Assessing global factors associated with tropical cyclone-related mortality: A population-based longitudinal study.

BACKGROUND

The underlying factors associated with the substantial global tropical cyclone (TC)-related mortality burden, characterized by its highly variable spatiotemporal patterns, remain unclear. We aimed to identify and assess the key factors associated with TC-related mortality on a global scale.

METHODS

We collected mortality records from 2034 locations in 68 countries/territories across five continents (2000-2019) to identify and assess the key factors associated with TC-related mortality on a global scale. Bayesian ensemble models were applied to estimate the associated mortality for each TC event in each location. A random forest regression (RFR) model was employed to assess the relative statistical importance of TC and location characteristics, as well as their interactions, regarding the TC-related mortality.

FINDINGS: For TC physical characteristics, the TC-associated cumulative rainfall consistently exhibited stronger influence on mortality than TC-induced surge-driven flood depth or maximum sustained windspeed. However, sociodemographic factors, including population traits (e.g., population density, proportion of the population aged ≤ 9 years, percent of the population aged ≥ 65 years) and socioeconomic and infrastructure development (e.g., built-up ratio), showed greater relative importance than the TC physical attributes and accounted for the majority of the explained variations in TC-related mortality. Furthermore, cumulative rainfall interacted strongly with local sociodemographic conditions and was potentially the most important associated factor for disparities in mortality arising from factor interactions.

INTERPRETATION: The findings highlight the critical role of sociodemographic factors in explaining the global spatiotemporal variability of TC-related mortality, surpassing the relative importance of TC intensity. TC-related rainfall could be a key associated physical factor of the global mortality burden.