Human and infrastructure exposure to large wildfires in the United States

Abstract

An increasing number of wildfire disasters occurred in recent years in the U.S. Here, we demonstrate that cumulative primary human exposure – population residing within large wildfires’ perimeters – was 594,850 people from 2000-2019 across the Contiguous U.S. (CONUS), 82% of which occurred in the Western U.S. Primary population exposure increased by 125% in CONUS in the past two decades, noting large uncertainty ranges. We show that population dynamics from 2000-2019 alone accounted for 24% of the observed increase rate in human exposure, whereas increased wildfire extent drove a majority of the observed trends. Additionally, we document widespread exposure of roads (412,155 km) and transmission powerlines (14,835 km) to large wildfires in CONUS, with an increased rate of 58% and 70% from 2000-2019, respectively. Our findings highlight the benefits of mitigation and adaptation efforts to help societies cope with wildfires.

Physical, Social, and Biological Attributes for Improved Understanding and Prediction of Wildfires: FPA FOD-Attributes Dataset

“…Interannual variability of fire ignitions is partially explained by seasonal climate and weather conditions, for example modulated through fuel receptiveness to ignitions and abundance of outdoor activities (Noonan-Wright et al, 2011;Finney et al, 2011). Decadal trends are mainly attributable to fire prevention strategies and climatic changes (e.g., increases in the number of critical fire danger days) (Noonan-Wright et al, 2011;Khorshidi et al, 2020;Alizadeh et al, 2023). Importantly, fire ignitions have temporal and spatial structures, enabling development of targeted fire prevention and response strategies (Douglas et al, 2001).…”

“…gridMET also provides daily fire danger indices based on Fuel Model G from the National Fire Danger Rating System 77 (Cohen and Deeming, 1985). gridMET is widely used in fire-related studies (Alizadeh et al, 2021(Alizadeh et al, , 2023.…”

“…Ecoregion shapefiles (i.e., vector data) are available at four levels: 15 Level 1 ecoregions, 50 Level 2 ecoregions, and 182 Level 3 ecoregions across North America, and 967 Level 4 ecoregions in the CONUS. Many fire-related studies used Level II or III ecoregions (Dennison et al, 2014;Alizadeh et al, 2021Alizadeh et al, , 2023, and we provide these two ecoregion classifications at the ignition point of each fire.…”

“…Wildfire (hereafter, fire) hazards have increased across many regions of the world in recent decades, increasing the burden on fire prevention and suppression efforts (Alizadeh et al, 2021;Modaresi Rad et al, 2023;Rad et al, 2023). Changes in climate have decreased the moisture content of living and dead vegetation, lengthened the fire season, and contributed to a significant increase in the number of critical fire danger days across much of the United States (Westerling, 2016;Dennison et al, 2014;Bowman et al, 2011).…”