Permafrost limnoscapes: Critical places at critical times

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Permafrost is present in half of Canada's territory and covers more than 20 million km2 in the northern hemisphere. It is the foundation of northern ecosystems and infrastructure. Because of recent climate change, which has been twice as rapid across the Arctic compared to elsewhere around the globe, permafrost stability is under threat. Potential impacts of its widespread thaw (e.g., soil erosion and subsidence) could be both progressive and catastrophic on natural and human systems. Moreover, because frozen soils in the North contain great amounts of organic carbon, aquatic systems formed by the thawing of ice-rich permafrost (so-called `thermokarst' lakes) can be considered as biogeochemical `hotspots', emitting greenhouse gases (GHGs) to the atmosphere and thus amplifying temperature increases. My research aims to characterize the impacts of climate-induced permafrost degradation on natural and human landscapes across the Arctic. I explore different spatial and temporal scales, with a special focus on the dynamics of aquatic ecosystems. For this Discovery program I will integrate fieldwork sampling along a `landscape continuum' (soil-water-sediments-gases), laboratory analyses, and geomatic tools (e.g., remote sensing) along three research axes: 1) characterizing the geophysical properties of Arctic soils that control freeze-thaw cycles and thermokarst inception; 2) quantifying GHG emissions from lake-rich permafrost landscapes or `limnoscapes', combining field measurements with airborne infrared imagery; 3) reconstructing past environmental critical changes that have affected northern lacustrine basins (e.g., carbon accumulation, lake level drawdown and desiccation) based on sediment core analysis. To better understand the spatial variations in these complex processes, my program is deployed at three study sites across the Canadian North: Cambridge Bay and Bylot Island, Nunavut (continuous permafrost in the Arctic), and western Hudson Bay Lowlands near Churchill, Manitoba (continuous-discontinuous permafrost boundary in the subarctic zone, in the world's second largest peatland area). My research program also aims at training the next generation of cold-region scientists, both in the field and in the lab/office space, acting as international leaders collaborating with northern communities across Canada. The broad question of whether the Arctic region will act as a global carbon source or sink in the future - greening and/or browning of the Arctic? - is a timely scientific and societal issue. Currently, Earth system models simulating future carbon sinks and sources in permafrost regions only include gradual and widespread thaw (as a `top-down' process), but do not include localized and abrupt disturbances. My integrated, field-intensive (`bottom-up') research program will help to improve such models with reliable data, thereby guiding mitigation decisions that will impact the future state of the Arctic and the global climate.