Retrogressive thaw slump susceptibility in the northern hemisphere permafrost region

Mean annual temperatures in the Arctic and subarctic have increased in recent decades, increasing the number of permafrost hazards. Retrogressive thaw slumps (RTSs), triggered by the thawing of ground ice in permafrost soil, have become more common in the Arctic. Many studies report an increase in RTS activity on a local or regional scale. In this study, the primary goals are to: (i) examine the spatial patterns of the RTS occurrences across the circumpolar permafrost region, (ii) assess the environmental factors associated with their occurrence and (iii) create the first susceptibility map for RTS occurrence across the Northern Hemisphere. Based on our results, we predicted high RTS susceptibility in the continuous permafrost regions above the 60th latitude, especially in northern Alaska, north-western Canada, the Yamal Peninsula, eastern Russia and the Qinghai-Tibetan Plateau. The model indicated that air temperature and soil properties are the most critical environmental factors for the occurrence of RTSs on a circumpolar scale. Especially, the climatic conditions of thaw season were highlighted. This study provided new insights into the circumpolar susceptibility of ice-rich permafrost soils to rapid permafrost-related hazards like RTSs and the associated impacts on landscape evolution, infrastructure, hydrology and carbon fluxes that contribute to global warming.</p

Long-term landscape impact of petroleum exploration, Melville Island, Canadian High Arctic

Industrial land use such as petroleum exploration and infrastructure development has important and lasting impacts on Arctic landscapes. Detailed, site-level investigations have noted impacts that include: vehicle tracks, surface and vegetation alteration, soil compaction, and degradation of ice wedge features. We investigated the long-term impact of an extended period of hydrocarbon exploration on Melville Island in the Canadian High Arctic using available remotely-sensed data supplemented with field observations over a ~370 km2 area. Aerial photographs from 1959, 1972, and 1977, and recent satellite imagery (2011 and 2013) were used to determine the effects of industrial activity over periods corresponding to pre-activity, mid-activity, and post-activity. We show that vehicle tracks, site disturbance and vegetative impacts are still evident after 40 years in this area. Permafrost has degraded at sites with concentrated activity (drill sites, airstrips) and changes to vegetation are clearly discernable. The results demonstrate the utility of this approach for assessment of land use impacts on High Arctic landscapes and provide a means to determine locations for more detailed site-specific field studies. These results may contribute to strategies for environmental monitoring in remote areas where access is impractical or resource-intensive.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

The Northwest Territories Thermokarst Mapping Collective: a northern-driven mapping collaborative toward understanding the effects of permafrost thaw

This paper documents the first comprehensive inventory of thermokarst and thaw-sensitive terrain indicators for a 2 million km2 region of northwestern Canada. This is accomplished through the Thermokarst Mapping Collective (TMC), a research collaborative to systematically inventory indicators of permafrost thaw sensitivity by mapping and aerial assessments across the Northwest Territories (NT), Canada. The increase in NT-based permafrost capacity has fostered science leadership and collaboration with government, academic, and community researchers to enable project implementation. Ongoing communications and outreach have informed study design and strengthened Indigenous and stakeholder relationships. Documentation of theme-based methods supported mapper training, and flexible data infrastructure facilitated progress by Canada-wide researchers throughout the COVID-19 pandemic. The TMC inventory of thermokarst and thaw-sensitive landforms agree well with fine-scale empirical mapping (69%–84% accuracy) and aerial inventory (74%–96% accuracy) datasets. National- and circumpolar-scale modelling of sensitive permafrost terrain contrasts significantly with TMC outputs, highlighting their limitations and the value of empirically based mapping approaches. We demonstrate that the multiparameter TMC outputs support a holistic understanding and refined depictions of permafrost terrain sensitivity, provide novel opportunities for regional syntheses, and inform future modelling approaches, which are urgently required to comprehend better what permafrost thaw means for Canada's North