Attribution of U.S. Economic Losses due to Tropical Cyclones

Abstract

Economic losses due to tropical cyclones have increased over time and can be potentially attributed to three factors: hazard, exposure, and vulnerability. Regardless of known increases in North American tropical cyclone frequency and intensity, the current literature attributes increases losses to exposure, increases in population and building value. Studies of tropical cyclone loss attribution typically utilize normalization to account for exposure over time. Normalization transforms loss data to account for temporal changes in socioeconomic conditions. However, these studies do not account for changes in spatial exposure, nor do they take into account hazard or vulnerability. This study begins with a traditional normalization of tropical cyclone economic losses in the U.S. form 1970-2018. It then explores a subset of these economic losses, Florida property damage from 1996-2018, and utilizes a normalization methodology that accounts for spatial differences in exposure. A positive but insignificant trend is observed in contrast to no trend under traditional normalization methodology. Finally, losses from two hurricanes approximately 20 years apart are compared using wind speeds to determine if the Florida Building Code successfully reduces vulnerability over time. A significant shift in vulnerability is observed, suggesting that vulnerability has been reduced over time. The study concludes that traditional normalization alone is insufficient in attributing increasing losses and that efforts to reduce both exposure and vulnerability are beneficial in counteracting potential tropical cyclone losses increases due to worsening tropical cyclones.