Arctic Climate Threat Indicator Set for Municipal Decision-Making

Rapid Arctic warming triggering natural hazards necessitates new climate risk and social impact tracking. During a series of interviews, mayors of Fairbanks, Alaska; Yellowknife, Canada; and Luleå Sweden identified the need for climate monitoring tools focused on urban Arctic environments. In response, this paper introduces the Arctic Climate Threat Indicator Set (ArCTISt) as a series of nine indicators and accompanying codes for Arctic municipal use. Four climate themes were incorporated into ArCTISt after identification as most relevant to constituent and municipal planning concerns by mayors: (1) extreme temperature variation, (2) extreme precipitation events, (3) wildfire risk, and (4) permafrost thaw. This study demonstrates an example use case, applying station records and projections from the World Climate Research Program’s Coupled Model Intercomparison Project (CMIP6) to project urban Arctic climate changes. ArCTISt first constructs a multi-model ensemble for each city, combining identified top-performing models and evaluating their ability to simulate city-specific seasonal patterns. Indicator results are then calculated using station and model inputs for a historical period (1981–2010) and future projections up to 2100. Findings indicate over 40 new heat wave days per year in all cities, intensifying precipitation in Fairbanks and Luleå, increasing wildfire risk, and intensified permafrost thaw potential in Fairbanks and Yellowknife under high emissions scenarios. Using these indicators, Arctic cities can better determine the most significant environmental challenges for municipal planning. Unlike other sustainability indicators requiring significant data collection and analysis, ArCTISt builds easily interpretable future scenarios and accompanying graphics designed for constituent communication and funding initiatives.