FSU study warns that routine coastal flooding could become a major deadly threat for older adults across the United States by the end of the century
Florida – Routine coastal flooding that many people barely notice today could become a major public health crisis for older Americans by the end of the century, according to a new study that warns of a dramatic rise in flood-related deaths if no action is taken.
The research, co-authored by Florida State University scholar Mathew Hauer, was published in The Lancet Planetary Health and paints a stark picture of how “nuisance flooding” may evolve into a deadly and persistent threat for coastal communities.
Unlike hurricanes or major storm surges, high-tide flooding is often shallow, predictable, and slow-moving. It is sometimes dismissed as little more than an inconvenience, especially when it briefly covers streets or disrupts commutes. But the study argues that this perception hides a far more serious risk, particularly for older adults who rely on timely medical care.
Researchers found that even ankle-deep water on roadways can create enough disruption to delay ambulances and emergency responders during critical situations. Those delays, they say, can mean the difference between life and death in emergencies such as cardiac arrest or stroke, where every minute matters.
“When we think about climate change threatening people’s lives, we picture hurricanes and heat waves,” Hauer said. “What we found is that the routine, ankle-deep flooding people have learned to live with is on track to kill more older adults than storm surge does in these same coastal areas. It’s a quiet, cumulative form of climate mortality, and until now nobody had put a national number on it.”
The study draws on demographic modeling and infrastructure analysis to estimate how rising seas and worsening coastal flooding will interact with aging populations. It concludes that without major adaptation efforts, premature deaths among Americans aged 65 and older linked to high-tide flooding could increase 43-fold by 2100.
That projection translates into nearly 10,000 additional deaths every year in coastal regions across the United States by the end of the century.
The researchers also calculated the economic impact of these projected deaths, estimating that total losses could reach as high as $1.1 trillion over time. Those costs reflect not only healthcare expenses, but also the broader economic consequences of premature mortality among older populations.
One of the study’s most important findings centers on timing and distance. Seniors living more than 8.85 minutes away from the nearest hospital face significantly higher risk during flood events, since even small delays in emergency response can become deadly under flooded conditions.
Florida emerges as the most at-risk state in the analysis, due to a combination of factors: a large elderly population, extensive low-lying coastal geography, and already frequent tidal flooding in many communities.
“The findings are a wake-up call for the Sunshine State, which stands at the epicenter of the issue,” the researchers wrote, noting that the state could account for 24% to 38% of all high-tide flooding deaths in coastal U.S. regions by 2060.
That projection would place Florida’s annual flood-related mortality among older adults somewhere between 360 and 1,590 deaths per year, depending on future conditions and adaptation efforts.
“Florida has twin threats of an older population and a large, low-lying coastal zone,” Hauer said. “So, the demography, the geography and climate change all combine to account for a large percentage of these anticipated deaths.”
Despite the grim outlook, the study emphasizes that many of these deaths are preventable. Researchers argue that targeted infrastructure investments could significantly reduce risk, with projections showing that premature deaths could fall by as much as 57% if key adaptations are implemented.
Those adaptations include elevating vulnerable roadways, improving emergency access routes, and strategically locating hospitals and critical care centers so that they remain reachable even during flood events.
“The deaths show up when an ambulance can’t get through and the adaptive infrastructure to prevent these are things we already know how to do,” Hauer said. “Simple things like raising roadways, better sited-hospitals, and other changes could make a significant impact on reducing this anticipated mortality. An ounce of prevention today is worth a pound of cure tomorrow.”
The study also recommends broader planning strategies, including strengthening road networks used for emergency services and considering the managed relocation of vulnerable populations to areas with better infrastructure and healthcare access.
Researchers from Arizona State University, Industrial Economics, and the International Food Policy Research Institute contributed to the report, which was funded by the U.S. Environmental Protection Agency.
In its conclusion, the study warns that the true cost of inaction may not only be measured in dollars, but in thousands of preventable deaths each year. For coastal communities already experiencing routine flooding, the message is clear: what once felt like a minor inconvenience could become one of the defining public health challenges of the century.
