Over recent decades, the societal and economic impacts of climate change have been seen to manifest uniquely in the Arctic. Pronounced warming trends disproportionately impact peoples of the Arctic in remote regions, especially Indigenous peoples (Martello, 2008; Vogel & Bullock, 2020; Lebel et. al., 2022). In the coastal Arctic communities of Nunavut, the Yukon and Northwest Territories, permafrost loss due to rising sea levels poses direct threat to communities (Greaves, 2021), as thaw slumping and sinkholes bring land stability into jeopardy. Sea level rise induced saltwater intrusion (SWI) of inland permafrost is an overlooked positive feedback, particularly important in the context of a warming climate. Climate feedbacks, characterized by their self-weakening or self-amplifying mechanisms, often increase the frequency and/or intensity of Earth’s climatic forces as a response to climate change. In fact, climate change induced sea ice loss has resulted in new surface wave regimes and erodibility of seas on coastlines in permafrost regions (Neilson et. al., 2022). Exposed permafrost thus lies at higher risk of degradation (thaw) because of the combined effects of sea level rise (SLR), land and ocean warming and coastal erosion (Fritz et al., 2017). As well as posing a natural hazard to Arctic towns and settlements, permafrost thaw has consequences for carbon mobilization and global climate, as well as ground water flow, storage and water quality (Schuur et. al., 2022, McKenzie & Voss, 2013). Coupled by challenges of food availability, human safety, health and security brought on by rapid shifts in climate and the environment (Ramage et. al., 2022), permafrost subsidence (sinkholes) and thaw slumping are one of the most understudied threats facing Arctic residents (Guimond et. al., 2021), particularly in coastal communities. The study of salt water infiltration in permafrost environments is in its infancy, likely because of a lack of field data, limitations in remote sensing data/techniques over the high latitudes, as well as the fact that subsurface impacts on permafrost bound coastlines are challenging to monitor (Guimond et. al., 2021). Additionally, salinity dependent groundwater flow models with solute exclusion and freeze thaw dynamics are in their early stages of development (King et. al., 2021; Ford et. al., 2021; Guimond et. al., 2021).
               Recent research by Guimond et. al., 2021 highlights the importance of understanding lateral permafrost thaw: the SWI driven degradation due to lateral heat exchange-induced melting (Sun et. al., 2022; Guimond et. al., 2021). Studying the links between rising sea levels and coastal permafrost thaw in the Arctic, this pioneering study modelled the physics of water flow in relation to energy and mass transport processes in coastal permafrost environments, incorporating water and energy transport with latent heat dynamics to simulate the interactions between permafrost thaw and groundwater flow. Their cryohydrogeological model accounted for the lower freezing point of saline water by incorporating a salinity dependent soil freezing curve, assuming a saturated aquifer and density dependent Darcian fluid flow. Using an adaptive time stepping approach, simulations were run from steady state initial conditions for a total of 120 years, based on the time onset of rapid arctic warming (1980) to 2100. In all, five sea-level change scenarios were simulated: one sea-level fall (−0.005 m/year), one constant sea level, and three SLR (0.002, 0.004 and 0.008 m/year) scenarios based on 2100 SLR projections (Guimond et. al., 2021). Additionally, five surface warming scenarios were also used: one with inundation-induced warming from overlying seawater, and three rates of inundation plus land and ocean warming based on Representative Concentration Pathways (RCPs) emission scenarios 2.6, 4.5, and 8.5. Model output was used to quantify permafrost volume per metre coastline (m3/m), with an ice saturated permafrost threshold of ≥30{23be86542a8e1516b0ed6a95b26b3e2077bdc5236f7744c744301444280dba4d} pore space ice saturation. Finally, considering that trends of air temperature warming are main drivers of permafrost thaw in all environments (i.e. top-down thaw), whereas SLR impacts affect only coastal zones (lateral thaw), Guimond et. al., (2021) compared thaw volumes between drivers by calculating the volume of permafrost change relative to the area of influence (m3/m2).
               Guimond et. al., (2021) found that sea level rise drives lateral permafrost thaw due to depressed freezing temperatures, reducing coastal ice saturated permafrost extent. The key takeaway from this paper was that a projected ice-saturated permafrost loss of 9.5{23be86542a8e1516b0ed6a95b26b3e2077bdc5236f7744c744301444280dba4d} per year was found under the RCP 8.5 admissions scenario and 0.008m/yr SLR. Although the RCP 8.5 has been long considered climate change’s “worst case disaster scenario”, climate scientists continue to warn us that without more drastic cuts to carbon emissions, the inconceivable increase in global average temperatures under an 8.5 RCP scenario is dangerously within reach (Meyer, 2019). Furthermore, under high sea level rise conditions, Guimond et. al., (2021) found that SWI outdid warming for greatest mechanism influencing rates of permafrost loss. The results of this study strongly suggest that sea level rise driven saltwater intrusion in coastal Arctic permafrost environments play a critical role on coastal permafrost degradation. Moreover, the paper foreshadows potential impacts of lateral thaw on coastal infrastructure, ocean-aquifer interactions and carbon mobilization due to SWI-driven thaw. Guimond et. al., (2021) make a compelling case for more academic research into the impacts and extent of SWI-driven thaw in coastal permafrost environments. Perhaps, future studies will attempt to identify areas of the Arctic Circle at highest risks for land subsidence hazards in light of this overlooked feedback mechanism.
               Four months after Guimond et. al., (2022) published, a BBC News story covered this unique example of climate change induced impacts on coastal communities in the Arctic. Rannard (2022) brought attention to evidence supporting the devastating impacts of warming permafrost in the Arctic, stating that 70{23be86542a8e1516b0ed6a95b26b3e2077bdc5236f7744c744301444280dba4d} of Arctic infrastructure and 30 to 50{23be86542a8e1516b0ed6a95b26b3e2077bdc5236f7744c744301444280dba4d} of critical infrastructure is at high risk of damage by 2050, with an associated cost in the tens of billions of dollars. The article draws on research on Russian tundra, emphasizing that up to 80{23be86542a8e1516b0ed6a95b26b3e2077bdc5236f7744c744301444280dba4d} of buildings are estimated to be damaged in cities built on coastal permafrost in these landscapes, the degrading lands affecting food security and accessibility inherent to traditional lifestyles. Foreshadowing the expenses and degradation of Arctic developments, Rannard (2022) brings attention to the 120,000 buildings, 40,000km of roads and 9500km of pipelines that are located on permafrost in the northern hemisphere. Interviewed Arctic residents in Kivalina, Alaska, emphasized that those who live on permafrost are already struggling, impacted by deformations in critical infrastructure such as highways, housing and air strips. In addition, the article brings attention to the unequal division of land during colonization of North America during the 19th and 20th centuries, with today’s villages facing limited options for relocation as land becomes unstable. Beyond mentioning this ever present disproportionate impact of colonization on Indigenous peoples, however, the article fails to expand on the societal implications of climate change in the Arctic and the political representations of Arctic Indigenous peoples that have been central to these claims. Furthermore, this article lacks discussion on the role of SWI induced lateral thaw and specifically, the role of sea level rise on permafrost thaw in coastal permafrost landscapes.
               Indeed, both Guimond et. al., (2021) and Rannard (2022) deliver important knowledge on the concerning phenomena that is lateral permafrost thaw. Nonetheless, it is apparent, however, that the two pieces have been cultivated for different reasons, are aimed at different audiences, and serve different purposes. Guimond et. al., (2021) is an academic grade research article with emphasis on modelling dynamics and results aimed to further explain the mechanisms behind saltwater intrusion in coastal permafrost environments. Geared towards an audience of polar researchers, students and other academics, the article serves as a baseline modelling framework for future SWI studies. While Guimond et. al., (2021) was able to project annual permafrost loss metrics under given climate warming scenarios, the dynamics of lateral thaw extent and cascading impacts on coastal infrastructure were out of the research scope. The paper’s discussion is notably minimal, however, with little in the ways of connecting the human impacts and risks associated with SWI-driven permafrost thaw, even under specific SLR scenarios. The inclusion of a discussion of the real-world impacts and the minority groups climate change is disproportionately affecting would have strengthen their argument for the need to better understand and model SWI permafrost thaw. Conversely, Rannard (2022) was written for popular media, the BBC article presenting a digestible dose of cryospheric science to a less exclusive audience. Although Rannard (2022) failed to go into depth on issues of the disproportionate impacts of climate change on Indigenous peoples in the Arctic, the article connects the reported impacts of coastal permafrost thaw to the unfair division of land during colonization of the Arctic in earlier centuries.
               Such differences between Guimond et. al. (2021) and Rannard (2022) could be explained by two major truths limiting the BBC article: 1) the challenge of delivering complex scientific research to a general audience, and 2) a lack of knowledge on the given subject. Despite being written for popular media audience, Rannard (2022) does a good job at introducing concepts such as land subsidence impacts, including infrastructure damage and food insecurity. However, Rannard (2022) was likely limited in allowable length for the article, and perhaps unaware of recent studies on SWI driven lateral permafrost thaw, and the sea ice losses that drive them (Nielson et. al., 2022).
                It is apparent that further research is needed on the overlooked feedback mechanism that is SWI driven permafrost thaw, highly tied to both oceanic and terrestrial processes. Above all else, however, an emphasis is needed within future studies on mitigating risk for vulnerability Arctic communities. Adequate planning for a mitigating the effects of this encroaching natural disaster should be prioritized, adopting collaborative frameworks such as Effective Adaptation Planning, where Indigenous perspectives in government help to advance adaptation to environmental climate change (Vogel & Bullock, 2021). Any approaches to planning for coastline protection, community relocation and the study of permafrost thaw itself should be coupled with the wisdom held by traditional knowledge holders of the Arctic’s Indigenous communities, recognizing the historic barriers between scientific research and Indigenous peoples in Canada, and that studies examining the implications of climate change in Arctic communities remain in their infancy (Ford et. al., 2021; Guimond et. al., 2021).
                 What is known as the “Canadian Arctic” is made up of Inuit territory, comprised of nine main groups inhabiting six cultural areas that, unlike provinces and territories, do not have strict borders (Parrott et. al., 2017). Perhaps the most heavily affected by permafrost thaw are communities of the Mackenzie Delta Inuit, Copper Inuit and Netsilik: residents of the periglacial environments showing the greatest thaw sensitivity to climate warming (Smith & Burgess, 2004). The following questions could be asked to an Elder or other knowledge holder the Netsilik peoples, for example, aimed at integrating a community level of knowing to Arctic resiliency planning:

1. What are the principal impacts of sea level rise that your community is experiencing, and which impacts would you like to see take priority in future mitigation efforts and research?
2. What, if any, government assistance has been offered to your community with regard to sea level rise?
3. Are some groups in the community more impacted than others? If so, could you elaborate on what these demographics would be?
4. Have you observed permafrost thaw and/or changes in sea ice dynamics impacting food security in your community or other communities?
5. Do you believe there are any mental or physical health-related effects of coastline degradation/ sea level rise impacts in your community? If so, would you be comfortable explaining what they are?

               Many undergraduate level students are interested in permafrost thaw and coastal studies alike. An undergraduate level honours research project aimed at contributing the the growing body of SWI induced permafrost thaw is one way to contribute meaningful action towards this issue. An honours-sized research project could encompass cryohydrogeological modelling to identify use at-risk coastal communities in the Canadian Arctic that lie vulnerable to retrogressive thaw slumps under different sea level rise scenarios. Several indices could be drawn upon in the modelling framework, including atmosphere, ocean, land and sea ice components. Using IPCC representative concentration pathways to simulate climatic conditions and sea level rise scenarios (PCIC, 2022), such a project would draw on recent research that rising sea level increases saltwater intrusion into permafrost environments, resulting in increased thaw slumping activity and sinkholes (Guimond et. al., 2021). While previous studies have modelled the degree of permafrost loss on coastal Arctic environments, predictive modelling of at-risk coastal environments could be translated as a resource for future planning around coastal impact mitigation. This project would further draw on the understanding that, in wake of climate change, reduced sea ice in the Arctic is resulting on more energetic waves interacting with shoreline environments, resulting in severe flooding risks in low-lying communities associated with large storm surges (Guimond et. al., 2021), which can reach >2m (Manson et. al., 2005). Considering factors such as permeability and permafrost type, topography and knowledge of taliks (aquifers), this project could serve as a baseline for vulnerability mapping within Arctic communities. Additionally, this project could include the gathering of knowledge on important locations in addition to settlement locations, prioritizing engagement with Arctic community members (see above questions). Such a project should focus on identifying at regions subjected to the highest degree of coastal erosion beyond the coastal communities themselves, considering locations of cultural heritage sites (e.g. burial sites, former and seasonal settlements). Indeed, a coupled approach to coastal Arctic vulnerability mapping considering both oceanic and terrestrial processes could prove valuable in the event of more worrisome SLR scenarios, in the unfortunate event they occur.



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