When Hurricane Otis smashed into Acapulco, Mexico, in October, the Category 5 storm left a trail of devastation in its wake. Because weather models had predicted that Otis would make landfall as a Category 1 hurricane, mitigation plans for a stronger storm had not been put into place in time. Now authorities estimate that rebuilding the resort city will take years. Less widely known is that the storm will probably also have long-lasting effects on the health of its residents.
In the aftermath of the hurricane, the residents of Acapulco are dealing with poor housing conditions, infrastructure devastation, flooding, and water and food insecurity. In other words, they are extremely stressed, and they’re not alone. As global warming intensifies storms, heat waves, floods and droughts, these events are getting under people’s skin and disrupting well-being in ways that persist long after the events themselves have subsided.
A cyclone can disrupt access to and availability and quality of water and food in short order. In the case of flooding, it’s not just stormwater that is often contaminated with waste—even tap water may need to be boiled if the power goes out. During drought or extreme heat conditions, people lose water as wells go dry from shrinking water tables and unsustainable groundwater use. Extreme climatic events also lead to the rapid death of crops and wildlife, along with supply chain issues that create food shortages and rising prices. Under such circumstances, households can go from relative water and food security to severe water and food insecurity in a matter of days.
Scientists have long understood the immediate effects of food or water shortages on the body: starvation, dehydration and organ failure. But only recently have they begun documenting the effects of such shortages on the brain. Earlier this year researchers at Georgetown University looked at how climatic shocks in Bangladesh affected mental health. They found that exposure to flooding in the previous year increased participants’ likelihood of depression by 31 percent, anxiety by 69 percent and co-occurring depression and anxiety by 87 percent. Women in Bangladesh suffer disproportionately during these floods, as Farhana Sultana of Syracuse University has documented in a separate study, in part because they bear the brunt of responsibility for managing water and food for their household, as well as taking care of their children.
This stress of living through extreme climatic events without sufficient buffering can impact the body in profound ways. A striking example comes from Puerto Rico, where researchers studied rhesus macaques on the island of Cayo Santiago after Hurricane Maria hit in 2017. The hurricane devastated the local ecological food and water resources. Afterward the macaques that were most affected exhibited changes in how their genes directed the production of proteins in their immune cells—changes associated with aging. Living through the storm accelerated their aging process, increasing their biological age by about two years, the equivalent of seven to eight human years.
Another study, published in October 2023, examined how exposure to the 2004 Indian Ocean tsunami affected a stress response mechanism known as the hypothalamic-pituitary-adrenal (HPA) axis in the long term. The HPA axis tells our body when it should be on guard and when it can relax. Women who were exposed had elevated post-traumatic stress in the two years following the disaster. More surprising was that 14 years later, the chronic stress from the disaster resulted in their HPA axis showing signs of “burnout”–basically, their body was unable to produce the extra stress hormones needed to mount an appropriate response to threats.
The ways in which people respond behaviorally to water and food shortages can further disrupt their health. During extreme climatic events, finding safe water to drink is critical, yet changing conditions affect perceptions of what water is acceptable to drink. When people encounter more frequent advisories to boil water and more notifications that they have been exposed to dangerous contaminants, their distrust of available water sources increases. As a result, they may voluntarily restrict the amount of water they consume, which can lead to dehydration, or they may reach for unhealthy alternatives to water, such as sugary sodas.
How dehydrated people rehydrate matters. In a series of experiments, researchers from the University at Buffalo had people exercise in hot, humid conditions and gave them water or soda to drink during and after the exercise. They found that when participants drank soda instead of water, their kidneys showed acute damage. One possible takeaway message from this finding: a hotter world with increased episodes of water scarcity might lead to increased rates of kidney disease. At the same time, as sea-level rise and saltwater intrusion threaten our supplies of drinking water, we face potentially increased exposures to sodium and chloride in our water. This increased salinity in drinking water not only makes it less palatable but also increases the risk of hypertension and impaired kidney function.
To mitigate the stress from water and food insecurity, it is important to understand how people cope with shortages not only individually but also at the community level. Anaís Roque of the Ohio State University and her colleagues studied how residents in three Puerto Rican communities dealt with severe power and water problems caused by Hurricane Maria. They found that 85 percent of households organized water-sharing networks with their families and neighbors, and people provided water to one another without the expectation of getting anything in return to cope with the water shortages. This water was critical for drinking, cooking and cleaning.
My own work with colleagues who study water insecurity has found that communities around the world share water to deal with water-related system failures. Borrowing water from others can cause stress by creating a feeling of obligation to return the favor, but after extreme climatic events, people nonetheless band together to try to help manage their water needs, as occurred after Hurricane Maria and the devastating wildfire on the island of Maui in Hawaii.
If governments and organizations are going to protect the public’s health, they must take urgent action to protect the planet. Cutting carbon emissions to prevent further damage is paramount. Likewise, they must act quickly to plant new varieties of crops and pastures that can tolerate drought, flooding and excess salt. There are many such measures they can and should take to make Earth safer for everyone.
But saving the environment is only part of the solution. It is critical for governments to understand the many ways in which climate change affects health directly and indirectly so that they allocate resources to marginalized groups such as single-headed households, as well as communities that are most likely to suffer disproportionately. They must invest proactively in building resilient infrastructure that can withstand extreme rainfall and flooding, identifying areas where saltwater intrusion is accelerating and building water desalination plants in those areas. They must also set up safety-net programs before disasters strike to distribute funds to help prevent future health consequences.
Climate change is one of humanity’s most pressing problems. If we do not tackle it now and allocate resources to communities appropriately, extreme climatic events such as Hurricane Otis will continue to compound stress, which changes our biology—and damages our health—in more ways and on longer timescales than we previously realized.
