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Rapid Permafrost Thaw in a Warming Arctic and Impacts on the Soil Organic Carbon Pool

Final Report Summary - PETA-CARB (Rapid Permafrost Thaw in a Warming Arctic and Impacts on the Soil Organic Carbon Pool)

This ERC project proposed to (1) establish a new interdisciplinary and internationally active research group integrating remote sensing, biogeochemistry, spatial data analysis, Quaternary geology, soil sciences, geomorphology, geochronology, and spatial modeling; (2) generate essential new data on thermokarst processes and SOC pool distribution and characteristics in permafrost regions highly necessary to project future climate change; (3) foster national and international collaborations; (4) contribute to several international science initiatives that focus on Arctic environmental dynamics and climate change feedbacks; (5) train one young researcher (Postdoc), two PhD students, and one engineer in science and technology; and (6) establish the Arctic Permafrost Geospatial Centre which will serve as a central archive hub and server for permafrost-related spatial datasets. In addition, it was proposed to provide opportunities for several Master students to conduct their thesis research in related science and technology fields within the ERC project.
We had clear success in all proposed goals and fully achieved theits scientific main objectives.
Focusing on study regions in Alaska and Siberia, we conducted systematic studies of rapid permafrost thaw by thermokarst, investigated its spatial and temporal dynamics, and analysed its interactions with the permafrost soil organic carbon (SOC) pool. We quantified deep SOC pools in the permafrost regions and within various landscape specific components, thereby significantly reducing uncertainties in first-order estimates of permafrost-carbon climate feedbacks. We identified previously unaccounted for large permafrost carbon pool components and assessed their vulnerability to rapid permafrost thaw and climate change. We created or contributed to several new synthesis datasets of high relevance to understand panarctic permafrost carbon pools or dynamics. In particular, we strongly expanded the knowledge on carbon pool size, distribution, characteristics, and vulnerabilities in deep permafrost soils, Yedoma deposits, thermokarst lake deposits, and Arctic river deltas of Alaska and Siberia. Due to their size and vulnerability to thaw and mobilization these carbon pools are of global relevance in a warming Arctic. Excellent contributions were made to quantitatively and qualitatively better understand thaw and carbon dynamics of thermokarst lake systems in modern and paleo-environmental contexts from the lake scale to the panarctic scale. Our permafrost carbon vulnerability assessment includes the first-time implementation of thermokarst processes in a panarctic-scale model, also taking into account the contribution of deep carbon pools to future carbon fluxes from permafrost regions.
We also achieved 1) the development and application of highly automated image processing workflows for analyzing temporally dense, spatially high resolution Landsat satellite data for quantification of permafrost region disturbances (lakes, lake change, thaw slumps, wildfires) across very large Arctic transects; 2) the development of statistical trend analysis tools to understand and quantify the rate of change detected in satellite image data; 3) the application of highly precise satellite-based stereo-photogrammetry to derive detailed digital elevation models across our study regions; 4) the establishment of survey grids using differential GPS and terrestrial laser scanning in remote Arctic regions that allow quantifying the effect of permafrost thaw subsidence on landscape topography; and 5) the development of land cover classification approaches combining satellite and digital elevation data to upscale field-measured soil carbon stocks to the landscape scale. We further established the Arctic Permafrost Geospatial Center as a data dissemination web portal for geospatial datasets targeting interested research and numerical modeling communities.
PETA-CARB directly or indirectly trained six postdocs, six PhD students, eleven Master students, and one technician. The team contributed to several high-level synthesis activities with international collaborators in the Permafrost Carbon Network. The team led or contributed to 65 publications on permafrost carbon pool characteristics and dynamics, thermokarst lake dynamics and related carbon fluxes, remote sensing of permafrost landscape changes, and paleo-environmental assessments of permafrost degradation.