Past and present thermokarst lake dynamics in the Yedoma Ice Complex region of North-Eastern Yakutia

Thermokarst lakes are typical components of the yedoma-alas dominated relief in the coastal lowlands of North- Eastern Yakutia and formed as a result of thawing Late Pleistocene ice-rich Yedoma Ice Complex (IC) deposits. The aim of our study is to estimate thermokarst lake area changes from the early Holocene onwards based on RS data. The decrease of thermokarst lake area from the early Holocene, taking into account total alas depression areas, is as much as 81-83 %. Modern climate warming has led to a general trend of thermokarst lake area decrease. Lake drainage occurs mostly on elevated sites with high Yedoma IC fraction while lake area increase is typical for low-lying areas with a small Yedoma IC fraction. The area increase of thermokarst ponds on flat, boggy yedoma surfaces indicates ice wedge degradation in response to rising summer air temperatures and precipitation

Ponding vs. baydzherakh formation on Yedoma uplands: Implications for modern thermokarst development and thaw subsidence in North Yakutia

Permafrost landscapes of Northern Yakutia recently experienced a widespread warming of mean annual air temperatures and mean positive daily air temperatures during the arctic summer (Federov et al, 2014). Especially in the tundra zone this has led to increased active layer thickness (ALT) and suggests that thermokarst processes reactivate or intensify. However, particularly in the light of the enormous area underlain by ice and carbon-rich permafrost, still only few observations of permafrost-thaw related landscape dynamics exist. Permafrost degradation has consequences for local hydrology, ecosystems, biogeochemical cycling, and sometimes communities. For example in East Siberia, widespread and irreversible thaw subsidence of up to 11 cm per year has been detected on the arctic island Muostakh (Günther et al., 2015), where coastal erosion at average rates of 1.8 m/yr has not only reduced the island’s area by 25% over more than 60 years, but also provides a constant renewal of the erosional base. In this case, favorable drainage conditions provide the prerequisite for active layer thickness deepening during warm summers, when ground ice stability thresholds are exceeded and ground ice thaw and subsequent terrain lowering take place. Our combined approach of ground-based ALT measurements and remote sensing-derived observations of elevation change revealed an inverse connection of shallow seasonal thaw and strong long-term subsidence, which is related to the minimum depth where permafrost thaw encounters pure ground ice bodies. In this study, we focus not only on monitoring thermokarst and subsidence, but also aim to find commonalities and differences of change or no change on yedoma uplands, slopes, and thaw depressions on the landscape scale using multi-temporal digital elevation models (DEMs) from historical aerial photographies, modern satellite stereo imagery, and on-site repeat laser scanning campaigns. In this context, a best practice strategy for remote sensing data fusion combining 2D and 3D information from very high resolution imagery (GeoEye, WorldView, Kompsat, Alos Prism), complemented by local field measurements (meterology, ground temperature, geodetic surveys) on the Bykovsky Peninsula and Sobo-Sise in the Lena Delta, has been developed. In order to capture a large variety of sites across the Yedoma region, additional sites at Cape Mamontov Klyk in the Anabar-Olenyok Lowland, Bolshoy Lyakhovsky on the New Siberian Islands, and Cape Maliy Chukochiy in the Kolyma Lowland with less or no topographical ground control, were considered from the perspective of larger areal coverage. Our high spatial resolution monitoring for the last decades and in comparison for the last years, shows that the current relief development in ice-rich permafrost enhances not only drainage of thermokarst lakes, but also drainage of the entire terrain, which leads to the formation of thermokarst mounds (baydzherakhs) on slopes of yedoma uplands. In contrast, simultaneous ponding on poorly drained massive Yedoma blocks in immediate proximity, suggests thermokarst development. However, formation of new thermokarst lakes on yedoma uplands is limited by topographical and stratigraphical constraints (Morgenstern et al., 2011). Geomorphological mapping of Yedoma and Alas surfaces, baydzherakh fields and areas of newly formed ponds allows to differentiate and link observed topographical changes to specific processes of either thermokarst or denudation. First results show that widespread modern baydzherakh formation is indicative for large-scale permafrost thaw subsidence on yedoma uplands. References: Morgenstern, A., Grosse, G., Günther, F., Fedorova, I. & L. Schirrmeister [2011]: Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta, The Cryosphere, 5, 849-867, doi:10.5194/tc-5-849-2011. Günther, F., Overduin, P.P., Yakshina, I.A., Opel, T., Baranskaya, A.V. & M.N. Grigoriev [2015]: Observing Muostakh disappear: permafrost thaw subsidence and erosion of a ground-ice-rich island in response to arctic summer warming and sea ice reduction, The Cryosphere, 9, 151-178, doi:10.5194/tc-9-151-2015

Landsat-Based Trend Analysis of Lake Dynamics across Northern Permafrost Regions

Lakes are a ubiquitous landscape feature in northern permafrost regions. They have a strong impact on carbon, energy and water fluxes and can be quite responsive to climate change. The monitoring of lake change in northern high latitudes, at a sufficiently accurate spatial and temporal resolution, is crucial for understanding the underlying processes driving lake change. To date, lake change studies in permafrost regions were based on a variety of different sources, image acquisition periods and single snapshots, and localized analysis, which hinders the comparison of different regions. Here, we present a methodology based on machine-learning based classification of robust trends of multi-spectral indices of Landsat data (TM, ETM+, OLI) and object-based lake detection, to analyze and compare the individual, local and regional lake dynamics of four different study sites (Alaska North Slope, Western Alaska, Central Yakutia, Kolyma Lowland) in the northern permafrost zone from 1999 to 2014. Regional patterns of lake area change on the Alaska North Slope (−0.69%), Western Alaska (−2.82%), and Kolyma Lowland (−0.51%) largely include increases due to thermokarst lake expansion, but more dominant lake area losses due to catastrophic lake drainage events. In contrast, Central Yakutia showed a remarkable increase in lake area of 48.48%, likely resulting from warmer and wetter climate conditions over the latter half of the study period. Within all study regions, variability in lake dynamics was associated with differences in permafrost characteristics, landscape position (i.e., upland vs. lowland), and surface geology. With the global availability of Landsat data and a consistent methodology for processing the input data derived from robust trends of multi-spectral indices, we demonstrate a transferability, scalability and consistency of lake change analysis within the northern permafrost region

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

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

Remote sensing of drained thermokarst lake basin successions

Thermokarst lakes are important factors for permafrost landscape dynamics and carbon cycling. Thermokarst lake cover is particularly high in Arctic lowlands with ice-rich permafrost. In many of these vast lowland regions, drained thermokarst lake basins of different age have been identified that overlap each other in space, suggesting intense dynamics of repeated lake formation and loss with complex carbon cycle histories during the Holocene [Grosse et al.,2013]. Observing the permafrost and ecosystem succession patterns following thermokarst lake drainage will help to better determining the landscape and regional scale impacts of lake loss on northern hydrology, permafrost aggradation, vegetation succession, carbon cycling, as well as spectral land surface property changes. Previous remote sensing approaches to study drained thermokarst lake basins used a combination of Landsat, high resolution satellite and aerial, and field data to quantify carbon stocks accumulated in post-drainage peat in drained thermokarst lake basins (DTLBs) for the northern Seward Peninsula in Northwest Alaska [Jones et al., 2012]. We here expand on this method by using different remote sensing products in combination with dating of lake drainage events. These events are identified based on the historical remote sensing record and accelerated mass spectrometry radiocarbon dating. The joint us of remote sensing and geochronological field data allows to assess the specific succession patterns of various DTLB types and their impacts on land surface properties in different Arctic permafrost regions (North Alaska, Northwest Alaska, North Siberia). The datasets used in this analysis include a range of remote sensing and topographic data, such as aerial photography, historic topographic maps, high resolution satellite images (Corona, Spot, Ikonos, Quickbird, Worldview, GeoEye), and imagery from the full Landsat archive as well as from the Moderate Resolution Imaging Spectrometer (MODIS) sensors. We report temporal trends of spectral properties based on Landsat multispectral indices for individual DTLBs of different ages, but also employ landscape-scale chronosequences allowing the analysis succession trajectories of DTLBs that drained well before the start of the remote sensing record. Here we are particularly focusing on the long-term impacts of lake drainage on changes in normalized difference vegetation index (NDVI), normalized difference moisture index (NDMI), normalized difference water index (NDWI), Tasseled Cap index (brightness, greenness, wetness), land surface temperatures, and albedo. We further conducted field studies including reconnaissance flights targeting historically drained lakes and cored DTLBs to sample for radiocarbon-dating of terrestrial peat layers indicative of the drainage event. Results of this ongoing study suggest a strong impact exerted by thermokarst lake drainage on land surface reflectance characteristics in thermokarst lowland regions. The information may be useful for parameterizing surface properties in land surface models of thermokarst-affected regions, particularly where increased lake drainage is projected to take place

Deep Yedoma permafrost: A synthesis of depositional characteristics and carbon vulnerability

Permafrost is a distinct feature of the terrestrial Arctic and is vulnerable to climate warming. Permafrost degrades in different ways, including deepening of a seasonally unfrozen surface and localized but rapid development of deep thaw features. Pleistocene ice-rich permafrost with syngenetic ice-wedges, termed Yedoma deposits, are widespread in Siberia, Alaska, and Yukon, Canada and may be especially prone to rapid-thaw processes. Freeze-locked organic matter in such deposits can be re-mobilized on short time-scales and contribute to a carbon cycle climate feedback. Here we synthesize the characteristics and vulnerability of Yedoma deposits by synthesizing studies on the Yedoma origin and the associated organic carbon pool. We suggest that Yedoma deposits accumulated under periglacial weathering, transport, and deposition dynamics in non-glaciated regions during the late Pleistocene until the beginning of late glacial warming. The deposits formed due to a combination of aeolian, colluvial, nival, and alluvial deposition and simultaneous ground ice accumulation. We found up to 130 gigatons organic carbon in Yedoma, parts of which are well-preserved and available for fast decomposition after thaw. Based on incubation experiments, up to 10% of the Yedoma carbon is considered especially decomposable and may be released upon thaw. The substantial amount of ground ice in Yedoma makes it highly vulnerable to disturbances such as thermokarst and thermo-erosion processes. Mobilization of permafrost carbon is expected to increase under future climate warming. Our synthesis results underline the need of accounting for Yedoma carbon stocks in next generation Earth-System-Models for a more complete representation of the permafrost-carbon feedback

Permafrost Deep Organic Matter: The IPA Yedoma Action Group

Die Action Group "The Yedoma Region: A Synthesis of Circum-Arctic Distribution and Thickness" der Internationalen Permafrost Assoziation (IPA) hat es zum Ziel die Verbreitung und Mächtigkeit von Yedoma Permafrost, einem spätpleitozänen sehr eisreichem Permafrost, zu quantifizieren. Yedoma ist durch Eisgehalte von bis zu 80vol% sehr anfällig gegenüber Erwärmung. Denn wenn das Bodeneis schmilzt und abgeführt wird sind Absenkungen der Bodenoberflächen von mehr als 30 Metern möglich, was deutliche Auswirkungen hat auf die Landschaft, samt Infrastruktur und menschlicher Landnutzung. Als Produkt dieses Projektes möchten wir hier eine circum-arktische Karte präsentieren. Diese Daten werden als Grundlage dazu dienen, den Kohlenstoffpool von Yedoma Ablagerungen realistisch in computergestützte Modelle zu implementieren und die zukünftigen Auswirkungen von Thermokarst und Thermoerosion auf die Treibhausgasemissionen abzuschätzen

PeRL:A circum-Arctic Permafrost Region Pond and Lake database

Ponds and lakes are abundant in Arctic permafrost lowlands. They play an important role in Arctic wetland ecosystems by regulating carbon, water, and energy fluxes and providing freshwater habitats. However, ponds, i.e., waterbodies with surface areas smaller than 1. 0 × 104ĝ€m2, have not been inventoried on global and regional scales. The Permafrost Region Pond and Lake (PeRL) database presents the results of a circum-Arctic effort to map ponds and lakes from modern (2002-2013) high-resolution aerial and satellite imagery with a resolution of 5ĝ€m or better. The database also includes historical imagery from 1948 to 1965 with a resolution of 6ĝ€m or better. PeRL includes 69 maps covering a wide range of environmental conditions from tundra to boreal regions and from continuous to discontinuous permafrost zones. Waterbody maps are linked to regional permafrost landscape maps which provide information on permafrost extent, ground ice volume, geology, and lithology. This paper describes waterbody classification and accuracy, and presents statistics of waterbody distribution for each site. Maps of permafrost landscapes in Alaska, Canada, and Russia are used to extrapolate waterbody statistics from the site level to regional landscape units. PeRL presents pond and lake estimates for a total area of 1. 4 × 106ĝ€km2 across the Arctic, about 17ĝ€% of the Arctic lowland ( < ĝ€300ĝ€mĝ€a.s.l.) land surface area. PeRL waterbodies with sizes of 1. 0 × 106ĝ€m2 down to 1. 0 × 102ĝ€m2 contributed up to 21ĝ€% to the total water fraction. Waterbody density ranged from 1. 0 × 10 to 9. 4 × 101ĝ€kmĝ'2. Ponds are the dominant waterbody type by number in all landscapes representing 45-99ĝ€% of the total waterbody number. The implementation of PeRL size distributions in land surface models will greatly improve the investigation and projection of surface inundation and carbon fluxes in permafrost lowlands. Waterbody maps, study area boundaries, and maps of regional permafrost landscapes including detailed metadata are available at https://doi.pangaea.de/10.1594/PANGAEA.868349

Spatial heterogeneity and environmental predictors of permafrost region soil organic carbon stocks

Large stocks of soil organic carbon (SOC) have accumulated in the Northern Hemisphere permafrost region, but their current amounts and future fate remain uncertain. By analyzing dataset combining >2700 soil profiles with environmental variables in a geospatial framework, we generated spatially explicit estimates of permafrost-region SOC stocks, quantified spatial heterogeneity, and identified key environmental predictors. We estimated that Pg C are stored in the top 3 m of permafrost region soils. The greatest uncertainties occurred in circumpolar toe-slope positions and in flat areas of the Tibetan region. We found that soil wetness index and elevation are the dominant topographic controllers and surface air temperature (circumpolar region) and precipitation (Tibetan region) are significant climatic controllers of SOC stocks. Our results provide first high-resolution geospatial assessment of permafrost region SOC stocks and their relationships with environmental factors, which are crucial for modeling the response of permafrost affected soils to changing climate

Quaternary deposits map of Yana-Indigirka and Kolyma lowlands tundra zone, R-55-57, based on Landsat imagery

The Quaternary geology map was created for the Yana-Indigirka (eastern part) and Kolyma lowlands, tundra and partly forest-tundra zones. The map corresponds to the nomenclature sheet of Government Geological Map R-(55)-57, northern part. The primary goal for creating the map is to enhance current knowledge of Quaternary deposits distribution in Yedoma regions in North-Eastern Siberia due to the lack of the geological maps of large scale for this region. For most area of the region maps of 1:200.000 scale are still not created and only geological maps of 1:1.000.000 scale exist. The Database of Quaternary Deposits from Maps of 1:1.000.000 scale, East and Central Siberia, is available via https://apgc.awi.de (Bryant et al., 2017, https://doi.org/10.5066/F7VT1Q89). The main Quaternary deposits on the Yana-Indigirka and Kolyma lowlands are late Pleistocene ice-rich Yedoma Ice Complex (LIII2-4), corresponded to yedoma uplands, and Holocene Alas Complexes (lbIV) formed in drained thermokarst lake basins (alases) due to the Yedoma IC thawing in the late Pleistocene-Holocene. High ice-rich Yedoma Ice Complex (IC) deposits are very vulnerable to observed climate warming, which lead to the landscape changes such as surface subsidence, thermokarst and thermoerosion processes activation, deepening of the active layer thickness, etc., as well as to remobilization of the buried freezelocked organic matter and contribution to greenhouse gases fluxes to the atmosphere. The map was created using Landsat images that allow the area of the yedoma uplands and alases to be clearly identified. The mapping of Quaternary deposits was done using Landsat TM 5 and 7 ETM+ satellite images acquired from August and July for the 2001-2010 period. Detecting of Quaternary deposits corresponded to landforms were conducted manually using spectral characteristics of satellite images, landform morphology, absolute heights and existing Quaternary Geology map of 1:1.000.000 scale. The working scale of the mapping was 1:30.000. Mapped Quaternary deposits are represented by six types: Yedoma IC, alas complex, alluvial, alluvial-marine, marine, and bedrocks. A comparison of the Quaternary deposit distribution as mapped with the Landsat satellite imagery and the 1:1.000.000 geological map revealed a 2.5-times overestimation of the Yedoma IC deposits extent area at the 1:1.000.000 scale. The Landsat-based map corresponds to 1:200.000 scale and provides important information about the distribution of yedoma uplands and thermokarst development during Holocene and is the basis for the analysis of yedoma-alas landscapes changes under modern climate warming. Detailed information about methods and results can be found in Veremeeva&Glushkova (2016) and Shmelev et al. (2017)