Rainfall, not wind, drives tropical cyclone deaths, global study finds
A worldwide analysis of cyclone fatalities reveals that heavy rainfall is a far stronger predictor of deaths than wind speed or storm surge. The finding reshapes how governments and disaster planners should allocate resources and design early-warning systems to protect vulnerable populations.
Originaltitel: Assessing global factors associated with tropical cyclone-related mortality: A population-based longitudinal study.
Infrastrukturinvesterare och klimatplanerare bör omvärdera prioriteringar när de bygger orkanmotstånd — sociodemografiska förhållanden avgör dödsfall långt mer än orkankraftens fysikaliska styrka. Forskare analyserade dödsfall från 2034 orkankatastrofer i 68 länder mellan 2000–2019 för att identifiera riskhöjare. Modeller visade att befolkningssammansättning, befolkningstäthet, infrastruktururbanisering och utvecklingsnivå förklarade huvuddelen av variationen i dödlighet. För orkanfysiken framstod ackumulerad nederbörd som väsentligt viktigare än vindstyrka eller översvämningsdjup. Nederbörd interagerade kraftigt med lokala sociodemografiska förutsättningar — denna växelverkan framträdde som den starkaste faktorn bakom dödlighetsklyft mellan regioner. Resultat från Southeast University (Nanjing) och Monash University påpekar att länder och städer med äldre befolkning, större tätheter och svagare infrastruktur möter oproportionerlig risk. För hållbarhetsplanerare innebär detta: anpassningskapacitet och sosyal motståndskraft väger tyngre än att bara förstärka fysisk infrastruktur mot extremväder.
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.