NATURAL HAZARD RISK ASSESSMENT IN A CHANGING WORLD

Data released by the National Oceanic and Atmospheric Administration/National Centers for Environmental Information indicate that in 2021 the U.S. experienced twenty distinct natural disasters that each caused damage of over a billion dollars, a total exceeded only by 2020’s twenty-two billion-dollar disasters. Vulnerability to loss, unless offset by intentional effort, tends to rise as population and the value of exposed assets increase. Exposure to hazardous events rises with increasing density of population and assets and with expansion of populations and assets into hazardous zones. Frequency, and perhaps the magnitude and intensity, of some natural hazard events such as flooding, severe storms, and wildfires appear to be increasing. Increased frequency of hazardous events raises the risk of losses to exposed populations and assets. If risk hazard is based on expected annual loss formulated on exposure, annualized frequencies, and historic loss ratios that are all too low for current frequency and vulnerability, risk hazard values can result in unrealistically low risk assessments compared with actual impacts of hazardous events. On warm, dry, windy December 30, 2021, the Marshall Fire burned more than 6,000 acres of urban-wildland interface in Boulder County, fifteen miles northwest of the Colorado Convention Center where the GSA 2022 Annual Meeting is being held. Two lives were lost. At least 1,084 homes with a total estimated value of half a billion dollars were destroyed. The current National Risk Index expected annual loss for Boulder County buildings is $3.97 million, two orders of magnitude below actual loss from this event. Other natural hazard events, such as the December 10, 2021, tornado outbreak in western Kentucky, defy statistical expectations for impact outcomes in affected counties. How does the disjoint between statistical prediction based on historical records, compared with the experience of actual losses from natural disasters, affect our planning, the outlay of resources ahead of hazardous events, the ability of people and property to survive hazardous events, and our response during and after events? Is it time to reassess the way we assess risk and to consider including more realistic outcomes for events that once were outside reasonably expected parameters?