow in permafrost regions of Yenisei and Kolyma rivers (Russia) [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC31B-1181, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Permafrost plays an important role in the hydrology of the northern regions. To investigate the role of climate change on permafrost degradation and hydrology, extensive field work was conducted in a series of small watersheds located in the discontinuous permafrost zone of the lower Yenisei River near Igarka, and in the continuous permafrost zone of the Kolyma River near Cherskii. Climatic, hydrologic and permafrost characteristics were monitored at both locations over a three year period and extended using historical data. Stable isotope composition of rain, snow, water from lakes and rivers, and various types of ground ice was used to determine various inputs and runoff pathways to a river flow in several watersheds. The study found that water flow of smaller creeks follows precipitation closely, while flow of larger rivers is affected by evaporation effects related to water storage in thermokarst lakes. Ground ice of the epigenetic permafrost near Igarka has a similar isotopic composition as that of Holocene permafrost and contemporary late summer precipitation. Ground ice of the syngenetic Pleistocene permafrost (Ice Complex) near Cherskii has a significantly lighter isotopic composition than pore water of the active and transient layers. Increases in air temperature resulted in thickening of the active-layer and melting of ice that reach the transient layer in continuous permafrost. In areas where the transient layer severely reduced as a result of intense forest fires and other landscape disturbances, ground ice from permafrost is also involved in hydrological processes. Progressive decrease in the seasonal freezing layer thickness and a lower permafrost table promoted more groundwater storage and redistribution of summer precipitation towards winter baseflow in discontinuous permafrost region. The major contribution of permafrost at both locations is not through the melting of ground ice, but through changes in soil properties affecting the water flow.

2016028189 Streletskiy, Dmitry A. (George Washington University, Washington, DC); Grebenets, Valery I.; Kerimov, Aligyushad G.; Kurchatova, Anna; Andruschenko, Fedor and Gubanov, Afanasiy. Thermal state of permafrost in urban environment under changing climatic conditions [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1217, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Risks and damage, caused by deformation of building and constructions in cryolithozone, are growing for decades. Worsening of cryo-ecological situation and loss of engineering-geocryological safety are induced by both technogenic influences on frozen basement and climate change. In such towns on permafrost as Vorkuta, Dixon more than 60% of objects are deformed, in Yakutsk, Igarka--nearly 40%, in Norilsk, Talnakh, Mirnij 35%, in old indigenous villages--approximately 100%; more than 80% ground dams with frozen cores are in poor condition. This situation is accompanied by activation of dangerous cryogenic processes. For example in growing seasonally-thaw layer is strengthening frost heave of pipeline foundation: only on Yamburg gas condensate field (Taz Peninsula) are damaged by frost heave and cut or completely replaced 3000-5000 foundations of gas pipelines. Intensity of negative effects strongly depends on regional geocryology, technogenic loads and climatic trends, and in Arctic we see a temperature rise-warming, which cause permafrost temperature rise and thaw). In built areas heat loads are more diverse: cold foundations (under the buildings with ventilated cellars or near thermosyphons) are close to warm areas with technogenic beddings (mainly sandy), that accumulate heat, close to underground collectors for communications, growing thaw zones around, close to storages of snows, etc. Note that towns create specific microclimate with higher air temperature. So towns are powerful technogenic (basically, thermal) presses, placed on permafrost; in cooperation with climate changes (air temperature rise, increase of precipitation) they cause permafrost degradation. The analysis of dozens of urban thermal fields, formed in variable cryological and soil conditions, showed, that nearly 70% have warming trend, 20%-cooling and in 10% of cases the situation after construction is stable. Triggered by warming of climate changes of vegetation, depth and temperature of seasonally thaw layer, summer precipitation regime and other natural parameters in combination with developing technogenesis require new strategy of the cryolithozone development.

2016028152 Subin, Zachary M. (Lawrence Berkeley National Laboratory, Berkeley, CA); Pau, George Shu Heng; Liu, Yaning; Riley, William J. and Koven, Charles. Application of reduced-order modeling to uncertainty in the vulnerability of permafrost carbon to climate change [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract B21D-0501, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Earth System Models (ESMs) are used to estimate terrestrial feedbacks to climate change, such as the permafrost-carbon feedback. Fully characterizing the range of possible future behavior given uncertainty in model structure and parameterization is computationally expensive. Because current ESMs typically employ land models with non-interacting gridcells, there is an opportunity for computational speedup by simulating a subset of the gridcells that are representative of the full model grid. Here, we use a reduced-order modeling technique Gappy Principle Orthogonal Decomposition with Empirical Interpolation (GPOD-EIP) to demonstrate the feasibility of efficiently characterizing the range of future responses to climate. We analyze 31 variable-configuration simulations in the Community Land Model 4.5 (CLM4.5) with GPOD-EIP and create a 20-element POD basis representing the characteristic spatial patterns of soil carbon concentration along with a representative subset of 20 to 100 of the original 20975 gridcells. We train GPOD-EIP with 10 of the 31 simulations chosen adaptively, and reconstruct the time-varying soil carbon distribution in the remaining simulations with a relative error of less than 1%. Highly-variable quantities such as the latent heat flux require a much larger basis and gridcell subset for accurate reconstruction, although their global-mean can be represented more readily. We demonstrate the use of GPOD-EIP in uncertainty quantification by efficiently characterizing the dependence of future carbon feedback on the explicit depth-dependence of soil carbon decomposition, interpolating between the extreme cases investigated in a recent published analysis. We conclude that GPOD-EIP represents a promising reduced-order modeling technique for ESM land-model data and other applications where gridded spatial fields need to be efficiently emulated.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/67344

2016028196 Uy, Kari Louis Quinto (Colgate University, Hamilton, NY); Natali, Susan; Kholodov, Alexander L. and Loranty, Michael M. Correlations between the heterogeneity of permafrost thaw depth and vegetation in Boreal forests and Arctic tundra in Alaska [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1224, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Global climate change induces rapid large scale changes in the far Northern regions of the globe, which include the thickening of the active layer of arctic and subarctic soils. Active layer depth, in turn, drives many changes to the hydrology and geochemistry of the soil, making an understanding of this layer essential to boreal forest and arctic tundra ecology. Because the structure of plant communities can affect the thermal attributes of the soil, they may drive variations in active layer depth. For instance, trees and tussocks create shade, which reduces temperatures, but also hold snow, which increases temperature through insulation; these aspects of vegetation can increase or decrease summer thaw. The goal of this project is to investigate correlations between the degree of heterogeneity of active layer depths, organic layer thickness, and aboveground vegetation to determine how these facets of Northern ecosystems interact at the ecosystem scale. Permafrost thaw and organic layer depths were measured along 20 m transects in twenty-four boreal forest and tundra sites in Alaska. Aboveground vegetation along these transects was characterized by measuring tree diameter at breast height (DBH), tussock dimensions, and understory biomass. Using the coefficient of variation as a measure of heterogeneity, we found a positive correlation between thaw depth variability and tussock volume variability, but little correlation between the former and tree DBH variability. Soil organic layer depth variability was also positively correlated with thaw depth variability, but weakly correlated with tree and tussock heterogeneity. These data suggest that low vegetation and organic layer control the degree of variability in permafrost thaw at the ecosystem scale. Vegetation can thus affect the microtopography of permafrost and future changes in the plant community that affect vegetation heterogeneity will drive corresponding changes in the variability of the soil.

2016028187 Walker, Donald A. (University of Alaska Fairbanks, Fairbanks, AK); Buchhorn, Marcel; Raynolds, Martha K.; Kanevskiy, Mikhail Z.; Matyshak, George V.; Shur, Yuri and Peirce, Jana. Effects of 45 years of heavy road traffic and infrastructure on permafrost and tundra at Prudhoe Bay, Alaska [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1215, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The upper permafrost of the Prudhoe Bay Oilfield, the largest oil field in both the United States and in North America, contains significant amounts of excess ground ice, mainly in ice wedges. An increase in infrastructure development and road traffic since the initial development of the Prudhoe Bay Oilfield in 1968 has resulted in extensive flooding, accumulation of road dust, and roadside snowbanks, all of which affect the vegetation and alter the thermal properties of the ground surface. As part of the NSF's Arctic Science, Engineering, and Education for Sustainability (ArcSEES) project, we established four transects in 2014 and 2015 to document the effects of infrastructure and heavy road traffic on adjacent tundra. Two transects were established perpendicular to the Prudhoe Bay Spine Road north of Lake Colleen and two perpendicular to the Dalton Highway next to the Deadhorse airstrip. Prior to infrastructure development in 1949, rather homogeneous networks of low-centered polygons with less than 30 cm of trough-rim elevation contrast covered both locations. We present the detailed results of vegetation analysis, ice-core drilling, and extensive topographic surveys along the transects. A time series of aerial photographs from 1949 to 2014 (yearly since 1969) documents the changing landscapes in relationship to the record of air-temperature, active layer depths, and permafrost temperatures at Deadhorse. Flooding, road dust, and snow drifts have all contributed to creating warmer soil temperatures and deeper active layers near the road. These factors have all contributed in different ways to alteration of the plant canopy. The altered plant canopies in turn further altered the surface albedo and the ground temperatures. Historical photos indicate that between 1989 and 2012 a regional thawing of the ice-wedges occurred, increasing the extent of thermokarst. Our analysis demonstrates the cumulative effects of infrastructure-related and climate-related factors to these ice-rich permafrost landscapes.

2016028169 Walvoord, Michelle A. (U. S. Geological Survey, Denver, CO); Jepsen, Steven M.; Rover, Jennifer; Voss, Clifford I. and Briggs, Martin A. Evolving hydrologic connectivity in discontinuous permafrost lowlands; what it means for lake systems [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-07, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Permafrost influence on the hydrologic connectivity of surface water bodies in high-latitude lowlands is complicated by subsurface heterogeneity and the propensity of the system to change over time. In general, permafrost limits the subsurface exchange of water, solute, and nutrients between lakes and rivers. It follows that permafrost thaw could enhance subsurface hydrologic connectivity among surface water bodies, but the impact of this process on lake distribution is not well known. Changes in the extent of lakes in interior Alaska have important ecological and societal impacts since lakes provide (1) critical habitat for migratory arctic shorebirds and waterfowl, fish, and wildlife, and (2) provisional, recreational, and cultural resources for local communities. We utilize electromagnetic imaging of the shallow subsurface and remote sensing of lake level dynamics in the Yukon Flats of interior Alaska, USA, together with water balance modeling, to gain insight into the influence of discontinuous permafrost on lowland lake systems. In the study region with relatively low precipitation, observations suggest that lakes that are hydrologically isolated during normal conditions are sustained by periodic river flooding events, including ice-jam floods that occur during river ice break-up. Climatically-influenced alterations in flooding frequency and intensity, as well as depth to permafrost, are quantitatively assessed in the context of lake maintenance. Scenario modeling is used to evaluate lake level evolution under plausible changing conditions. Model results demonstrate how permafrost degradation can reduce the dependence of typical lowland lakes on flooding events. Study results also suggest that river flooding may recharge a more spatially widespread zone of lakes and wetlands under future scenarios of permafrost table deepening and enhanced subsurface hydrologic connectivity.

2016025083 Moorman, Brian J. (University of Calgary, Department of Geography, Calgary, AB, Canada) and Stevens, Christopher. Using ground penetrating radar to aid in the modeling of shallow water sedimentation and permafrost growth in the Mackenzie Delta, Canada [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 248, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

Permafrost is know to extend out into the shallow water areas in the Arctic. This can include lakes rivers and deltas. Due to rapid sedimentation, the shallow water zone (i.e. water depths less than 2 m) in the Mackenzie Delta in the Western Canadian Arctic is very extensive, extending up to 15 km seaward of the coastline. As well, the bathymetry in this zone is complex and has been known to change dramatically over short periods of time. Following in the footsteps of Professor Derald Smith, Ground-Penetrating Radar (GPR) surveys were undertaken to map bathymetric changes and the presence and depth of frozen ground. The results of repeated GPR surveys revealed a number of remarkable aspects of this deltaic system. First, the bathymetry and hence the zone of bottom-fast ice varied dramatically both spatially and temporally. Second, thermal reflections could be easily distinguished from sedimentary reflections in the sub-bottom sediments. Using the GPR results as input into a thermal model, the distribution of sub-bottom frozen ground could be modeled from the water depth and the seasonal ice-contact time. By combining the geophysical data with multi-temporal remotely sensed synthetic-aperture radar (satellite SAR) data, shallow water bathymetric maps and permafrost aggradation and degradation maps were able to be created for large areas. As such, the changes in sedimentation and permafrost conditions in the shallow water zone can now be monitored from year to year in response to changing hydrological and climatological conditions.

2016028191 Bolton, William R. (University of Alaska Fairbanks, Fairbanks, AK); Lara, Mark J.; Genet, Helene; Romanovsky, Vladimir E. and McGuire, Anthony David. Initial conceptualization and application of the Alaska thermokarst model [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1219, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Thermokarst topography forms whenever ice-rich permafrost thaws and the ground subsides due to the volume loss when ground ice transitions to water. The Alaska Thermokarst Model (ATM) is a large-scale, state-and-transition model designed to simulate transitions between landscape units affected by thermokarst disturbance. The ATM uses a frame-based methodology to track transitions and proportion of cohorts within a 1-km2 grid cell. In the arctic tundra environment, the ATM tracks thermokarst-related transitions among wetland tundra, graminoid tundra, shrub tundra, and thermokarst lakes. In the boreal forest environment, the ATM tracks transitions among forested permafrost plateau, thermokarst lakes, collapse scar fens and bogs. The transition from one cohort to another due to thermokarst processes can take place if thaw reaches ice-rich ground layers either due to pulse disturbance (i.e. large precipitation event or fires), or due to gradual active layer deepening that eventually results in penetration of the protective layer. The protective layer buffers the ice-rich soils from the land surface and is critical to determine how susceptible an area is to thermokarst degradation. The rate of terrain transition in our model is determined by a set of rules that are based upon the ice-content of the soil, the drainage efficiency (or the ability of the landscape to store or transport water), the cumulative probability of thermokarst initiation, distance from rivers, lake dynamics (increasing, decreasing, or stable), and other factors. Tundra types are allowed to transition from one type to another (for example, wetland tundra to graminoid tundra) under favorable climatic conditions. In this study, we present our conceptualization and initial simulation results from in the arctic (the Barrow Peninsula) and boreal (the Tanana Flats) regions of Alaska.

2016028170 Chen Jie (Chinese University of Hong Kong, Institute of Space and Earth Information Science, Hong Kong, China); Liu Lin; Lin Hui; Zhang Tingjun and Cao Bin. Using PSinSAR to detect thermokarst-induced surface subsidence in Eboling Mountain on the Qinghai-Tibet Plateau of China [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-08, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Thermokarst, a process that characterizes landforms caused by thawing of ice-rich permafrost, is a key indicator of permafrost degradation. Surface dynamics of thermokarst processes on Qinghai-Tibet Plateau (QTP) of China, is still poorly quantified or understood. It is also challenging to detect and measure surface subsidence due to loss of subsurface ice over a large area. In this study, the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique is used to retrieve surface subsidence located at Eboling Mountain, near the northern edge of the QTP. Persistent Scatterer (PS) refers to stable natural or man-made object with good coherence in temporal domain. Based on the assumption that the residual phase of nearby PS is smaller than , we can retrieve the unwrapped phase associated with the sparsely irregular data. Using 17 L-band ALOS-1 PALSAR images taken from 2006 to 2011, we find linear deformation trends of up to 50 millimeters per year and seasonal subsidence of up to 80 millimeters over the area where thermokarst gullies are present (location: 38.01°N, 100.90°E), associated with thermokarst development and seasonal thawing of active layer, respectively. Furthermore, to the northwest and northeast of the Eboling thermokarst area, there are several small areas with large subsidence trends, which may also be related to thermokarst processes. This study demonstrates that the PSInSAR technique has the ability to map and quantify thermokarst-induced subsidence spanning multiple years using ALOS-1 PALSAR images. Yet as the thermokarst processes are much more complex in nature than a simple subsidence trend, more efforts are required (1) to validate the PSInSAR results with in situ measurements, (2) to better separate thermokarst-induced subsidence from seasonal ground elevation changes by including winter PSInSAR data and accounting for frost heave processes, and (3) to quantify potential aliasing problem due to the sparse temporal sampling rate of the PSInSAR data. This study promises a potential of using PSInSAR to identify thermokarst landforms, map and quantify surface subsidence due to permafrost degradation, and assess its impacts over large areas on the QTP.

2016028134 Emerson, Joanne B. (Ohio State University Main Campus, Columbus, OH); Varner, Ruth K.; Johnson, Joel E.; Owusu-Dommey, Akosua; Binder, Morgan; Woodcroft, Ben J.; Wik, Martin; Freitas, Nancy L.; Boyd, Joel A.; Crill, Patrick M.; Saleska, Scott R.; Tyson, Gene W. and Rich, Virginia I. Linking sediment microbial communities to carbon cycling in high-latitude lakes [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract B21C-0454, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

It is well recognized that thawing permafrost peatlands are likely to provide a positive feedback to climate change via CH4 and CO2 emissions. High-latitude lakes in these landscapes have also been identified as sources of CH4 and CO2 loss to the atmosphere. To investigate microbial contributions to carbon loss from high-latitude lakes, we characterized sediment geochemistry and microbiota via cores collected from deep and shallow regions of two lakes (Inre Harrsjon and Mellersta Harrsjon) in Arctic Sweden in July, 2012. These lakes are within the Stordalen Mire long-term ecological area, a focal site for investigating the impacts of climate change-related permafrost thaw, and the lakes in this area are responsible for ~55% of the CH4 loss from this hydrologically interconnected system. Across 40 samples from 4 to 40 cm deep within four sediment cores, Illumina 16S rRNA gene sequencing revealed that the sedimentary microbiota was dominated by candidate phyla OP9 and OP8 (Atribacteria and Aminicenantes, respectively, including putative fermenters and anaerobic respirers), predicted methanotrophic Gammaproteobacteria, and predicted methanogenic archaea from the Thermoplasmata Group E2 clade. We observed some overlap in community structure with nearby peatlands, which tend to be dominated by methanogens and Acidobacteria. Sediment microbial communities differed significantly between lakes, by overlying lake depth (shallow vs. deep), and by depth within a core, with each trend corresponding to parallel differences in biogeochemical measurements. Overall, our results support the potential for significant microbial controls on carbon cycling in high-latitude lakes associated with thawing permafrost, and ongoing metagenomic analyses of focal samples will yield further insight into the functional potential of these microbial communities and their dominant members.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/86169

2016028183 García-García, Almudena (St. Francis Xavier University, Climate & Atmospheric Sciences Institute, Antigonish, NB, Canada); Cuesta-Valero, Francisco José; Smerdon, Jason E. and Beltrami, Hugo. Thermal coupling between air and ground temperatures in the CMIP5 historical and future simulations [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23I-1210, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The thermal coupling between air and ground temperatures is investigated herein for General Circulation Models (GCMs) that participated in the fifth phase of the Coupled Model Intercomparison Project (CMIP5). For each simulation, we evaluate the regional relationship between air and ground temperatures to study surface energy fluxes and the attenuation of the annual temperature signal across the air-ground interface and into the shallow subsurface for North America. Our results show that the transport of energy across the air-ground interface and into the shallow subsurface is different across GCMs and is dependent on the land surface models that each employs. The variability of the difference between air and ground temperatures is high among simulations and is not dependent on the depth of the bottom boundary of the subsurface soil model. The difference between air and ground temperatures differs significantly from observations. Additionally, while the variability among GCMs can be explained by the physics of the land surface models, the regional variability of the air-ground coupling is associated with the model treatment of soil properties as well as snow and vegetation processes within GCMs. The difference between air and ground temperatures at high latitudes within the majority of the CMIP5 models is directly proportional to the amount of snow on the ground, due to the insulating effect of snow cover. On the other hand, the difference between air and ground temperatures at low latitudes within some of the CMIP5 models is inversely proportional to the vegetation cover (leaf area index), due to changes in latent and sensible heat fluxes. The large variability among GCMs and the marked dependency of the results on the choice of the land-surface model illustrates the need for improving the simulation of air-ground coupling in land-surface models towards a robust simulation of near-surface processes, such as permafrost and soil carbon stability within GCMs.

2016028145 Hannah, David M. (University of Birmingham, Birmingham, United Kingdom); Docherty, Catherine and Milner, Alexander. Drivers of river water temperature space-time variability in Northeast Greenland [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract B21D-0472, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Water temperature plays an important role in stream ecosystem functioning; however, water temperature dynamics in high Arctic environments have received relatively little attention. Given that global climate is predicted to change most at high latitudes, it is vital we broaden our knowledge of space-time variability in Arctic river temperature to understand controlling processes and potential consequences of climate change. To address this gap, our research aims: (1) to characterise seasonal and diel patterns of variability over three summer and two winter seasons with contrasting hydrometeorological conditions, (2) to unravel the key drivers influencing thermal regimes and (3) to place these results in the context of other snow/glacier-melt dominated environments. Fieldwork was undertaken in July-September 2013, 2014 and 2015 close to the Zackenberg Research Station in Northeast Greenland--an area of continuous permafrost with a mean July air temperature of 6°C. Five streams were chosen that drain different water source contributions (glacier melt, snow melt, groundwater). Data were collected at 30 minute intervals using micro-dataloggers. Air temperature data were collected within 7 km by the Greenland Survey. Weather conditions were highly variable between field campaigns, with 2013 experiencing below average, and 2014 and 2015 above average, snowfall. Summer water temperatures appear to be high in comparison to some Arctic streams in Alaska and in Svalbard. Winter snowfall extent decreases stream water temperature; and water temperature increases with atmospheric exposure time (distance from source)--illustrating the intertwined controls of water and heat fluxes. These Greenland streams are most strongly influenced by snowmelt, but groundwater contributions could increase with a changing climate due to increased active layer thickness, which may result in increased river temperature with implications for aquatic biodiversity and ecosystem functioning.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/71806

2016028193 Jones, Benjamin M. (U. S. Geological Survey, Alaska Science Center, Anchorage, AK); Grosse, Guido; Larsen, Christopher F.; Hayes, Daniel J.; Arp, Christopher D.; Liu Lin and Miller, Eric. Post-fire thermokarst development along a planned road corridor in Arctic Alaska [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1221, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Wildfire disturbance in northern high latitude regions is an important factor contributing to ecosystem and landscape change. In permafrost influenced terrain, fire may initiate thermokarst development which impacts hydrology, vegetation, wildlife, carbon storage and infrastructure. In this study we differenced two airborne LiDAR datasets that were acquired in the aftermath of the large and severe Anaktuvuk River tundra fire, which in 2007 burned across a proposed road corridor in Arctic Alaska. The 2009 LiDAR dataset was acquired by the Alaska Department of Transportation in preparation for construction of a gravel road that would connect the Dalton Highway with the logistical camp of Umiat. The 2014 LiDAR dataset was acquired by the USGS to quantify potential post-fire thermokarst development over the first seven years following the tundra fire event. By differencing the two 1 m resolution digital terrain models, we measured permafrost thaw subsidence across 34% of the burned tundra area studied, and observed less than 1% in similar, undisturbed tundra terrain units. Ice-rich, yedoma upland terrain was most susceptible to thermokarst development following the disturbance, accounting for 50% of the areal and volumetric change detected, with some locations subsiding more than six meters over the study period. Calculation of rugosity, or surface roughness, in the two datasets showed a doubling in microtopography on average across the burned portion of the study area, with a 340% increase in yedoma upland terrain. An additional LiDAR dataset was acquired in April 2015 to document the role of thermokarst development on enhanced snow accumulation and subsequent snowmelt runoff within the burn area. Our findings will enable future vulnerability assessments of ice-rich permafrost terrain as a result of shifting disturbance regimes. Such assessments are needed to address questions focused on the impact of permafrost degradation on physical, ecological, and socio-economic processes.

URL: https://agu.confex.com/agu/fm15/meetingapp.cgi/Paper/66359

2016028184 Necsoiu, Marius (Southwest Research Institute, San Antonio, TX); Onaca, Alexandru; Ardelean, Florina; Sirbu, Flavius and Magori, Brigitte. Slow geomorphologic evolution of rock glaciers in marginal periglacial environment of Southern Carpathians (Romania) [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1212, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The development of remote sensing techniques in the last several decades now permits surveying areas that are difficult to access and allows capturing geomorphological processes that operate at low deformation rates. In marginal periglacial environments, where the kinematics of the rock glaciers are defined by slow flow, specific remote sensing techniques (e.g., optical image cross-correlation techniques or multitemporal interferometry) are preferred because they are capable of providing ground displacement accuracies on the order of a few mm. Recent multi-temporal image analysis of high-resolution optical and radar satellite imagery of the Retezat Mountains (in the southern Carpathian Mountains of Romania) rock glaciers revealed very low rates of deformation and confirmed that active rock glaciers still exist here. These findings were supported by geophysical investigations (electrical resistivity tomography and ground penetrating radar) and thermal monitoring, which confirmed the patchy distribution of permafrost within the investigated rock glaciers. Given the high depth of the active layer (between 5 and 10 m) and the limited thickness of the ground ice bodies, the permafrost in the Retezat Mountains was assumed to exist in marginal conditions. The sporadic permafrost from the alpine zone of the southern Carpathians is extremely sensitive to environmental changes and responds directly to air temperature fluctuations. As an example, geophysical investigations between 2007 and 2014 revealed significant ground ice disappearance from one of the studied rock glaciers (i.e., Pietrele) as a result of rising air temperature. Optical satellite data revealed that the disappearance of ground ice led to accelerated movement of this rock glacier after 2007. The variability of horizontal movement is strongly controlled by the ground thermal regime. The results confirm the hypothesis that permafrost is not in equilibrium with the present-day climate in the Romanian Carpathians and will probably disappear completely in the next few decades.

2016028185 Necsoiu, Marius (Southwest Research Institute, San Antonio, TX) and Onaca, Alexandru. Detecting rock glacier dynamics in Southern Carpathians mountains using high-resolution optical and multi-temporal SAR satellite imagery [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1213, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

This research provided the first documented assessment of the dynamics of rock glaciers in Southern Carpathian Mountains over almost half a century (1968-2014). The dynamics of four representative rock glaciers were assessed using complementary satellite-based optical and radar remote sensing techniques. We investigated the dynamics of the area using co-rectification of paired optical satellite datasets acquired by SPOT5, WV-1, Pleiades, and Corona to estimate short term (7 years) and longer term changes (44 years). Accurately rectifying and co-registering Corona KH-4B imagery allowed us to expand the time horizon over which changes in this alpine environment could be analyzed. The displacements revealed by this analysis correlate with variations in local slope of the rock glaciers, and presence or absence of permafrost. For radar analysis, nine ascending ALOS-1 PALSAR images were used based clear sky and absence of snow groundcover (i.e. June-October). Although decorrelation limits the ability to perform quantitative InSAR analyses, loss of coherence was useful in detecting subtle changes in active rock glacier environments, as well as other mass movements including rock falls, rock avalanches, debris flows, creep of permafrost, and solifluction. Small Baseline Subset (SBAS) InSAR analysis successfully quantified rates of change for unstable areas. The results of this investigation, although based on limited archived imagery, demonstrate that correlation analysis, coherence analysis, and multitemporal InSAR techniques can yield useful information for detecting creeping permafrost in a complex mountain environment, such as Retezat Mountains. Our analyses showed that rock glaciers in the Southern Carpathian Mountains are experiencing very slow annual movement of only a few cm per year. Results of the remote sensing analyses are consistent with field observations of permafrost occurrence at these sites (for more, please see Abstract ID# 68413). The combined optical/radar approach can be widely applicable to other regions where information on glacier rock dynamics is scarce or completely absent, with wider implications for understanding the effects of climate change on rock glaciers around the world.

2016028165 Radosavljevic, Boris (Alfred Wegener Institute, Helmholtz-Center for Polar and Marine Research Potsdam, Potsdam, Germany); Lantuit, Hugues; Overduin, Paul P. and Fritz, Michael. Coastal hazard vulnerability assessment; a case study of erosion and flooding on Herschel Island, Yukon Territory, Canada [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC22C-03, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Coastal infrastructure, cultural, and archeological sites are increasingly vulnerable to erosion and flooding along permafrost coasts. Amplified warming of the Arctic, sea level rise, lengthening of the open water period, and a predicted increase in frequency of major storms compound these threats. Mitigation necessitates decision-making tools at an appropriate scale. We present a study of coastal erosion combining it with a flooding risk assessment for the culturally important historic settlement on Herschel Island, a UNESCO World Heritage candidate site. The resulting map may help local stakeholders devise management strategies to cope with rapidly changing environmental conditions. We analyzed shoreline movement using the Digital Shoreline Analysis System (DSAS) after digitizing shorelines from 1952, 1970, and 2011. Using these data, forecasts of shoreline positions were made for 20 and 50 years into the future. Flooding risk was assessed using a cost-distance map based on a high-resolution Light Detection and Ranging (LiDAR) dataset and current Intergovernmental Panel on Climate Change sea level estimates. Widespread erosion characterizes the study area. The rate of shoreline movement for different periods of the study ranges from -5.5 to 2.7 m·a-1 (mean -0.6 m·a-1). Mean coastal retreat decreased from -0.6 m·a-1 to -0.5 m·a-1, for 1952-1970 and 1970-2000, respectively, and increased to -1.3 m·a-1 in the period 2000-2011. Ice-rich coastal sections, and coastal sections most exposed to wave attack exhibited the highest rates of coastal retreat. The geohazard map resulting from shoreline projections and flood risk analysis indicates that most of the area occupied by the historic settlement is at extreme or very high risk of flooding, and some buildings are vulnerable to coastal erosion. The results of this study indicate a greater threat by coastal flooding than erosion. Our assessment may be applied in other locations where limited data are available.

2016028192 Schaefer, Kevin M. (University of Colorado, National Snow and Ice Data Center, Boulder, CO); Chen, Albert C.; Liu Lin; Parsekian, Andrew; Jafarov, Elchin E.; Panda, Santosh K. and Zebker, Howard A. Realizing the full potential of remotely sensed active layer thickness (ReSALT) products [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1220, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The Remotely Sensed Active Layer Thickness (ReSALT) product uses the Interferometric Synthetic Aperture Radar (InSAR) technique to measure ground subsidence, active layer thickness (ALT), and thermokarst activity in permafrost regions. ReSALT supports research for the Arctic-Boreal Vulnerability Experiment (ABoVE) field campaign in Alaska and northwest Canada and is a precursor for a potential Nasa-Isro Synthetic Aperture Radar (NISAR) product. ALT is a critical parameter for monitoring the status of permafrost and thermokarst activity is one of the key drivers of change in permafrost regions. The ReSALT product currently includes 1) long-term subsidence trends resulting from the melting and subsequent drainage of excess ground ice in permafrost-affected soils, 2) seasonal subsidence resulting from the expansion of soil water into ice as the active layer freezes and thaws, and 3) ALT estimated from the seasonal subsidence assuming a vertical profile of water within the soil column. ReSALT includes uncertainties for all parameters and is validated against in situ measurements from the Circumpolar Active Layer Monitoring (CALM) network, Ground Penetrating Radar and mechanical probe measurements. We present high resolution ReSALT products on the North Slope of Alaska: Prudhoe Bay, Barrow, Toolik Lake, Happy Valley, and the Anaktuvuk fire zone. We believe that the ReSALT product could be expanded to include maps of individual thermokarst features identified as spatial anomalies in the subsidence trends, with quantified expansion rates. We illustrate the technique with multiple examples of thermokarst features on the North Slope of Alaska. Knowing the locations and expansion rates for individual features allows us to evaluate risks to human infrastructure. Our results highlight the untapped potential of the InSAR technique to remotely sense ALT and thermokarst dynamics over large areas of the Arctic.

2016028197 Sjoberg, Ylva (Stockholm University, Stockholm, Sweden); Coon, Ethan; Sannel, Britta; Pannetier, Romain; Harp, Dylan R.; Frampton, Andrew; Painter, Scott L. and Lyon, Steve W. Field observations and numerical modeling of the thermal effects of groundwater flow through a Subarctic fen [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1225, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Field observations and numerical modeling of ground temperatures are the main tools for understanding current and projecting future permafrost changes in the rapidly warming Arctic. Traditionally, most studies have focused on vertical fluxes of heat through the ground. Groundwater can transport heat in both lateral and vertical directions but its influence on ground temperatures at local scales in permafrost environments is not well understood. In this study field observations from a subarctic fen located within the sporadic permafrost zone are combined with numerical simulations for investigating coupled water and thermal fluxes. Ground temperature profiles and groundwater levels were observed in boreholes at the Tavvavuoma study site in northern Sweden. Based on these observations, one- and two-dimensional simulations down to 2 m depth across a gradient of permafrost conditions both within and surrounding the fen, were set up. To quantify the influence of groundwater flows on the ground temperature, two-dimensional scenarios representing the fen under various groundwater fluxes were developed. The observations suggest that lateral groundwater flows significantly affect ground temperatures. This is corroborated by modeling results that show seasonal ground ice melts 1 month earlier when a lateral groundwater flux is present. Further, although the thermal regime may be dominated by vertically conducted heat fluxes during most of the year, isolated high groundwater flow events can be potentially important for ground temperatures. Sporadic permafrost environments contain substantial portions of unfrozen ground, often with active groundwater flow paths such as fens. Knowledge of this heat transport mechanism is therefore important for understanding permafrost dynamics in these environments.

2016028194 Ulrich, Mathias (University of Leipzig, Institute for Geography, Leipzig, Germany); Iijima, Yoshihiro; Park, Hotaek and Fedorov, Alexander N. Size, distribution and evolution of thermokarst lakes in Central Yakutia, Russia [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC23J-1222, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The permafrost landscape of Central Yakutia is subject to rapid modifications as a result of intensive land use, extreme weather, and the current global warming. With regard to the predicted increase in precipitation and temperature due to climate change, quantitative knowledge of the small-scale variability of active thermokarst processes is required. Here, we analyzed size and frequency distribution of lakes >0.1 ha on different geomorphological ice-rich permafrost terraces east of Yakutsk using Landsat 8 data and we mapped the change of thermokarst and alas lakes since 1944 at the Yukechi study site using historical airborne and current satellite data and analyzed growth rates and thaw subsidence. Generally, larger lakes in higher frequency are dominating lower and younger terraces, while higher and older terraces are dominated by smaller lakes. In particular, smaller lakes in less density are distributed on older and more ice-rich terraces while the younger and less ice-rich terraces are characterized by highest lake densities and larger lakes. Remote sensing analysis at the Yukechi study site indicate that lake-level changes of residual alas lakes during the past 70 years were mainly affected by the winter precipitation and the annual water balance. In the meanwhile, extensive agricultural use in the post-war period led to the disturbance of the thermal and hydrological balance of the permafrost and results in rapid and sustained growth of young thermokarst lakes on undegraded ice-rich permafrost deposits. Climatic parameters, however, are affecting only growing rates within certain time periods. The mean growth rate of all mapped thermokarst lakes at Yukechi is 0.8±0.6 m a-1, with a mean thaw subsidence of 7.0±1.6 cm a-1. Our results indicate that topography, geomorphology, and surficial cryolithology are important controlling factors on the distribution of lakes. Furthermore, thermokarst activity is influenced by climatic parameters but it is accelerated by anthropogenic land use. Further studies of multi-temporal images are necessary to validate these results.

2016027662 Veraart, Annelies J. (Netherlands Institute of Ecology, Department of Microbial Ecology, Wageningen, Netherlands); Steenbergh, Anne K.; Ho, Adrian; Kim, Sang Yoon and Bodelier, Paul L. E. Beyond nitrogen; the importance of phosphorus for CH4 oxidation in soils and sediments: in Mechanisms controlling greenhouse gas emissions from soils (Kim, Pil Joo, editor; et al.), Geoderma, 259-260, p. 337-346, illus. incl. 3 tables, 73 ref., December 2015. Meeting: 20th world congress of soil science; International conference of the International Union of Soil Sciences, June 8-13, 2014, Jeju, South Korea. Netherlands Institute of Ecology Publ. No. 5828.

Wetlands, lakes and agricultural soils are important sources and sinks of the greenhouse gas methane. The only known methane sink of biological nature is the oxidation by methanotrophic microorganisms, these organisms therefore provide an important ecosystem service. To protect this ecosystem service, it is important to maintain methanotrophic microorganism diversity, especially under increased anthropogenically-induced environmental pressures, such as imbalanced input of nutrients to ecosystems. There is therefore an urgent need to understand how N and P affect the structure and activity of methane oxidizing communities. Numerous research studies have already shown variable effects of N-addition on methane oxidation: small additions tend to stimulate methane oxidation, whereas large additions are inhibitory. There is however still a large knowledge gap concerning effects of P on methane oxidation. Here, we present data on the relation between methane oxidation and various measures of P in 50 drainage ditches, and summarize literature reporting relations between P and methane oxidation in wetlands and soils. Additionally, we review experiments on effects of P, N and N + P addition on both low affinity and high affinity methane oxidation. In our set of drainage ditches, as well as studies on wetland and permafrost soils, P content is positively correlated to methane oxidation, though it also co-correlates with many other variables. However, results from P-additions in rice paddies, agricultural soils, landfills, peat bogs, permafrost soils and forests were more variable: sometimes inhibiting (2 studies), other times stimulating methane oxidation (4 studies), and sometimes showing no effect (5 studies). Two studies report increased methanotroph (pmoA) abundance following P-fertilization, but little is known about effects of P on methanotroph community structure and its consequences for methane consumption. By mining methanotrophic genomes for genes involved in N and P-related processes, we demonstrate that variability in N/P related traits (influencing acquisition, uptake and metabolism) does not reflect DNA-based phylogeny. This review points to a need for better mechanistic understanding of the effects of P on methane oxidation, and the role of traits of methanotrophic community members in regulating this process. Abstract Copyright (2015) Elsevier, B.V.

2016028216 Walker, Donald A. (University of Alaska Fairbanks, Institute of Arctic Biology, Fairbanks, AK); Kofinas, Gary; Raynolds, Martha K.; Kanevskiy, Mikhail Z.; Shur, Yuri; Ambrosius, Ken; Matyshak, George V.; Romanovsky, Vladimir E.; Kumpula, Timo; Forbes, Bruce C.; Khukmotov, Artem; Leibman, Marina O.; Khitun, Olga; Lemay, Mickaël; Allard, Michel; Lamoureux, Scott F.; Bell, Trevor; Forbes, Donald L.; Vincent, Warwick F.; Kuznetsova, Elena; Streletskiy, Dmitry A.; Shiklomanov, Nikolay I.; Fondahl, Gail; Petrov, Andrey; Roy, Louis-Philippe; Schweitzer, Peter and Buchhorn, Marcel. Rapid ArcTic changes due to Infrastructure and Climate (RATIC) in the Russian North [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract GC31B-1183, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The Rapid Arctic Transitions due to Infrastructure and Climate (RATIC) initiative is a forum developed by the International Arctic Science Committee (IASC) Terrestrial, Cryosphere, and Social & Human working groups for developing and sharing new ideas and methods to facilitate the best practices for assessing, responding to, and adaptively managing the cumulative effects of Arctic infrastructure and climate change. An IASC white paper summarizes the activities of two RATIC workshops at the Arctic Change 2014 Conference in Ottawa, Canada and the 2015 Third International Conference on Arctic Research Planning (ICARP III) meeting in Toyama, Japan (Walker & Pierce, ed. 2015). Here we present an overview of the recommendations from several key papers and posters presented at these conferences with a focus on oil and gas infrastructure in the Russian north and comparison with oil development infrastructure in Alaska. These analyses include: (1) the effects of gas- and oilfield activities on the landscapes and the Nenets indigenous reindeer herders of the Yamal Peninsula, Russia; (2) a study of urban infrastructure in the vicinity of Norilsk, Russia, (3) an analysis of the effects of pipeline-related soil warming on trace-gas fluxes in the vicinity of Nadym, Russia, (4) two Canadian initiatives that address multiple aspects of Arctic infrastructure called Arctic Development and Adaptation to Permafrost in Transition (ADAPT) and the ArcticNet Integrated Regional Impact Studies (IRIS), and (5) the effects of oilfield infrastructure on landscapes and permafrost in the Prudhoe Bay region, Alaska.

2016023134 Burchwell, Andrew (Ohio State University, Columbus, OH). Nuclear well log properties of natural gas hydrate reservoirs [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 82, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

Characterizing gas hydrate in a reservoir typically involves a full suite of geophysical well logs. The effort to understand and further characterize permafrost and ocean floor reservoirs is critical in quantifying gas hydrates as a geohazard and potential future resource. The most common method involves using resistivity measurements to quantify the decrease in electrically conductive water when replaced with gas hydrate. Compressional velocity measurements are also used because the gas hydrates strengthen the moduli of the sediment significantly. At many gas hydrate sites, nuclear well logs, which include the photoelectric effect, formation sigma, carbon/oxygen ratio and neutron porosity are also collected but often not used. In fact, the nuclear response of a gas hydrate reservoir is not known. In this research we will focus on the nuclear log response in gas hydrate reservoirs at the Mallik Field at the Mackenzie Delta, Northwest Territories, Canada and the Gas Hydrate Joint Industry Project Leg 2 sites in the northern Gulf of Mexico. Nuclear logs may add increased robustness to the investigation into the properties of gas hydrates and some types of logs may offer an opportunity to distinguish between gas hydrate and ice permafrost. For example, a true formation sigma log measures the thermal neutron capture cross section of a formation and pore constituents. Chlorine has a high absorption potential, and is used to determine the amount of saline water within pore spaces. Gas hydrate offers a difference in elemental composition than water-saturated intervals. In permafrost areas, the carbon/oxygen ratio may vary between gas hydrate and permafrost, due to the increase of carbon in gas hydrate accumulations. At the Mallik site, we observe a hydrate-bearing sand (1085-1107 m) above a water-bearing sand (1107-1140 m), which was confirmed through core samples and mud gas analysis We observe a decrease in the photoelectric absorption in the water sand of ~0.5 barnes/e-, as well as an increase in the formation sigma readings of ~5 capture units in the water-bearing sand. This is further correlated with the carbon/oxygen ratio showing a decrease of 20% in the water sand. In future research, we will quantify the effect of gas hydrate on the nuclear logs at the Mallik well and compare it to wells in the Gulf of Mexico.

2016023397 Keating, Kristina (Rutgers University, Department of Earth and Environmental Sciences, Newark, NJ). The use of nuclear magnetic resonance to characterize the near surface for geophysical applications [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 182, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

Nuclear magnetic resonance (NMR) is an emerging method in near surface geophysics that allows for the direct detection of hydrogen protons in water or oil. Measurements, which can be made in the field, using a surface-based system or a borehole-logging tool, and in the laboratory, can thus provide information about the water content distribution in the region of interest. Furthermore, the NMR response is sensitive to the physical and chemical properties of the pore space, which has allowed the NMR measurement to be used to estimate porosity and permeability in saturated systems and the saturation and relative hydraulic conductivity in unsaturated systems. More recently NMR measurements have been used to monitor the chemical reactions associated with contaminant remediation. This presentation will give an overview of the use of laboratory, borehole, and surface based NMR methods for the characterization of near surface sediments. Laboratory examples will be given showing the link between NMR measurements, water content, permeability, and the chemical properties of materials. Field examples will be given showing standard applications of NMR including determining the water content with depth, as well as novel applications of NMR including determining the distribution of permafrost and monitoring contaminant remediation.

2016020762 Hrbacek, Filip (Masaryk University, Department of Geography, Brno, Czech Republic) and Laska, Kamil. Soil thermal properties at two different sites on James Ross Island in the period 2012/13 [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-283, 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.

URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-283.pdf

2016027663 Seo, Juyoung (Yonsei University, School of Civil and Environmental Engineering, Seoul, South Korea); Jang, Inyoung; Jung, Ji Young; Lee, Yoo Kyung and Kang, Hojeong. Warming and increased precipitation enhance phenol oxidase activity in soil while warming induces drought stress in vegetation of an Arctic ecosystem: in Mechanisms controlling greenhouse gas emissions from soils (Kim, Pil Joo, editor; et al.), Geoderma, 259-260, p. 347-353, illus. incl. 3 tables, 35 ref., December 2015. Meeting: 20th world congress of soil science; International conference of the International Union of Soil Sciences, June 8-13, 2014, Jeju, South Korea.

Global climate change models predict that surface temperature and precipitation will increase in the Polar regions. Arctic tundra soils contain a large amount of carbon, which may be vulnerable to decomposition under potential climate change. However, mechanistic understanding of the decomposition process and the consequent changes remains lacking. In the present study, we conducted a manipulation experiment at an arctic soil system in Cambridge Bay, Canada, where temperature and precipitation were increased artificially by installing open top chambers and adding distilled water during growing seasons. After one and half year of environmental manipulation, we investigated extracellular enzyme activities, which are related to decomposition, and analyzed stable isotope signatures (d13C and d15N) in soils and plants, which are related to water and nitrogen availability. Hydrolase (b-d-glucosidase, cellobiase, N-acetyl-glucosidase and aminopeptidase) activity did not differ significantly under different treatments. However, phenol-oxidase showed higher activity under warming combined with increased precipitation than under other treatments. Stable isotope ratio (d13C) in plants revealed that drought stress in vegetation was induced under warming. We concluded that in the long term, climate change may amplify the feedback of soil to climate change in arctic tundra soil. Abstract Copyright (2015) Elsevier, B.V.

2016028008 Collins, Andrew L. (National Park Service, Denali National Park and Preserve, Center for Resources, Science, and Learning, Denali Park, AK); Rosenberg, Russell H. and Capps, Denny M. Mass movements in the parks; Geocorps and geohazards at the top of North America [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 471, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

Changing climate and growing infrastructure are increasingly making mass movement events an object of study across professional disciplines. Debris flows and landslides are relevant to everyone from road crews to real estate agents, but the number of driving factors involved in understanding and predicting them can be dizzying--especially with the added variable of frozen ground. In Alaska and similar high-latitude climates this is becoming a persistent problem. Following a massive debris slide in October, 2013, Geocorps and Denali National Park and Preserve provided the opportunity for a Geohazards Specialist to assist in mass movement inventorying, monitoring, and mitigation planning. In the first year, this led to the development of a catalog, maps, and risk analyses based on known mass movement events in the park, geohazard education and outreach programs, publishing of a publicly available educational fact sheet, presentation of risk analyses and mitigation plans at a regional geotechnical conference, and extensive discussion to determine the needs and capabilities of a park monitoring program. The second year provided an opportunity to build on the work of the first, as well as work with other federal agencies to develop an inter-agency, nation-wide Unstable Slope Management Program, develop and implement an interpretation scheme based around natural hazards, and explore more remote hazards for integration into existing databases. Though some variables are still not well-constrained, valuable advances have been made in beginning to determine the origin, cause, and potential effects of mass movements along the park road corridor. These combined efforts and experiences demonstrate a thorough commitment to furthering the respective missions of the National Park Service and the Geological Society of America by serving both science and the users of our National Parks.

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