Hurricanes and tropical storms in the United States contribute to a surge in deaths for up to 15 years after the storms hit, new research suggests.
While official statistics usually record only direct deaths from storms—averaging 24 per storm, mainly from drowning or trauma—this new analysis shows a much larger hidden toll.
The research, published in Nature, comes just days after Hurricane Helene hit the Southeast, leaving more than 100 people dead. But the study looks further ahead, estimating that the average tropical cyclone indirectly causes between 7,000 and 11,000 excess deaths, far exceeding the official estimates.
In total, they believe hurricanes and tropical storms have caused between 3.6 million and 5.2 million deaths in the U.S. since 1930—more than all deaths nationwide from motor vehicle accidents.
"These numbers are much larger than the direct deaths we see quoted in newspapers," senior study author Solomon Hsiang told Newsweek. "We think this reshapes how we think about the overall scale of impact that these storms are having on our survival."
The study analyzed data from 501 tropical cyclones between 1930 and 2015, building on earlier research suggesting long-term economic damage from hurricanes. The team found that deaths linked to these storms continue for years, with many occurring far after floodwaters have receded and media attention has shifted.
The main category of excess deaths was broad, including diabetes, suicides and other unrecorded causes. Cardiovascular disease ranked next, followed by cancer.
While the study identifies the association between excess deaths and tropical cyclones, the underlying mechanisms are not identified. The authors posit several possibilities, including economic distress, changes in social networks and a reassignment of public finances for recovery efforts.
"We don't know what is happening is probably a combination of many of those things or all of them," Hsiang said.
A key finding was the stark inequality in these long-term death rates. Black Americans are three times more likely to die in the aftermath of a hurricane than white Americans, confirming long-held concerns about unequal recovery efforts and the lasting effects on vulnerable communities.
"That was a very challenging finding," Hsiang said. "People have talked about environmental justice as being a big concern, and we think that this is important because while people have been discussing it, it's been hard to measure what is happening. This is one of the first pieces of hard evidence."
The researchers also found that tropical cyclones are responsible for 25 percent of infant deaths and 15 percent of deaths among people aged 1 to 44 in the U.S.
"These are infants born years after a tropical cyclone, so they couldn't have even experienced the event themselves in utero," lead study author Rachel Young said in a statement. She explained that this points to a broader economic and maternal health crisis that can linger for years after a disaster.
The study's findings are concerning for areas that have historically experienced fewer hurricanes, too. These regions tend to see a higher spike in cyclone-related deaths, as local governments and health systems may not have adapted to the long-term health risks posed by these storms.
As climate change is expected to increase the intensity of tropical storms, the researchers hope their findings will inform research into disaster management and climate adaptation strategies. In the immediate aftermath of Hurricane Helene, their research takes on even greater urgency.
"Helene has obviously been incredibly devastating," Hsiang said. "That is clearly a tragedy for those communities and those families. We need to deal with the current emergency situation, but then our results indicate there is going to be a massive impact over the next 15 years.
"We need to rethink how we support those communities in the long run as they recover—not just in the short run when it feels like an emergency and it's showing up in the news."
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References
Young, R., & Hsiang, S. (2024). Mortality caused by tropical cyclones in the United States. Nature. https://doi.org/10.1038/s41586-024-07945-5
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