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Predictions of how rapid warming will affect Arctic soil carbon (C) stocks are limited by an uneven sampling distribution across the pan-arctic region. Working in an understudied region of the Arctic, this project aims to improve our understanding of the quantities and controls on soil C. Specifically, we combined soil C data for three vegetation types, polar desert, mesic tundra, and wet meadow, with a vegetation classification to upscale soil C stocks on South Baffin Island. The uploaded dataset contains two sets of paired files. 1) Metadata and geochemistry files to report soil biogeochemical data from 51 soil cores collected on South Baffin Island in July, 2022. 2) A record of the code and dataset used to generate a vegetation classification and soil C upscaling estimate for the study region. 

Abstract As Arctic regions warm rapidly, it is unclear whether high‐latitude soil carbon (C) will decrease or increase. Predicting future dynamics of Arctic soil C stocks requires a better understanding of the quantities and controls of soil C. We explore the relationship between vegetation and surface soil C in an understudied region of the Arctic: Baffin Island, Nunavut, Canada. We combined soil C data for three vegetation types—polar desert, mesic tundra, and wet meadow—with a vegetation classification to upscale soil C stocks. Surface soil C differed significantly across vegetation types, and interactions existed between vegetation type and soil depth. Polar desert soils were consistently mineral, with relatively thin organic layers, low percent C, and high bulk density. Mesic soils exhibited an organic‐rich epipedon overlying mineral soil. Wet meadows were consistently organic soil with low bulk density and high percent C. For the top 20 cm, polar desert contained the least soil C (2.17 ± 0.48 kg m⁻²); mesic tundra had intermediate C (8.92 ± 0.74 kg m⁻²); wet meadow stored the most C (13.07 ± 0.69 kg m⁻²). Extrapolating to the top 30 cm, our results suggest that approximately 44 Tg C is stored in the study region with a mean landscape soil C stock of 2.75 kg m⁻²for non‐water areas. Combining vegetation mapping with local soil C stocks considerably narrows the range of estimates from other upscaling approaches (27–189 Tg) for soil C on South Baffin Island. 

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 1014 − 175 + 194 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. 

Abstract Climate warming in high‐latitude regions is thawing carbon‐rich permafrost soils, which can release carbon to the atmosphere and enhance climate warming. Using a coupled model of long‐term peatland dynamics (Holocene Peat Model, HPM‐Arctic), we quantify the potential loss of carbon with future climate warming for six sites with differing climates and permafrost histories in Northwestern Canada. We compared the net carbon balance at 2100 CE resulting from new productivity and the decomposition of active layer and newly thawed permafrost peats under RCP8.5 as a high‐end constraint. Modeled net carbon losses ranged from −3.0 kg C m⁻²(net loss) to +0.1 kg C m⁻²(net gain) between 2015 and 2100. Losses of newly thawed permafrost peat comprised 0.2%–25% (median: 1.6%) of “old” C loss, which were related to the residence time of peat in the active layer before being incorporated into the permafrost, peat temperature, and presence of permafrost. The largest C loss was from the permafrost‐free site, not from permafrost sites. C losses were greatest from depths of 0.2–1.0 m. New C added to the profile through net primary productivity between 2015 and 2100 offset ∼40% to >100% of old C losses across the sites. Differences between modeled active layer deepening and flooding following permafrost thaw resulted in very small differences in net C loss by 2100, illustrating the important role of present‐day conditions and permafrost aggradation history in controlling net C loss.