Description: The land-ocean interface in the Arctic is a sensitive environment facing severe changes due to rising global air temperatures. In particular, Arctic river deltas are rapidly changing permafrost landscapes which will become more dynamic due to sea-level rise, longer thaw periods, changes in river discharge, increased storm-surge flooding and thawing permafrost. As a result, previously frozen river delta deposits are becoming available for microbial decomposition as permafrost thaws. However, very few studies have focused on Arctic deltas and estimates of deltaic carbon stocks are even more limited. Therefore, we compiled 140 soil cores (new and already published soil cores), consisting of more than 1400 samples from 17 different deltas around the Arctic Ocean. In addition, we mapped the spatial extent of more than 250 Arctic deltas in order to accurately assess the carbon and nitrogen stock estimations for Arctic deltas. Our study shows that Arctic river delta deposits contain a considerable amount of carbon and nitrogen. The ongoing thaw and degradation of these permafrost deposits resulting from global climate warming might release additional carbon and nitrogen with implications for Arctic waters and biogeochemical cycles. The additional export of terrestrial carbon and nitrogen will alter biogeochemical processes not only in the nearshore zone, but throughout the Arctic Ocean. With this study we will improve our understanding of changing terrestrial carbon and nitrogen deposits and their contribution to a changing Arctic Ocean.

Description: The Action Group called ‘Standardized methods across Permafrost Landscapes: from Arctic Soils to Hydrosystems’ (SPLASH) is a community-driven effort aiming to provide a suite of standardized field strategies for sampling mineral and organic components in soils, sediments, and water across permafrost landscapes. This unified approach will allow data from different landscape interfaces, field locations and seasons to be shared and compared, thus improving our understanding of the processes occurring during lateral transport in circumpolar Arctic watersheds.

Description: Beavers are starting to colonize low arctic tundra regions in Alaska and Canada, which hasimplications for surface water changes and ice-rich permafrost degradation. In this study, weassessed the spatial and temporal dynamics of beaver dam building in relation to surface waterdynamics and thermokarst landforms using sub-meter resolution satellite imagery acquiredbetween 2002 and 2019 for two tundra areas in northwestern Alaska. In a 100 km2study area nearKotzebue, the number of dams increased markedly from 2 to 98 between 2002 and 2019. In a430 km2study area encompassing the entire northern Baldwin Peninsula, the number of damsincreased from 94 to 409 between 2010 and 2019, indicating a regional trend. Correlating data onbeaver dam numbers with surface water area mapped for 12 individual years between 2002 and2019 for the Kotzebue study area showed a significant positive correlation (R2=0.61; p 〈 .003).Beaver-influenced waterbodies accounted for two-thirds of the 8.3% increase in total surface waterareain the Kotzebue study area during the 17 year period. Beavers specifically targeted thermokarstlandforms in their dam building activities. Flooding of drained thermokarst lake basins accountedfor 68% of beaver-influenced surface water increases, damming of lake outlets accounted for 26%,and damming of beaded streams accounted for 6%. Surface water increases resulting from beaverdam building likely exacerbated permafrost degradation in the region, but dam failure alsofactored into the drainage of several thermokarst lakes in the northern Baldwin Peninsula studyregion, which could promote local permafrost aggradation in freshly exposed lake sediments. Ourfindings highlight that beaver-driven ecosystem engineering must be carefully considered whenaccounting for changes occurring in some permafrost regions, and in particular, regional surfacewater dynamics in low Arctic and Boreal landscapes.

Description: Soils are warming as air temperatures rise across the Arctic and Boreal region concurrent with the expansion of tall-statured shrubs and trees in the tundra. Changes in vegetation structure and function are expected to alter soil thermal regimes, thereby modifying climate feedbacks related to permafrost thaw and carbon cycling. However, current understanding of vegetation impacts on soil temperature is limited to local or regional scales and lacks the generality necessary to predict soil warming and permafrost stability on a pan-Arctic scale. Here we synthesize shallow soil and air temperature observations with broad spatial and temporal coverage collected across 106 sites representing nine different vegetation types in the permafrost region. We showed ecosystems with tall-statured shrubs and trees (〉 40 cm) have warmer shallow soils than those with short-statured tundra vegetation when normalized to a constant air temperature. In tree and tall shrub vegetation types, cooler temperatures in the warm season do not lead to cooler mean annual soil temperature indicating that ground thermal regimes in the cold-season rather than the warm-season are most critical for predicting soil warming in ecosystems underlain by permafrost. Our results suggest that the expansion of tall shrubs and trees into tundra regions can amplify shallow soil warming, and could increase the potential for increased seasonal thaw depth and increase soil carbon cycling rates and lead to increased carbon dioxide loss and further permafrost thaw.

Description: The permafrost region is warming at an unprecedented pace. Changing climate increases the vulnerability of permafrost. Borehole observations and ground temperature modelling across the permafrost zone indicate a global rise in permafrost temperatures. Feedback mechanisms in a warming Arctic, such as increases in wildfires, sea-ice loss or infrastructure development will further contribute to permafrost destabilization on various scales. So far, observations of permafrost region disturbances (PRD) typically focus on regional scales and holistic, pan-arctic observations are lacking. Here we present the current advances of a pan-arctic analysis of rapid permafrost landscape dynamics from 2000-2020 based on globally available satellite data (Landsat, Sentinel-2) and machine-learning methods. We expand upon previous continental-scale studies towards a pan-arctic detection and mapping of typical PRD. We analyze the spatial distribution and dynamics of lakes, wildfires and retrogressive thaw slumps (RTS) across the entire pan-arctic permafrost region. Preliminary results reveal that each PRD type has typical occurrence hot-spots. RTS are often found in regions with preserved buried glacier ice. Lake dynamics are most pronounced in ice-rich permafrost terrains along the margin of continuous permafrost. Wildfires are most dominant in arid, boreal regions. Long-term dynamics are superimposed by short-term weather conditions, such as heatwaves and precipitation events, which recently have been shown to trigger or enhance disturbances significantly. The analysis of current disturbance hot-spots and the understanding of PRD dynamics and trajectories will enhance quantifying carbon fluxes and projecting future landscape dynamics. Rapidly growing streams of remote sensing data with high spatial and temporal resolution together with new Artificial-Intelligence techniques will help to improve the monitoring of PRD across the entire pan-arctic with more detail and higher accuracy.

Description: Lakes and drained lake basins (DLBs) are dominant landforms across Arctic lowland regions. The long-term dynamics of lake formation and drainage is evident in the abundance of lakes and DLBs covering as much as 80% of the landscape in various regions of Arctic Alaska, Russia, and Canada. Lake drainage can be triggered through different mechanisms such as lake tapping by an adjacent stream, bank overflow or ice wedge degradation. Following drainage, DLBs can become valuable grazing land for caribou and reindeer as well as usable land for infrastructure development due to low ground ice content in recent DLBs. In addition, DLBs can be sites for soil organic carbon accumulation in the form of peat which also play a role for carbon cycling. Comprehensive and accurate mapping of DLB distribution, age and drainage mechanism, will further inform our understanding of their role in permafrost landscape evolution across varying timescales. DLBs differ from the surrounding terrain in vegetation structure and composition, soil moisture, elevation, size and types of ice-wedge polygons and other parameters that make them an identifiable target based on remote sensing data. Here, we present a novel approach to map DLBs in permafrost landscapes with a specific focus on the North Slope of Alaska as well as select areas in Siberia and northwestern Canada. To map DLBs, we combined multispectral satellite imagery (Landsat-8 and Sentinel-2), Synthetic Aperture Radar (SAR) acquisitions (Sentinel-1), and DEM data (ArcticDEM). To cover the entire study area in each region, we included Landsat-8 acquisitions from all available years and Sentinel-2 for 2016 and 2018 to create cloud-free mosaics. The classification combines methodologies from pixel-based and object-based image analysis. To allow for processing of these large datasets that cover more than 200.000 km2, a classification workflow was developed in Google Earth Engine. Preliminary results show good agreement of our classification with previously published data sets for subsets of our North Slope study area. This work marks the first attempt to map DLBs at the pan-Arctic scale. Our results highlight the importance of treating areas of different surficial geology and vegetation communities separately in the classification process to ensure higher classification accuracy.

Description: The presence of ground ice in Arctic soils exerts a major effect on permafrost hydrology and ecology, and factors prominently into geomorphic landform development. As most ground ice has accumulated in near-surface permafrost, it is sensitive to variations in atmospheric conditions. Typical and regionally widespread permafrost landforms such as pingos, ice-wedge polygons, and rock glaciers are closely tied to ground ice. However, under ongoing climate change, suitable environmental spaces for preserving landforms associated with ice-rich permafrost may be rapidly disappearing. We deploy a statistical ensemble approach to model, for the first time, the current and potential future environmental conditions of three typical permafrost landforms, pingos, ice-wedge polygons and rock glaciers across the Northern Hemisphere. We show that by midcentury, the landforms are projected to lose more than one-fifth of their suitable environments under a moderate climate scenario (RCP4.5) and on average around one-third under a very high baseline emission scenario (RCP8.5), even when projected new suitable areas for occurrence are considered. By 2061–2080, on average more than 50% of the recent suitable conditions can be lost (RCP8.5). In the case of pingos and ice-wedge polygons, geographical changes are mainly attributed to alterations in thawing-season precipitation and air temperatures. Rock glaciers show air temperature-induced regional changes in suitable conditions strongly constrained by topography and soil properties. The predicted losses could have important implications for Arctic hydrology, geo- and biodiversity, and to the global climate system through changes in biogeochemical cycles governed by the geomorphology of permafrost landscapes. Moreover, our projections provide insights into the circumpolar distribution of various ground ice types and help inventory permafrost landforms in unmapped regions.

Description: Permafrost coasts make up roughly one third of all coasts worldwide. Their erosion leads to the release of previously locked organic carbon, changes in ecosystems and the destruction of cultural heritage, infrastructure and whole communities. Since rapid environmental changes lead to an intensification of Arctic coastal dynamics, it is of great importance to adequately quantify current and future coastal changes. However, the remoteness of the Arctic and scarcity of data limit our understanding of coastal dynamics at a pan-Arctic scale and prohibit us from getting a complete picture of the diversity of impacts on the human and natural environment. In a joint effort of the EU project NUNATARYUK and the NSF project PerCS-Net, we seek to close this knowledge gap by collecting and analyzing all accessible high-resolution shoreline position data for the Arctic coastline. These datasets include geographical coordinates combined with coastal positions derived from archived data, surveying data, air and space born remote sensing products, or LiDAR products. The compilation of this unique dataset will enable us to reach unprecedented data coverage and will allow us a first insight into the magnitude and trends of shoreline changes on a pan-Arctic scale with locally highly resolved temporal and spatial changes in shoreline dynamics. By comparing consistently derived shoreline change data from all over the Arctic we expect that the trajectory of coastal change in the Arctic becomes evident. A synthesis of some initial results will be presented in the 2020 Arctic Report Card on Arctic Coastal Dynamics. This initiative is an ongoing effort – new data contributions are welcome!

Description: Permafrost thaw has been observed at several locations across the pan-Arctic in recent decades, yet the pan-Arctic extent and potential spatial-temporal variations in thaw are poorly constrained. Thawing of ice-rich permafrost can be inferred and quantified with satellite imagery due to the subsequent differential ground subsidence and erosion that in turn affects land surface cover. Information contained within existing and rapidly growing collections of high-resolution satellite imagery (Big Imagery) is here extracted across the Arctic region through a collaboration between software engineers, computer- and earth scientists. More specifically, we are a) developing geospatial data down to sub-meter resolution, and also b) enabling discovery and knowledge-generation through visualization tools. This cyberinfrastructure platform, the Permafrost Discovery Gateway (PDG), is being designed with input from users of the PDG, e.g. primarily the Arctic earth science community but also the general public. The PDG builds upon other NSF supported data management resources (Arctic Data Center and Clowder) and the Fluid Earth Viewer. The Fluid Earth Viewer, which is the first visualization tool implemented into the PDG, was initially created for the public to explore atmospheric and oceanographic visualizations and is here modified to support permafrost geospatial products, and a number of community built analytic tools to identify permafrost artifacts within satellite imagery. The effort also includes workflow optimization of remote sensing code for pan-Arctic sub-meter scale mapping of ice-wedge polygons from optical imagery. We are additionally actively engaging with the user-community to ensure that the PDG becomes useful, both in terms of the type of data contained within the PDG and the design of the visualization tools. The PDG has the potential to fill key Arctic science gaps, such as bridging plot to pan-Arctic scale findings, while also serving as a resource informing decisions regarding the economy, security, and resilience of the Arctic region.