Even as Taiwan barricades itself as the typhoon approaches Krathon and the United States faces the ravages of the hurricane Helene, a study published Wednesday estimates that the long-term mortality burden of such phenomena is around 300 times higher than official figures.
The hurricane Helene caused at least 155 deaths in the southeastern United States, the hurricane John at least 16 in Mexico last week, and two people died in Taiwan even before the typhoon Krathon makes landfall Thursday morning.
But immediate deaths from tropical cyclones — also called hurricanes or typhoons, depending on where they strike — are only a fraction of their impact on mortality in subsequent years, according to a study published in the journal Nature, the first to use statistical modeling.
Researchers looked at 501 tropical cyclones that struck the continental United States between 1930 and 2015 and analyzed the number of excess deaths from all causes over the following 15 years.
The average number of officially reported deaths during these different storms was 24. But if we take into account indirect deaths in subsequent years, the average number of victims is between 7,000 and 11,000, around 300 times more than the official figures, estimates the study.
That is, hurricanes accounted for three to five percent of all deaths recorded in affected areas of the Atlantic coast of the United States in the 85 years studied, according to its authors.
With the total number of deaths in this period approaching five million, cyclones may have overall caused a mortality burden greater than that of car accidents, infectious diseases or wartime deaths, the study adds.
Researchers were “very surprised and very skeptical” when they first saw the devastating and lasting effect of cyclones on communities, Rachel Young, lead author of the study, told Agence France-Presse. and researcher at the University of Berkeley (United States).
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With Solomon Hsiang, a researcher at Stanford, they searched for years for other explanations for these deaths, in vain. Their study, however, did not establish a direct link between a particular hurricane and excess mortality.
These researchers have put forward several ideas on how hurricanes may have contributed to excess mortality over the years. Rachel Young used the example of someone using retirement savings to repair their home after a hurricane, and then finding themselves short of money for their health care.
Previous research has also shown that local and state budgets are smaller in areas affected by hurricanes, she said.
And many people are unaware of the long-term health effects associated with the aftermath of a cyclone, said Rachel Young.
According to the study, babies born even five to 10 years after a storm are much more likely to die prematurely in areas hit by a cyclone.
Black people are also more exposed. Even accounting for other factors, living in a region hit by a hurricane contributed to 15.6 percent of black deaths in the United States between 1930 and 2015, researchers estimate.
The numbers vary from state to state: 13% of all deaths in Florida, 11% in North Carolina, 9% in South Carolina and 8% in Louisiana in the period studied can be attributed to hurricanes, according to the study.
If climate change pushes hurricanes to new areas, it could lead to higher mortality rates in inexperienced regions, Rachel Young warned.
For Stephen Burgess, an epidemiologist at the University of Cambridge who was not involved in the research, the study has a solid methodology. “The authors ask the question: what if there were no tropical cyclones? But this is not a factor that we can change,” he judged.