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Abstract Currently, more than half of the world’s human population lives in urban areas, which are increasingly affected by climate hazards. Little is known about how multi-hazard environments affect people, especially those living in urban areas in northern latitudes. This study surveyed homeowners in Anchorage and Fairbanks, USA, Alaska’s largest urban centers, to measure individual risk perceptions, mitigation response, and damages related to wildfire, surface ice hazards, and permafrost thaw. Up to one third of residents reported being affected by all three hazards, with surface ice hazards being the most widely distributed, related to an estimated $25 million in annual damages. Behavioral risk response, policy recommendations for rapidly changing urban environments, and the challenges to local governments in mitigation efforts are discussed. 

Abstract Increased wildfire activity has raised concerns among communities about how to assess and prepare for this threat. There is a need for wildfire hazard assessment approaches that capture local variability to inform decisions, produce results understood by the public, and are updatable in a timely manner. We modified an existing approach to assess decadal wildfire hazards based primarily on ember dispersal and wildfire proximity, referencing landscape changes from 1984 through 2014. Our modifications created a categorical flammability hazard scheme, rather than dichotomous, and integrated wildfire exposure results across spatial scales. We used remote sensed land cover from four historical decadal points to create flammability hazard and wildfire exposure maps for three arctic communities (Anchorage and Fairbanks, Alaska and Whitehorse, Yukon). Within the Fairbanks study area, we compared 2014 flammability hazard, wildfire exposure, and FlamMap burn probabilities among burned (2014–2023) and unburned areas. Unlike burn probabilities, there were significantly higher in exposure values among burned and unburned locations (Wilcoxon;p < 0.001) and exposure rose as flammability hazard classes increased (Kruskal–Wallis;p < 0.001). Very high flammability hazard class supported 75% of burned areas and burns tended to occur in areas with 60% exposure or greater. Areas with high exposure values are more prone to burn and thus desirable for mitigation actions. By working with wildfire practitioners and communities, we created a tool that rapidly assesses wildfire hazards and is easily modified to help identify and prioritize mitigation activities. 

While wildfires can be beneficial and part of a natural process, there have been numerous instances around the world, particularly in recent years, where wildfires have had devastating consequences for society. Weather conditions have created extreme wildfire behavior, resulting in speeds and intensities that can overpower suppression resources. It is ever more critical that communities and agencies take actions to mitigate and prevent wildfire disasters. We have developed a tool that enables wildfire practitioners to assess the risk of wildfire to structures in a straightforward, rapid, and affordable manner. The approach leverages information often collected by communities (e.g., building footprints, zoning) and available vegetation datasets. In conjunction with local wildfire management regulations, our project also used wildfire exposure to help identify wildland-urban interface boundaries. We used this approach on three communities in the Arctic (Anchorage and Fairbanks, Alaska, and Whitehorse, Yukon) to assess wildfire risk. We determined that there is considerable wildfire risk in urban Arctic communities, with a greater percentage of structures at high or very high risk in Fairbanks (26 percent (%)) and Whitehorse (22%) compared to Anchorage (14%). Combining local wildfire management practices with wildfire exposure is a successful way to identify meaningful Wildland Urban Interface (WUI) boundaries, which are essential for obtaining mitigation funds and planning. The key to producing updatable wildfire risk and vulnerability maps is accurate, up-to-date information on vegetation, building footprints, and zoning. With this information and the tool outlined here, communities and agencies have a way to inform community wildfire protection plans and identify impactful mitigation actions. 

We modified an existing approach to assess decadal wildfire hazards based primarily on ember dispersal and wildfire proximity, referencing landscape changes from 1984 through 2014. Our modifications created a categorial flammability hazard scheme, rather than dichotomous, and the integration of wildfire exposure results across spatial scales. We used remote sensed land cover from four decadal points to create flammability hazard and wildfire exposure maps for three arctic communities (Anchorage and Fairbanks, Alaska and Whitehorse, Yukon). Within the Fairbanks study area, we compared 2014 flammability hazard, wildfire exposure, and FlamMap burn probabilities among burned (2014-2021) and unburned areas. Exposure values were greater in burned than unburned, unlike burn probabilities. These datasets reflect the hazardous fuels or flammability hazard layers used in the process. 

A map of degraded ice wede polygon terrain for the lidar mapped portion of the Fairbanks North Star Borough. The purpose of this mapping effort is to identify areas with massive ice present. Mapping of high ground-ice content areas was conducted by manually digitizing ice wedge polygon terrain at a scale of 1:2000 using lidar data. Lidar data covering 2,208 square kilometers (km²) of the Fairbanks North Star Borough (FNSB) were acquired in 2018 from the United States Geological Survey (USGS). Elevation tiles with 1 meter (m) spatial resolution were downloaded from the Alaska Division of Geological and Geophysical Surveys (https://elevation.alaska.gov/). A hillshade mosaic was generated in ArcGIS Pro and used to identify areas of ice wedge polygon degradation, which appear as surface grids of ~10 m wide polygons. A limitation of this mapping approach is that massive ground ice may occur without a surface expression, and thus our mapped extent should be considered conservative. The dataset is provided in the Alaska Albers NAD83 coordinate system. 

The boreal forest of northwestern North America covers an extensive area, contains vast amounts of carbon in its vegetation and soil, and is characterized by extensive wildfires. Catastrophic crown fires in these forests are fueled predominantly by only two evergreen needle-leaf tree species, black spruce (Picea mariana (Mill.) B.S.P.) and lodgepole pine (Pinus contorta Dougl. ex Loud. var. latifolia Engelm.). Identifying where these flammable species grow through time in the landscape is critical for understanding wildfire risk, damages, and human exposure. Because medium resolution landcover data that include species detail are lacking, we developed a compound modeling approach that enabled us to refine the available evergreen forest category into highly flammable species and less flammable species. We then expanded our refined landcover at decadal time steps from 1984 to 2014. With the aid of an existing burn model, FlamMap, and simple succession rules, we were able to predict future landcover at decadal steps until 2054. Our resulting land covers provide important information to communities in our study area on current and future wildfire risk and vegetation changes and could be developed in a similar fashion for other areas. 

We developed a compound modeling approach that enabled us to refine the available evergreen forest category in the original Arctic Boreal Vulnerability Experiment (ABoVE) dataset (https://daac.ornl.gov/ABOVE/guides/Annual_Landcover_ABoVE.html) to include black and white spruce and hemlock. The data is a geotiff (30 meter resolution) with 17 land cover classes. The published paper with the methods can be found at: https://doi.org/10.3390/f14081577. This archive includes 1984, 1994, 2004, 2014 and predicted 2024, 2034, 2044, and 2054. Because medium resolution landcover data that include species detail are lacking, we developed a compound modeling approach that enabled us to refine the available evergreen forest category into highly flammable species and less flammable species. We then expanded our refined landcover at decadal time steps from 1984 to 2014. With the aid of an existing burn model, FlamMap, and simple succession rules, we were able to predict future landcover at decadal steps until 2054. Our resulting land covers provide important information to communities in our study area on current and future wildfire risk and vegetation changes and could be developed in a similar fashion for other areas. These data will then be used to assess wildfire hazards and risk. 

We modified an existing approach to assess decadal wildfire hazards based primarily on ember dispersal and wildfire proximity, referencing landscape changes from 1984 through 2014. Our modifications created a categorial flammability hazard scheme, rather than dichotomous, and the integration of wildfire exposure results across spatial scales. We used remote sensed land cover from four decadal points to create flammability hazard and wildfire exposure maps for three arctic communities (Anchorage and Fairbanks, Alaska and Whitehorse, Yukon). Within the Fairbanks study area, we compared 2014 flammability hazard, wildfire exposure, and FlamMap burn probabilities among burned (2014-2021) and unburned areas. Exposure values were greater in burned than unburned, unlike burn probabilities.