With torrential rain and devastating flooding, Hurricane Helene, fueled by higher-than-usual tropical moisture, made landfall in Florida and wrought devastation throughout the Southeastern United States. Extreme amounts of rainfall turned creeks into rivers, sweeping towns away with the current. Appalachian communities in North Carolina were particularly hard hit, and casualties numbered over 200, making Helene the third-deadliest hurricane of the 21st century.
More recently, wildfires in Los Angeles, sparked under human-caused circumstances, are violently burning because of parched landscapes that have not seen enough rainfall. In tandem with these dry conditions, gale-force Santa Ana winds, likely made more powerful by human-caused climate change, have fanned the flames into fierce infernos, already destroying over 20,000 structures and ending dozens of lives to date.
These events are not isolated anomalies – they are part of an accelerating pattern of severe weather, driven by a warming planet. With each new storm, each new blaze, the toll on human health grows more dire: lives lost, communities fractured, and mental and physical scars that linger long after the skies clear. These events and others demonstrate that the long-feared effects of climate change are here and developing rapidly. To this end, what are the mechanisms driving this extreme weather, how do they relate to human-induced (anthropogenic) climate change, and what are the expected health effects? More importantly, what can we do to prevent further devastation and safeguard health in the face of a warming planet?
The Science Behind Extreme Weather
The Sixth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), released in 2021, highlighted that the rise in human-produced greenhouse gases has increased the frequency and intensity of extreme weather events. Furthermore, according to the National Centers for Environmental Information (NCEI), the U.S. has seen a significant increase in billion-dollar weather and climate disasters, with the average number of events per year rising from 9 (between 1980 and 2020) to 23 between (2020-2024).
Human activities, primarily the burning of fossil fuels, are the primary drivers of the climate crisis and, by extension, the increasing severity and frequency of extreme weather events. The production and use of fossil fuels like methane gas, sometimes referred to as natural gas, release significant amounts of greenhouse gases (GHG) like carbon dioxide (CO2), methane (CH4) and others into the atmosphere, all of which trap heat from the sun that would otherwise escape into the atmosphere. According to the International Energy Agency (IEA), CO2 emissions from fossil fuel combustion accounted for nearly 75% of global greenhouse gas emissions in 2022.
Methane, a potent greenhouse gas with a global warming potential approximately 28 times greater than CO2 over a 100-year period, and more than 80 times greater over a 20-year period, plays a critical role in driving atmospheric instability. A significant source of methane emissions comes from shale gas operations, which involve hydraulic fracturing (fracking) to extract methane gas from deep underground. While methane gas is often touted as a “cleaner” energy source, its production, processing, and transportation result in substantial methane leaks, with a single shale gas well potentially emitting 27.8 billion metric tons of CO2 over the lifetime of its operation. The U.S. Environmental Protection Agency (EPA) estimates that methane emissions from oil and gas operations represent 30% of total U.S. methane emissions, one of the largest contributors to greenhouse gas.
The science behind increasingly severe weather events is closely tied to the warming climate. The three best-understood ways in which climate change is affecting acute weather events are warming oceans, warmer air temperatures, and rising sea levels. Warmer oceans provide a stronger “fuel” for tropical storms, increasing their wind speed and severity should they make landfall. With warmer air temperatures comes more moisture evaporation, which leads to drier conditions on the ground, but more moisture in the atmosphere. This, too, can increase storm severity and precipitation quantity, which has implications for flooding. Finally, rising sea levels from increased global temperatures lead to higher storm surges, increasing flooding. Methane reduction is seen as the premier way to reduce the impacts of melting sea ice that leads to rising ocean levels.
Acute Health Outcomes
The effects of changes in severe weather can manifest acutely during the events, or they can occur chronically over time through prolonged exposure or displacement due to storms. The immediate health impacts of severe weather are often life-threatening, resulting in injuries and fatalities. Floods, for instance, are among the deadliest weather-related disasters, with drowning being the primary cause of death. The Federal Emergency Management Agency (FEMA) advises affected people to never attempt to enter or drive through floodwaters, regardless of one’s ability to swim. Additionally, the Centers for Disease Control and Prevention (CDC) reports that over half of flood-related fatalities occur when people attempt to drive through floodwaters. Storms that generate high winds like tornadoes and hurricanes are dangerous due to flying debris, which can lead to severe trauma, broken bones, lacerations, and other physical harm.
Outside of causing direct injuries, severe weather events can place enormous strain on the health system. Hospitals may lose power during storms, impeding life-saving procedures. In 2017, Hurricane Maria’s landfall on Puerto Rico caused widespread hospital outages both in the immediate and long term, jeopardizing health in the wake of the hurricane and beyond. The National Weather Service highlights the risk of lowered access to emergency care during severe weather, as roads may be blocked or destroyed, preventing ambulances and first responders from reaching those in need.
Chronic Health Consequences
Beyond the immediate aftermath of severe weather, sweeping changes in weather events also have long-term health implications. Studies show that exposure to waterborne disease and long-term effects from illness increase in the wake of severe storm events. In weather events such as wildfires, respiratory issues are common, as smoke contains fine particulate matter (PM2.5) that can penetrate deep into the lungs and exacerbate conditions like asthma or chronic obstructive pulmonary disease (COPD). The National Institutes of Health (NIH) warns that prolonged exposure to wildfire smoke increases the risk of cardiovascular events, such as heart attacks and strokes.
For those reliant on medication or regular doctor’s visits, displacement due to severe storms can disrupt treatment regimens, leading to exacerbations of chronic conditions like diabetes or hypertension. Decreased access to treatment causes many individuals to struggle to obtain necessary prescriptions, compounding health risks. In the case of evacuations where individuals are housed in long-term shelters, water, sanitation, and hygiene (WASH) can become a major vector of disease outbreak, most notably for the most vulnerable members of the population.
Perhaps one of the least well-understood long-term impacts of severe weather exacerbations are mental health impacts. Survivors of hurricanes, floods, and other disasters frequently experience post-traumatic stress disorder (PTSD), anxiety, and depression. Research from the Pan American Health Organization indicates that hurricanes Katrina and Irma resulted in substantial increases in mental health service needs in affected areas, with many individuals requiring long-term care.
Protecting Health in a Stormy Future
As we continue to face the growing health threats posed by climate change and severe weather, it is essential that we take proactive steps to protect ourselves and our communities. From community preparedness to personal actions and policy advocacy, each of us has a role to play in addressing the challenges posed by extreme weather. Large-scale polluters, in many ways the root cause of the climate crisis, should also commensurately contribute to climate solutions that would safeguard the health of communities they work in or serve.
Community Preparedness
Preparedness at the community level is critical to minimizing health risks during severe weather events. Local governments, organizations, and health systems must invest in infrastructure that supports vulnerable populations during emergencies. FEMA and the U.S. Climate Resilience Toolkit provide guidelines for communities to strengthen their resilience to climate impacts. By advocating for such infrastructure investments, we can ensure that everyone, especially those most at risk, has access to the resources they need to stay safe.
Personal Action
While community-wide measures are important, individual preparedness also plays a key role in reducing the health impacts of extreme weather, especially if you are at risk of injury or illness from severe storms. The U.S. Department of Homeland Security (DHS) prepares Ready.gov, a resource that allows users to check what natural disasters and storm events their area might be susceptible to, and the steps people can take to protect their health and wellbeing. Additionally, the CDC Severe Weather Guidelines offer practical resources and tips to guide your preparation.
Policy and Advocacy
We must advocate for policies that address the root causes of severe weather and climate change. Reducing greenhouse gas emissions is the most effective long-term strategy for limiting future risks to human health. Supporting policies that promote renewable energy, such as wind and solar power, is essential to transitioning away from fossil fuels. Climate policies like the Inflation Reduction Act offer significant opportunities to reduce emissions and invest in a sustainable future without jeopardizing economic growth. The EPA also has resources to help you find state and local environmental policy efforts that can help improve your local environment. By supporting these policies and advocating for stronger climate action, we can help shape a healthier, more resilient world.
Author's Note:
Climate scientists often find themselves correcting the differences between weather and climate. “It snowed 3 feet last night – so much for climate change,” some skeptics might argue. The problem with that thinking is that observations of the weather and changes in larger climate trends are fundamentally different. Weather refers to short-term atmospheric conditions in a specific time and place, which can vary day by day, hour by hour. Experts measure weather in short timeframes, as far out as a few weeks, or even just a few minutes. Climate, on the other hand, looks at the average weather patterns and trends over a longer time period, typically 30 years or more, in a specific region or globally. Scientists studying the climate look at large-scale, far-reaching trends that take place over the course of decades or even millennia. Instead of measuring acute temperatures, precipitation, or humidity day by day, climate science looks at long-term average changes in these variables. The fundamental differences between weather and climate can be thought of like this: weather is a chapter in a book; climate is the book’s overall theme.
The distinction between weather and climate matters because misunderstanding the difference can lead to downplaying the seriousness of climate change. Skeptics might also find value in ignoring long-term trends in favor of short-term fluctuations, choosing to see what is happening here and now and not addressing the overall systemic changes that are occurring. Finally, whether intentionally or unintentionally, this distinction can be leveraged to spread climate misinformation, further delaying progress in taking action against the most serious effects of climate change.
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