Wildfire evacuation patterns and syndromes across Canada's forested regions

Human exposure to wildfire is increasing in many regions globally-a trend likely to continue as climate change drives increases in wildfire activity and human populations continue to expand into fire-prone landscapes. In Canada, this trend is reflected by a steady increase in the annual number of wildfire evacuations since the 1980s. Evacuations can be costly and cause severe stress, even when homes remain undamaged. Because many factors driving community vulnerability are likely correlated, classifying at-risk communities into groups whose members share common drivers of wildfire vulnerability will be helpful in identifying the key wildfire evacuation "syndromes" that are repeated in different parts of the landscape. Understanding these syndromes will aid in anticipating and mitigating the effects of future fire exposure. Here, we classify the populated places across Canada's forested regions into 19 groups using variables describing their potential vulnerability to wildfire, including the surrounding land cover, land use and infrastructure, and the local fire regime. Then, we evaluate the utility of these groups by comparing actual wildfire exposure among the groups using a unique dataset of 1043 wildfire evacuations from 1980 to 2019. We identified three main evacuation syndromes that represent 79% of all evacuations and are distinct in their geographic distribution, the characteristics of the fires that drove the evacuations, the communities exposed, and the likely mode of evacuation. In remote areas dominated by conifer forest, evacuations were driven primarily by lightning-ignited fires in the summer. Exposed communities typically lacked access to the road network, making it important to plan for evacuation by air. In less remote mixedwood forest areas, evacuations were driven largely by human-ignited fires in the spring, and most communities had access to major roads. In interior British Columbia, evacuations were mainly in the summer and driven by both lightning- and human-ignited fires. These areas experienced the greatest increase in evacuation frequency over the last two decades, reflecting the local trend of increasing wildfire activity. These differences highlight how the major risk factors vary spatially across the forested regions and temporally over the fire season-knowledge that will facilitate more effective planning for future fire seasons.