Quantifying the mechanisms and wider impacts of accelerated erosion in ice-rich permafrost coasts

Analyses of the Western Canadian Arctic coastline have revealed substantial increases (up to 110%) in coastal erosion over the last two decades, following a sustained period of relatively consistent retreat since the first aerial surveys in the 1950s. Arctic permafrost cliffs comprise over 34% of the Earth’s coastlines, yet understanding of the sensitivities and impacts of accelerating coastal erosion in these regions remains extremely limited. Accelerated rates of retreat have been accompanied by higher frequencies and magnitudes of collapse, threatening coastal communities, nearshore and back barrier ecosystems, and critical infrastructure across the Arctic. The NERC (Natural Environment Research Council) UK-Canada bursary program has enabled the addition of UK expertise to enhance and complement a wider comprehensive assessment of the state of the Beaufort Sea coast, currently being undertaken by Natural Resources Canada. The bursary support has facilitated the development of new ideas that combine in-depth local knowledge and long-term datasets developed by Natural Resources Canada, with novel approaches to detail the thermodynamic behaviour and thaw processes at key sites. Multi-platform and multi-resolution survey approaches have been combined with novel in situ monitoring and targeted geochemical sampling to add new dimensions to the understanding of permafrost cliff erosion processes and their impact within the coastal zone. Here we present a summary of the NERC UK-Canada Bursary funded research into the drivers, responses, and wider impacts of permafrost coast erosion. It is important to set the long-term erosion trends in context and re-evaluate previous rates and inferences of the resultant contribution of material into the coastal zone. Peninsula Point within the Pingo Canadian Landmark (~10 km west of Tuktoyaktuk) proved to be an excellent study site with clear and variable exposures of massive ground ice. We set the long-term erosion trends in context with photogrammetric analysis of historic aerial imagery and use of unmanned aerial vehicles (UAVs) as a tool for contemporary volumetric change detection. Time-lapse imagery helps us investigate the contribution of specific failure mechanisms and the relative influence of and interplay between extreme storm events and more frequent processes. Innovative geophysical approaches (both passive and active seismic) have been used to identify and model key sub-surface layers, critical to understanding future geomorphic behaviour and thermal responses. The thawing and decomposition of frozen organic carbon poses a threat to the global climate and a component of this research has employed a combination of point-based and diffuse source gas monitoring to help establish the flux and wider impacts of permafrost coast erosion processes. Through the combination of three-dimensional photogrammetric temperature mapping and in situ monitoring this research is building towards a better understanding of climate driven coastal change, which will ultimately lead to enhanced community resilience to permafrost landscape change