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Infrastructure built on perennially frozen ice-rich ground relies heavily on thermally stable subsurface conditions. Climate warming-induced deepening of ground thaw puts such infrastructure at risk of failure. For better assessing the risk of large-scale future damage to Arctic infrastructure, improved strategies for model-based approaches are urgently needed. We used the laterally-coupled one-dimensional heat conduction model CryoGrid3 to simulate permafrost degradation affected by linear infrastructure. We present a case study of a gravel road built on continuous permafrost (Dalton highway, Alaska) and forced our model under historical and strong future warming conditions (following the RCP8.5 scenario). As expected, the presence of a gravel road in the model leads to higher net heat flux entering the ground compared to a reference run without infrastructure, and thus a higher rate of thaw. Further, our results suggest that road failure is likely a consequence of lateral destabilization due to talik formation in the ground beside the road, rather than a direct consequence of a top-down thawing and deepening of the active layer below the road centre. In line with previous studies, we identify enhanced snow accumulation and ponding (both a consequence of infrastructure presence) as key factors for increased soil temperatures and road degradation. Using differing horizontal model resolutions we show that it is possible to capture these key factors and their impact on thawing dynamics with a low number of lateral model units, underlining the potential of our model approach for use in pan-arctic risk assessments. Our results suggest a general two-phase behaviour of permafrost degradation: an initial phase of slow and gradual thaw, followed by a strong increase in thawing rates after exceedance of a critical ground warming. The timing of this transition and the magnitude of thaw rate acceleration differ strongly between undisturbed tundra and infrastructure-af

PermaRisk is a young investigator’s research group that simulates erosion processes in permafrost landscapes under warming climate and conducts risk assessments for ecosystems and infrastructure within the Arctic. Diverse ecological, social, and financial risks are associated with potential damages to ecosystem functions and infrastructure caused by permafrost thaw. Communication with local stakeholders in the Arctic such as the Bureau of Land Management in Alaska or town communities in Canada are integral to the research of PermaRisk. Local indigenous knowledge will help researchers to better understand past and current landscape changes and their impact on local life and infrastructure. PermaRisk promotes a transparent and open communication between research and society. Here, we present the tool of digital storytelling and how it is used to portray both the stories of the research project and the scientists as well as the stories of the people affected by climate change in the Arctic. Digital storytelling allows the combination of photos, videos, sound bites, interviews, graphics, maps, and data into compelling, entertaining, and interactive stories. Research data and materials brought back from fieldwork are used to look into questions like: What drives these scientists to do what they do? How do they do it? Why does it matter? To whom does it matter? How are local communities affected by Arctic climate change? How do they perceive the change and the research? In the final product, the project’s main research findings are translated into accessible storylines about erosion and permafrost and placed within the socio-ecological context of climate change in the Arctic and globally. Finished Stories will be used for community outreach and public relations to advocate science. Furthermore, they will be integrated into teaching at German universities and schools to invite interactive learning and situate the research in concrete, real-life situations and communities.

Permafrost landscapes and high northern infrastructure are under threat of erosion as a consequence of thawing permafrost across the Arctic due to a rapidly warming climate. The young investigator group PermaRisk aims to provide a novel approach for the simulation of erosion and mass wasting processes in permafrost landscapes under a warming climate. The project aims to deliver comprehensive risk assessments for Arctic ecosystems and infrastructure taking into account different processes of permafrost degradation. Current model approaches used to simulate the degradation of permafrost under a warming climate are highly simplistic since they only consider one-dimensional (top-down) thawing and ignore lateral processes such as soil erosion and mass wasting which are the most abundant form of thaw in many regions. Thus, current model assessments are most likely far too conservative in their estimates of permafrost thaw impacts. It therefore remains uncertain how climate warming and permafrost thaw will affect (i) the intensity of erosion and mass wasting processes and (ii) essential ecosystem functions, landscape characteristics, and infrastructure. It also remains unclear (iii) whether any erosion-induced landscape changes further accelerate permafrost thaw. In order to answer these critical questions, land surface models (LSMs) require a new level of realism in order to adequately project permafrost thaw dynamics. Within the PermaRisk project, the permafrost model CryoGrid3 will be extended with an erosion scheme that allows to represent lateral processes within the limited framework of one dimensional LSMs. The new concept will be applied and validated at three Arctic key sites in Alaska (Deadhorse/Prudhoe Bay), Canada (Arviat), and Siberia (Lena-River-Delta). Furthermore, 21st century climate impact projections for the key sites are scheduled as a basis for thorough risk analyses concerning potential damages to critical ecosystem functions and infrastructure for th