Ingmar Nitze

A lake-centric geospatial database to guide research and inform management decisions in an Arctic watershed in northern Alaska experiencing climate and land-use changes

Lakes are dominant and diverse landscape features in the Arctic, but conventional land cover classification schemes typically map them as a single uniform class. Here, we present a detailed lake-centric geospatial database for an Arctic watershed in northern Alaska. We developed a GIS dataset consisting of 4362 lakes that provides information on lake morphometry, hydrologic connectivity, surface area dynamics, surrounding terrestrial ecotypes, and other important conditions describing Arctic lakes. Analyzing the geospatial database relative to fish and bird survey data shows relations to lake depth and hydrologic connectivity, which are being used to guide research and aid in the management of aquatic resources in the National Petroleum Reserve in Alaska. Further development of similar geospatial databases is needed to better understand and plan for the impacts of ongoing climate and land-use changes occurring across lake-rich landscapes in the Arctic.

Reduced arctic tundra productivity linked with landform and climate change interactions

Arctic tundra ecosystems have experienced unprecedented change associated with climate warming over recent decades. Across the Pan-Arctic, vegetation productivity and surface greenness have trended positively over the period of satellite observation. However, since 2011 these trends have slowed considerably, showing signs of browning in many regions. It is unclear what factors are driving this change and which regions/landforms will be most sensitive to future browning. Here we provide evidence linking decadal patterns in arctic greening and browning with regional climate change and local permafrost-driven landscape heterogeneity. We analyzed the spatial variability of decadal-scale trends in surface greenness across the Arctic Coastal Plain of northern Alaska (~60,000 km²) using the Landsat archive (1999–2014), in combination with novel 30 m classifications of polygonal tundra and regional watersheds, finding landscape heterogeneity and regional climate change to be the most important factors controlling historical greenness trends. Browning was linked to increased temperature and precipitation, with the exception of young landforms (developed following lake drainage), which will likely continue to green. Spatiotemporal model forecasting suggests carbon uptake potential to be reduced in response to warmer and/or wetter climatic conditions, potentially increasing the net loss of carbon to the atmosphere, at a greater degree than previously expected.

Tundra landform and vegetation productivity trend maps for the Arctic Coastal Plain of northern Alaska

Arctic tundra landscapes are composed of a complex mosaic of patterned ground features, varying in soil moisture, vegetation composition, and surface hydrology over small spatial scales (10–100 m). The importance of microtopography and associated geomorphic landforms in influencing ecosystem structure and function is well founded, however, spatial data products describing local to regional scale distribution of patterned ground or polygonal tundra geomorphology are largely unavailable. Thus, our understanding of local impacts on regional scale processes (e.g., carbon dynamics) may be limited. We produced two key spatiotemporal datasets spanning the Arctic Coastal Plain of northern Alaska (~60,000 km2) to evaluate climate-geomorphological controls on arctic tundra productivity change, using (1) a novel 30 m classification of polygonal tundra geomorphology and (2) decadal-trends in surface greenness using the Landsat archive (1999–2014). These datasets can be easily integrated and adapted in an array of local to regional applications such as (1) upscaling plot-level measurements (e.g., carbon/energy fluxes), (2) mapping of soils, vegetation, or permafrost, and/or (3) initializing ecosystem biogeochemistry, hydrology, and/or habitat modeling.

Landscapes and thermokarst lake area changes in Yedoma regions under modern climate conditions, Kolyma lowland tundra

Apart from people in cold region communities and a small – although steadily growing – scientific community, the general public knows very little about permafrost properties, its dynamics in response to climate change, and the research going on in the field. We are addressing this by making permafrost science accessible to children, youth, their parents, and teachers. We are producing a 100% outreach-related project that aims at ‘Fostering permafrost research to the ends of the Earth’ (http://ipa.arcticportal.org), but with a casual approach via a series of comic strips. Cartoons are excellent ways to communicate messages in today’s media landscape: they are graphic, funny and direct, and can be rapidly shared via social media to reach many people. Our outreach project targets the general public, focusing on young students who have to choose career paths at the high school or college levels. By introducing them to permafrost research activities, particularly fieldwork, our ‘Frozen-Ground Cartoon’ will enhance the dissemination of permafrost knowledge and broaden the international community of permafrost ‘lovers’. This new project is coordinated by a core group of permafrost early career researchers from Canada, Germany, Sweden and Portugal (in collaboration with an ‘external senior advisor’), and is endorsed by the International Permafrost Association (IPA) as a targeted ‘Action Group’ (http://ipa.arcticportal.org/activities/action-groups). Here we present an overview of our Action Group, including main objectives, significance, and potential future outcomes.The Arctic is affected by rapid climate change, which has substantial impact on permafrost regions and the world as a whole (Raynolds et al., 2014). In the last 30 years Arctic temperatures have risen 0.6 °C per decade, twice as fast as the global average (AMAP, 2011, Schuur et al., 2015). This in turn leads to the degradation of ice-rich permafrost (Grosse et al., 2011) and modifies drainage, increases mass movements and alters landscapes (Nelson et al., 2001; Anisimov et al., 2007, Romanovsky et al., 2010b). Although permafrost regions are not densely populated, their economic importance has increased substantially in recent decades. This is related to the abundance of natural resources in the polar region and improved methods of hydrocarbon extraction, transportation networks to population centers and engineering maintenance systems (Nelson et al., 2002; Mazhitova et al., 2004, AMAP, 2011). The Yamal Peninsula in North West Siberia is experiencing some of the most rapid land cover and land use changes in the Arctic due to a combination of climate change and gas development in one of the most extensive industrial complexes (Kumpula et al., 2006; Walker et al., 2011; Leibman et al., 2015). Specific geological conditions with nutrient-poor sands, massive tabular ground ice and extensive landslides intensify these impacts (Walker et al., 2011). The combination of high natural erosion potential and anthropogenic influence cause extremely intensive rates of erosion (Gubarkov et al., 2014). A considerable amount of recent work has focused on the effects of industrial development to ecological and social implications (Forbes, 1999; Kumpula et al., 2010; Walker et al., 2011). This study aims at exemplarily investigating a region that has been affected by natural and anthropogenic large-scale disturbances within a very short period. The construction of the world’s northernmost railway for the Bovanenkvo Gas Field was finished in 2010. In addition the region experienced an extremly warm and wet summer in 2012. The objectives of this study are • to map surface disturbances of central Yamal between 2010 and 2013/2015 based on highresolution satellite imagery and on the most recent SPOT5-TAKE-5 imagery in 2015, • to quantify natural and anthropogenic impacts in terms of permafrost degradation, • to use meteorological data from the nearest climate station (Marre Sale, Yamal) and from reanalyses climate data on air temperature and precipitation.Previous studies have shown that arctic river delta systems are areas of accumulation of geochemical substances at the sea-river mixing zone. In the Lena River Delta our previous work shows the tendencies of water runoff redistribution changes and heterogeneity of suspended supply distribution along the delta branches, accumulation and erosion zone in the different parts of the delta. Nevertheless, the processes of geochemical flow transformation in the subaerial deltas are so far underestimated. In order to close this gap, we sampled water, suspended and bottom sediments in the Lena River Delta in the summer seasons of 2010 and 2014. Most of the sampling points were tight to the profiles of hydrological measurements held in the delta and highlighted in Fedorova et al. [2015]. The results show that geochemical transformation of the Lena River runoff is taking place in the delta. The most active time for the transformation is the summer season due to the activity of sediment accumulation and biogeochemical processes. Hydrological conditions in the delta affect also its hydrogeochemical characteristics. Furcation of the delta branches affects the hydrodynamic conditions of different delta areas. The factors influencing the geochemical characteristics of the delta were identified on the base of geochemical indexes approach applied to sediments and statistical factor analysis. Based on geochemical indexes (Al/Na, Si/Al, Fe/Mn and Fe/Al ratios) similar conditions were determined for the main branch of the Lena, the upstream parts of Bykovskaya and Tumatskaya branches and in Olenekskaya branch near Chay-Tumus. Despite of high runoff the branches are characterized by element accumulation, which can be explained by decreasing of flow turbulence and specificity redox conditions in these areas. Bottom sediments are one of the most important indicators of geochemical transformation processes. The results of statistical factor analysis show three main factors for formation of the these geochemical conditions in the delta: 1. the general water flow of the Lena River, which is influenced by the lithogenous base of the river catchment, 2. the cryogenic condition of the Lena Delta (permafrost degradation processes and cryogenic weathering) and 3. biogeochemical transformation during redistribution of chemical water components , suspended matter and bottom sediments. Acknowledgements The research was supported by grant No. 14-05-00787 A of Russian Foundation for Basic Research References Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015.In order to understand the influence of surrounding catchment characteristics on the CDOM concentration different types of surface waters in the Lena river delta region were investigated regarding their geochemical composition. The Lena River Delta consists of three geomorphological main terraces that differ in their relief, hydrological and cryolithological characteristics, which possibly influences the content of dissolved substances in their associated water bodies and in the neighboring river branches. During summer seasons of 2013-2014 water samples were collected from river branches as well as from lakes and melt-water streams on the first and the third main terraces and analyzed them for concentrations of colored dissolved organic matter (CDOM), dissolved organic carbon (DOC), and main and trace elements (Na, K, Mg, Ca, HCO3, F, Cl, SO4, Fe, Si, Sr). This type of research was carried out for surface waters in the Lena delta region for the first time. Statistical analysis revealed several correlations between CDOM, DOC and mineral ions. For example, R-squared (the coefficient of determination) for CDOM and Cl and for CDOM and Na in Lena River branches were 0.52 and 0.51, respectively. Correlation between CDOM and F was also found for melt-water streams from the Ice Complex (third terrace) (R-squared = 0.5). Analysis of the relationship between CDOM and DOC showed strong correlation of these parameters for lakes (R-squared = 0.98) and lower correlation for river branches (R- squared = 0.48). In streams formed by the thawing of Ice Complex deposits on the third terrace was found the highest values of CDOM and DOC, but a correlation between them was not observed. A clear dependency was found out between CDOM and DOC correlation and the location of lakes on different terraces with specific permafrost conditions. A stronger correlation was observed for the lakes located on the third terrace (Ice Complex) compared to lakes located on the first terrace (Samoylov Island). Usually, lakes on the first terrace get flooded by river waters during spring, whereas lakes of the third terrace are not affected by river water inflow and have more stable conditions. The Lena delta branches are influenced by differing surrounding conditions, therefore CDOM and DOC concentrations change during summer season and did not show strong correlations.A large amount of organic carbon stored in permafrost soils across the high latitudes is vulnerable to thaw, decomposition and release to the atmosphere as a result of climate warming. Findings from observational, experimental and modeling studies all suggest that this process could lead to a significant positive feedback on future radiative forcing from terrestrial ecosystems to the Earth’s climate system. With respect to the magnitude and timing of this feedback, however, observational data show large variability across sites, experimental studies are few, and different models result in a wide range of responses. These issues represent fundamental limitations on improving our confidence in projecting future permafrost carbon release and associated climate feedbacks. Recent studies have brought new insight into – and even quantitative estimates for – these issues through broader data synthesis and model-data integration approaches. But, how representative of the circumarcticscale variability in permafrost carbon vulnerability are the data and models from these studies? To address this question, we developed a geospatial data synthesis and analysis framework designed to represent and characterize the variability in permafrost carbon vulnerability across the northern high latitudes. Here, we describe the rationale and methods used to develop the regionalization scheme, and then use the framework to assess the spatial representativeness of, and the variability described by, existing data sets defining the fundamental components and environmental drivers of permafrost carbon vulnerability. The Permafrost Regionalization Map (PeRM) considers the regional-scale environmental factors that generally determine the spatial variability in permafrost carbon vulnerability across the Arctic. The broadly-defined regional classification is based on a circumarctic spatial representation of the major environmental controls on a) the rate and extent of permafrost degradation and thaw, b) the quantity and quality of soil organic matter stocks, and c) the form of permafrost carbon emissions as CO2 and CH4. We chose a generalized, pragmatic approach that resulted in a feasible number of regional subdivisions (i.e.,‘reporting units’) based on an intersection of spatial data layers according to permafrost extent, permafrost distribution, climate regime, biome and terrain. The utility of the PeRM framework is demonstrated here through areal density analysis and spatial summaries of existing data collections describing the fundamental components of permafrost carbon vulnerability. We use this framework to describe the spatial representativeness and variability in measurements within and across PeRM regions using observational data sets describing active layer thickness, soil pedons and carbon storage, long-term incubations for carbon turnover rates, and site-level monitoring of CO2 and CH4 fluxes from arctic tundra and boreal forest ecosystems. We then use these regional summaries of the observational data to benchmark the results of a process-based biogeochemical model for its skill in representing the magnitudes and spatial variability in these key indicators. Finally, we discuss the on-going use of this framework as a basis for higher-resolution mapping of key regions of particular vulnerability to both press (active layer thickening) and pulse (thermokarst development) disturbances. This work is guiding on-going research toward characterizing permafrost degradation and associated vegetation changes through multi-scale remote sensing. Overall, this spatial data synthesis framework work provides a critical bridge between the abundant but disordered observational and experimental data collections and the development of higher-complexity process representation of the permafrost carbon feedback in geospatial modeling frameworks.Nowadays due to climate change the interest to the hydrological processes in the permafrost affected regions is growing. Permafrost soil is important carbon pool and thawing can cause the increase of carbon outflow from Arctic river basins. During Russian-German expeditions Lena-2012 and 2013 some measurements were carried out on the catchment of the Fish Lake on Samoylovsky Island in the Lena River delta. Fish Lake is a thermokarstpolygonal lake, and the landscape of its catchment is typical for the Arctic polygonal tundra. These measurements were done in order to study the DOC income to the lake from an active layer of the catchment. Measurements of the DOC concentration in the pore water and the depth of seasonal thawing were made at 21 points in the 1,52 sq km catchment. The points were selected in different parts of the polygons to consider the heterogeneity of the landscape. Samples for DOC were analyzed in the field using a Spectro::lyser probe and in the lab with a Shimadzu TOC-L probe. In August the depth of the active layer was between 20 and 60 cm: 20-30 cm on the polygon rims, 30-60 cm in the polygon centers and near the lake. During the month when the measurements were made the depth increased by 10-15. For August the DOC concentration in the pore water of the active layer was 8-51 mg/l, for July – 5-30 mg/l, which correlates with the results of other researches in Arctic region. The changes in DOC concentration in pore water for the different thaw depth were examined. Maximum was observed on the depth 35-40 cm for July and 45-55 cm for August. So, for the same depth the variance in the concentration was the most significant. The DOC flux to the Fish Lake was calculated using the mean measured concentration and water runoff from the catchment (Ogorodnikova, 2011). The DOC daily flux to the lake is evaluated as about 0,8 kg per day and the flow rate is 0,5 kg/ km2*day, which is in ten time less than for the lake catchment of southern areas (Moore, 2003). Prolongation of field measurements is necessary for reasons clarifying and for better understanding of DOC flux formation processes under different conditions including thawing increase.About 25 % of the land mass of northern hemisphere is underlain by permafrost, which is one of the largest carbon pools. Yedoma Ice Complex is a particularly ice-rich type of permafrost. As a consequence of rapid climate warming of the Arctic, permafrost is affected by degradation processes like thermokarst. Thereby organic carbon is partially dissolved (DOC) in thermokarst lakes, and transported via rivers into the Arctic Ocean. On this way, large parts of DOC are mineralized by microbial processes and emitted as CO2 and CH4 to the atmosphere. The influence of different landforms in thermokarst affected permafrost regions on DOC concentration has not been thoroughly investigated. Addressing this research gap, this thesis examined the relationship between landscape units, water chemistry and hydrology for a small study site in the Lena River Delta, Siberia. On the basis of GeoEye satellite imagery eight landscape units were determined. These include thermokarst lakes and streams on the first terrace and on Yedoma Ice Complex, Yedoma Ice Complex streams, which are fed by the Ice Complex, Yedoma Ice Complex uplands, first terrace relict lake, and the Olenyokskaya Channel. Concerning pH value, electrical conductivity, isotopic composition and DOC concentration summer surface water samples and soil water samples of 2013 and 2014 were analyzed. These analyzes revealed that the system of the thermokarst lake Lucky Lake, its drainage flow path and source waters on Yedoma Ice Complex, is divided by landscape units. Source waters show significantly higher DOC concentrations and lower electrical conductivity than Lucky Lake and the drainage flow path. This suggests that labile organic carbon of Yedoma Ice Complex reaches the lake by degradation. Yedoma Ice Complex lake processes, despite evaporation, further reduce DOC concentration rapidly, probably by mineralization of labile DOC. Along the drainage flow path no further decrease of DOC concentration was observed, despite of changing discharge. Using discharge data of 2013 a DOC flux of about 220 kg in 29 days for the study site was calculated. A temporal variability of DOC concentration during the sampling periods was not determined using the utilized data.Methane emissions from northern high latitude wetlands are one of the largest natural sources of atmospheric methane, contributing an estimated 20% of the natural terrestrial methane emissions to the atmosphere. Methane fluxes vary among wetland types and are generally higher in peatlands, wetlands with > 40 cm of organic soil, than in wetlands with mineral soils. However, permafrost aggradation in peatlands reduces methane fluxes through the drying of the peat surface, which can decrease both methane production and increase methane oxidation within the peat. We reconstruct methane emissions from peatlands during the Holocene using a synthesis of peatland environmental classes determined from plant macrofossil records in peat cores from > 250 sites across the pan-arctic. We find methane emissions from peatlands decreased by 20% during the Little Ice Age due to the aggradation of permafrost within peatlands during this period. These bottom-up estimates of methane emissions for the present day are in agreement with other regional estimates and are significantly lower than the peak in peatland methane emissions 1300 years before present. Our results indicate that methane emissions from high latitude wetlands have been an important contributor to atmospheric methane concentrations during the Holocene and will likely change in the future with permafrost thaw.Situated in the Yana-Highlands, the Batagai profile is one of the few inland permafrost outcrops in Yakutia and, for the time being, the biggest and most active thermoerosional cirque worldwide. With Yerkhoyansk recorded as place of the pole of cold, the Yana Highlands represent the region with the most severe climatic continentality in the northern hemisphere. In contrast to the numerous sequences in today’s coastal lowlands, the Batagai sequence was always unaffected by maritime climate influence during its formation and thus better indicates the macro-climate evolution in NE-Siberia. As result of intense thermal degradation, the outcrop formed within 30 years only and cut deep into ice-rich permafrost deposits. The 60 m deep outcrop is now about 850 m in diameter, but erosion rates as high as 15 m/year are changing the dimensions continuously. The Batagai profile thus represents a unique window into the past (and future) of ice-rich permafrost deposits in Yakutia. Field based observations have shown that the permafrost sequence consists of 4 distinct units: below a thin Holocene surface cover, a 30 meter thick Ice Complex with characteristic thick ice wedges has formed. At the base of the Ice Complex, there is an up to 2 m thick layer of plant material including large woody remains. Subjacent to this organic layer of supposedly Eemian origin, there is a horizontally stratified unit composed of silty-sand and without thick syngenetic ice wedges presumably deposited during the Middle Pleistocene. At the very base of the sequence, there appears to emerge another unit including syngenetic ice wedges. This unit was not accessible for sampling. The accessible upper about 45 meter of the sequence were sampled from top to bottom in one meter steps using, due to the difficult accessibility of the permafrost wall, thermokarst mounds in the less steep part of the outcrop. The samples were taken for sedimentological analyses and especially for plant macrofossil and other palaeoecological studies. Whereas sediments give insight into the genesis of the sequence, fossil plant macroremains provide information on local vegetation patterns and habitats at the time of deposition; while palynological analyses reflect the regional vegetation and climate history. First palaeobotanical results will be represented in Session 13: Palaeoenvironments in permafrost affected areas. The sedimentological analyses revealed that, despite clearly delimitable bedding units visible at the outcrop, there is no distinct litho-stratigraphical differentiation recognizable in the grain size distribution or other sedimentological parameters. Accordingly, the sequence is characterized by a grain size signature typical for Ice Complex deposits. In comparison to other Yakutian ice-rich permafrost sequences, e.g. in the coastal lowlands, the Batagai profile is however distinguished by a higher fraction of fine sand over the whole recorded sequence. This might be due to increased aeolian deposition from local sources, e.g. from barren ridges in the highlands uncovered by vegetation. The assumption that aeolian deposition played a substantial role in the formation of the sequence is also suggested by impressive dunes in the immediate vicinity of the profile at the boundary of Batagai city.The interaction and feedbacks between surface water and permafrost are fundamental processes shaping the surface of continuous permafrost landscapes. Lake-rich regions of Arctic lowlands, such as coastal plains of northern Alaska, Siberia, and Northwest Canada, where shallow thermokarst lakes often cover 20-40% of the land surface are a pronounced example of these permafrost processes. In these same Arctic coastal regions, current rates of near-surface atmospheric warming are extremely high, 0.8 °C / decade for example in Barrow, Alaska, primarily due to reductions in sea ice extent (Wendler et al., 2014). The thermal response of permafrost over recent decades is also rapid, warming approximately 0.6°C / decade for example at Deadhorse, Alaska, yet this permafrost is still very cold, less than -6°C (Romanovsky et al., 2015). The temperature departure created by water in lakes set in permafrost is well recognized and where mean annual bed temperatures (MABT) are above 0 °C, a talik develops (Brewer, 1958). The critical depth of water in lakes where taliks form is generally in excess of maximum ice thickness, which has historically been around 2 m in northern Alaska. Thus, lakes that are shallower than the maximum ice thickness, which are the majority of water bodies in many Arctic coastal lowlands, should maintain sublake permafrost and have a shallow active layer if MABT’s are below freezing. Recent analysis, however, suggests a lake ice thinning trend of 0.15 m / decade for lakes on the Barrow Peninsula, such that the maximum ice thickness has shifted to less than 1.5 m since the early 2000’s. We hypothesized that the surface areas most sensitive to Arctic climate warming are below lakes with depths that are near or just below this critical maximum ice thickness threshold primarily because of changing winter climate and reduced ice growth. This hypothesis was tested using field observations of MABT, ice thickness, and water depth collected from lakes of varying depths and climatic zones on the coastal plain and foothills of northern Alaska. A model was developed to explain variation in lake MABT by partitioning the controlling processes between ice-covered and open-water periods. As expected, variation in air temperature explained a high amount of variation in bed temperature (72%) and this was improved to 80% by including lake depth in this model. Bed temperature during the much longer ice-covered period, however, was controlled by lake depth relative to regional maximum ice thickness, termed the Effective Depth Ratio (EDR). A piecewise linear regression model of EDR explained 96% of the variation in bed temperature with key EDR breaks identified at 0.75 and 1.9. These breaks may be physically meaningful towards understanding the processes linking lake ice to bed temperatures and sublake permafrost thaw. For example if regional lake ice grows to 1.5 m thick, the first break is at lake depth of 1.1 m, which will freeze by mid-winter and may separate lakes with active-layers from lakes with shallow taliks. The second EDR break for the same ice thickness is at a lake depth of 2.9 m, which may represent the depth where winter thermal stratification becomes notable (greater than 1 °C) and possibly indicative of lakes that have well developed taliks that store and release more heat. We then combined these ice-covered and open-water models to evaluate the sensitivity of MABT to varying lake and climate forcing scenarios and hindcast longer-term patterns of lake bed warming. This analysis showed that MABT in shallow lakes were most sensitive to changes in ice thickness, whereas ice thickness had minimal impact on deeper lakes and variation in summer air temperature had a very small impact on MABT across all lake depths. Using this model, forced with Barrow climate data, suggests that shallow lake beds (1-m depth) have warmed substantially over the last 30 years (0.8 °C / decade) and more importantly now have an MABT that exceeds 0 °C. Deeper lake beds (3-m depth), however, are suggested to be warming at a much slower rate (0.3 °C / decade), compared to both air temperature (0.8 °C/ decade) and permafrost (0.6 °C/ decade). This contrasting sensitivity and responses of lake thermal regimes relative to surrounding permafrost thermal regimes paint a dramatic and dynamic picture of an evolving Arctic land surface as climate change progresses. We suggest that the most rapid areas of permafrost degradation in Arctic coastal lowlands are below shallow lakes and this response is driven primarily by changing winter conditions. References: Brewer, M. C. (1958), The thermal regime of an arctic lake, Transactions of the American Geophysical Union, 39, 278-284. Romanovsky, V. E., S. L. Smith, H. H. Christiansen, N. I. Shiklomanov, D. A. Streletskiy, D. S. Drozdov, G. V. Malkova, N. G. Oberman, A. L. Kholodov, and S. S. Marchenko, (2015). The Arctic Terrestrial Permafrost in “State of the Climate in 2014” . Bulletin of the American Meteorological Society, 96, 7, 139-S141, 2015 Wendler, G., B. Moore, and K. Galloway (2014), Strong temperature increase and shrinking sea ice in Arctic Alaska, The Open Atmospheric Science Journal, 8, 7-15.Rapid temperature rise during recent decades (IPCC 2013) is causing permafrost in the Arctic to warm and thaw. This thaw exposes previously frozen soil organic carbon (SOC) to microbial decomposition, generating greenhouse gases methane (CH4) and carbon dioxide (CO2) in a feedback process that leads to further warming and thaw. A growing number of studies model the future permafrost carbon feedback (PCF) to climate warming [Koven et al., 2015, Schneider von Deimling et al., 2015]. However, despite observations of widespread permafrost thaw during recent decades and forecasts of thaw during the next 25-100 years [Koven et al., 2015], no research has quantified the PCF for recent decades. This is in part due to the difficulty of detecting the net movement of old carbon from permafrost to the atmosphere over years and decades amidst large input and output fluxes from ecosystem carbon exchange. In contrast to terrestrial environments, thermokarst lakes provide a direct conduit for processing and emission of old permafrost carbon to the atmosphere, and these emissions are more readily detectable. Results here are based on Walter Anthony et al. [submitted], whereby we quantified the permafrost SOC input to a variety of thermokarst and glacial lakes in Alaska and Siberia in thermokarst zones, defined as areas where land surfaces have transitioned to open lakes due to permafrost thaw during the past 60 years, the historical period most commonly covered by remote-sensing data sets. We also quantified the resulting methane emitted from these active thermokarst lake zones. Using field work, numerical modeling of thaw bulbs, remote sensing and spatial data analysis we will report on the relationship between methane emissions from thermokarst zones and SOC inputs to lakes across gradients of permafrost and climate in Alaska. We will also define the relationship between radiocarbon ages of methane and permafrost soil carbon entering into lakes upon thaw. We will report on the presentday PCF relationship between thaw of permafrost SOC and resulting greenhouse gas release. An extrapolation of our results to the panarctic permafrost region will be presented and compared to permafrost carbon mass balance approaches. The fraction of the terrestrial permafrost carbon pool that has been released as methane from thermokarst along lake margins during the past 60 years will be evaluated relative to early Holocene thermokarst lake emissions and projected permafrost carbon emissions by year 2100. The data will be placed in the context of large regional temperature increases in the Arctic, up to 7.5 °C by 2100, and thicker, organic-rich Holocene-aged deposits subject to thaw and aerobic decomposition as active layer deepens. We will report on the inflection of large permafrost carbon emissions that is imminently expected to occur and whether or not it has commenced. References: Koven, C.D.; Schuur, E.A.G.; Schadel, C.; Bohn, T.J.; Burke, E.J.; Chen, G.; Chen, X.; Ciais, P.; Grosse, G.; Harden, J.W.; Hayes, D.J.; Hugelius, G.; Jafarov, E.E.; Krinner, G.; Kuhry, P.; Lawrence, D.M.; MacDougall, A.H.; Marchenko, S.S.; McGuire, A.D.; Natali, S.M.; Nicolsky, D.J.; Olefeldt, D.; Peng, S.; Romanovsky, V.E.; Schaefer, K.M.; Strauss, J.; Treat, C.C. and Turetsky, M. [2015]: A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback. Trans. R. Soc. A, 373, doi:10.1098/rsta.2014.0423. Schneider von Deimling, T.; Grosse, G.; Strauss, J.; Schirrmeister, L.; Morgenstern, A.; Schaphoff, S.; Meinshausen, M. and Boike, J. [2015]: Observationbased modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity. Biogeosciences, 12(11):3469–3488, doi:10.5194/bg-12-3469-2015. Walter Anthony, K.; Daanen, R.; Anthony, P.; Schneider von Deimling, T.; Ping, C.-L.; Chanton, J. and Grosse, G. [submitted]: Ancient methane emissions from ˜60 years of permafrost thaw in arctic lakes.Vast parts of Arctic Siberia are underlain by ice-rich permafrost, which is exposed to different processes of degradation due to global warming. Thermal erosion as a key process for landscape degradation in these regions causes the recent reactivation and formation of new landforms like thermo-erosional valleys and gullies. However, a statistical assessment about the decisive factors and the locations most susceptible to this phenomenon is still missing. We investigated the influence of different environmental parameters on the occurrence of recently observed thermal erosion using a GIS-based approach and statistical modeling by logistic regression. The study site is located on an island within the Arctic Lena River Delta and is mainly composed of ice- and organic-rich deposits of the Yedomatype Ice Complex. Field surveys and mapping on the basis of high-resolution remotely sensed data revealed that thermal erosion occurs predominantly i) on very steep slopes along the margins of the island, ii) in the upper reaches of deeply incised valleys and iii) in gullies. In order to detect the regulation factors for those thermo-erosional landforms, we derived several environmental parameters using a high-resolution DEM and satellite imagery. We chose a stepwise logistic regression approach to reduce the full set of potential parameters. This approach allowed the selection of a parsimonious model, i.e. a best-fit model using as few parameters as possible. The parameters Contribution of warm open surface water, Relief ratio, Direct solar radiation and Snow accumulation turned out to be the decisive factors for thermal erosion. Uncertainties in the model due to sampling and model selection were valuated both statistically and spatially through the generation of 100 models. Receiver Operating Characteristics (ROCs) were used to validate the spatial predictive capability of each model run. The consensus map as the median of all 100 susceptibility models represents the final susceptibility map. The agreement between mapped and predicted erosion turned out to be generally very high within the study site, confirmed by an Area under the ROC curve (AUC) of 0.957 for the consensus map. The variability of predicted erosion probabilities between the single models is about four percentage points per cell within the study site and thus, very low. We attributed the slight mismatches between observed and predicted erosion to the generation of the explanatory environmental parameters and the modeling approach. Model results seem promising for the spatial prediction of susceptible sites for thermal erosion and, thus, could be a tool to explain the geomorphic forming in this rapidly changing environment. As these results are based on a single case study, future investigation should focus on the transferability of the model by applying an external validation on other sites with comparable environmental conditions.Permafrost soil organic carbon (C) in the Yedoma region comprises a large fraction of the total circumpolar permafrost C pool, yet estimates based on different approaches during the past decade have led to disagreement in the size and composition of the Yedoma region permafrost C pool. This research aims to reconcile different approaches and show that after accounting for thermokarst and fluvial erosion processes of this interglacial period, the Yedoma region C pool (456 ± 45 Pg C) is the sum of 172 ± 19 Pg Holocene-aged C and 284 ± 40 Pg Pleistocene-aged C. The size of the present-day Pleistocene-aged yedoma C pool was originally estimated to be 450 Pg based on a mean deposit thickness of 25 m, 1×106 km2 areal extent, 2.6% total organic C content, 1.65times103 kg m−3dry bulk density, and 50% volumetric ice wedge content (Zimov et al. 2006). This estimate assumed that 17% of the Last Glacial Maximum yedoma C stock was lost to greenhouse gas production and emission when 50% of yedoma thawed beneath lakes during the Holocene. However, the regional scale yedoma C pool estimate of Zimov et al. (2006) did not include any Holocene C and assumed that all of the 450 Pg C was Pleistocene-aged. In subsequent global permafrost C syntheses, soil organic C content (SOCC, kg C m−2) data from the Northern Circumpolar Soil C Database (NCSCD) and Zimov et al. (2006) were used to estimate the soil organic C pool for the Yedoma region (450 Pg), assuming only Pleistocene-aged yedoma C from 3 to 25 m (407 Pg), and a mixture of C ages in the 0 to 3 m interval (43 Pg). A more recent synthesis of Yedoma-region C stocks based on extensive sampling by Strauss et al. (2013) took into account lower C bulk density values of yedoma, higher organic C concentrations of yedoma, a larger landscape fraction of thermokarst (70% of Yedoma region area), the larger C concentration of thermokarst, and remote-sensing based quantification of ice-wedge volumes. This synthesis produced lower meanand median-based estimates of Yedoma-region C, 348+73 Pg and 211 +160/-153 Pg respectively. However, Strauss et al. (2013) focused on the remaining undisturbed yedoma and refrozen surface thermokarst deposits and thus did not include taberite deposits, which are the re-frozen remains of yedoma previously thawed beneath thermokarst lakes and still present in large quantities on the landscape. In our study (Walter Anthony et al. 2014), we measured the dry bulk density directly on 89 yedoma and 311 thermokarst-basin samples, including taberites, collected in four yedoma subregions of the North Siberian Kolyma Lowlands. Multiplying the organic matter content of an individual sample by the same sample’s measured bulk density yielded an organic C bulk density data set for yedoma samples that was normally distributed. Combining our subregion-specific organic C bulk density results with those of Strauss et al. (2013) for other yedoma subregions extending to the far western extent of Siberian yedoma, we determined a mean organic C bulk density of yedoma for the total Yedoma region (26 ± 1.5 kg C m-3), which is similar to that previously suggested by Strauss et al. (2013) (27 kg C m-3 mean based approach; 16 kg C m-3 median based approach). Our estimate of the organic C pool size of undisturbed yedoma permafrost (129 ± 30 Pg Pleistocene C) in the 396,600 ± 39,700 km2 area that has not been degraded by thermokarst since the Last Glacial Maximum (Table 1) is based on this regional-mean C bulk density value. Our calculation also assumes an average yedoma deposit thickness of 25 m and 50% volumetric massive ice wedge content, as in previous estimates (Zimov et al. 2006, NCSCD; Table 1). Similar results found in the recent study of the Yedoma-region C inventory by Strauss et al.(2013) corroborate our estimate of the undisturbed yedomaEarth’s Polar Regions are not included in the school curriculum in Saxony, SE Germany. However, in the media their role in climate change is often emphasized. Understanding the related connections is difficult for the pupils and therefore has little influence on their climate relevant behavior. Climate change and the connection to the Polar Regions could be approached multidisciplinary as a comprehensive topic in various school subjects. At the KOMPAKT School in Zwickau, twelve pupils of grade 6 were interested in permafrost as a subject and dedicated several weeks to the topic. The goals included understanding basic principles, build on those to gain specific knowledge and finally find possibilities to use this knowledge in school. In the first part of the project, the students built a simplified model that allowed studying permafrost thaw and the related consequences. These studies were accompanied by observations of thawing and freezing of different soil and vegetation samples. The students reported their observations becoming familiar with keeping records of the setup and the experiments’ outcome. They used their protocols to create a documentation of the experimental work. The cooperation with the Alfred Wegener Institute in Potsdam then allowed the pupils to connect to scientists working on permafrost, to learn about the scientific questions those scientists address, and how and where they worked on. The pupils had the pos- sibility to ask questions about fieldwork and follow up lab work during a visit at AWI in Potsdam. An additional part of the project was the collection of information from permafrost related articles in newspapers and journals. The pupils are not used to long, scientific texts, the extraction of relevant content and relating this information to their own knowledge was very difficult. One key insight of this part of the project was that results of scientific research can lead to vastly different interpretations. Complete answers, as the pupils know them from class, are not provided. Rather, scientific research means to discuss results from different perspectives to struggle together for realistic explanations of nature phenomena. In the final stage of the project, the pupils took part in an excursion to Westerwald around Dornburg, where phenomena related to freezing processes could be observed in- situ. The pupils were encouraged to find explanations for their observations themselves. Some theories were astonishingly accurate. During the project, we always discussed the respons- ibility that each of us has towards the protection of nature. Do we have influence on nature at all? Are children and teenager also affected? This discussion is carried on beyond the project. All participating students are now encouraged to take part in the dis- cussion with their new insights from the classroom exercises. They can also better relate to the public discussion of climate change. They learned new ways to pose questions and that at times, it can be dif- ficult to obtain answers. They have worked on one specific subject during a long time and are now able to stimulate discussion in class whenever permafrost or Earth’s climate are topics. They can resort to the results of their own model and experiments and their observations as well. They can give information to others and maybe intrigue them with the subject. From this point of view, the project was a complete success.Under future climate change scenarios, Arctic coastal waters are believed to receive higher terrestrial organic matter (OM) fluxes. Permafrost carbon is increasingly mobilized upon thaw from rivers draining permafrost terrain and from eroding permafrost coasts. Once received, the coastal waters are the transformation zone for terrestrial OM, although quantities, especially those of dissolved organic matter (DOM) released by coastal erosion, are largely unknown. This nearshore zone plays a crucial role in Arctic biogeochemical cycling, as here the released material is destined to be (1) mineralized into greenhouse gases, (2) incorporated into marine primary production, (3) buried in nearshore sediments or (4) transported offshore. In this presentation, we show data on DOM quantities in surface water in the nearshore zone of the southern Beaufort Sea from two consecutive summer seasons under different meteorological conditions. Colored dissolved organic matter (cDOM) properties help to differentiate the terrestrial from the marine DOM component. Figure 1 shows DOC concentrations and salinities for 23 and 24 days in the summer seasons of 2013 and 2014, respectively. DOC concentrations in the nearshore zone of the southern Beaufort Sea vary between about 1.5 and 5 mg C L-1. In the Lena River Delta, bay water, river water, and permafrost meltwater creeks yielded similar values between 5.8 and 5.9 mg C L-1 (Dubinenkov et al., 2015). Similarly, Fritz et al. (2015) found DOC concentrations in ice wedges between 1.6 and 28.6 mg C L-1. In 2013, the first half of July was characterized by low salinity between 8 and 15 psu and high DOC concentrations of 3.5 to 5 mg C L-1. Then, a sudden change in water properties occurred after a major storm which lasted for at least 2 days. This storm led to strongly decreased DOC (1.5 to 2.5 mg C L-1) concentration and increasing salinity (14 to 28 psu) in surface water, probably due to upwelling In 2014, a more stable situation in both salinity and DOC prevailed, with relatively high salinity (23 to 29 psu) and low DOC concentration (1.5 to 2.5 mg C L-1). This pattern was due to rather windy and wavy conditions throughout the whole season. The water column in 2014 was likely well-mixed and DOC-poor because saline waters have probably been transported from the offshore to the nearshore. We recognized a significant negative correlation between DOC and salinity, independent from varying meteorological conditions. In general, this suggests a conservative mixing between DOC derived from terrestrial/permafrost runoff and marine DOC. The low salinity in July 2013 was probably due to prolonged sea-ice presence in the sampled area. This leads to the assumption that DOC also originates from melting sea ice. Quantitatively more important will be terrestrial runoff which is relatively rich in DOC. A stable stratification in the nearshore zone and calm weather conditions will increase the influence of terrestrial-derived DOM. The strength of the terrestrial influence can be estimated by salinity measures as they directly correlate with DOC concentrations; the lower the salinity the stronger the terrestrial influence. We conclude that the terrestrial imprint of coastal erosion on DOM concentrations in the nearshore zone is significant. We see that DOC concentrations are significantly elevated also compared to riverine input in front of river mouths and deltas. Meteorological conditions play a major role for the strength of the terrestrial DOM signal, which can vary on short timescales. Our approach is different from ship-based oceanography because we study DOM that is directly derived from thawing permafrost coasts, explicitly excluding rivers. When qualifying DOM origin from permafrost landscapes apart from rivers we have to take into consideration the different DOM mobilization pathways. 1) Surface runoff and near-surface groundwater flow mainly drain and flush the active layer. 2) Melting ground ice releases DOM. 3) Ground ice meltwater leaches DOM from sedimentary OM upon permafrost thaw on land. 4) DOM is leached from sedimentary OM upon contact with sea water. The latter three will mobilize old OM which is believed to be highly bioavailable (see Vonk et al., 2013a, b). References: Dubinenkov, I., Flerus, R., Schmitt-Kopplin, P., Kattner, G., Koch, B.P., 2015. Origin-specific molecular signatures of dissolved organic matter in the Lena Delta. Biogeochemistry 123, 1-14. Fritz, M., Opel, T., Tanski, G., Herzschuh, U., Meyer, H., Eulenburg, A., Lantuit, H., 2015. Dissolved organic carbon (DOC) in Arctic ground ice. The Cryosphere 9, 737-752. Vonk, J.E., Mann, P.J., Davydov, S., Davydova, A., Spencer, R.G.M., Schade, J., Sobczak, W.V., Zimov, N., Zimov, S., Bulygina, E., Eglinton, T.I., Holmes, R.M., 2013a. High biolability of ancient permafrost carbon upon thaw. Geophysical Research Letters 40, 2689-2693. Vonk, J.E., Mann, P.J., Dowdy, K.L., Davydova, A., Davydov, S.P., Zimov, N., Spencer, R.G.M., Bulygina, E.B., Eglinton, T.I., Holmes, R.M., 2013b. Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw. Environmental Research Letters 8, 035023.Thermokarst lakes are important factors for permafrost landscape dynamics and carbon cycling. Thermokarst lake cover is especially high in Arctic lowlands with ice-rich permafrost. In most of these regions, multiple lake generations have been identified that overlap each other in space and time, giving rise to the hypothesis of thermokarst lake cycling and its association with complex cryostratigraphical conditions where multiple lacustrine and palustrine sequences may follow on top of each other and talik and carbon cycle histories are complicated. In northwestern Alaska on the northern Seward Peninsula, ice-rich permafrost lowlands have strongly been affected by thermokarst during the Holocene and up to six generations of lake basins overlap spatially (Jones et al., 2012). Modern thermokarst lakes are also abundant in this region and expand gradually by thermo-erosion along shores (Jones et al., 2011). We here report on the analysis of multi-temporal remote sensing data for a 12,200 km2 lowland area in the relatively warm continuous permafrost zone of the northern Seward Peninsula, demonstrating that thermokarst lake drainage in this region was occurring on a massive scale from 1949-2015. Contrary to most previous studies that suggest an increase in thermokarst lake area in continuous permafrost, we observed a significant net decrease in thermokarst lake area largely due to catastrophic lake drainage. Lateral lake expansion by thermo-erosion continued but did not offset the net area loss. Climate data analysis revealed a potential correlation with increased winter precipitation that may have resulted in a combination of high lake water levels, increased spring runoff with higher potential for drainage channel formation, and near-surface permafrost degradation, ultimately enhancing lake drainage. The observed magnitude of lake drainage implicates strong and lasting impacts on regional hydrology, biogeochemical cycling, surface energy budgets, state of the permafrost, ecosystem character, waterfowl and fish habitats, and subsistence lifestyles in the study region, portions of which belong to the Bering Land Bridge National Preserve. The datasets used in this analysis include a wide range of remote sensing images and topographic data available for this region, such as aerial photography, historic topographic maps, high resolution satellite images (Corona, Spot, Ikonos, Quickbird, Worldview, GeoEye), and the full Landsat archive. Field studies included reconnaissance flights targeting freshly drained lakes and ground based data collection such as lake basin coring. Our findings suggest that a significant portion of lakes in this region has drained over the last decades and that in particular large lakes are vulnerable to disappearance. Initial analyses of relationships of lake drainages with permafrost distribution in the region suggest positive correlations between lake loss and permafrost degradation in much of the region. Our findings highlight that permafrost and lake-rich landscapes in Alaska are already changing rapidly and permanently in a warming world. This set of studies was supported by funding from NASA Carbon Cycle Sciences, NSF Arctic System Sciences, the European Research Council, and the Western Alaska Landscape Conservation Cooperative. References: Jones B, Grosse G, Arp CD, Jones MC, Walter Anthony KM, Romanovsky VE (2011): Modern thermokarst lake dynamics in the continuous permafrost zone, northern Seward Peninsula, Alaska. Journal of Geophysical Research – Biogeosciences, 116, G00M03. Jones MC, Grosse G, Jones BM, Walter Anthony KM (2012): Peat accumulation in a thermokarstaffected landscape in continuous ice-rich permafrost, Seward Peninsula, Alaska. Journal of Geophysical Research – Biogeosciences, 117, G00M07.Preface The Local Organizing Committee (LOC) of the Eleventh International Conference on Permafrost (ICOP2016) is excited about the breadth and the quality of the abstracts submitted for this conference. It was the first time that ICOP topical sessions were not set by the organizing committee in a top-down manner. Instead, sessions were submitted from the bottom-up by groups of researchers and engineers from all over the world. This grassroots effort prompted the submission of many innovative topics covering the full range of modern permafrost research. It also facilitated not only the engagement of the core permafrost community, but also of science disciplines traditionally less involved in ICOPs. In total, 51 session proposals were received by the LOC. These were submitted by up to three conveners including at least one early career researcher from the Permafrost Young Researchers Network (PYRN). After the evaluation process by the International Scientific Committee (ISC) and the LOC, including the addition of strategic topics and the combination of sessions with thematic overlap, 40 topical sessions were eventually opened for abstract submission. There was yet another novelty compared to previous ICOPs: the submission of contributions was not divided into abstracts and papers, in favor of a quicker and uniform review process allowing for the submission deadline to be set closer to the conference. This opened the possibility for authors to present recent results in the rapidly evolving field of permafrost research. Abstracts of up to 3000 words were allowed, either plain or formatted with subheadings, and including one figure, table or equation. We received the extraordinary number of 980 abstracts. This number varied between 79 and 0 among sessions, which led to a further consolidation into the final set of 32 sessions presented in this abstract volume. Abstract evaluation was placed in the hands of the session conveners. The vast majority of abstracts (97 %) was deemed eligible to be accepted for presentation during the conference, either immediately or after revision by the authors. The reduced number of abstracts presented in this volume is mostly due to the inability of travelling to the conference for some authors. We are very delighted that the modified procedures for the compilation of the scientific conference program proved so successful and wish to extend our gratitude to the session conveners and ISC members for their tremendous efforts and great support in compiling such a high-quality program. We also wish to thank Hans-Wolfgang Hubberten, Lydia Polakowski, Matthias Fuchs, Ingmar Nitze, Samuel Stettner, Karina Schollaen, Hugues Lantuit, and Guido Grosse for their technical help in the final editing phase of this abstract volume. Frank Gunther and Anne MorgensternFreshwater ostracods (Crustacea, Ostracoda) are of interest in modern biological studies, while fossil records of ostracod valves enable us to reconstruct past lacustrine environments. The about 1mm long crustaceans carry a calcite carapace that is biomineralized from dissolved components in the ambient water, and completely envelopes their body. Ostracods inhabit almost all aquatic environments, even shallow freshwater ponds in the vast circumartic permafrost areas. In high-latitude areas, ostracod species diversity, their modern ecological demands, and instrumental records of environmental parameters are only scarcely documented. Such reference information is the key to quantitatively reconstruct past environments from fossil ostracod assemblages. This gap in ostracod data limits their use as biological indicators in the Arctic, where the effects of future climate warming are expected to be strongest. The objective of the study presented here was to extend the data set on arctic freshwater ostracods and environmental records by characterizing presentday habitat conditions, abundance and diversity of ostracod assemblages in periglacial freshwaters on Svalbard. The aims of this project were 1. to conduct an inventory of the abundance, diversity and ecological ranges of the freshwater ostracods living in polygon ponds in Adventdalen near Longyearbyen (78°11’11”N, 15°55’20”E), 2. to determine the present-day hydrochemical and sedimentary characteristics of ostracod habitats, and 3. to witness temporal variability in a polygon pond during the Arctic summer season 2013. The study site was located near the University Centre on Svalbard (UNIS)-run monitoring site for thermal contraction cracking in ice-wedge polygons on a river terrace in outer Adventdalen (Christiansen 2005). Permafrost on Svalbard is estimated to be of late Holocene age with temperatures of -5.2 to -5.6 °C in boreholes in the Adventdalen area (Christiansen et al. 2010). Ice-wedge polygons form in cold-climate environments under permafrost conditions and are the most common periglacial patterned ground features in the Arctic (Minke et al. 2007). Since the permafrost table efficiently blocks drainage pathways, surface depressions hold ponding water during summer, and freeze solid in winter. Those shallow periglacial surface freshwaters, called polygon ponds, are hotspots of biological activity in the otherwise hostile tundra. They provide diverse habitats to aquatic communities including freshwater ostracods. For this study, we choose an area with polygon ponds that are known to persist during the summer season. Our sampling scheme of 13 ponds in total comprised collecting freshwater ostracod individuals, pond water and sediment samples. One species, Tonnacypris glacialis (SARS, 1890), was found in only one of the sampled sites, the pond AD-01 (Fig. 1). Continuous water temperature records directly below the water surface in AD-01, and at the sediment surface in about 25cm water depth were collected between July 20 and September 25, 2013. We measured water and thaw depth in the pond centre and the thaw depth of the surrounding polygon rim. The last record at September 25, 2013 completed the observation season with the presence of 2-3cm lake ice. Preliminary results suggest the pond water is welloxygenated and dilute with slightly acidic pH. The hydrochemical fingerprint and sedimentary characteristics of inter- and intrapolygon ponds may allow a differentiation between the two subtypes for the first time, and are subject of ongoing work. Active-layer thickness was around 40-100 cmin polygon rims, we measured about 50-80 cm thaw depth under pond centres. A considerable increase in water surface area extend occurred in the monitored pond after a rain period. The records obtained from this and similar studies in the Siberian Arctic demonstrate that small and shallow periglacial surface waters are sensitive to local permafrost and climate variations. References Christiansen HH. 2005. Thermal regime of icewedge cracking in Adventdalen, Svalbard. Permafrost and Periglacial Processes 16: 87-98. Christiansen HH, Etzelmuller B, Isaksen K, Juliussen H, Farbrot H, Humlum O, Johansson M, Ingeman-Nielsen T, Kristensen L, Hjort J, Holmlund P, Sannel ABK, Sigsgaard C, Akerman HJ, Foged N, Blikra LH, Pernosky MA, Odegard RS. 2010. The thermal state of permafrost in the Nordic Area during the International Polar Year 2007–2009. Permafrost and Periglacial Processes 21: 156–181. Minke M, Donner N, Karpov N, de Klerk P, Joosten H. 2007. Distribution, diversity, development and dynamics of polygon mires: examples from Northeast Yakutia (NE Siberia). Peatlands International 1: 36-40.Ground-penetrating radar (GPR) reflection imaging is a popular geophysical tool to explore subsurface structures in a non-invasive manner. In terms of GPR, reflective interfaces are defined by contrasts in dielectric permittivity, which result from, for example, variations in soil moisture or ice content. GPR is very suitable for electrically high resistive environments, such as frozen ground (typically > 10,000 m). Here, GPR can be used to explore structural targets at depths up to tens of meters. Furthermore, GPR can be employed to explore more shallow environments where detailed information on the decimeter scale is required. In consequence, 2D GPR reflection profiling is used on different spatial scales in permafrost applications such as active layer characterization and imaging of pingos. However, a 3D strategy might be essential for obtaining a reliable image of subsurface structures, if the geometry of such targets is complex (e.g., structures vary in three dimensions). Additionally, 3D data allow to identify out-of-plane reflection events which might interfere with reflections from target structures. This advantage is especially interesting for the application of GPR in cold environments, where out-of-plane reflections are favored due to a broadened radiation characteristic of GPR antennas on frozen ground compared to unfrozen ground. Here, we present a carefully designed 3D GPR acquisition and processing strategy (Schennen et al., 2016) and employ it to an exemplary data set. Our field site covers an area of approximately 20 m×70 m and is located on top of a Yedoma hill on Bol’shoy Lyakhovsky Island, Northern Siberia. Nearby borehole information provides cryostratigraphic details (up to a depth of approximately 30 m) interpreted in terms of three major stratigraphic units. These comprise two ice complex strata, which enclose a unit of floodplain deposits. Additional ground-truth is available from a 18 m high outcrop of the upper ice complex next to our survey area. Here, we observe large (up to 10 m wide) ice-wedges segmenting the ice- and organic-rich, loess-like sediments. In our unmigrated 3D GPR data, time slices show distinct circular diffraction features. As we move on to succeeding slices, we observe that these features originate from locations below thermokarst mounds, expand with a velocity of 0.17 m/ns, and interfere with each other at later traveltimes (Fig. 1a-d). They result in a complex 3D distribution of diffracted energy evident in the entire data cube. Thus, a 3D migration approach (e.g., Allroggen et al., 2014) is essential to correctly image subsurface structures. Thereby we consider also topographic variations and possible subsurface velocity variations. In our migration result, we observe two distinct horizontal features at depths larger than 20 m. Taking borehole data into account, we interpret these features as the base of the upper ice complex unit and the underlying floodplain deposits, respectively. Furthermore, we are able to trace both interfaces in our data cube and compile our interpretation into a 3D cryostratigraphic model (Fig. 1e), which can be used to scale up borehole and outcrop information. In a concluding 2D vs. 3D comparison, we extract exemplary 2D profiles from our unprocessed 3D data to simulate a 2D GPR acquisition and processing strategy on the same field site. Thus, we are able to investigate the impact of data reduction on each processing step. Comparing results of our 2D and 3D processing strategies demonstrate, that a 3D GPR surveying and processing strategy is critical in complex permafrost settings. Allroggen N, Tronicke J, Delock M, Boniger U. 2014. Topographic migration of 2D and 3D groundpenetrating radar data considering variable velocities. Near Surface Geophysics 13: 253-259.DOI: 10.3997/1873-0604.2014037 Schennen S, Tronicke J, Wetterich S, Allroggen N, Schwamborn G, Schirrmeister L. 2016. 3D GPR imaging of ice complex deposits in northern East Siberia. Geophysics, 81: 1-9.DOI: 10.1190/GEO2015-0129.1The Lena River delta is one of the hydrologically entertaining objects. Hundreds channels and thousands lakes as well as thawing ice complex and permafrost active layer dynamic allow to investigate spatial-temporal coherence of different scale hydrological processes. During 15 years Russian-German scientific collaboration on hydrological, hydrochemical and hydrobiological studies have been operated on different water objects for cause-effect relation of large and specific micro processes indication. Transient liquid-frozen water phase change is significant not only for active layer runoff forming but also for hydrochemical and biological specific. Thus, maximum of DOC is in the overlaying soil layer than permafrost border [Bobrova et al., 2013]. It could be used for modeling of runoff forming and biological activity estimation. Measured temperature of lacustrine bottom sediment of one thermokarst lake on Samoylov Island shows maximal volume 3,7 °C on 1,75 cm beneath water-sediment border [Skorospekhova, 2015]. It is also can be interpreted as biological processes activity, for example, organic material destruction with additional heating. It could be observed more detail and can be used for modeling of a lake thermic regime. Hydrobiological specificity shows similarity of species in the channels and lakes, poorness of biodiversity, especially in big channel; only stagnant in summer season Bulkurskaya channel has more zooplankton species in four times than the main river channel [Nigamatzyanova et al., 2015]. Decline of water turbidity from the delta top to channel edges is about 5-8 times [Charkin et al., 2009]. Considerable turbidity increase is formed according to permafrost thawing and can reach 500 g l-1 including high concentration of carbon and biogenic elements. Thermokarst lake degradation [Morgenstern et al., 2011] plays also an important role for permafrost hydrology in the delta. Outflow from an ice complex forms a high local suspended supply in adjacent river branches and influences on biological processes consequently [Dubinenkov et al., 2015]. Underestimated effect of water and sediment discharge increase in the middle part of river branches had been marked [Fedorova et al., 2015]. Head flux of the large Lena River forms taliks under channels with more sophisticated affect in the shoreline zone of the Laptev Sea due to aquifer dynamic and mixing of fresh and salt water. Talik effect on hydrology and sedimentation (and suspended material transformation) in the central part of the delta is currently carried out according to geophysical and hydrogeological methods. First field measurements are planned to be done in April 2016 and results will be presented in the ICOP 2016. The studies have been done with support of RFBR grant 14-05-00787 and 15-35-50949, in the framework of Russian-German projects “ CarboPerm” and “Scientific station “Samoylov Island”. The project for both SPBU and DFG funding had also applied for field and scientific investigation as well. References Bobrova, O.; Fedorova, I.; Chetverova, A.; Runkle, B. and Potapova, T. Input of Dissolved Organic Carbon for Typical Lakes in Tundra Based on Field Data of the Expedition Lena–2012. In Proceedings of the 19th International Northern Research Basins Symposium and Workshop, Southcentral Alaska, USA – August 11–17, 2013, 2013. Charkin, A.N.; Dudarev, O.V.; Semiletov, I.P.; Fedorova, I.; Chetverova, A.A.; J., Vonk; Sanchez- Garcia, L.; Gustafsson, o. and Andersson, P. edimentation in the System of the Delta Lena River - the South Western Part of Buor-Haya Gulf (the Laptev Sea). In The 16th International Symposium on Polar Sciences. Incheon, Korea. 2009, 2009. Dubinenkov, I.; Flerus, R.; Schmitt-Kopplin, P.; Kattner, G. and Koch, B.P. [2015]: Origin-specific molecular signatures of dissolved organic matter in the Lena Delta. Biogeochemistry, 123(1):1–14, doi:10.1007/s10533-014-0049-0. Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015. Morgenstern, A.; Grosse, G.; Gunther, F.; Fedorova, I. and Schirrmeister, L. [2011]: Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta. The Cryosphere, 5(4):849–867, doi:10.5194/tc-5-849-2011. Nigamatzyanova, G.; Frolova, L.; Chetverova, A. and Fedorova, I. Hydrobiological investigation of branches of the Lena River edge zone. In Uchenye Zapiski Kazanskogo Universiteta, Seriya Estestvennye Nauki. 2015. in Russian. Skorospekhova, T. Report of a spring campaign of the expedition “Lena 2015”. AARI’s library stock, 2015.Polygon tundra with tundra-steppe vegetation cover and growing syngenetic ice-wedge nets evolved during stadial and interstadial periods of the late Quaternary in non-glaciated Beringia. The depositional relict of such environments is called Ice Complex (IC; ледовый комплекс [ledovyi kompleks] in Russian) permafrost. The IC archives preserve information of past periglacial and climate landscape conditions of mid- and late Pleistocene Beringian environments. In certain locations of the East Siberian Arctic, IC remnants of different age and extent are known. While using IC deposits as archives of palaeo-landscape and palaeo-environmental dynamics, summer and winter conditions over large time-scales are detectable. Commonly applied summer proxy include palaeontological proxy such as pollen, plant macrofossils, insect fossils and, most prominent, mammal fossils of the Mammoth fauna, while geochemical and stable isotope properties of ground ice allow for insights into freezing and winter conditions. IC chronologies are challenging because the deposition and post-sedimentary preservation of ice-rich permafrost are triggered by palaeo-relief settings and related processes as well as by the intensity of thermokarst. This complicates geochronological interpretations, as representatives of consecutive late Quaternary periods may be found at laterally different positions and altitudes in coastal and riverine exposures. Shifts between permafrost aggradation and degradation over time frequently cause gaps in sequences. Furthermore, numerical dating of IC mainly includes different approaches such as radiocarbon (14C) dating of organic material, infrared and optically-stimulated luminescence (IRSL, OSL) dating on feldspar and quartz grains, radioisotope disequilibria of thorium-230 to uranium-234 (230Th/U) dating of peat, and chlorine-36 to chloride ratios (36Cl/Cl) of ground ice. The application of various geochronologic methods to cover the age intervals of certain IC deposits implies that different permafrost components (organic, mineralic, ice) as well as different geochemical and physical properties have to be employed. At the southern coast of Bolshoy Lyakhovsky Island at least four distinct IC strata were previously described and dated, which cover among the longest time interval of late Quaternary terrestrial permafrost deposition in East Siberia; starting about 200 kyr ago. With this contribution we seek to present and discuss our current understanding of IC chronologies preserved on the New Siberian Archipelago including MIS2 Yedoma (Sartan) IC, MIS3 Yedoma (Molotkov) IC, MIS5 Buchchagy IC, and MIS7a Yukagir IC. Geocryological and palaeo-environmental proxy data highlight past periglacial landscape and deposition processes to deduce past climate conditions and Beringian palaeo-ecological settings and dynamics.Permafrost influences roughly 80% of the Alaskan landscape (Jorgenson et al. 2008). Permafrost presence is determined by a complex interaction of climatic, topographic, and ecological conditions operating over long time scales such that it may persist in regions with a mean annual air temperature (MAAT) that is currently above 0 °C (Jorgenson et al. 2010). Ecosystem-protected permafrost may be found in these regions with present day climatic conditions that are no longer conducive to its formation (Shur and Jorgenson, 2007). The perennial frozen deposits typically occur as isolated patches that are highly susceptible to degradation. Press disturbances associated with climate change and pulse disturbances, such as fire or human activities, can lead to immediate and irrevocable permafrost thaw and ecosystem modification in these regions. In this study, we document the presence of residual permafrost plateaus on the western Kenai Peninsula lowlands of southcentral Alaska (Figure 1a), a region with a MAAT of 1.5±1 °C (1981 to 2010). In September 2012, field studies conducted at a number of black spruce plateaus located within herbaceous wetland complexes documented frozen ground extending from 1.4 to 6.1 m below the ground surface, with thaw depth measurements ranging from 0.49 to >1.00 m. Ground penetrating radar surveys conducted in the summer and the winter provided additional information on the geometry of the frozen ground below the forested plateaus. Continuous ground temperature measurements between September 2012 and September 2015, using thermistor strings calibrated at 0 °C in an ice bath before deployment, documented the presence of permafrost. The permafrost (1 m depth) on the Kenai Peninsula is extremely warm with mean annual ground temperatures that range from -0.05 to -0.11 °C. To better understand decadal-scale changes in the residual permafrost plateaus on the Kenai Peninsula, we analyzed historic aerial photography and highresolution satellite imagery from ca. 1950, ca. 1980, 1996, and ca. 2010. Forested permafrost plateaus were mapped manually in the image time series based on our field observations of characteristic landforms with sharply defined scalloped edges, marginal thermokarst moats, and collapse-scar depressions on their summits. Our preliminary analysis of the image time series indicates that in 1950, permafrost plateaus covered 20% of the wetland complexes analyzed in the four change detection study areas, but during the past six decades there has been a 50% reduction in permafrost plateau extent in the study area. The loss of permafrost has resulted in the transition of forested plateaus to herbaceous wetlands. The degradation of ecosystem-protected permafrost on the Kenai Peninsula likely results from a combination of press and pulse disturbances. MAAT has increased by 0.4 °C/decade since 1950, which could be causing top down permafrost thaw in the region. Tectonic activity associated with the Great Alaska Earthquake of 1964 caused the western Kenai Peninsula to lower in elevation by 0.7 to 2.3 m (Plafker 1969), potentially altering groundwater flow paths and influencing lateral as well as bottom up permafrost degradation. Wildfires have burned large portions of the Kenai Peninsula lowlands since 1940 and the rapid loss of permafrost at one site between 1996 and 2011 was in response to fires that occurred in 1996 and 2005. Better understanding the resilience and vulnerability of the Kenai Peninsula ecosystem-protected permafrost to degradation is of importance for mapping and predicting permafrost extent across colder permafrost regions that are currently warming.Arctic clastic coastlines are some of the most dynamic in the world and have a large impact on cultural and natural resources. Sea ice plays an important role in the erosion and accretion dynamics of these coastlines, and sea ice cover is currently declining at >10% per decade. As a result of declining sea ice cover and an increase in the duration of open water days in the Arctic Ocean, we need to know more about coastal processes in polar seas, specifically how sea ice decline changes coastal processes, the rate at which such coastal changes can occur, and how the effects of declining sea ice interacts with local coastline characteristics including wave fetch, bathymetry, permafrost properties onshore, and pre-existing coastal geomorphology. To assess the influence of sea ice decline on permafrost coastal dynamics we selected two segments of the coastline in NW Alaska with contrasting geography, surficial geology and geomorphology. Study site A, Cape Krusenstern National Monument (CAKR), has a wave-dominated, west- to south-west facing, coarseclastic shoreline. Accreted beach ridges, barrier-closed lagoons, permafrost bluffs, longshore gravel bars, and gravelly beaches characterize coastal geomorphology. Study site B, the Bering Land Bridge National Park and Preserve (BELA), has a north-facing coastline with a shoreline characterized by yedoma and thermokarst basin permafrost bluffs, aggrading spits, sandy barrier islands, and open lagoons. To establish rates of coastal change and identify key geomorphological processes, we digitally mapped the shoreline of both study areas using aerial photographs (1-meter resolution or better) and sub-meter resolution World View-2 satellite imagery from 2003 and 2014, respectively. We compared our data to the results of previous studies based on imagery taken between 1950 and 2003 (Lestak et al., 2010). To better understand the relationship between geomorphology and rates of change, we established geomorphological landform classes for both study areas. We mapped coastal changes within a subset of each study area, using sub meter resolution imagery, over annual time steps to help us better quantify variations in the rate of event driven coastline change. Mapping results for the period 2003 to 2014 suggest a change in erosion rates within both study sites. Erosion rates for the period 1950 to 2003 in BELA and CAKR were -0.12 m/yr and -0.98 m/yr respectively, where the negative signs indicate shoreline retreat (Gorokhovich and Leiserowiz, 2012). These rates, for the period between 2003 and 2014, increased in CAKR to -0.86 and decreased in BELA to -0.69 m/yr. Rates of erosion were found to vary according to geomorphology, with overwash fans in BELA exhibiting the highest rates of change at -1.3 m/yr. Significant changes in geomorphology were observed for this time period including the development of a 200-meter long spit in CAKR, degradation of ice wedges on upland yedoma bluffs in BELA, and the infilling of numerous barrier island ponds due to overwash events in BELA. Our results illustrate the complexity of coastal responses along Arctic coastlines even within close proximity. To ensure robust projections of future coastal change, further mapping and analysis at intraannual and sub-meter spatial resolution is necessary to firmly tie together cause and effect of arctic coastal processes with a changing climate. References: 1. Gorokhovich, Y., Leiserowiz, A., 2012. Historical and Future Coastal Changes in Northwest Alaska. J. Coast. Res. 28, 174–186. 2. Lestak, L.R., Manley, W.F., Parrish, E.G., 2010. Digital Shoreline Analysis of Coastal Change in Bering Land Bridge NP (BELA) and Cape Krusenstern NM (CAKR), Northwest Alaska: Fairbanks, AK: National Park Service, Arctic Network I&M Program. Geospatial Dataset-2184176.Recent landscape changes in the Yedoma region are particularly pronounced in varying thermokarst lake areas reflecting the reaction of the land surface on modern climate changes. However, although thermokarst lake change detection is essential for the quantification of water body expansion and drainage within a region, remote sensing-derived surface reflection trends additionally provide valuable information about the general landscape development. The aim of this research is to reveal the regularities of landscape and thermokarst lakes area changes in the Kolyma lowland tundra in comparison with meteorological data and geological and geomorphological features. The Kolyma lowland tundra occupies about 44500 km2 and is located in Northeast Yakutia within the continuous permafrost zone. Mapping of Quaternary deposits using Landsat images shows that Yedoma (Last Pleistocene remnants formed by ice-rich silty to sandy syngenetic deposits with large polygonal ice wedges) occupies only 16 % of the entire region, while the largest part of it is occupied by alas complex (72 %), formed as a result of Yedoma thaw during the Holocene (Veremeeva and Glushkova, 2016). For the analysis of the landscape and thermokarst lakes area changes of the last 15 years, the entire available Landsat archive from 1999 until 2015 was used for time-series analysis. For this purpose around 800 scenes were processed with an automated workflow, undergoing several necessary processing steps, such as masking, data distribution and calculation of multi-spectral indices. Multi-spectral indices (Landsat Tasseled Cap, NDVI, NDWI, NDMI) were calculated for each unobstructed (cloud-, shadow- and snow-free) observation within the summer months (June to September) between 1999 and 2015. A robust linear trend analysis has been applied to each pixel for the spatial representation of changes of different land surface properties over the observation period. This map shows the magnitude and direction of changes for each multi-spectral index, which are used as proxies for different land-surface properties. For single locations, the entire time-series can be further analyzed in more detail. For the period from 1999 till 2005 air temperatures and precipitation have been analysed for several weather stations that existed in the region. The Landsat time series analysis for the last 15 years shows that the northern part of the region became wetter over the last 5 – 6 years. The alases are particularly affected by the wetting trend. The analysis of the meteo-data shows a trend of increasing air temperature and especially precipitation during the summer from 2010. The wetness increase, particularly on the coastal zone, is supported by the fact that air temperature trends are the largest at near-coastal meteorological stations. This increase of air temperatures and precipitation is likely connected to the reduced sea ice cover (Bekryaev et al., 2010). The strongest wetness increase were observed in the most northern part of the region within a 50 km wide zone along the East-Siberian sea shore between lowest stream of the Alazeya and Galgavaam rivers. This region is characterised by average terrain heights about 10-20 m, the yedoma and thermokarst lakes area here is about 10-20 %. There are less increase of wetness in the southern and eastern part of the coastal zone between Galgavaam and Bolshaya Chukochya rivers which is characterized by average heights of 0-10 m. The lakes area here is about 40 % and yedoma covers less then 10 % of the territory. Thus the strongest wetness trend for the northern coastal zone can be explained by the high degree of yedoma preservation and its thawing due to the coastal location and higher impact of the increasing temperatures and precipitation. For the recent past from 1999 to 2015, thermokarst lake changes were analysed visually based on the time series trend. For most thermokarst lakes of the Kolyma lowland tundra lake area was increasing from 1999 till 2015, however the trend is not significant. Some of the lakes partially or completely drained. Thermokarst lakes area coverage was quantified based on seven Landsat 8 images for the time period 2013 – 2014. In order to ensure consistency regarding surface moisture, only images acquired from August till September have been used. Atmospheric correction of each image was done for radiometric normalization across the dataset. An increase in ground resolution of the 30m multi-spectral data was achieved through resolution merge with the panchromatic channel to 15m pixel size. Subsequent mosaicking, classification and raster to vector conversion was done for the entire Kolyma lowland tundra. Thermokarst lakes cover about 12.9 % of the Kolyma lowland tundra. For the key investigation area located in the southern tundra around Lake Bolshoy Oler, which covers an area of 2800 km2 , a comparison with lakes mapped in CORONA images from July 21, 1965 and lakes mapped in the 2014 Landsat mosaic was carried for analysis of changes over time during a period of up to 50 years. The overall thermokarst lake area for this region in 1965 and 2014 was 590 and 549 km2 respectively. This corresponds to a limnicity decrease of 1.5 % within the study site from 21.1 to 19.6 %. About one third of this lake area decrease is due to partial drainage of big lakes with the area in 1965 and 2014 of 141.8 and 96.3 km2, respectively. Analysis of the summer air temperature and precipitation trends from the 1965 till 2015 also shown the trend of their increasing. Therefore, despite the fact that many persistent thermokarst lakes in the Kolyma lowland tundra are increasing in area, modern climate conditions generally seem to favor further relief drainage development. Consequently, thermokarst lake drainage outpaces thermokarst lake growth. This heterogeneous pattern suggests that permafrost degradation and aggradation in the region proceed simultaneously close together. Acknowledgements: This study was supported by the Russian foundation for basic research grant 14-05-31368 and by the ERC grant 338335. References: Bekryaev R.V., Polyakov I.V., Alexeev V.A. 2010. Role of polar amplification in temperature variations and modern Arctic warming. J. Clim. 23(14): 3888– 906. Veremeeva A.A., Gklushkova N.V. 2016. Relief formation in the regions of the Ice Complex deposit occurrence: remote sensing and GIS-studies, tundra zone of Kolyma lowland, Northeast Siberia. Earth’s Cryosphere, vol. XX, 1, pp.15-25.The investigation of microbial ecosystems in permafrost sediments is an important approach to understand the role of microbial organic matter transformation in permafrost sediments for past and future climate changes, and is of high relevance in today’s geoscience research (Wagner, 2008) due to the current debate on the temperature vulnerability of permafrost deposits. Especially, the interplay between the organic substrate and the distribution of the living and past microbial communities in Late Pleistocene (Yedoma) and Holocene permafrost deposits, as well as the substrate potential of the organic matter stored in potentially thawing permafrost deposits are in the focus of the current study. Our investigation is part of the BMBF CarboPerm project an interdisciplinary Russian-German cooperation on the formation, turnover and release of carbon from Siberian permafrost landscapes. Sample material derived from terrestrial permafrost cores drilled at the coast of Bour Khaya in the North-Eastern Siberian Arctic. The gathered core material comprises Late Pleistocene to early Holocene deposits separated by an ice wedge. The microbial life markers (intact phospholipids, PLs) prove the presence of currently living microorganisms in the entire permafrost sequence and show the highest concentration in the uppermost sample indicating an abundant microbial life in the active layer. In comparison, the PL profile is strongly decreased in the underlying permafrost deposits. Nevertheless, the inventory of the Phospholipid fatty acids (PLFAs) suggests that the cell membrane temperature adaptation to cold environmental conditions is mainly regulated via the ratio between iso- and anteiso-fatty acids (FAs) as well as the ratio between saturated and unsaturated FAs. The surface samples show higher proportions of anteiso and unsaturated FAs (adaptation to cooler conditions), which might derive from the fact that surface layers are more affected from the harsh Siberian winter conditions than the deeper constantly cold permafrost deposits, where the above-ground temperature extremes are buffered due to the overlying deposits. Indeed within the deeper permafrost sequence the variations of the ratios are rather small, indicating adaptation to similar constantly cold temperature conditions. Other microbial markers (GDGTs), already partly degraded and, therefore, not indicating microbial life, reveal similarities with the TOC content and an increase especially in Late Pleistocene deposits. This suggests increased microbial life during intervals in the Late Pleistocene presumably caused by periods of moisture and temperature increased environments. Pore water analysis reveals the presence of low molecular weight organic acids (LMWOA) such as acetate, being excellent substrates for microbial metabolism. In the Late Pleistocene deposits below the ice wedge the substrate depth profiles show significant similarities to the TOC content. These points to a link between the organic matter and the LMWOA concentrations solved in the pore water and to the potential of those permafrost layers to provide substrates for microbial greenhouse gas production. In contrast, in the active layer the LMWOA concentrations are low, reflecting an active microbial turnover in the surface layers. Ester cleavage experiments on the residual organic matter resulted in the release of ester linked LMWOAs forming a potential substrate pool when released in future. These bound LMWOA profiles are even better correlated to the TOC content suggesting that the deeper permafrost deposits (older organic material)are not significantly different from those in the surface sediment (fresh organic material). Overall this indicates that the organic matter stored in the permafrost deposits and, therefore, removed from the surface carbon cycle is not much different in terms of organic matter quality than the fresh surface organic material. Considering the discussed increase of permafrost thawing, this might imply a strong impact on the generation of greenhouse gases from permafrost areas in future with its feedback on climate evolution. In a second and ongoing study, four terrestrial permafrost cores spanning from the Eemian interglacial into the Holocene form Bol’shoy Lyakhovsky Island are investigated with the focus on the differences and potential of the organic matter by comparing Eemian, Late Pleistocene and Holocene deposits. First results already reveal similar relations between the living and dead microbial communities with respect to the availability of free substrates, and the quality and amount of the total organic carbon. The results on the future potential of these deposits will also be presented.The permafrost landscape of Central Yakutia is subject to rapid modifications due to intensive land use, extreme weather, and the current global warming. With regard to the predicted increase in precipitation and temperature as a result of climate change, quantitative knowledge of the small-scale variability of active thermokarst processes is required. Here, we mapped the change of thermokarst and alas lakes (i.e. residual lakes in alas basins) for 11 times covering periods of 2 to 18 years between 1944 and 2014 at the Yukechi study site (61.761289° N/130.470602° E). Historical airborne, current satellite as well as field data were utilized in analyzing lake-area changes and thaw subsidence on local scale. Additionally, a unique dataset of longterm climatic and ground-temperature data could be used in multivariate statistics to identify the climatological and/or general driving and inducing factors of thermokarst and alas-lake changes. On regional scale, size and distribution of lakes >0.1ha were analyzed on different ice-rich permafrost terraces in the Lena-Aldan-Amga interfluve region east of Yakutsk on the basis of Landsat 8 data from July 2013. Regionally, larger lakes distributed in higher frequency are dominating lower terraces. Smaller lakes dominate higher terraces. In particular, smaller lakes are distributed in less density on older and more ice-rich terraces while highest lake densities and larger lakes characterize younger and less ice-rich terraces. Remote sensing analyses at the Yukechi study site indicate that alas-lake levels are increasing strongly end of the 1960s and since the 1990s until present, but their area decrease in the 1940s, 1950s, 1970s, and 1980s. The mean rate of alas-lake-radius change for the 70 year time span account for 1.6 ± 2.9 m/yr. In the meanwhile, extensive agricultural use in the postwar period on the Yedoma ice-rich permafrost deposits led to a rapid and sustained growth of young thermokarst lakes over the entire time span. This is initiated by the strong disturbance of the thermal and hydrological balance of the permafrost. The mean rate of lake-radius change of all mapped thermokarst lakes is 1.2 ± 1.0 m/yr. The mean thaw subsidence below the thermokarst lakes account for 6.2 ± 1.4 cm/yr. Our statistical analyses indicate that climatic parameters (i.e. precipitation, air and ground temperature, and evaporation) show higher correlations with thermokarst-lake changes than with alas-lake changes. In particular, the influence of annual air temperature changes and evaporation is higher on thermokarst-lake level changes than on alas-lake level changes. However, the influence of precipitation, especially winter precipitation, is lower. Deeper ground temperature changes (3.2m depth) show higher correlation with thermokarst-lake changes, while the influence of ground temperatures in 1.6m depth is similar. Multiple regression analyses reveal more complex interrelations of climatic and ground thermal conditions with thermokarst and alas lake changes but further study is needed to validate these results. Our results show, however, that topography, geomorphology, and surficial cryolithology are important controlling factors on the regional distribution and size of the lakes. Furthermore, thermokarst activity is influenced by climatic parameters but it is accelerated and rapidly induced by disturbing factors such as land use. Climatic parameters are strongly affecting growing rates within certain time periods of thermokarst lakes but they do not lead to remarkable reductions or the disappearance of the lakes during the whole observation period. Alas lakes are increasing and decreasing. Distinguishing main controlling factors, however, are hampered probably due to larger catchment areas and subsurface hydrological conditions.The course of permafrost degradation depends on climate, vegetation, disturbance, and excess groundice content and distribution, which vary over time. The first three of these drivers are undergoing considerable change with arctic warming. Using combined lake-sediment records, field observations, aerial 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 that is identified as yedoma. A switch to warmer, moister conditions during deglaciation triggered substantial thermal erosion and transport of silt, which washed into existing basins and formed widespread linear corrugations cutting across the uplands. Lakes began to form via thermokarst as early as 13,000 cal yr BP. Lakes intersect the corrugations, indicating lake formation followed initial landscape instability. Charcoal in basal sediments indicates fire may have influenced lake initiation. Small-scale surface topography revealed by LiDAR images includes deep gullies, features resembling lake drainage channels, and lowered lake shorelines. After ca 10,000 yr BP the region became colonized by dense evergreen conifer forest, which likely served to stabilize and insulate the ground surface, preventing the continuation of the high rates of permafrost degradation recorded in the earliest Holocene. Initial lake lowering and generation of steep local topography favouring drying of uplands, plus a summer water deficit, have also likely combined to shift the system to a more quiescent state through much of the Holocene. However, these changes have not prevented lake drainage events entirely. In 2013, several lakes drained or partially drained, possibly in response to fires and a high spring melt-water volume. The observed pattern of drainage is echoed in the older features preserved on the land surface. Based on the Holocene evolution of the region, increasing regional moisture and/or fire disturbance in the future could lead to an increase in permafrost degradation and lake drainage events.Bol’shoy Lyakhovsky, the southernmost island of the New Siberian Archipelago, holds the longest record of palaeoenvironmental history in the non-glaciated Siberian Arctic preserved in permafrost. It stretches back to ~200 kyr before present and includes prominent last interglacial thermokarst and Yedoma (Ice Complex) sections. Yet, it is unknown, whether or not the depositional history of the site is affected by the deglaciation of the northern part of the New Siberian Archipelago. Potentially, it could give insight into the break-up of the proposed MIS 6 ice sheet located on the East Siberian Sea shelf (Jakobsson et al., 2014). The lithostratigraphy of southern part of the island consists of palaeosols, floodplain and lake deposits, subaerial Yedoma and lacustrine to palustrine alas formations. Large ice wedges (partially up to several meters high and thick), segregation and pore ice record a syngenetic freezing of the Yedoma silts. Polymodal particle size distributions suggest that more than one transport mechanism drove sediment accumulation from more than one source. Recent papers conclude that the palaeoclimate record matches the general Late Quaternary climate history in northern Siberia (Andreev et al., 2011; Wetterich et al., 2011). From a multi proxy data set we focus on (i) the mineral composition (63-125 μm fraction) to determine the provenance of the deposits and to identify possible changes of transport pathways. Complementary, we use (ii) pore ice hydrochemistry as a means to track changes of the soil solution that principally reflects the site’s chemical weathering history preserved in permafrost. Presumably the two approaches complement each other, since the weathering solution should largely reflect the mineral matter composition. The heavy mineral association suggests that most of the minerals derive from the underlying bedrock (Upper Jurassic-Lower Cretaceous sandstones and Upper Cretacous granites and diorites); among others it has high amounts of ilmenite and leucoxene, epidote, pyroxenes and amphiboles, along with garnet, tourmaline, apatite, and sphene. Ratios of stable versus unstable mineral associations show that the Late Quaternary strata overlying bedrock are enriched in more stable minerals (i.e. zircon, tourmaline, ilmenite), whereas more unstable minerals (i.e. amphiboles and pyroxenes) dominate the chronostratigraphically younger Quaternary strata. A remarkably high portion of weathered mica appears in MIS4 to MIS3 deposits and raises the question upon particular hydrodynamic conditions during that time, e.g. a floodplain environment that persisted for several thousands to ten thousands of years. It may have produced various impulses of flooding with floating particles that settle out quickly on the banks of the channel and on the leeward side. Overall pore ice chemistry shows that high electrical conductivity corresponds to low ice content ( 60 wt.-%) the electrical conductivity is low. When compared with the average ion composition of tundra and taiga rivers, the whole core record is enriched in the sodium- potassium load, which partially even dominates over the combined calcium-magnesium load. We preliminary conclude that the observed trends of heavy mineral and pore ice chemical variations in the Bol’shoy Lyakhovsky cores reflect short-distance material transport from weathered bedrock in the depositional area. The enrichment of mica in ice-rich deposits suggests floodplain hydrodynamics in the area during MIS 4 to MIS3. The fairly constant ionic proportions of the light soluble load in the ground ice confirm a local origin of the weathering solutes. High amounts of potassium are linked to the weathering of the granitic bedrock. Distinct concentration gradients in the downcore electrical conductivity are caused by postdepositional ionic migration from the bedrock weathering crust into the overlying Late Quaternary strata, by intensified weathering during the Last Interglacial (MIS5e), and by stable surfaces that promoted effective (e.g. cryogenic) weathering during the last Glacial (MIS4 to MIS3). Andreev, A.A., Schirrmeister, L., Tarasov, P.E., Ganopolski, A., Brovkin, V., Siegert, C., ... & Hubberten, H.-W. (2011). Vegetation and climate history in the Laptev Sea region (Arctic Siberia) during Late Quaternary inferred from pollen records. Quaternary Science Reviews, 30, 2182-2199. Jakobsson, M., Andreassen, K., Bjarnadottir, L.R., Dove, D., Dowdeswell, J.A., England, J.H., ... & Larsen, N.K. (2014). Arctic Ocean glacial history. Quaternary Science Reviews, 92, 40-67. Wetterich, S., Tumskoy, V., Rudaya, N., Andreev, A.A., Opel, T., Meyer, H., ... & Huls, M. (2014). Ice Complex formation in arctic East Siberia during the MIS3 Interstadial. Quaternary Science Reviews, 84, 39- 55.Ice wedges are the most abundant type of ground ice in the ice-rich permafrost deposits of the Northeast Siberian Arctic. They are formed by the periodic repetition of frost cracking and subsequent crack filling and refreezing in spring, mostly by melt water of winter snow. Ice wedges can be studied by means of stable-water isotopes. Their isotopic composition is directly linked to atmospheric precipitation (i.e. winter snow) and, therefore, indicative of past climate conditions during the cold season even though also genetic aspects, i.e. sublimation, melting and refreezing in the snowpack and the frost crack, have to be taken into account. In this contribution we present stable-water isotope data of ice wedges from the Oyogos Yar coast of the Dmitry Laptev Strait (72.7°N, 143.5°E). Ice wedges and surrounding sediments were studied and sampled in 2002 and 2007. Ice-wedge stable-water isotopes were analyzed in the stable-isotope lab of the Alfred Wegener Institute in Potsdam, Germany. Sediments and ice wedges were dated using (a) OSL dating, (b) 36Cl/Cl dating (Blinov et al., 2009), (c) radiocarbon dating as well as (d) stratigraphic correlation based on ice-wedge stable isotopes. Based on our chronology the studied ice wedges correspond to different stratigraphic units of the Late Quaternary. These are (1) an Ice Complex of MIS5 age (Wetterich et al., in press), (2) Early Weichselian (MIS4 to MIS3) flood plain deposits, (3) the Middle Weichselian Yedoma Ice Complex of MIS3 age and (d) Holocene themokarst deposits (Opel et al., 2011). Ice wedge stable-water isotope data indicate substantial variations in Northeast Siberian Arctic winter climate conditions (δ18O) as well as shifts in the moisture generation and transport patterns (d excess) during the Late Quaternary, in particular between Glacial and Interglacial but also over the last centuries. An ice wedge of the MIS5 Ice Complex exhibits mean δ18O and d excess values of -33‰ and 7‰, respectively, representing very cold winter temperatures. Small multi-stage ice wedges corresponding to the MIS4 to MIS3 flood plain deposits showed two clusters of isotope values: (1) in their lower parts, i.e. composite sand-ice wedges or “polosatics”, δ18O values of -31 to -28‰ (d excess of 0-5‰) and (2) in their upper parts (classical ice wedge) δ18O values of -34‰ (d excess of 5‰), reflecting rather different formation conditions than climate differences under very cold climate conditions. The huge syngenetic ice wedges of the Weichselian Yedoma Ice Complex (MIS3) are characterized by mean δ18O values of -33‰ to -29‰ and mean d-excess values between 4 and 8‰ corresponding to different altitude levels and reflecting cold to very cold winter temperatures. On top of the Ice Complex as well as in a thermokarst depression of Late Glacial origin, Holocene ice wedges could be found. They have been grown predominantly in the Middle to Late Holocene and exhibit mean δ18O values of about -25‰ and mean d-excess values of 8‰, mirroring distinctly warmer winter temperatures in the Holocene. Recently grown (modern) ice wedges of the last decades are characterized by mean δ18O values of about -21‰ and mean d excess values of 8‰, testifying the recent winter warming in the Arctic. Blinov A, Alfimov V, Beer J, Gilichinsky D, Schirrmeister L, Kholodov A, Nikolskiy P, Opel T, Tikhomirov D, Wetterich S. 2009. Ratio of 36Cl/Cl in ground ice of east Siberia and its application for chronometry. Geochemistry Geophysics Geosystems 10, Q0AA03. Opel T, Dereviagin AY, Meyer H, Schirrmeister L, Wetterich S, 2011. Palaeoclimatic Information from Stable Water Isotopes of Holocene Ice Wedges on the Dmitrii Laptev Strait, Northeast Siberia, Russia. Permafrost and Periglacial Processes 22, 84-100. Wetterich S, Tumskoy V, Rudaya N, Kuznetsov V, Maksimov F, Opel T, Meyer H, Andreev AA, Schirrmeister L, in press. Ice Complex permafrost of MIS5 age in the Dmitry Laptev Strait coastal region (East Siberian Arctic). Quaternary Science Reviews.Over the past two decades, the International Arctic Science Committee (IASC) and the Scientific Committee on Antarctic Research (SCAR) have organized activities focused on international and interdisciplinary perspectives for advancing Arctic and Antarctic research cooperation and knowledge dissemination in many areas (e.g. Kennicutt et al., 2014). For permafrost science, however, no consensus document exists at the international level to identify future research priorities, although the International Permafrost Association (IPA) highlighted the need for such a document during the 10th International Conference on Permafrost in 2012. Four years later, this presentation, which is based on the results obtained by Fritz et al. (2015), outlines the outcome of an international and interdisciplinary effort conducted by early career researchers (ECRs). This effort was designed as a contribution to the Third International Conference on Arctic Research Planning (ICARP III). In June 2014, 88 ERCs convened during the Fourth European Conference on Permafrost to identify future priorities for permafrost research. We aimed to meet our goals of hosting an effective large group dialogue by means of online question development followed by a “World Cafe” conversational process. An overview of the process is provided in Figure 1. This activity was organized by the two major early career researcher associations Permafrost Young Researchers’ Network (PYRN) and the Association of Polar Early career Scientists (APECS), as well as the regional research projects PAGE21 (EU) and ADAPT (Canada). Participants were provided with live instructions including criteria regarding what makes a research question (Sutherland et al., 2011). The top five questions that emerged from this process are: (1) How does permafrost degradation affect landscape dynamics at different spatial and temporal scales? (2) How can ground thermal models be improved to better reflect permafrost dynamics at high spatial resolution? (3) How can traditional environmental knowledge be integrated in permafrost research? (4) What is the spatial distribution of different ground-ice types and how susceptible is ice-rich permafrost to future environmental change? (5) What is the influence of infrastructures on the thermal regime and stability of permafrost in different environmental settings? As the next generation of permafrost researchers, we see the need and the opportunity to participate in framing the future research priorities. Across the polar sciences, ECRs have built powerful networks, such as the Association of Polar Early Career Scientists (APECS) and the Permafrost Young Researchers Network (PYRN), which have enabled us to efficiently consult with the community. Many participants of this community-input exercise will be involved in and also affected by the Arctic science priorities during the next decade. Therefore, we need to (i) contribute our insights into larger efforts of the community such as the Permafrost Research Priorities initiative by the Climate and Cryosphere (CliC) project together with the IPA and (ii) help identify relevant gaps and a suitable roadmap for the future of Arctic research. Critical evaluation of the progress made since ICARP II and revisiting the science plans and recommendations will be crucial. IASC and the IPA, together with SCAR on bipolar activities, should coordinate the research agendas in a proactive manner engaging all partners, including funding agencies, policy makers, and local communities. Communicating our main findings to society in a dialogue between researchers and the public is a priority. Special attention must be given to indigenous peoples living on permafrost, where knowledge exchange creates a mutual benefit for science and local communities. The ICARP III process is an opportunity to better communicate the global importance of permafrost to policy makers and the public.Destruction mechanisms and dynamics of the Arctic coast, also in the western sector of the Russian Arctic, are studied in detail, including the use of remote sensing data. However, data on thermal abrasion and thermo denudation of Kolguev island is quite limited. Some estimates were presented in article of M.A.Velikotsky (1998). Estimation of thermos denudation rates near the Sauchiha river mouth for the period 1948-2002 years was done by the authors earlier (Kizyakov& Perednya, 2003). To obtain data about the modern (after 2002) shoreline retreat rates and growth of thermal cirque a high resolution remote sensing data were involved in our research. Part of the western coast of the Kolguev island was inspected in field work conducted on 2002 by ECI SB RAS, together with VNIIOkeangeologia. The object of research was the part of coast, including a group of three coastal thermal cirques, located 3.5 km south of the Sauchiha river mouth. In 2012, within the framework of the project ‘Geoportal of MSU’ operational satellite imaging was done on Kolguev island by satellite FORMOSAT-2. High resolution satellite imagery provides ample opportunities for visual interpretation of coastal landforms. Aerial photographs (1948 and 1968), surveying materials (2002), high-resolution satellite images (2009 and 2012) became basis to study the dynamics of the coast and thermal cirques in the key area. For key area were calculated: retreat rates of the edge of the coastal terraces and thermal cirques for the periods 1948-1968, 1968-2002, 2002-2009, 2009-2012; retreat rates of the foot of the coastal terrace for the periods 2002-2009, 2009-2012; volume of the material enters the coastal zone by the thermal abrasion for one linear km of a coast (Kizyakov et al., 2013). Average long-term rates of retreat of the coastal terrace during 1948-2012 varied from 0.7 to 2.4 m/year; 2002-2012 varied from 1.7 to 2.4 m/year. Identified rates are distinctive for the part of coast from the mouth of Krivaya river to the curve of coastline near the mouth of the Gusinaya river - a length is 60.5 km. These rates are in 1.1-1.5 times lower than average rates of retreat of thermal cirque edges which are connected with melting of massive ice deposits. Averaged growth rates of the thermal cirques in 1948-2002 was 2.4 m/year; in 2002-2012 was - 2.6 m/year. The maximum growth rate on some sections in 2009-2012 were 14.5-15.1 m/year. These rates are the largest for the previously recorded in the Western sector of the Russian Arctic. The cause of the abnormally high rates is an increase the annual amount of positive air temperatures, which in 2011-2012 was 1.4-1.5 times higher than the long-term average. The determined rates of the development of thermal cirque can be extended to the north from the key area (near the Sauchiha river mouth) to the Gusinaya river mouth with total length of 32.3 km. The next plans on studying the coastal dynamics on Kolguev Island - using additional satellite images for the purposes of: detailization of interannual dynamics through the analysis of more short time span series of satellite images, definition of variations of the coastal destruction rates on the Western and Northern coasts. References: Velikotsky M.A. Characteristics of modern coastal dynamics of the Kolguev Island // Dynamics of the Russian Arctic coasts, Moscow, MSU – 1989 – P.93- 101 (In Russian) Kizyakov A.I., Perednya D.D. Destruction of coasts on the Yugorsky Peninsula and on Kolguev Island (Russia) // Permafrost: Abstr. of the 8th Intern. Conf. (Zurich, Switzerland, 21–25 July 2003). Zurich, Switzerland – 2003 – P. 79–80. Kizyakov A.I., Zimin M.V., Leibman M.O., Pravikova N.V. Monitoring the rate of thermal denudation and thermal abrasion on the western coast of Kolguev Island using high resolution satellite images // Earth Cryosphere (Kriosfera Zemli). – 2013, XVII, No. 4 – P. 15-25 (In Russian).

Massive thermokarst lake area loss in continuous ice-rich permafrost of the northern Seward Peninsula, Northwestern Alaska, 1949-2015

Apart from people in cold region communities and a small – although steadily growing – scientific community, the general public knows very little about permafrost properties, its dynamics in response to climate change, and the research going on in the field. We are addressing this by making permafrost science accessible to children, youth, their parents, and teachers. We are producing a 100% outreach-related project that aims at ‘Fostering permafrost research to the ends of the Earth’ (http://ipa.arcticportal.org), but with a casual approach via a series of comic strips. Cartoons are excellent ways to communicate messages in today’s media landscape: they are graphic, funny and direct, and can be rapidly shared via social media to reach many people. Our outreach project targets the general public, focusing on young students who have to choose career paths at the high school or college levels. By introducing them to permafrost research activities, particularly fieldwork, our ‘Frozen-Ground Cartoon’ will enhance the dissemination of permafrost knowledge and broaden the international community of permafrost ‘lovers’. This new project is coordinated by a core group of permafrost early career researchers from Canada, Germany, Sweden and Portugal (in collaboration with an ‘external senior advisor’), and is endorsed by the International Permafrost Association (IPA) as a targeted ‘Action Group’ (http://ipa.arcticportal.org/activities/action-groups). Here we present an overview of our Action Group, including main objectives, significance, and potential future outcomes.The Arctic is affected by rapid climate change, which has substantial impact on permafrost regions and the world as a whole (Raynolds et al., 2014). In the last 30 years Arctic temperatures have risen 0.6 °C per decade, twice as fast as the global average (AMAP, 2011, Schuur et al., 2015). This in turn leads to the degradation of ice-rich permafrost (Grosse et al., 2011) and modifies drainage, increases mass movements and alters landscapes (Nelson et al., 2001; Anisimov et al., 2007, Romanovsky et al., 2010b). Although permafrost regions are not densely populated, their economic importance has increased substantially in recent decades. This is related to the abundance of natural resources in the polar region and improved methods of hydrocarbon extraction, transportation networks to population centers and engineering maintenance systems (Nelson et al., 2002; Mazhitova et al., 2004, AMAP, 2011). The Yamal Peninsula in North West Siberia is experiencing some of the most rapid land cover and land use changes in the Arctic due to a combination of climate change and gas development in one of the most extensive industrial complexes (Kumpula et al., 2006; Walker et al., 2011; Leibman et al., 2015). Specific geological conditions with nutrient-poor sands, massive tabular ground ice and extensive landslides intensify these impacts (Walker et al., 2011). The combination of high natural erosion potential and anthropogenic influence cause extremely intensive rates of erosion (Gubarkov et al., 2014). A considerable amount of recent work has focused on the effects of industrial development to ecological and social implications (Forbes, 1999; Kumpula et al., 2010; Walker et al., 2011). This study aims at exemplarily investigating a region that has been affected by natural and anthropogenic large-scale disturbances within a very short period. The construction of the world’s northernmost railway for the Bovanenkvo Gas Field was finished in 2010. In addition the region experienced an extremly warm and wet summer in 2012. The objectives of this study are • to map surface disturbances of central Yamal between 2010 and 2013/2015 based on highresolution satellite imagery and on the most recent SPOT5-TAKE-5 imagery in 2015, • to quantify natural and anthropogenic impacts in terms of permafrost degradation, • to use meteorological data from the nearest climate station (Marre Sale, Yamal) and from reanalyses climate data on air temperature and precipitation.Previous studies have shown that arctic river delta systems are areas of accumulation of geochemical substances at the sea-river mixing zone. In the Lena River Delta our previous work shows the tendencies of water runoff redistribution changes and heterogeneity of suspended supply distribution along the delta branches, accumulation and erosion zone in the different parts of the delta. Nevertheless, the processes of geochemical flow transformation in the subaerial deltas are so far underestimated. In order to close this gap, we sampled water, suspended and bottom sediments in the Lena River Delta in the summer seasons of 2010 and 2014. Most of the sampling points were tight to the profiles of hydrological measurements held in the delta and highlighted in Fedorova et al. [2015]. The results show that geochemical transformation of the Lena River runoff is taking place in the delta. The most active time for the transformation is the summer season due to the activity of sediment accumulation and biogeochemical processes. Hydrological conditions in the delta affect also its hydrogeochemical characteristics. Furcation of the delta branches affects the hydrodynamic conditions of different delta areas. The factors influencing the geochemical characteristics of the delta were identified on the base of geochemical indexes approach applied to sediments and statistical factor analysis. Based on geochemical indexes (Al/Na, Si/Al, Fe/Mn and Fe/Al ratios) similar conditions were determined for the main branch of the Lena, the upstream parts of Bykovskaya and Tumatskaya branches and in Olenekskaya branch near Chay-Tumus. Despite of high runoff the branches are characterized by element accumulation, which can be explained by decreasing of flow turbulence and specificity redox conditions in these areas. Bottom sediments are one of the most important indicators of geochemical transformation processes. The results of statistical factor analysis show three main factors for formation of the these geochemical conditions in the delta: 1. the general water flow of the Lena River, which is influenced by the lithogenous base of the river catchment, 2. the cryogenic condition of the Lena Delta (permafrost degradation processes and cryogenic weathering) and 3. biogeochemical transformation during redistribution of chemical water components , suspended matter and bottom sediments. Acknowledgements The research was supported by grant No. 14-05-00787 A of Russian Foundation for Basic Research References Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena Delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015.In order to understand the influence of surrounding catchment characteristics on the CDOM concentration different types of surface waters in the Lena river delta region were investigated regarding their geochemical composition. The Lena River Delta consists of three geomorphological main terraces that differ in their relief, hydrological and cryolithological characteristics, which possibly influences the content of dissolved substances in their associated water bodies and in the neighboring river branches. During summer seasons of 2013-2014 water samples were collected from river branches as well as from lakes and melt-water streams on the first and the third main terraces and analyzed them for concentrations of colored dissolved organic matter (CDOM), dissolved organic carbon (DOC), and main and trace elements (Na, K, Mg, Ca, HCO3, F, Cl, SO4, Fe, Si, Sr). This type of research was carried out for surface waters in the Lena delta region for the first time. Statistical analysis revealed several correlations between CDOM, DOC and mineral ions. For example, R-squared (the coefficient of determination) for CDOM and Cl and for CDOM and Na in Lena River branches were 0.52 and 0.51, respectively. Correlation between CDOM and F was also found for melt-water streams from the Ice Complex (third terrace) (R-squared = 0.5). Analysis of the relationship between CDOM and DOC showed strong correlation of these parameters for lakes (R-squared = 0.98) and lower correlation for river branches (R- squared = 0.48). In streams formed by the thawing of Ice Complex deposits on the third terrace was found the highest values of CDOM and DOC, but a correlation between them was not observed. A clear dependency was found out between CDOM and DOC correlation and the location of lakes on different terraces with specific permafrost conditions. A stronger correlation was observed for the lakes located on the third terrace (Ice Complex) compared to lakes located on the first terrace (Samoylov Island). Usually, lakes on the first terrace get flooded by river waters during spring, whereas lakes of the third terrace are not affected by river water inflow and have more stable conditions. The Lena delta branches are influenced by differing surrounding conditions, therefore CDOM and DOC concentrations change during summer season and did not show strong correlations.A large amount of organic carbon stored in permafrost soils across the high latitudes is vulnerable to thaw, decomposition and release to the atmosphere as a result of climate warming. Findings from observational, experimental and modeling studies all suggest that this process could lead to a significant positive feedback on future radiative forcing from terrestrial ecosystems to the Earth’s climate system. With respect to the magnitude and timing of this feedback, however, observational data show large variability across sites, experimental studies are few, and different models result in a wide range of responses. These issues represent fundamental limitations on improving our confidence in projecting future permafrost carbon release and associated climate feedbacks. Recent studies have brought new insight into – and even quantitative estimates for – these issues through broader data synthesis and model-data integration approaches. But, how representative of the circumarcticscale variability in permafrost carbon vulnerability are the data and models from these studies? To address this question, we developed a geospatial data synthesis and analysis framework designed to represent and characterize the variability in permafrost carbon vulnerability across the northern high latitudes. Here, we describe the rationale and methods used to develop the regionalization scheme, and then use the framework to assess the spatial representativeness of, and the variability described by, existing data sets defining the fundamental components and environmental drivers of permafrost carbon vulnerability. The Permafrost Regionalization Map (PeRM) considers the regional-scale environmental factors that generally determine the spatial variability in permafrost carbon vulnerability across the Arctic. The broadly-defined regional classification is based on a circumarctic spatial representation of the major environmental controls on a) the rate and extent of permafrost degradation and thaw, b) the quantity and quality of soil organic matter stocks, and c) the form of permafrost carbon emissions as CO2 and CH4. We chose a generalized, pragmatic approach that resulted in a feasible number of regional subdivisions (i.e.,‘reporting units’) based on an intersection of spatial data layers according to permafrost extent, permafrost distribution, climate regime, biome and terrain. The utility of the PeRM framework is demonstrated here through areal density analysis and spatial summaries of existing data collections describing the fundamental components of permafrost carbon vulnerability. We use this framework to describe the spatial representativeness and variability in measurements within and across PeRM regions using observational data sets describing active layer thickness, soil pedons and carbon storage, long-term incubations for carbon turnover rates, and site-level monitoring of CO2 and CH4 fluxes from arctic tundra and boreal forest ecosystems. We then use these regional summaries of the observational data to benchmark the results of a process-based biogeochemical model for its skill in representing the magnitudes and spatial variability in these key indicators. Finally, we discuss the on-going use of this framework as a basis for higher-resolution mapping of key regions of particular vulnerability to both press (active layer thickening) and pulse (thermokarst development) disturbances. This work is guiding on-going research toward characterizing permafrost degradation and associated vegetation changes through multi-scale remote sensing. Overall, this spatial data synthesis framework work provides a critical bridge between the abundant but disordered observational and experimental data collections and the development of higher-complexity process representation of the permafrost carbon feedback in geospatial modeling frameworks.Nowadays due to climate change the interest to the hydrological processes in the permafrost affected regions is growing. Permafrost soil is important carbon pool and thawing can cause the increase of carbon outflow from Arctic river basins. During Russian-German expeditions Lena-2012 and 2013 some measurements were carried out on the catchment of the Fish Lake on Samoylovsky Island in the Lena River delta. Fish Lake is a thermokarstpolygonal lake, and the landscape of its catchment is typical for the Arctic polygonal tundra. These measurements were done in order to study the DOC income to the lake from an active layer of the catchment. Measurements of the DOC concentration in the pore water and the depth of seasonal thawing were made at 21 points in the 1,52 sq km catchment. The points were selected in different parts of the polygons to consider the heterogeneity of the landscape. Samples for DOC were analyzed in the field using a Spectro::lyser probe and in the lab with a Shimadzu TOC-L probe. In August the depth of the active layer was between 20 and 60 cm: 20-30 cm on the polygon rims, 30-60 cm in the polygon centers and near the lake. During the month when the measurements were made the depth increased by 10-15. For August the DOC concentration in the pore water of the active layer was 8-51 mg/l, for July – 5-30 mg/l, which correlates with the results of other researches in Arctic region. The changes in DOC concentration in pore water for the different thaw depth were examined. Maximum was observed on the depth 35-40 cm for July and 45-55 cm for August. So, for the same depth the variance in the concentration was the most significant. The DOC flux to the Fish Lake was calculated using the mean measured concentration and water runoff from the catchment (Ogorodnikova, 2011). The DOC daily flux to the lake is evaluated as about 0,8 kg per day and the flow rate is 0,5 kg/ km2*day, which is in ten time less than for the lake catchment of southern areas (Moore, 2003). Prolongation of field measurements is necessary for reasons clarifying and for better understanding of DOC flux formation processes under different conditions including thawing increase.About 25 % of the land mass of northern hemisphere is underlain by permafrost, which is one of the largest carbon pools. Yedoma Ice Complex is a particularly ice-rich type of permafrost. As a consequence of rapid climate warming of the Arctic, permafrost is affected by degradation processes like thermokarst. Thereby organic carbon is partially dissolved (DOC) in thermokarst lakes, and transported via rivers into the Arctic Ocean. On this way, large parts of DOC are mineralized by microbial processes and emitted as CO2 and CH4 to the atmosphere. The influence of different landforms in thermokarst affected permafrost regions on DOC concentration has not been thoroughly investigated. Addressing this research gap, this thesis examined the relationship between landscape units, water chemistry and hydrology for a small study site in the Lena River Delta, Siberia. On the basis of GeoEye satellite imagery eight landscape units were determined. These include thermokarst lakes and streams on the first terrace and on Yedoma Ice Complex, Yedoma Ice Complex streams, which are fed by the Ice Complex, Yedoma Ice Complex uplands, first terrace relict lake, and the Olenyokskaya Channel. Concerning pH value, electrical conductivity, isotopic composition and DOC concentration summer surface water samples and soil water samples of 2013 and 2014 were analyzed. These analyzes revealed that the system of the thermokarst lake Lucky Lake, its drainage flow path and source waters on Yedoma Ice Complex, is divided by landscape units. Source waters show significantly higher DOC concentrations and lower electrical conductivity than Lucky Lake and the drainage flow path. This suggests that labile organic carbon of Yedoma Ice Complex reaches the lake by degradation. Yedoma Ice Complex lake processes, despite evaporation, further reduce DOC concentration rapidly, probably by mineralization of labile DOC. Along the drainage flow path no further decrease of DOC concentration was observed, despite of changing discharge. Using discharge data of 2013 a DOC flux of about 220 kg in 29 days for the study site was calculated. A temporal variability of DOC concentration during the sampling periods was not determined using the utilized data.Methane emissions from northern high latitude wetlands are one of the largest natural sources of atmospheric methane, contributing an estimated 20% of the natural terrestrial methane emissions to the atmosphere. Methane fluxes vary among wetland types and are generally higher in peatlands, wetlands with > 40 cm of organic soil, than in wetlands with mineral soils. However, permafrost aggradation in peatlands reduces methane fluxes through the drying of the peat surface, which can decrease both methane production and increase methane oxidation within the peat. We reconstruct methane emissions from peatlands during the Holocene using a synthesis of peatland environmental classes determined from plant macrofossil records in peat cores from > 250 sites across the pan-arctic. We find methane emissions from peatlands decreased by 20% during the Little Ice Age due to the aggradation of permafrost within peatlands during this period. These bottom-up estimates of methane emissions for the present day are in agreement with other regional estimates and are significantly lower than the peak in peatland methane emissions 1300 years before present. Our results indicate that methane emissions from high latitude wetlands have been an important contributor to atmospheric methane concentrations during the Holocene and will likely change in the future with permafrost thaw.Situated in the Yana-Highlands, the Batagai profile is one of the few inland permafrost outcrops in Yakutia and, for the time being, the biggest and most active thermoerosional cirque worldwide. With Yerkhoyansk recorded as place of the pole of cold, the Yana Highlands represent the region with the most severe climatic continentality in the northern hemisphere. In contrast to the numerous sequences in today’s coastal lowlands, the Batagai sequence was always unaffected by maritime climate influence during its formation and thus better indicates the macro-climate evolution in NE-Siberia. As result of intense thermal degradation, the outcrop formed within 30 years only and cut deep into ice-rich permafrost deposits. The 60 m deep outcrop is now about 850 m in diameter, but erosion rates as high as 15 m/year are changing the dimensions continuously. The Batagai profile thus represents a unique window into the past (and future) of ice-rich permafrost deposits in Yakutia. Field based observations have shown that the permafrost sequence consists of 4 distinct units: below a thin Holocene surface cover, a 30 meter thick Ice Complex with characteristic thick ice wedges has formed. At the base of the Ice Complex, there is an up to 2 m thick layer of plant material including large woody remains. Subjacent to this organic layer of supposedly Eemian origin, there is a horizontally stratified unit composed of silty-sand and without thick syngenetic ice wedges presumably deposited during the Middle Pleistocene. At the very base of the sequence, there appears to emerge another unit including syngenetic ice wedges. This unit was not accessible for sampling. The accessible upper about 45 meter of the sequence were sampled from top to bottom in one meter steps using, due to the difficult accessibility of the permafrost wall, thermokarst mounds in the less steep part of the outcrop. The samples were taken for sedimentological analyses and especially for plant macrofossil and other palaeoecological studies. Whereas sediments give insight into the genesis of the sequence, fossil plant macroremains provide information on local vegetation patterns and habitats at the time of deposition; while palynological analyses reflect the regional vegetation and climate history. First palaeobotanical results will be represented in Session 13: Palaeoenvironments in permafrost affected areas. The sedimentological analyses revealed that, despite clearly delimitable bedding units visible at the outcrop, there is no distinct litho-stratigraphical differentiation recognizable in the grain size distribution or other sedimentological parameters. Accordingly, the sequence is characterized by a grain size signature typical for Ice Complex deposits. In comparison to other Yakutian ice-rich permafrost sequences, e.g. in the coastal lowlands, the Batagai profile is however distinguished by a higher fraction of fine sand over the whole recorded sequence. This might be due to increased aeolian deposition from local sources, e.g. from barren ridges in the highlands uncovered by vegetation. The assumption that aeolian deposition played a substantial role in the formation of the sequence is also suggested by impressive dunes in the immediate vicinity of the profile at the boundary of Batagai city.The interaction and feedbacks between surface water and permafrost are fundamental processes shaping the surface of continuous permafrost landscapes. Lake-rich regions of Arctic lowlands, such as coastal plains of northern Alaska, Siberia, and Northwest Canada, where shallow thermokarst lakes often cover 20-40% of the land surface are a pronounced example of these permafrost processes. In these same Arctic coastal regions, current rates of near-surface atmospheric warming are extremely high, 0.8 °C / decade for example in Barrow, Alaska, primarily due to reductions in sea ice extent (Wendler et al., 2014). The thermal response of permafrost over recent decades is also rapid, warming approximately 0.6°C / decade for example at Deadhorse, Alaska, yet this permafrost is still very cold, less than -6°C (Romanovsky et al., 2015). The temperature departure created by water in lakes set in permafrost is well recognized and where mean annual bed temperatures (MABT) are above 0 °C, a talik develops (Brewer, 1958). The critical depth of water in lakes where taliks form is generally in excess of maximum ice thickness, which has historically been around 2 m in northern Alaska. Thus, lakes that are shallower than the maximum ice thickness, which are the majority of water bodies in many Arctic coastal lowlands, should maintain sublake permafrost and have a shallow active layer if MABT’s are below freezing. Recent analysis, however, suggests a lake ice thinning trend of 0.15 m / decade for lakes on the Barrow Peninsula, such that the maximum ice thickness has shifted to less than 1.5 m since the early 2000’s. We hypothesized that the surface areas most sensitive to Arctic climate warming are below lakes with depths that are near or just below this critical maximum ice thickness threshold primarily because of changing winter climate and reduced ice growth. This hypothesis was tested using field observations of MABT, ice thickness, and water depth collected from lakes of varying depths and climatic zones on the coastal plain and foothills of northern Alaska. A model was developed to explain variation in lake MABT by partitioning the controlling processes between ice-covered and open-water periods. As expected, variation in air temperature explained a high amount of variation in bed temperature (72%) and this was improved to 80% by including lake depth in this model. Bed temperature during the much longer ice-covered period, however, was controlled by lake depth relative to regional maximum ice thickness, termed the Effective Depth Ratio (EDR). A piecewise linear regression model of EDR explained 96% of the variation in bed temperature with key EDR breaks identified at 0.75 and 1.9. These breaks may be physically meaningful towards understanding the processes linking lake ice to bed temperatures and sublake permafrost thaw. For example if regional lake ice grows to 1.5 m thick, the first break is at lake depth of 1.1 m, which will freeze by mid-winter and may separate lakes with active-layers from lakes with shallow taliks. The second EDR break for the same ice thickness is at a lake depth of 2.9 m, which may represent the depth where winter thermal stratification becomes notable (greater than 1 °C) and possibly indicative of lakes that have well developed taliks that store and release more heat. We then combined these ice-covered and open-water models to evaluate the sensitivity of MABT to varying lake and climate forcing scenarios and hindcast longer-term patterns of lake bed warming. This analysis showed that MABT in shallow lakes were most sensitive to changes in ice thickness, whereas ice thickness had minimal impact on deeper lakes and variation in summer air temperature had a very small impact on MABT across all lake depths. Using this model, forced with Barrow climate data, suggests that shallow lake beds (1-m depth) have warmed substantially over the last 30 years (0.8 °C / decade) and more importantly now have an MABT that exceeds 0 °C. Deeper lake beds (3-m depth), however, are suggested to be warming at a much slower rate (0.3 °C / decade), compared to both air temperature (0.8 °C/ decade) and permafrost (0.6 °C/ decade). This contrasting sensitivity and responses of lake thermal regimes relative to surrounding permafrost thermal regimes paint a dramatic and dynamic picture of an evolving Arctic land surface as climate change progresses. We suggest that the most rapid areas of permafrost degradation in Arctic coastal lowlands are below shallow lakes and this response is driven primarily by changing winter conditions. References: Brewer, M. C. (1958), The thermal regime of an arctic lake, Transactions of the American Geophysical Union, 39, 278-284. Romanovsky, V. E., S. L. Smith, H. H. Christiansen, N. I. Shiklomanov, D. A. Streletskiy, D. S. Drozdov, G. V. Malkova, N. G. Oberman, A. L. Kholodov, and S. S. Marchenko, (2015). The Arctic Terrestrial Permafrost in “State of the Climate in 2014” . Bulletin of the American Meteorological Society, 96, 7, 139-S141, 2015 Wendler, G., B. Moore, and K. Galloway (2014), Strong temperature increase and shrinking sea ice in Arctic Alaska, The Open Atmospheric Science Journal, 8, 7-15.Rapid temperature rise during recent decades (IPCC 2013) is causing permafrost in the Arctic to warm and thaw. This thaw exposes previously frozen soil organic carbon (SOC) to microbial decomposition, generating greenhouse gases methane (CH4) and carbon dioxide (CO2) in a feedback process that leads to further warming and thaw. A growing number of studies model the future permafrost carbon feedback (PCF) to climate warming [Koven et al., 2015, Schneider von Deimling et al., 2015]. However, despite observations of widespread permafrost thaw during recent decades and forecasts of thaw during the next 25-100 years [Koven et al., 2015], no research has quantified the PCF for recent decades. This is in part due to the difficulty of detecting the net movement of old carbon from permafrost to the atmosphere over years and decades amidst large input and output fluxes from ecosystem carbon exchange. In contrast to terrestrial environments, thermokarst lakes provide a direct conduit for processing and emission of old permafrost carbon to the atmosphere, and these emissions are more readily detectable. Results here are based on Walter Anthony et al. [submitted], whereby we quantified the permafrost SOC input to a variety of thermokarst and glacial lakes in Alaska and Siberia in thermokarst zones, defined as areas where land surfaces have transitioned to open lakes due to permafrost thaw during the past 60 years, the historical period most commonly covered by remote-sensing data sets. We also quantified the resulting methane emitted from these active thermokarst lake zones. Using field work, numerical modeling of thaw bulbs, remote sensing and spatial data analysis we will report on the relationship between methane emissions from thermokarst zones and SOC inputs to lakes across gradients of permafrost and climate in Alaska. We will also define the relationship between radiocarbon ages of methane and permafrost soil carbon entering into lakes upon thaw. We will report on the presentday PCF relationship between thaw of permafrost SOC and resulting greenhouse gas release. An extrapolation of our results to the panarctic permafrost region will be presented and compared to permafrost carbon mass balance approaches. The fraction of the terrestrial permafrost carbon pool that has been released as methane from thermokarst along lake margins during the past 60 years will be evaluated relative to early Holocene thermokarst lake emissions and projected permafrost carbon emissions by year 2100. The data will be placed in the context of large regional temperature increases in the Arctic, up to 7.5 °C by 2100, and thicker, organic-rich Holocene-aged deposits subject to thaw and aerobic decomposition as active layer deepens. We will report on the inflection of large permafrost carbon emissions that is imminently expected to occur and whether or not it has commenced. References: Koven, C.D.; Schuur, E.A.G.; Schadel, C.; Bohn, T.J.; Burke, E.J.; Chen, G.; Chen, X.; Ciais, P.; Grosse, G.; Harden, J.W.; Hayes, D.J.; Hugelius, G.; Jafarov, E.E.; Krinner, G.; Kuhry, P.; Lawrence, D.M.; MacDougall, A.H.; Marchenko, S.S.; McGuire, A.D.; Natali, S.M.; Nicolsky, D.J.; Olefeldt, D.; Peng, S.; Romanovsky, V.E.; Schaefer, K.M.; Strauss, J.; Treat, C.C. and Turetsky, M. [2015]: A simplified, data-constrained approach to estimate the permafrost carbon–climate feedback. Trans. R. Soc. A, 373, doi:10.1098/rsta.2014.0423. Schneider von Deimling, T.; Grosse, G.; Strauss, J.; Schirrmeister, L.; Morgenstern, A.; Schaphoff, S.; Meinshausen, M. and Boike, J. [2015]: Observationbased modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity. Biogeosciences, 12(11):3469–3488, doi:10.5194/bg-12-3469-2015. Walter Anthony, K.; Daanen, R.; Anthony, P.; Schneider von Deimling, T.; Ping, C.-L.; Chanton, J. and Grosse, G. [submitted]: Ancient methane emissions from ˜60 years of permafrost thaw in arctic lakes.Vast parts of Arctic Siberia are underlain by ice-rich permafrost, which is exposed to different processes of degradation due to global warming. Thermal erosion as a key process for landscape degradation in these regions causes the recent reactivation and formation of new landforms like thermo-erosional valleys and gullies. However, a statistical assessment about the decisive factors and the locations most susceptible to this phenomenon is still missing. We investigated the influence of different environmental parameters on the occurrence of recently observed thermal erosion using a GIS-based approach and statistical modeling by logistic regression. The study site is located on an island within the Arctic Lena River Delta and is mainly composed of ice- and organic-rich deposits of the Yedomatype Ice Complex. Field surveys and mapping on the basis of high-resolution remotely sensed data revealed that thermal erosion occurs predominantly i) on very steep slopes along the margins of the island, ii) in the upper reaches of deeply incised valleys and iii) in gullies. In order to detect the regulation factors for those thermo-erosional landforms, we derived several environmental parameters using a high-resolution DEM and satellite imagery. We chose a stepwise logistic regression approach to reduce the full set of potential parameters. This approach allowed the selection of a parsimonious model, i.e. a best-fit model using as few parameters as possible. The parameters Contribution of warm open surface water, Relief ratio, Direct solar radiation and Snow accumulation turned out to be the decisive factors for thermal erosion. Uncertainties in the model due to sampling and model selection were valuated both statistically and spatially through the generation of 100 models. Receiver Operating Characteristics (ROCs) were used to validate the spatial predictive capability of each model run. The consensus map as the median of all 100 susceptibility models represents the final susceptibility map. The agreement between mapped and predicted erosion turned out to be generally very high within the study site, confirmed by an Area under the ROC curve (AUC) of 0.957 for the consensus map. The variability of predicted erosion probabilities between the single models is about four percentage points per cell within the study site and thus, very low. We attributed the slight mismatches between observed and predicted erosion to the generation of the explanatory environmental parameters and the modeling approach. Model results seem promising for the spatial prediction of susceptible sites for thermal erosion and, thus, could be a tool to explain the geomorphic forming in this rapidly changing environment. As these results are based on a single case study, future investigation should focus on the transferability of the model by applying an external validation on other sites with comparable environmental conditions.Permafrost soil organic carbon (C) in the Yedoma region comprises a large fraction of the total circumpolar permafrost C pool, yet estimates based on different approaches during the past decade have led to disagreement in the size and composition of the Yedoma region permafrost C pool. This research aims to reconcile different approaches and show that after accounting for thermokarst and fluvial erosion processes of this interglacial period, the Yedoma region C pool (456 ± 45 Pg C) is the sum of 172 ± 19 Pg Holocene-aged C and 284 ± 40 Pg Pleistocene-aged C. The size of the present-day Pleistocene-aged yedoma C pool was originally estimated to be 450 Pg based on a mean deposit thickness of 25 m, 1×106 km2 areal extent, 2.6% total organic C content, 1.65times103 kg m−3dry bulk density, and 50% volumetric ice wedge content (Zimov et al. 2006). This estimate assumed that 17% of the Last Glacial Maximum yedoma C stock was lost to greenhouse gas production and emission when 50% of yedoma thawed beneath lakes during the Holocene. However, the regional scale yedoma C pool estimate of Zimov et al. (2006) did not include any Holocene C and assumed that all of the 450 Pg C was Pleistocene-aged. In subsequent global permafrost C syntheses, soil organic C content (SOCC, kg C m−2) data from the Northern Circumpolar Soil C Database (NCSCD) and Zimov et al. (2006) were used to estimate the soil organic C pool for the Yedoma region (450 Pg), assuming only Pleistocene-aged yedoma C from 3 to 25 m (407 Pg), and a mixture of C ages in the 0 to 3 m interval (43 Pg). A more recent synthesis of Yedoma-region C stocks based on extensive sampling by Strauss et al. (2013) took into account lower C bulk density values of yedoma, higher organic C concentrations of yedoma, a larger landscape fraction of thermokarst (70% of Yedoma region area), the larger C concentration of thermokarst, and remote-sensing based quantification of ice-wedge volumes. This synthesis produced lower meanand median-based estimates of Yedoma-region C, 348+73 Pg and 211 +160/-153 Pg respectively. However, Strauss et al. (2013) focused on the remaining undisturbed yedoma and refrozen surface thermokarst deposits and thus did not include taberite deposits, which are the re-frozen remains of yedoma previously thawed beneath thermokarst lakes and still present in large quantities on the landscape. In our study (Walter Anthony et al. 2014), we measured the dry bulk density directly on 89 yedoma and 311 thermokarst-basin samples, including taberites, collected in four yedoma subregions of the North Siberian Kolyma Lowlands. Multiplying the organic matter content of an individual sample by the same sample’s measured bulk density yielded an organic C bulk density data set for yedoma samples that was normally distributed. Combining our subregion-specific organic C bulk density results with those of Strauss et al. (2013) for other yedoma subregions extending to the far western extent of Siberian yedoma, we determined a mean organic C bulk density of yedoma for the total Yedoma region (26 ± 1.5 kg C m-3), which is similar to that previously suggested by Strauss et al. (2013) (27 kg C m-3 mean based approach; 16 kg C m-3 median based approach). Our estimate of the organic C pool size of undisturbed yedoma permafrost (129 ± 30 Pg Pleistocene C) in the 396,600 ± 39,700 km2 area that has not been degraded by thermokarst since the Last Glacial Maximum (Table 1) is based on this regional-mean C bulk density value. Our calculation also assumes an average yedoma deposit thickness of 25 m and 50% volumetric massive ice wedge content, as in previous estimates (Zimov et al. 2006, NCSCD; Table 1). Similar results found in the recent study of the Yedoma-region C inventory by Strauss et al.(2013) corroborate our estimate of the undisturbed yedomaEarth’s Polar Regions are not included in the school curriculum in Saxony, SE Germany. However, in the media their role in climate change is often emphasized. Understanding the related connections is difficult for the pupils and therefore has little influence on their climate relevant behavior. Climate change and the connection to the Polar Regions could be approached multidisciplinary as a comprehensive topic in various school subjects. At the KOMPAKT School in Zwickau, twelve pupils of grade 6 were interested in permafrost as a subject and dedicated several weeks to the topic. The goals included understanding basic principles, build on those to gain specific knowledge and finally find possibilities to use this knowledge in school. In the first part of the project, the students built a simplified model that allowed studying permafrost thaw and the related consequences. These studies were accompanied by observations of thawing and freezing of different soil and vegetation samples. The students reported their observations becoming familiar with keeping records of the setup and the experiments’ outcome. They used their protocols to create a documentation of the experimental work. The cooperation with the Alfred Wegener Institute in Potsdam then allowed the pupils to connect to scientists working on permafrost, to learn about the scientific questions those scientists address, and how and where they worked on. The pupils had the pos- sibility to ask questions about fieldwork and follow up lab work during a visit at AWI in Potsdam. An additional part of the project was the collection of information from permafrost related articles in newspapers and journals. The pupils are not used to long, scientific texts, the extraction of relevant content and relating this information to their own knowledge was very difficult. One key insight of this part of the project was that results of scientific research can lead to vastly different interpretations. Complete answers, as the pupils know them from class, are not provided. Rather, scientific research means to discuss results from different perspectives to struggle together for realistic explanations of nature phenomena. In the final stage of the project, the pupils took part in an excursion to Westerwald around Dornburg, where phenomena related to freezing processes could be observed in- situ. The pupils were encouraged to find explanations for their observations themselves. Some theories were astonishingly accurate. During the project, we always discussed the respons- ibility that each of us has towards the protection of nature. Do we have influence on nature at all? Are children and teenager also affected? This discussion is carried on beyond the project. All participating students are now encouraged to take part in the dis- cussion with their new insights from the classroom exercises. They can also better relate to the public discussion of climate change. They learned new ways to pose questions and that at times, it can be dif- ficult to obtain answers. They have worked on one specific subject during a long time and are now able to stimulate discussion in class whenever permafrost or Earth’s climate are topics. They can resort to the results of their own model and experiments and their observations as well. They can give information to others and maybe intrigue them with the subject. From this point of view, the project was a complete success.Under future climate change scenarios, Arctic coastal waters are believed to receive higher terrestrial organic matter (OM) fluxes. Permafrost carbon is increasingly mobilized upon thaw from rivers draining permafrost terrain and from eroding permafrost coasts. Once received, the coastal waters are the transformation zone for terrestrial OM, although quantities, especially those of dissolved organic matter (DOM) released by coastal erosion, are largely unknown. This nearshore zone plays a crucial role in Arctic biogeochemical cycling, as here the released material is destined to be (1) mineralized into greenhouse gases, (2) incorporated into marine primary production, (3) buried in nearshore sediments or (4) transported offshore. In this presentation, we show data on DOM quantities in surface water in the nearshore zone of the southern Beaufort Sea from two consecutive summer seasons under different meteorological conditions. Colored dissolved organic matter (cDOM) properties help to differentiate the terrestrial from the marine DOM component. Figure 1 shows DOC concentrations and salinities for 23 and 24 days in the summer seasons of 2013 and 2014, respectively. DOC concentrations in the nearshore zone of the southern Beaufort Sea vary between about 1.5 and 5 mg C L-1. In the Lena River Delta, bay water, river water, and permafrost meltwater creeks yielded similar values between 5.8 and 5.9 mg C L-1 (Dubinenkov et al., 2015). Similarly, Fritz et al. (2015) found DOC concentrations in ice wedges between 1.6 and 28.6 mg C L-1. In 2013, the first half of July was characterized by low salinity between 8 and 15 psu and high DOC concentrations of 3.5 to 5 mg C L-1. Then, a sudden change in water properties occurred after a major storm which lasted for at least 2 days. This storm led to strongly decreased DOC (1.5 to 2.5 mg C L-1) concentration and increasing salinity (14 to 28 psu) in surface water, probably due to upwelling In 2014, a more stable situation in both salinity and DOC prevailed, with relatively high salinity (23 to 29 psu) and low DOC concentration (1.5 to 2.5 mg C L-1). This pattern was due to rather windy and wavy conditions throughout the whole season. The water column in 2014 was likely well-mixed and DOC-poor because saline waters have probably been transported from the offshore to the nearshore. We recognized a significant negative correlation between DOC and salinity, independent from varying meteorological conditions. In general, this suggests a conservative mixing between DOC derived from terrestrial/permafrost runoff and marine DOC. The low salinity in July 2013 was probably due to prolonged sea-ice presence in the sampled area. This leads to the assumption that DOC also originates from melting sea ice. Quantitatively more important will be terrestrial runoff which is relatively rich in DOC. A stable stratification in the nearshore zone and calm weather conditions will increase the influence of terrestrial-derived DOM. The strength of the terrestrial influence can be estimated by salinity measures as they directly correlate with DOC concentrations; the lower the salinity the stronger the terrestrial influence. We conclude that the terrestrial imprint of coastal erosion on DOM concentrations in the nearshore zone is significant. We see that DOC concentrations are significantly elevated also compared to riverine input in front of river mouths and deltas. Meteorological conditions play a major role for the strength of the terrestrial DOM signal, which can vary on short timescales. Our approach is different from ship-based oceanography because we study DOM that is directly derived from thawing permafrost coasts, explicitly excluding rivers. When qualifying DOM origin from permafrost landscapes apart from rivers we have to take into consideration the different DOM mobilization pathways. 1) Surface runoff and near-surface groundwater flow mainly drain and flush the active layer. 2) Melting ground ice releases DOM. 3) Ground ice meltwater leaches DOM from sedimentary OM upon permafrost thaw on land. 4) DOM is leached from sedimentary OM upon contact with sea water. The latter three will mobilize old OM which is believed to be highly bioavailable (see Vonk et al., 2013a, b). References: Dubinenkov, I., Flerus, R., Schmitt-Kopplin, P., Kattner, G., Koch, B.P., 2015. Origin-specific molecular signatures of dissolved organic matter in the Lena Delta. Biogeochemistry 123, 1-14. Fritz, M., Opel, T., Tanski, G., Herzschuh, U., Meyer, H., Eulenburg, A., Lantuit, H., 2015. Dissolved organic carbon (DOC) in Arctic ground ice. The Cryosphere 9, 737-752. Vonk, J.E., Mann, P.J., Davydov, S., Davydova, A., Spencer, R.G.M., Schade, J., Sobczak, W.V., Zimov, N., Zimov, S., Bulygina, E., Eglinton, T.I., Holmes, R.M., 2013a. High biolability of ancient permafrost carbon upon thaw. Geophysical Research Letters 40, 2689-2693. Vonk, J.E., Mann, P.J., Dowdy, K.L., Davydova, A., Davydov, S.P., Zimov, N., Spencer, R.G.M., Bulygina, E.B., Eglinton, T.I., Holmes, R.M., 2013b. Dissolved organic carbon loss from Yedoma permafrost amplified by ice wedge thaw. Environmental Research Letters 8, 035023.Thermokarst lakes are important factors for permafrost landscape dynamics and carbon cycling. Thermokarst lake cover is especially high in Arctic lowlands with ice-rich permafrost. In most of these regions, multiple lake generations have been identified that overlap each other in space and time, giving rise to the hypothesis of thermokarst lake cycling and its association with complex cryostratigraphical conditions where multiple lacustrine and palustrine sequences may follow on top of each other and talik and carbon cycle histories are complicated. In northwestern Alaska on the northern Seward Peninsula, ice-rich permafrost lowlands have strongly been affected by thermokarst during the Holocene and up to six generations of lake basins overlap spatially (Jones et al., 2012). Modern thermokarst lakes are also abundant in this region and expand gradually by thermo-erosion along shores (Jones et al., 2011). We here report on the analysis of multi-temporal remote sensing data for a 12,200 km2 lowland area in the relatively warm continuous permafrost zone of the northern Seward Peninsula, demonstrating that thermokarst lake drainage in this region was occurring on a massive scale from 1949-2015. Contrary to most previous studies that suggest an increase in thermokarst lake area in continuous permafrost, we observed a significant net decrease in thermokarst lake area largely due to catastrophic lake drainage. Lateral lake expansion by thermo-erosion continued but did not offset the net area loss. Climate data analysis revealed a potential correlation with increased winter precipitation that may have resulted in a combination of high lake water levels, increased spring runoff with higher potential for drainage channel formation, and near-surface permafrost degradation, ultimately enhancing lake drainage. The observed magnitude of lake drainage implicates strong and lasting impacts on regional hydrology, biogeochemical cycling, surface energy budgets, state of the permafrost, ecosystem character, waterfowl and fish habitats, and subsistence lifestyles in the study region, portions of which belong to the Bering Land Bridge National Preserve. The datasets used in this analysis include a wide range of remote sensing images and topographic data available for this region, such as aerial photography, historic topographic maps, high resolution satellite images (Corona, Spot, Ikonos, Quickbird, Worldview, GeoEye), and the full Landsat archive. Field studies included reconnaissance flights targeting freshly drained lakes and ground based data collection such as lake basin coring. Our findings suggest that a significant portion of lakes in this region has drained over the last decades and that in particular large lakes are vulnerable to disappearance. Initial analyses of relationships of lake drainages with permafrost distribution in the region suggest positive correlations between lake loss and permafrost degradation in much of the region. Our findings highlight that permafrost and lake-rich landscapes in Alaska are already changing rapidly and permanently in a warming world. This set of studies was supported by funding from NASA Carbon Cycle Sciences, NSF Arctic System Sciences, the European Research Council, and the Western Alaska Landscape Conservation Cooperative. References: Jones B, Grosse G, Arp CD, Jones MC, Walter Anthony KM, Romanovsky VE (2011): Modern thermokarst lake dynamics in the continuous permafrost zone, northern Seward Peninsula, Alaska. Journal of Geophysical Research – Biogeosciences, 116, G00M03. Jones MC, Grosse G, Jones BM, Walter Anthony KM (2012): Peat accumulation in a thermokarstaffected landscape in continuous ice-rich permafrost, Seward Peninsula, Alaska. Journal of Geophysical Research – Biogeosciences, 117, G00M07.Preface The Local Organizing Committee (LOC) of the Eleventh International Conference on Permafrost (ICOP2016) is excited about the breadth and the quality of the abstracts submitted for this conference. It was the first time that ICOP topical sessions were not set by the organizing committee in a top-down manner. Instead, sessions were submitted from the bottom-up by groups of researchers and engineers from all over the world. This grassroots effort prompted the submission of many innovative topics covering the full range of modern permafrost research. It also facilitated not only the engagement of the core permafrost community, but also of science disciplines traditionally less involved in ICOPs. In total, 51 session proposals were received by the LOC. These were submitted by up to three conveners including at least one early career researcher from the Permafrost Young Researchers Network (PYRN). After the evaluation process by the International Scientific Committee (ISC) and the LOC, including the addition of strategic topics and the combination of sessions with thematic overlap, 40 topical sessions were eventually opened for abstract submission. There was yet another novelty compared to previous ICOPs: the submission of contributions was not divided into abstracts and papers, in favor of a quicker and uniform review process allowing for the submission deadline to be set closer to the conference. This opened the possibility for authors to present recent results in the rapidly evolving field of permafrost research. Abstracts of up to 3000 words were allowed, either plain or formatted with subheadings, and including one figure, table or equation. We received the extraordinary number of 980 abstracts. This number varied between 79 and 0 among sessions, which led to a further consolidation into the final set of 32 sessions presented in this abstract volume. Abstract evaluation was placed in the hands of the session conveners. The vast majority of abstracts (97 %) was deemed eligible to be accepted for presentation during the conference, either immediately or after revision by the authors. The reduced number of abstracts presented in this volume is mostly due to the inability of travelling to the conference for some authors. We are very delighted that the modified procedures for the compilation of the scientific conference program proved so successful and wish to extend our gratitude to the session conveners and ISC members for their tremendous efforts and great support in compiling such a high-quality program. We also wish to thank Hans-Wolfgang Hubberten, Lydia Polakowski, Matthias Fuchs, Ingmar Nitze, Samuel Stettner, Karina Schollaen, Hugues Lantuit, and Guido Grosse for their technical help in the final editing phase of this abstract volume. Frank Gunther and Anne MorgensternFreshwater ostracods (Crustacea, Ostracoda) are of interest in modern biological studies, while fossil records of ostracod valves enable us to reconstruct past lacustrine environments. The about 1mm long crustaceans carry a calcite carapace that is biomineralized from dissolved components in the ambient water, and completely envelopes their body. Ostracods inhabit almost all aquatic environments, even shallow freshwater ponds in the vast circumartic permafrost areas. In high-latitude areas, ostracod species diversity, their modern ecological demands, and instrumental records of environmental parameters are only scarcely documented. Such reference information is the key to quantitatively reconstruct past environments from fossil ostracod assemblages. This gap in ostracod data limits their use as biological indicators in the Arctic, where the effects of future climate warming are expected to be strongest. The objective of the study presented here was to extend the data set on arctic freshwater ostracods and environmental records by characterizing presentday habitat conditions, abundance and diversity of ostracod assemblages in periglacial freshwaters on Svalbard. The aims of this project were 1. to conduct an inventory of the abundance, diversity and ecological ranges of the freshwater ostracods living in polygon ponds in Adventdalen near Longyearbyen (78°11’11”N, 15°55’20”E), 2. to determine the present-day hydrochemical and sedimentary characteristics of ostracod habitats, and 3. to witness temporal variability in a polygon pond during the Arctic summer season 2013. The study site was located near the University Centre on Svalbard (UNIS)-run monitoring site for thermal contraction cracking in ice-wedge polygons on a river terrace in outer Adventdalen (Christiansen 2005). Permafrost on Svalbard is estimated to be of late Holocene age with temperatures of -5.2 to -5.6 °C in boreholes in the Adventdalen area (Christiansen et al. 2010). Ice-wedge polygons form in cold-climate environments under permafrost conditions and are the most common periglacial patterned ground features in the Arctic (Minke et al. 2007). Since the permafrost table efficiently blocks drainage pathways, surface depressions hold ponding water during summer, and freeze solid in winter. Those shallow periglacial surface freshwaters, called polygon ponds, are hotspots of biological activity in the otherwise hostile tundra. They provide diverse habitats to aquatic communities including freshwater ostracods. For this study, we choose an area with polygon ponds that are known to persist during the summer season. Our sampling scheme of 13 ponds in total comprised collecting freshwater ostracod individuals, pond water and sediment samples. One species, Tonnacypris glacialis (SARS, 1890), was found in only one of the sampled sites, the pond AD-01 (Fig. 1). Continuous water temperature records directly below the water surface in AD-01, and at the sediment surface in about 25cm water depth were collected between July 20 and September 25, 2013. We measured water and thaw depth in the pond centre and the thaw depth of the surrounding polygon rim. The last record at September 25, 2013 completed the observation season with the presence of 2-3cm lake ice. Preliminary results suggest the pond water is welloxygenated and dilute with slightly acidic pH. The hydrochemical fingerprint and sedimentary characteristics of inter- and intrapolygon ponds may allow a differentiation between the two subtypes for the first time, and are subject of ongoing work. Active-layer thickness was around 40-100 cmin polygon rims, we measured about 50-80 cm thaw depth under pond centres. A considerable increase in water surface area extend occurred in the monitored pond after a rain period. The records obtained from this and similar studies in the Siberian Arctic demonstrate that small and shallow periglacial surface waters are sensitive to local permafrost and climate variations. References Christiansen HH. 2005. Thermal regime of icewedge cracking in Adventdalen, Svalbard. Permafrost and Periglacial Processes 16: 87-98. Christiansen HH, Etzelmuller B, Isaksen K, Juliussen H, Farbrot H, Humlum O, Johansson M, Ingeman-Nielsen T, Kristensen L, Hjort J, Holmlund P, Sannel ABK, Sigsgaard C, Akerman HJ, Foged N, Blikra LH, Pernosky MA, Odegard RS. 2010. The thermal state of permafrost in the Nordic Area during the International Polar Year 2007–2009. Permafrost and Periglacial Processes 21: 156–181. Minke M, Donner N, Karpov N, de Klerk P, Joosten H. 2007. Distribution, diversity, development and dynamics of polygon mires: examples from Northeast Yakutia (NE Siberia). Peatlands International 1: 36-40.Ground-penetrating radar (GPR) reflection imaging is a popular geophysical tool to explore subsurface structures in a non-invasive manner. In terms of GPR, reflective interfaces are defined by contrasts in dielectric permittivity, which result from, for example, variations in soil moisture or ice content. GPR is very suitable for electrically high resistive environments, such as frozen ground (typically > 10,000 m). Here, GPR can be used to explore structural targets at depths up to tens of meters. Furthermore, GPR can be employed to explore more shallow environments where detailed information on the decimeter scale is required. In consequence, 2D GPR reflection profiling is used on different spatial scales in permafrost applications such as active layer characterization and imaging of pingos. However, a 3D strategy might be essential for obtaining a reliable image of subsurface structures, if the geometry of such targets is complex (e.g., structures vary in three dimensions). Additionally, 3D data allow to identify out-of-plane reflection events which might interfere with reflections from target structures. This advantage is especially interesting for the application of GPR in cold environments, where out-of-plane reflections are favored due to a broadened radiation characteristic of GPR antennas on frozen ground compared to unfrozen ground. Here, we present a carefully designed 3D GPR acquisition and processing strategy (Schennen et al., 2016) and employ it to an exemplary data set. Our field site covers an area of approximately 20 m×70 m and is located on top of a Yedoma hill on Bol’shoy Lyakhovsky Island, Northern Siberia. Nearby borehole information provides cryostratigraphic details (up to a depth of approximately 30 m) interpreted in terms of three major stratigraphic units. These comprise two ice complex strata, which enclose a unit of floodplain deposits. Additional ground-truth is available from a 18 m high outcrop of the upper ice complex next to our survey area. Here, we observe large (up to 10 m wide) ice-wedges segmenting the ice- and organic-rich, loess-like sediments. In our unmigrated 3D GPR data, time slices show distinct circular diffraction features. As we move on to succeeding slices, we observe that these features originate from locations below thermokarst mounds, expand with a velocity of 0.17 m/ns, and interfere with each other at later traveltimes (Fig. 1a-d). They result in a complex 3D distribution of diffracted energy evident in the entire data cube. Thus, a 3D migration approach (e.g., Allroggen et al., 2014) is essential to correctly image subsurface structures. Thereby we consider also topographic variations and possible subsurface velocity variations. In our migration result, we observe two distinct horizontal features at depths larger than 20 m. Taking borehole data into account, we interpret these features as the base of the upper ice complex unit and the underlying floodplain deposits, respectively. Furthermore, we are able to trace both interfaces in our data cube and compile our interpretation into a 3D cryostratigraphic model (Fig. 1e), which can be used to scale up borehole and outcrop information. In a concluding 2D vs. 3D comparison, we extract exemplary 2D profiles from our unprocessed 3D data to simulate a 2D GPR acquisition and processing strategy on the same field site. Thus, we are able to investigate the impact of data reduction on each processing step. Comparing results of our 2D and 3D processing strategies demonstrate, that a 3D GPR surveying and processing strategy is critical in complex permafrost settings. Allroggen N, Tronicke J, Delock M, Boniger U. 2014. Topographic migration of 2D and 3D groundpenetrating radar data considering variable velocities. Near Surface Geophysics 13: 253-259.DOI: 10.3997/1873-0604.2014037 Schennen S, Tronicke J, Wetterich S, Allroggen N, Schwamborn G, Schirrmeister L. 2016. 3D GPR imaging of ice complex deposits in northern East Siberia. Geophysics, 81: 1-9.DOI: 10.1190/GEO2015-0129.1The Lena River delta is one of the hydrologically entertaining objects. Hundreds channels and thousands lakes as well as thawing ice complex and permafrost active layer dynamic allow to investigate spatial-temporal coherence of different scale hydrological processes. During 15 years Russian-German scientific collaboration on hydrological, hydrochemical and hydrobiological studies have been operated on different water objects for cause-effect relation of large and specific micro processes indication. Transient liquid-frozen water phase change is significant not only for active layer runoff forming but also for hydrochemical and biological specific. Thus, maximum of DOC is in the overlaying soil layer than permafrost border [Bobrova et al., 2013]. It could be used for modeling of runoff forming and biological activity estimation. Measured temperature of lacustrine bottom sediment of one thermokarst lake on Samoylov Island shows maximal volume 3,7 °C on 1,75 cm beneath water-sediment border [Skorospekhova, 2015]. It is also can be interpreted as biological processes activity, for example, organic material destruction with additional heating. It could be observed more detail and can be used for modeling of a lake thermic regime. Hydrobiological specificity shows similarity of species in the channels and lakes, poorness of biodiversity, especially in big channel; only stagnant in summer season Bulkurskaya channel has more zooplankton species in four times than the main river channel [Nigamatzyanova et al., 2015]. Decline of water turbidity from the delta top to channel edges is about 5-8 times [Charkin et al., 2009]. Considerable turbidity increase is formed according to permafrost thawing and can reach 500 g l-1 including high concentration of carbon and biogenic elements. Thermokarst lake degradation [Morgenstern et al., 2011] plays also an important role for permafrost hydrology in the delta. Outflow from an ice complex forms a high local suspended supply in adjacent river branches and influences on biological processes consequently [Dubinenkov et al., 2015]. Underestimated effect of water and sediment discharge increase in the middle part of river branches had been marked [Fedorova et al., 2015]. Head flux of the large Lena River forms taliks under channels with more sophisticated affect in the shoreline zone of the Laptev Sea due to aquifer dynamic and mixing of fresh and salt water. Talik effect on hydrology and sedimentation (and suspended material transformation) in the central part of the delta is currently carried out according to geophysical and hydrogeological methods. First field measurements are planned to be done in April 2016 and results will be presented in the ICOP 2016. The studies have been done with support of RFBR grant 14-05-00787 and 15-35-50949, in the framework of Russian-German projects “ CarboPerm” and “Scientific station “Samoylov Island”. The project for both SPBU and DFG funding had also applied for field and scientific investigation as well. References Bobrova, O.; Fedorova, I.; Chetverova, A.; Runkle, B. and Potapova, T. Input of Dissolved Organic Carbon for Typical Lakes in Tundra Based on Field Data of the Expedition Lena–2012. In Proceedings of the 19th International Northern Research Basins Symposium and Workshop, Southcentral Alaska, USA – August 11–17, 2013, 2013. Charkin, A.N.; Dudarev, O.V.; Semiletov, I.P.; Fedorova, I.; Chetverova, A.A.; J., Vonk; Sanchez- Garcia, L.; Gustafsson, o. and Andersson, P. edimentation in the System of the Delta Lena River - the South Western Part of Buor-Haya Gulf (the Laptev Sea). In The 16th International Symposium on Polar Sciences. Incheon, Korea. 2009, 2009. Dubinenkov, I.; Flerus, R.; Schmitt-Kopplin, P.; Kattner, G. and Koch, B.P. [2015]: Origin-specific molecular signatures of dissolved organic matter in the Lena Delta. Biogeochemistry, 123(1):1–14, doi:10.1007/s10533-014-0049-0. Fedorova, I.; Chetverova, A.; Bolshiyanov, D.; Makarov, A.; Boike, J.; Heim, B.; Morgenstern, A.; Overduin, P. P.; Wegner, C.; Kashina, V.; Eulenburg, A.; Dobrotina, E. and Sidorina, I. [2015]: Lena delta hydrology and geochemistry: long-term hydrological data and recent field observations. Biogeosciences, 12(2):345–363, doi:10.5194/bg-12-345-2015. Morgenstern, A.; Grosse, G.; Gunther, F.; Fedorova, I. and Schirrmeister, L. [2011]: Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta. The Cryosphere, 5(4):849–867, doi:10.5194/tc-5-849-2011. Nigamatzyanova, G.; Frolova, L.; Chetverova, A. and Fedorova, I. Hydrobiological investigation of branches of the Lena River edge zone. In Uchenye Zapiski Kazanskogo Universiteta, Seriya Estestvennye Nauki. 2015. in Russian. Skorospekhova, T. Report of a spring campaign of the expedition “Lena 2015”. AARI’s library stock, 2015.Polygon tundra with tundra-steppe vegetation cover and growing syngenetic ice-wedge nets evolved during stadial and interstadial periods of the late Quaternary in non-glaciated Beringia. The depositional relict of such environments is called Ice Complex (IC; ледовый комплекс [ledovyi kompleks] in Russian) permafrost. The IC archives preserve information of past periglacial and climate landscape conditions of mid- and late Pleistocene Beringian environments. In certain locations of the East Siberian Arctic, IC remnants of different age and extent are known. While using IC deposits as archives of palaeo-landscape and palaeo-environmental dynamics, summer and winter conditions over large time-scales are detectable. Commonly applied summer proxy include palaeontological proxy such as pollen, plant macrofossils, insect fossils and, most prominent, mammal fossils of the Mammoth fauna, while geochemical and stable isotope properties of ground ice allow for insights into freezing and winter conditions. IC chronologies are challenging because the deposition and post-sedimentary preservation of ice-rich permafrost are triggered by palaeo-relief settings and related processes as well as by the intensity of thermokarst. This complicates geochronological interpretations, as representatives of consecutive late Quaternary periods may be found at laterally different positions and altitudes in coastal and riverine exposures. Shifts between permafrost aggradation and degradation over time frequently cause gaps in sequences. Furthermore, numerical dating of IC mainly includes different approaches such as radiocarbon (14C) dating of organic material, infrared and optically-stimulated luminescence (IRSL, OSL) dating on feldspar and quartz grains, radioisotope disequilibria of thorium-230 to uranium-234 (230Th/U) dating of peat, and chlorine-36 to chloride ratios (36Cl/Cl) of ground ice. The application of various geochronologic methods to cover the age intervals of certain IC deposits implies that different permafrost components (organic, mineralic, ice) as well as different geochemical and physical properties have to be employed. At the southern coast of Bolshoy Lyakhovsky Island at least four distinct IC strata were previously described and dated, which cover among the longest time interval of late Quaternary terrestrial permafrost deposition in East Siberia; starting about 200 kyr ago. With this contribution we seek to present and discuss our current understanding of IC chronologies preserved on the New Siberian Archipelago including MIS2 Yedoma (Sartan) IC, MIS3 Yedoma (Molotkov) IC, MIS5 Buchchagy IC, and MIS7a Yukagir IC. Geocryological and palaeo-environmental proxy data highlight past periglacial landscape and deposition processes to deduce past climate conditions and Beringian palaeo-ecological settings and dynamics.Permafrost influences roughly 80% of the Alaskan landscape (Jorgenson et al. 2008). Permafrost presence is determined by a complex interaction of climatic, topographic, and ecological conditions operating over long time scales such that it may persist in regions with a mean annual air temperature (MAAT) that is currently above 0 °C (Jorgenson et al. 2010). Ecosystem-protected permafrost may be found in these regions with present day climatic conditions that are no longer conducive to its formation (Shur and Jorgenson, 2007). The perennial frozen deposits typically occur as isolated patches that are highly susceptible to degradation. Press disturbances associated with climate change and pulse disturbances, such as fire or human activities, can lead to immediate and irrevocable permafrost thaw and ecosystem modification in these regions. In this study, we document the presence of residual permafrost plateaus on the western Kenai Peninsula lowlands of southcentral Alaska (Figure 1a), a region with a MAAT of 1.5±1 °C (1981 to 2010). In September 2012, field studies conducted at a number of black spruce plateaus located within herbaceous wetland complexes documented frozen ground extending from 1.4 to 6.1 m below the ground surface, with thaw depth measurements ranging from 0.49 to >1.00 m. Ground penetrating radar surveys conducted in the summer and the winter provided additional information on the geometry of the frozen ground below the forested plateaus. Continuous ground temperature measurements between September 2012 and September 2015, using thermistor strings calibrated at 0 °C in an ice bath before deployment, documented the presence of permafrost. The permafrost (1 m depth) on the Kenai Peninsula is extremely warm with mean annual ground temperatures that range from -0.05 to -0.11 °C. To better understand decadal-scale changes in the residual permafrost plateaus on the Kenai Peninsula, we analyzed historic aerial photography and highresolution satellite imagery from ca. 1950, ca. 1980, 1996, and ca. 2010. Forested permafrost plateaus were mapped manually in the image time series based on our field observations of characteristic landforms with sharply defined scalloped edges, marginal thermokarst moats, and collapse-scar depressions on their summits. Our preliminary analysis of the image time series indicates that in 1950, permafrost plateaus covered 20% of the wetland complexes analyzed in the four change detection study areas, but during the past six decades there has been a 50% reduction in permafrost plateau extent in the study area. The loss of permafrost has resulted in the transition of forested plateaus to herbaceous wetlands. The degradation of ecosystem-protected permafrost on the Kenai Peninsula likely results from a combination of press and pulse disturbances. MAAT has increased by 0.4 °C/decade since 1950, which could be causing top down permafrost thaw in the region. Tectonic activity associated with the Great Alaska Earthquake of 1964 caused the western Kenai Peninsula to lower in elevation by 0.7 to 2.3 m (Plafker 1969), potentially altering groundwater flow paths and influencing lateral as well as bottom up permafrost degradation. Wildfires have burned large portions of the Kenai Peninsula lowlands since 1940 and the rapid loss of permafrost at one site between 1996 and 2011 was in response to fires that occurred in 1996 and 2005. Better understanding the resilience and vulnerability of the Kenai Peninsula ecosystem-protected permafrost to degradation is of importance for mapping and predicting permafrost extent across colder permafrost regions that are currently warming.Arctic clastic coastlines are some of the most dynamic in the world and have a large impact on cultural and natural resources. Sea ice plays an important role in the erosion and accretion dynamics of these coastlines, and sea ice cover is currently declining at >10% per decade. As a result of declining sea ice cover and an increase in the duration of open water days in the Arctic Ocean, we need to know more about coastal processes in polar seas, specifically how sea ice decline changes coastal processes, the rate at which such coastal changes can occur, and how the effects of declining sea ice interacts with local coastline characteristics including wave fetch, bathymetry, permafrost properties onshore, and pre-existing coastal geomorphology. To assess the influence of sea ice decline on permafrost coastal dynamics we selected two segments of the coastline in NW Alaska with contrasting geography, surficial geology and geomorphology. Study site A, Cape Krusenstern National Monument (CAKR), has a wave-dominated, west- to south-west facing, coarseclastic shoreline. Accreted beach ridges, barrier-closed lagoons, permafrost bluffs, longshore gravel bars, and gravelly beaches characterize coastal geomorphology. Study site B, the Bering Land Bridge National Park and Preserve (BELA), has a north-facing coastline with a shoreline characterized by yedoma and thermokarst basin permafrost bluffs, aggrading spits, sandy barrier islands, and open lagoons. To establish rates of coastal change and identify key geomorphological processes, we digitally mapped the shoreline of both study areas using aerial photographs (1-meter resolution or better) and sub-meter resolution World View-2 satellite imagery from 2003 and 2014, respectively. We compared our data to the results of previous studies based on imagery taken between 1950 and 2003 (Lestak et al., 2010). To better understand the relationship between geomorphology and rates of change, we established geomorphological landform classes for both study areas. We mapped coastal changes within a subset of each study area, using sub meter resolution imagery, over annual time steps to help us better quantify variations in the rate of event driven coastline change. Mapping results for the period 2003 to 2014 suggest a change in erosion rates within both study sites. Erosion rates for the period 1950 to 2003 in BELA and CAKR were -0.12 m/yr and -0.98 m/yr respectively, where the negative signs indicate shoreline retreat (Gorokhovich and Leiserowiz, 2012). These rates, for the period between 2003 and 2014, increased in CAKR to -0.86 and decreased in BELA to -0.69 m/yr. Rates of erosion were found to vary according to geomorphology, with overwash fans in BELA exhibiting the highest rates of change at -1.3 m/yr. Significant changes in geomorphology were observed for this time period including the development of a 200-meter long spit in CAKR, degradation of ice wedges on upland yedoma bluffs in BELA, and the infilling of numerous barrier island ponds due to overwash events in BELA. Our results illustrate the complexity of coastal responses along Arctic coastlines even within close proximity. To ensure robust projections of future coastal change, further mapping and analysis at intraannual and sub-meter spatial resolution is necessary to firmly tie together cause and effect of arctic coastal processes with a changing climate. References: 1. Gorokhovich, Y., Leiserowiz, A., 2012. Historical and Future Coastal Changes in Northwest Alaska. J. Coast. Res. 28, 174–186. 2. Lestak, L.R., Manley, W.F., Parrish, E.G., 2010. Digital Shoreline Analysis of Coastal Change in Bering Land Bridge NP (BELA) and Cape Krusenstern NM (CAKR), Northwest Alaska: Fairbanks, AK: National Park Service, Arctic Network I&M Program. Geospatial Dataset-2184176.Recent landscape changes in the Yedoma region are particularly pronounced in varying thermokarst lake areas reflecting the reaction of the land surface on modern climate changes. However, although thermokarst lake change detection is essential for the quantification of water body expansion and drainage within a region, remote sensing-derived surface reflection trends additionally provide valuable information about the general landscape development. The aim of this research is to reveal the regularities of landscape and thermokarst lakes area changes in the Kolyma lowland tundra in comparison with meteorological data and geological and geomorphological features. The Kolyma lowland tundra occupies about 44500 km2 and is located in Northeast Yakutia within the continuous permafrost zone. Mapping of Quaternary deposits using Landsat images shows that Yedoma (Last Pleistocene remnants formed by ice-rich silty to sandy syngenetic deposits with large polygonal ice wedges) occupies only 16 % of the entire region, while the largest part of it is occupied by alas complex (72 %), formed as a result of Yedoma thaw during the Holocene (Veremeeva and Glushkova, 2016). For the analysis of the landscape and thermokarst lakes area changes of the last 15 years, the entire available Landsat archive from 1999 until 2015 was used for time-series analysis. For this purpose around 800 scenes were processed with an automated workflow, undergoing several necessary processing steps, such as masking, data distribution and calculation of multi-spectral indices. Multi-spectral indices (Landsat Tasseled Cap, NDVI, NDWI, NDMI) were calculated for each unobstructed (cloud-, shadow- and snow-free) observation within the summer months (June to September) between 1999 and 2015. A robust linear trend analysis has been applied to each pixel for the spatial representation of changes of different land surface properties over the observation period. This map shows the magnitude and direction of changes for each multi-spectral index, which are used as proxies for different land-surface properties. For single locations, the entire time-series can be further analyzed in more detail. For the period from 1999 till 2005 air temperatures and precipitation have been analysed for several weather stations that existed in the region. The Landsat time series analysis for the last 15 years shows that the northern part of the region became wetter over the last 5 – 6 years. The alases are particularly affected by the wetting trend. The analysis of the meteo-data shows a trend of increasing air temperature and especially precipitation during the summer from 2010. The wetness increase, particularly on the coastal zone, is supported by the fact that air temperature trends are the largest at near-coastal meteorological stations. This increase of air temperatures and precipitation is likely connected to the reduced sea ice cover (Bekryaev et al., 2010). The strongest wetness increase were observed in the most northern part of the region within a 50 km wide zone along the East-Siberian sea shore between lowest stream of the Alazeya and Galgavaam rivers. This region is characterised by average terrain heights about 10-20 m, the yedoma and thermokarst lakes area here is about 10-20 %. There are less increase of wetness in the southern and eastern part of the coastal zone between Galgavaam and Bolshaya Chukochya rivers which is characterized by average heights of 0-10 m. The lakes area here is about 40 % and yedoma covers less then 10 % of the territory. Thus the strongest wetness trend for the northern coastal zone can be explained by the high degree of yedoma preservation and its thawing due to the coastal location and higher impact of the increasing temperatures and precipitation. For the recent past from 1999 to 2015, thermokarst lake changes were analysed visually based on the time series trend. For most thermokarst lakes of the Kolyma lowland tundra lake area was increasing from 1999 till 2015, however the trend is not significant. Some of the lakes partially or completely drained. Thermokarst lakes area coverage was quantified based on seven Landsat 8 images for the time period 2013 – 2014. In order to ensure consistency regarding surface moisture, only images acquired from August till September have been used. Atmospheric correction of each image was done for radiometric normalization across the dataset. An increase in ground resolution of the 30m multi-spectral data was achieved through resolution merge with the panchromatic channel to 15m pixel size. Subsequent mosaicking, classification and raster to vector conversion was done for the entire Kolyma lowland tundra. Thermokarst lakes cover about 12.9 % of the Kolyma lowland tundra. For the key investigation area located in the southern tundra around Lake Bolshoy Oler, which covers an area of 2800 km2 , a comparison with lakes mapped in CORONA images from July 21, 1965 and lakes mapped in the 2014 Landsat mosaic was carried for analysis of changes over time during a period of up to 50 years. The overall thermokarst lake area for this region in 1965 and 2014 was 590 and 549 km2 respectively. This corresponds to a limnicity decrease of 1.5 % within the study site from 21.1 to 19.6 %. About one third of this lake area decrease is due to partial drainage of big lakes with the area in 1965 and 2014 of 141.8 and 96.3 km2, respectively. Analysis of the summer air temperature and precipitation trends from the 1965 till 2015 also shown the trend of their increasing. Therefore, despite the fact that many persistent thermokarst lakes in the Kolyma lowland tundra are increasing in area, modern climate conditions generally seem to favor further relief drainage development. Consequently, thermokarst lake drainage outpaces thermokarst lake growth. This heterogeneous pattern suggests that permafrost degradation and aggradation in the region proceed simultaneously close together. Acknowledgements: This study was supported by the Russian foundation for basic research grant 14-05-31368 and by the ERC grant 338335. References: Bekryaev R.V., Polyakov I.V., Alexeev V.A. 2010. Role of polar amplification in temperature variations and modern Arctic warming. J. Clim. 23(14): 3888– 906. Veremeeva A.A., Gklushkova N.V. 2016. Relief formation in the regions of the Ice Complex deposit occurrence: remote sensing and GIS-studies, tundra zone of Kolyma lowland, Northeast Siberia. Earth’s Cryosphere, vol. XX, 1, pp.15-25.The investigation of microbial ecosystems in permafrost sediments is an important approach to understand the role of microbial organic matter transformation in permafrost sediments for past and future climate changes, and is of high relevance in today’s geoscience research (Wagner, 2008) due to the current debate on the temperature vulnerability of permafrost deposits. Especially, the interplay between the organic substrate and the distribution of the living and past microbial communities in Late Pleistocene (Yedoma) and Holocene permafrost deposits, as well as the substrate potential of the organic matter stored in potentially thawing permafrost deposits are in the focus of the current study. Our investigation is part of the BMBF CarboPerm project an interdisciplinary Russian-German cooperation on the formation, turnover and release of carbon from Siberian permafrost landscapes. Sample material derived from terrestrial permafrost cores drilled at the coast of Bour Khaya in the North-Eastern Siberian Arctic. The gathered core material comprises Late Pleistocene to early Holocene deposits separated by an ice wedge. The microbial life markers (intact phospholipids, PLs) prove the presence of currently living microorganisms in the entire permafrost sequence and show the highest concentration in the uppermost sample indicating an abundant microbial life in the active layer. In comparison, the PL profile is strongly decreased in the underlying permafrost deposits. Nevertheless, the inventory of the Phospholipid fatty acids (PLFAs) suggests that the cell membrane temperature adaptation to cold environmental conditions is mainly regulated via the ratio between iso- and anteiso-fatty acids (FAs) as well as the ratio between saturated and unsaturated FAs. The surface samples show higher proportions of anteiso and unsaturated FAs (adaptation to cooler conditions), which might derive from the fact that surface layers are more affected from the harsh Siberian winter conditions than the deeper constantly cold permafrost deposits, where the above-ground temperature extremes are buffered due to the overlying deposits. Indeed within the deeper permafrost sequence the variations of the ratios are rather small, indicating adaptation to similar constantly cold temperature conditions. Other microbial markers (GDGTs), already partly degraded and, therefore, not indicating microbial life, reveal similarities with the TOC content and an increase especially in Late Pleistocene deposits. This suggests increased microbial life during intervals in the Late Pleistocene presumably caused by periods of moisture and temperature increased environments. Pore water analysis reveals the presence of low molecular weight organic acids (LMWOA) such as acetate, being excellent substrates for microbial metabolism. In the Late Pleistocene deposits below the ice wedge the substrate depth profiles show significant similarities to the TOC content. These points to a link between the organic matter and the LMWOA concentrations solved in the pore water and to the potential of those permafrost layers to provide substrates for microbial greenhouse gas production. In contrast, in the active layer the LMWOA concentrations are low, reflecting an active microbial turnover in the surface layers. Ester cleavage experiments on the residual organic matter resulted in the release of ester linked LMWOAs forming a potential substrate pool when released in future. These bound LMWOA profiles are even better correlated to the TOC content suggesting that the deeper permafrost deposits (older organic material)are not significantly different from those in the surface sediment (fresh organic material). Overall this indicates that the organic matter stored in the permafrost deposits and, therefore, removed from the surface carbon cycle is not much different in terms of organic matter quality than the fresh surface organic material. Considering the discussed increase of permafrost thawing, this might imply a strong impact on the generation of greenhouse gases from permafrost areas in future with its feedback on climate evolution. In a second and ongoing study, four terrestrial permafrost cores spanning from the Eemian interglacial into the Holocene form Bol’shoy Lyakhovsky Island are investigated with the focus on the differences and potential of the organic matter by comparing Eemian, Late Pleistocene and Holocene deposits. First results already reveal similar relations between the living and dead microbial communities with respect to the availability of free substrates, and the quality and amount of the total organic carbon. The results on the future potential of these deposits will also be presented.The permafrost landscape of Central Yakutia is subject to rapid modifications due to intensive land use, extreme weather, and the current global warming. With regard to the predicted increase in precipitation and temperature as a result of climate change, quantitative knowledge of the small-scale variability of active thermokarst processes is required. Here, we mapped the change of thermokarst and alas lakes (i.e. residual lakes in alas basins) for 11 times covering periods of 2 to 18 years between 1944 and 2014 at the Yukechi study site (61.761289° N/130.470602° E). Historical airborne, current satellite as well as field data were utilized in analyzing lake-area changes and thaw subsidence on local scale. Additionally, a unique dataset of longterm climatic and ground-temperature data could be used in multivariate statistics to identify the climatological and/or general driving and inducing factors of thermokarst and alas-lake changes. On regional scale, size and distribution of lakes >0.1ha were analyzed on different ice-rich permafrost terraces in the Lena-Aldan-Amga interfluve region east of Yakutsk on the basis of Landsat 8 data from July 2013. Regionally, larger lakes distributed in higher frequency are dominating lower terraces. Smaller lakes dominate higher terraces. In particular, smaller lakes are distributed in less density on older and more ice-rich terraces while highest lake densities and larger lakes characterize younger and less ice-rich terraces. Remote sensing analyses at the Yukechi study site indicate that alas-lake levels are increasing strongly end of the 1960s and since the 1990s until present, but their area decrease in the 1940s, 1950s, 1970s, and 1980s. The mean rate of alas-lake-radius change for the 70 year time span account for 1.6 ± 2.9 m/yr. In the meanwhile, extensive agricultural use in the postwar period on the Yedoma ice-rich permafrost deposits led to a rapid and sustained growth of young thermokarst lakes over the entire time span. This is initiated by the strong disturbance of the thermal and hydrological balance of the permafrost. The mean rate of lake-radius change of all mapped thermokarst lakes is 1.2 ± 1.0 m/yr. The mean thaw subsidence below the thermokarst lakes account for 6.2 ± 1.4 cm/yr. Our statistical analyses indicate that climatic parameters (i.e. precipitation, air and ground temperature, and evaporation) show higher correlations with thermokarst-lake changes than with alas-lake changes. In particular, the influence of annual air temperature changes and evaporation is higher on thermokarst-lake level changes than on alas-lake level changes. However, the influence of precipitation, especially winter precipitation, is lower. Deeper ground temperature changes (3.2m depth) show higher correlation with thermokarst-lake changes, while the influence of ground temperatures in 1.6m depth is similar. Multiple regression analyses reveal more complex interrelations of climatic and ground thermal conditions with thermokarst and alas lake changes but further study is needed to validate these results. Our results show, however, that topography, geomorphology, and surficial cryolithology are important controlling factors on the regional distribution and size of the lakes. Furthermore, thermokarst activity is influenced by climatic parameters but it is accelerated and rapidly induced by disturbing factors such as land use. Climatic parameters are strongly affecting growing rates within certain time periods of thermokarst lakes but they do not lead to remarkable reductions or the disappearance of the lakes during the whole observation period. Alas lakes are increasing and decreasing. Distinguishing main controlling factors, however, are hampered probably due to larger catchment areas and subsurface hydrological conditions.The course of permafrost degradation depends on climate, vegetation, disturbance, and excess groundice content and distribution, which vary over time. The first three of these drivers are undergoing considerable change with arctic warming. Using combined lake-sediment records, field observations, aerial 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 that is identified as yedoma. A switch to warmer, moister conditions during deglaciation triggered substantial thermal erosion and transport of silt, which washed into existing basins and formed widespread linear corrugations cutting across the uplands. Lakes began to form via thermokarst as early as 13,000 cal yr BP. Lakes intersect the corrugations, indicating lake formation followed initial landscape instability. Charcoal in basal sediments indicates fire may have influenced lake initiation. Small-scale surface topography revealed by LiDAR images includes deep gullies, features resembling lake drainage channels, and lowered lake shorelines. After ca 10,000 yr BP the region became colonized by dense evergreen conifer forest, which likely served to stabilize and insulate the ground surface, preventing the continuation of the high rates of permafrost degradation recorded in the earliest Holocene. Initial lake lowering and generation of steep local topography favouring drying of uplands, plus a summer water deficit, have also likely combined to shift the system to a more quiescent state through much of the Holocene. However, these changes have not prevented lake drainage events entirely. In 2013, several lakes drained or partially drained, possibly in response to fires and a high spring melt-water volume. The observed pattern of drainage is echoed in the older features preserved on the land surface. Based on the Holocene evolution of the region, increasing regional moisture and/or fire disturbance in the future could lead to an increase in permafrost degradation and lake drainage events.Bol’shoy Lyakhovsky, the southernmost island of the New Siberian Archipelago, holds the longest record of palaeoenvironmental history in the non-glaciated Siberian Arctic preserved in permafrost. It stretches back to ~200 kyr before present and includes prominent last interglacial thermokarst and Yedoma (Ice Complex) sections. Yet, it is unknown, whether or not the depositional history of the site is affected by the deglaciation of the northern part of the New Siberian Archipelago. Potentially, it could give insight into the break-up of the proposed MIS 6 ice sheet located on the East Siberian Sea shelf (Jakobsson et al., 2014). The lithostratigraphy of southern part of the island consists of palaeosols, floodplain and lake deposits, subaerial Yedoma and lacustrine to palustrine alas formations. Large ice wedges (partially up to several meters high and thick), segregation and pore ice record a syngenetic freezing of the Yedoma silts. Polymodal particle size distributions suggest that more than one transport mechanism drove sediment accumulation from more than one source. Recent papers conclude that the palaeoclimate record matches the general Late Quaternary climate history in northern Siberia (Andreev et al., 2011; Wetterich et al., 2011). From a multi proxy data set we focus on (i) the mineral composition (63-125 μm fraction) to determine the provenance of the deposits and to identify possible changes of transport pathways. Complementary, we use (ii) pore ice hydrochemistry as a means to track changes of the soil solution that principally reflects the site’s chemical weathering history preserved in permafrost. Presumably the two approaches complement each other, since the weathering solution should largely reflect the mineral matter composition. The heavy mineral association suggests that most of the minerals derive from the underlying bedrock (Upper Jurassic-Lower Cretaceous sandstones and Upper Cretacous granites and diorites); among others it has high amounts of ilmenite and leucoxene, epidote, pyroxenes and amphiboles, along with garnet, tourmaline, apatite, and sphene. Ratios of stable versus unstable mineral associations show that the Late Quaternary strata overlying bedrock are enriched in more stable minerals (i.e. zircon, tourmaline, ilmenite), whereas more unstable minerals (i.e. amphiboles and pyroxenes) dominate the chronostratigraphically younger Quaternary strata. A remarkably high portion of weathered mica appears in MIS4 to MIS3 deposits and raises the question upon particular hydrodynamic conditions during that time, e.g. a floodplain environment that persisted for several thousands to ten thousands of years. It may have produced various impulses of flooding with floating particles that settle out quickly on the banks of the channel and on the leeward side. Overall pore ice chemistry shows that high electrical conductivity corresponds to low ice content ( 60 wt.-%) the electrical conductivity is low. When compared with the average ion composition of tundra and taiga rivers, the whole core record is enriched in the sodium- potassium load, which partially even dominates over the combined calcium-magnesium load. We preliminary conclude that the observed trends of heavy mineral and pore ice chemical variations in the Bol’shoy Lyakhovsky cores reflect short-distance material transport from weathered bedrock in the depositional area. The enrichment of mica in ice-rich deposits suggests floodplain hydrodynamics in the area during MIS 4 to MIS3. The fairly constant ionic proportions of the light soluble load in the ground ice confirm a local origin of the weathering solutes. High amounts of potassium are linked to the weathering of the granitic bedrock. Distinct concentration gradients in the downcore electrical conductivity are caused by postdepositional ionic migration from the bedrock weathering crust into the overlying Late Quaternary strata, by intensified weathering during the Last Interglacial (MIS5e), and by stable surfaces that promoted effective (e.g. cryogenic) weathering during the last Glacial (MIS4 to MIS3). Andreev, A.A., Schirrmeister, L., Tarasov, P.E., Ganopolski, A., Brovkin, V., Siegert, C., ... & Hubberten, H.-W. (2011). Vegetation and climate history in the Laptev Sea region (Arctic Siberia) during Late Quaternary inferred from pollen records. Quaternary Science Reviews, 30, 2182-2199. Jakobsson, M., Andreassen, K., Bjarnadottir, L.R., Dove, D., Dowdeswell, J.A., England, J.H., ... & Larsen, N.K. (2014). Arctic Ocean glacial history. Quaternary Science Reviews, 92, 40-67. Wetterich, S., Tumskoy, V., Rudaya, N., Andreev, A.A., Opel, T., Meyer, H., ... & Huls, M. (2014). Ice Complex formation in arctic East Siberia during the MIS3 Interstadial. Quaternary Science Reviews, 84, 39- 55.Ice wedges are the most abundant type of ground ice in the ice-rich permafrost deposits of the Northeast Siberian Arctic. They are formed by the periodic repetition of frost cracking and subsequent crack filling and refreezing in spring, mostly by melt water of winter snow. Ice wedges can be studied by means of stable-water isotopes. Their isotopic composition is directly linked to atmospheric precipitation (i.e. winter snow) and, therefore, indicative of past climate conditions during the cold season even though also genetic aspects, i.e. sublimation, melting and refreezing in the snowpack and the frost crack, have to be taken into account. In this contribution we present stable-water isotope data of ice wedges from the Oyogos Yar coast of the Dmitry Laptev Strait (72.7°N, 143.5°E). Ice wedges and surrounding sediments were studied and sampled in 2002 and 2007. Ice-wedge stable-water isotopes were analyzed in the stable-isotope lab of the Alfred Wegener Institute in Potsdam, Germany. Sediments and ice wedges were dated using (a) OSL dating, (b) 36Cl/Cl dating (Blinov et al., 2009), (c) radiocarbon dating as well as (d) stratigraphic correlation based on ice-wedge stable isotopes. Based on our chronology the studied ice wedges correspond to different stratigraphic units of the Late Quaternary. These are (1) an Ice Complex of MIS5 age (Wetterich et al., in press), (2) Early Weichselian (MIS4 to MIS3) flood plain deposits, (3) the Middle Weichselian Yedoma Ice Complex of MIS3 age and (d) Holocene themokarst deposits (Opel et al., 2011). Ice wedge stable-water isotope data indicate substantial variations in Northeast Siberian Arctic winter climate conditions (δ18O) as well as shifts in the moisture generation and transport patterns (d excess) during the Late Quaternary, in particular between Glacial and Interglacial but also over the last centuries. An ice wedge of the MIS5 Ice Complex exhibits mean δ18O and d excess values of -33‰ and 7‰, respectively, representing very cold winter temperatures. Small multi-stage ice wedges corresponding to the MIS4 to MIS3 flood plain deposits showed two clusters of isotope values: (1) in their lower parts, i.e. composite sand-ice wedges or “polosatics”, δ18O values of -31 to -28‰ (d excess of 0-5‰) and (2) in their upper parts (classical ice wedge) δ18O values of -34‰ (d excess of 5‰), reflecting rather different formation conditions than climate differences under very cold climate conditions. The huge syngenetic ice wedges of the Weichselian Yedoma Ice Complex (MIS3) are characterized by mean δ18O values of -33‰ to -29‰ and mean d-excess values between 4 and 8‰ corresponding to different altitude levels and reflecting cold to very cold winter temperatures. On top of the Ice Complex as well as in a thermokarst depression of Late Glacial origin, Holocene ice wedges could be found. They have been grown predominantly in the Middle to Late Holocene and exhibit mean δ18O values of about -25‰ and mean d-excess values of 8‰, mirroring distinctly warmer winter temperatures in the Holocene. Recently grown (modern) ice wedges of the last decades are characterized by mean δ18O values of about -21‰ and mean d excess values of 8‰, testifying the recent winter warming in the Arctic. Blinov A, Alfimov V, Beer J, Gilichinsky D, Schirrmeister L, Kholodov A, Nikolskiy P, Opel T, Tikhomirov D, Wetterich S. 2009. Ratio of 36Cl/Cl in ground ice of east Siberia and its application for chronometry. Geochemistry Geophysics Geosystems 10, Q0AA03. Opel T, Dereviagin AY, Meyer H, Schirrmeister L, Wetterich S, 2011. Palaeoclimatic Information from Stable Water Isotopes of Holocene Ice Wedges on the Dmitrii Laptev Strait, Northeast Siberia, Russia. Permafrost and Periglacial Processes 22, 84-100. Wetterich S, Tumskoy V, Rudaya N, Kuznetsov V, Maksimov F, Opel T, Meyer H, Andreev AA, Schirrmeister L, in press. Ice Complex permafrost of MIS5 age in the Dmitry Laptev Strait coastal region (East Siberian Arctic). Quaternary Science Reviews.Over the past two decades, the International Arctic Science Committee (IASC) and the Scientific Committee on Antarctic Research (SCAR) have organized activities focused on international and interdisciplinary perspectives for advancing Arctic and Antarctic research cooperation and knowledge dissemination in many areas (e.g. Kennicutt et al., 2014). For permafrost science, however, no consensus document exists at the international level to identify future research priorities, although the International Permafrost Association (IPA) highlighted the need for such a document during the 10th International Conference on Permafrost in 2012. Four years later, this presentation, which is based on the results obtained by Fritz et al. (2015), outlines the outcome of an international and interdisciplinary effort conducted by early career researchers (ECRs). This effort was designed as a contribution to the Third International Conference on Arctic Research Planning (ICARP III). In June 2014, 88 ERCs convened during the Fourth European Conference on Permafrost to identify future priorities for permafrost research. We aimed to meet our goals of hosting an effective large group dialogue by means of online question development followed by a “World Cafe” conversational process. An overview of the process is provided in Figure 1. This activity was organized by the two major early career researcher associations Permafrost Young Researchers’ Network (PYRN) and the Association of Polar Early career Scientists (APECS), as well as the regional research projects PAGE21 (EU) and ADAPT (Canada). Participants were provided with live instructions including criteria regarding what makes a research question (Sutherland et al., 2011). The top five questions that emerged from this process are: (1) How does permafrost degradation affect landscape dynamics at different spatial and temporal scales? (2) How can ground thermal models be improved to better reflect permafrost dynamics at high spatial resolution? (3) How can traditional environmental knowledge be integrated in permafrost research? (4) What is the spatial distribution of different ground-ice types and how susceptible is ice-rich permafrost to future environmental change? (5) What is the influence of infrastructures on the thermal regime and stability of permafrost in different environmental settings? As the next generation of permafrost researchers, we see the need and the opportunity to participate in framing the future research priorities. Across the polar sciences, ECRs have built powerful networks, such as the Association of Polar Early Career Scientists (APECS) and the Permafrost Young Researchers Network (PYRN), which have enabled us to efficiently consult with the community. Many participants of this community-input exercise will be involved in and also affected by the Arctic science priorities during the next decade. Therefore, we need to (i) contribute our insights into larger efforts of the community such as the Permafrost Research Priorities initiative by the Climate and Cryosphere (CliC) project together with the IPA and (ii) help identify relevant gaps and a suitable roadmap for the future of Arctic research. Critical evaluation of the progress made since ICARP II and revisiting the science plans and recommendations will be crucial. IASC and the IPA, together with SCAR on bipolar activities, should coordinate the research agendas in a proactive manner engaging all partners, including funding agencies, policy makers, and local communities. Communicating our main findings to society in a dialogue between researchers and the public is a priority. Special attention must be given to indigenous peoples living on permafrost, where knowledge exchange creates a mutual benefit for science and local communities. The ICARP III process is an opportunity to better communicate the global importance of permafrost to policy makers and the public.Destruction mechanisms and dynamics of the Arctic coast, also in the western sector of the Russian Arctic, are studied in detail, including the use of remote sensing data. However, data on thermal abrasion and thermo denudation of Kolguev island is quite limited. Some estimates were presented in article of M.A.Velikotsky (1998). Estimation of thermos denudation rates near the Sauchiha river mouth for the period 1948-2002 years was done by the authors earlier (Kizyakov& Perednya, 2003). To obtain data about the modern (after 2002) shoreline retreat rates and growth of thermal cirque a high resolution remote sensing data were involved in our research. Part of the western coast of the Kolguev island was inspected in field work conducted on 2002 by ECI SB RAS, together with VNIIOkeangeologia. The object of research was the part of coast, including a group of three coastal thermal cirques, located 3.5 km south of the Sauchiha river mouth. In 2012, within the framework of the project ‘Geoportal of MSU’ operational satellite imaging was done on Kolguev island by satellite FORMOSAT-2. High resolution satellite imagery provides ample opportunities for visual interpretation of coastal landforms. Aerial photographs (1948 and 1968), surveying materials (2002), high-resolution satellite images (2009 and 2012) became basis to study the dynamics of the coast and thermal cirques in the key area. For key area were calculated: retreat rates of the edge of the coastal terraces and thermal cirques for the periods 1948-1968, 1968-2002, 2002-2009, 2009-2012; retreat rates of the foot of the coastal terrace for the periods 2002-2009, 2009-2012; volume of the material enters the coastal zone by the thermal abrasion for one linear km of a coast (Kizyakov et al., 2013). Average long-term rates of retreat of the coastal terrace during 1948-2012 varied from 0.7 to 2.4 m/year; 2002-2012 varied from 1.7 to 2.4 m/year. Identified rates are distinctive for the part of coast from the mouth of Krivaya river to the curve of coastline near the mouth of the Gusinaya river - a length is 60.5 km. These rates are in 1.1-1.5 times lower than average rates of retreat of thermal cirque edges which are connected with melting of massive ice deposits. Averaged growth rates of the thermal cirques in 1948-2002 was 2.4 m/year; in 2002-2012 was - 2.6 m/year. The maximum growth rate on some sections in 2009-2012 were 14.5-15.1 m/year. These rates are the largest for the previously recorded in the Western sector of the Russian Arctic. The cause of the abnormally high rates is an increase the annual amount of positive air temperatures, which in 2011-2012 was 1.4-1.5 times higher than the long-term average. The determined rates of the development of thermal cirque can be extended to the north from the key area (near the Sauchiha river mouth) to the Gusinaya river mouth with total length of 32.3 km. The next plans on studying the coastal dynamics on Kolguev Island - using additional satellite images for the purposes of: detailization of interannual dynamics through the analysis of more short time span series of satellite images, definition of variations of the coastal destruction rates on the Western and Northern coasts. References: Velikotsky M.A. Characteristics of modern coastal dynamics of the Kolguev Island // Dynamics of the Russian Arctic coasts, Moscow, MSU – 1989 – P.93- 101 (In Russian) Kizyakov A.I., Perednya D.D. Destruction of coasts on the Yugorsky Peninsula and on Kolguev Island (Russia) // Permafrost: Abstr. of the 8th Intern. Conf. (Zurich, Switzerland, 21–25 July 2003). Zurich, Switzerland – 2003 – P. 79–80. Kizyakov A.I., Zimin M.V., Leibman M.O., Pravikova N.V. Monitoring the rate of thermal denudation and thermal abrasion on the western coast of Kolguev Island using high resolution satellite images // Earth Cryosphere (Kriosfera Zemli). – 2013, XVII, No. 4 – P. 15-25 (In Russian).