Risky Development: Increasing Exposure to Natural Hazards in the United States

Abstract

More than half of the structures in the contiguous United States are exposed to potentially devastating natural hazards.• Growth rates in hotspots exceed the national trend.• Risk assessments can be improved by considering multiple hazards, mitigation history and fine-scale data on the built environment.

U.S. fires became larger, more frequent, and more widespread in the 2000s

“…This is evident in burned forests of the intermountain West, where solar forcing on snow has exhibited a fourfold increase in the 2000s and led to earlier snowmelt and lower streamflow during the summer ( 39 ). Cascading impacts could ultimately compromise ecosystem services including water supply, recreation, tourism, and air quality for the 30 million Americans and >900,000 residential properties exposed to significant fire hazard ( 40 , 41 ).…”

“…Even if our data do not point to a statistically significant increase in annual area burned in the East, it is possible that changes in fire dynamics may also be underway, signaled by (i) increased fire frequency, (ii) potential nonstationarity of the daily area burned time series, (iii) changes in the tail of the fire size-frequency distribution reflecting devastating events such as the Great Smokies fire complex in 2016, and (iv) in the spatial rearrangement of ignition points. As housing developments continue to expand into flammable vegetation ( 41 ), fires will increasingly jeopardize lives and properties, and suppression costs, which already represent >50% of U.S. Forest Service budget, will rise ( 42 ). High-cost, high-loss events like the 2018 Camp Fire in California, which resulted in 85 fatalities and damage estimated at 16.5 billion USD, exemplify this rising risk and indicate that fire suppression capabilities may have already been exceeded.…”

Fires that matter: reconceptualizing fire risk to include interactions between humans and the natural environment

“…For millennia, people have started and managed fires [31], and fire regimes have co-evolved with societies as their economies shifted toward hunting-gathering, pastoralism, farming, and industrialization [24,32,33]. Today, settlement patterns significantly alter the number of homes in harm's way [34], increase fire ignitions [14], and sustain combustion [15,35]. Firescapes are thus a palimpsest of ecological and historical processes, shaped by waves of land use and urban expansion.…”

Creating a Nationwide Composite Hazard Index Using Empirically Based Threat Assessment Approaches Applied to Open Geospatial Data

“…Moreover, despite continuous hazard mitigation efforts, the costs of weather and climate disasters are increasing in the US. This escalating trend is due to a combination of increased exposure, vulnerability, and changes in the frequency and magnitude of climate extremes [7,8]. Mitigating future hazard impacts requires an improved understanding of the spatial extent of hazard threats faced by communities, the expected severity of consequences for known hazards, and the intersection of threats and consequences with vulnerable populations and infrastructure.…”

“…Officially released in 2003, the EPA's CRA focuses on community-scale approaches to solve the problems of toxic exposure by explicitly incorporating measures of social and cultural vulnerabilities for holistic risk assessments (i.e., by recognizing that communities are often impacted by multiple risks at once such that "a collection of individual stressors (occur) simultaneously and multiply") [31] (pp. [6][7][8][9][10][11][12][13][14]. Cumulative risk, therefore, is defined by the EPA "as the combination of risks posed by aggregate exposure to multiple agents or stressors (including chemical, biologic, radiologic, physical, and psychologic stressors affecting human and the environment) in which aggregate exposure is exposure by all routes and pathways and from all sources of each given agent or stressor".…”