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 mil-lion 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 commu-nications and outreach have informed study design and strengthened Indigenous and stakeholder relationships. Documen-tation 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 limi-tations 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 syn-theses, and inform future modelling approaches, which are urgently required to comprehend better what permafrost thaw means for Canada's North.