Climate Change and Hurricanes

Climate change has strengthened hurricanes in the United States, resulting in an increase in property damage and the number of lives lost. According to the National Oceanic and Atmospheric Administration (NOAA), because of climate change, storms are strengthening into Category 4 and 5 hurricanes, which cause catastrophic devastation. NOAA predicts that this trend will continue throughout the twenty-first century.

The number of Category 4 or 5 hurricanes in the United States has increased significantly in the 2010s and 2020s. Nine Category 4 or 5 hurricanes have hit the US mainland from 2017 to 2024: Hurricane Harvey (2017), Hurricane Irma (2017), Hurricane Michael (2018), Hurricane Laura (2020), Hurricane Ida (2021), Hurricane Ian (2022), Hurricane Lee (2023), Hurricane Beryl (2024), Hurricane Helene (2024), and Hurricane Milton (2024).

While hurricanes are categorized by wind speeds, heavy rainfall also plays a role in their destructiveness and death toll. For example, the heavy rainfall brought in with Hurricane Ian caused flash flooding in inland areas of Florida. Ian made landfall in Florida as a Category 4 storm on September 28, 2022. It claimed at least 144 lives and caused nearly $113 billion in damage. Hurricane Helene, a Category 4 storm that struck land on September 24, 2024, claimed about 230 lives. Helene unleashed about 20 inches of rain and affected six US states, causing about $40 billion in damage. Scientists are not yet sure whether climate change is increasing the number of hurricanes in the United States, but they are certain that it is making them more powerful. An increase in water temperature caused by climate change, such as in the Gulf of Mexico, increases the chance of a storm becoming stronger by about 50 percent.

Background

A hurricane is a powerful, violent storm that forms near the equator over warm ocean water. The term “hurricane” is used to refer to storms that form over the Atlantic Ocean or the eastern Pacific Ocean. Other terms may be used to describe these storms, such as “typhoons” and “severe tropical cyclones,” depending on their location. However, these terms all describe the same type of storm.

To form, hurricanes need warm, moist air, which is generally found over warm ocean water. This need for warmth is the reason that hurricanes form only in tropical regions, where the water is about 80 degrees Fahrenheit. Hurricane season refers to the time of year when hurricanes are most likely to occur. In the Atlantic Ocean, hurricane season is from June to November, when the water is warmest.

In addition to warmth, hurricanes need wind. Easterly winds from Africa help create hurricanes over the Atlantic Ocean. As the wind blows over the ocean’s surface, water evaporates into vapor and rises. The water vapor then condenses into water droplets, which form large cumulonimbus clouds, or storm clouds.

To be considered a hurricane, a storm must pass through four stages: tropical disturbance, tropical depression, tropical storm, and hurricane. A tropical disturbance is a cluster of thunderstorm clouds that stretch for at least 100 miles and last for 24 hours. A tropical disturbance may or may not become a tropical depression, which only occurs under precise conditions. The water must be very warm, and the lower and middle part of the atmosphere must contain a significant amount of moisture. Winds must be strong enough to make the clouds spin around a low-pressure center. If these conditions are all present, the tropical disturbance becomes a tropical depression.

If the pressure in the center of a tropical depression drops and air rushes in, strong winds occur. If these wind speeds increase above 39 miles per hour, the system is called a tropical storm. If a tropical storm passes over very warm water and the pressure in the center further drops, then the wind speeds significantly increase, and the system gets rounder and forms an “eye.” When this happens, it is a hurricane. As the hurricane passes over warm water, it pulls in more water vapor and heat, which makes the wind stronger and the rainfall heavier.

Hurricanes are categorized according to the Saffir-Simpson Hurricane Wind Scale. A Category 1 storm has winds that are 75–95 miles per hour and will produce damage; a Category 2 storm has winds that are 96–110 miles per hour and will cause extensive damage; a Category 3 storm has winds that are 111–129 miles per hour and will cause devastating damage; a Category 4 hurricane has winds that are 130–156 miles per hour and is likely to cause catastrophic damage; and a Category 5 hurricane has winds in excess of 157 miles per hour and will cause catastrophic damage, making most of an area uninhabitable for weeks or months.

Overview

Climate change refers to long-term alterations in a region’s weather, such as an increase or a decrease in temperature and rainfall. Global warming is an overall increase in Earth’s temperature that is largely caused by burning fossil fuels, which releases gases that trap heat in Earth’s atmosphere. Climate change includes global warming as well as other changes caused by people that affect the weather, such as deforestation. Climate change has strengthened hurricanes because it has caused an increase in the temperature of the surface of oceans, a rise in sea levels, and changes in the atmosphere.

Changes Affecting Hurricanes

If the temperature of the surface of an ocean rises, wind speeds increase, which can make a hurricane stronger. This spike in temperature also increases the amount of rainfall caused by a hurricane, which can cause flooding. For example, Hurricane Harvey made landfall in Texas and Louisiana in August 2017. The towns of Nederland and Groves, Texas, received more than 60 inches of rain, which caused unprecedented flooding that inundated hundreds of thousands of homes. Scientists from Stony Brook University and Lawrence Berkely National Laboratory believe that climate change increased the amount of rainfall brought by Hurricane Ian by 10 percent. During Hurricane Ian, more than 20 inches of rain fell in twelve to twenty-four hours in a wide area of land from Port Charlotte to Orlando, Florida, causing catastrophic flooding. Hurricane Helene also had extremely heavy rain, causing catastrophic flooding in North Carolina.

Rising sea levels also contribute to the devastation caused by hurricanes by increasing deadly storm surge, which is the amount of water strong winds push onto land. The average sea level has risen more than 6 inches worldwide since 1900. Scientists expect sea levels to rise an additional 1 to 2.5 feet during the twenty-first century. Higher storm surge has the potential to significantly increase the death toll caused by a hurricane. The Medical Examiners Commission concluded that many of the 144 deaths caused by Hurricane Ian were due to storm surge, which was 15 feet high in some areas. Had the height of the storm surge been even a few feet lower, the death toll would have been much lower. In 2024, Hurricane Helene's storm surge peaked at 15 feet. Helene killed about 230 people. Thirty-five people were killed by Hurricane Milton in 2024, some from storm surge, which reached 11 feet in Tampa Bay, Florida.

Hurricanes in the twenty-first century travel more slowly than those of the past. This slow-down allows them to linger longer over a region, causing more severe damage from high winds, heavy rainfall, and storm surge. Scientists believe the decrease in the speed of hurricanes may be because of atmospheric changes from climate change. For example, Hurricane Dorian in 2019 remained over the Grand Bahama Island for fourteen hours. This Category 5 hurricane caused massive destruction.

Cost of Hurricanes

Stronger hurricanes increase the number of human lives lost. Hurricane Katrina, a 2005 Category 5 storm, caused about 1,800 deaths. Hurricane Maria, a 2017 Category 5 storm that made landfall in Puerto Rico, was responsible for nearly 3,000 deaths. The property destruction caused by hurricanes can also pose a threat. Stagnant flood water puts people at risk of waterborne and mosquito-borne illnesses as well as environmental contaminants. Damage to infrastructure can make transportation impossible, making it difficult for people to receive medical care.

The financial risk of powerful hurricanes is also high. According to NOAA, the six costliest hurricanes in US history are Hurricane Katrina ($186.3 billion), Hurricane Harvey ($148.8 billion), Hurricane Ian ($113 billion), Hurricane Maria ($107.1 billion), Hurricane Sandy ($81.9 billion), and Hurricane Ida ($78.7 billion). The high cost of damage caused by strong hurricanes hurts the country’s economy as well as affected businesses and individuals. Insurance companies quickly become overwhelmed and receiving payment for claims could take months or even years. Insurance adjusters may whittle down claims by thousands of dollars, such as reducing the cost to replace a storm-damaged roof because of everyday wear and tear. Some claims are denied outright, leaving residents without their homes. According to the New York Post, some homeowners’ claims were denied after Hurricane Ian because their homes were flooded, and homeowner policies do not cover flooding. However, many residents claim that most of the damage to their homes was caused by wind, not water. According to WPST News, Lee County, one of the areas hardest hit by Hurricane Ian, had 246,161 claims reported. Of those, 48,334 were denied payment.

State and federal governments become financially overburdened by the damage caused by strong hurricanes. They must pay for clean-up, infrastructure repairs, and temporary housing for displaced survivors, among many other costs. Most of these costs are the responsibility of the Federal Emergency Management Agency (FEMA). After Hurricane Ian, FEMA provided $871 million to households affected by the storm. The Small Business Administration (SBA) provided $1.4 billion in disaster loans, and the National Flood Insurance Program paid $1.72 billion in claims to survivors.

Future Hurricanes

According to experts, unless greenhouse gas emissions are immediately reduced to halt global warming, the hurricanes of the future will continue to be strong. Scientists predict temperatures to rise by 4 degrees Fahrenheit by 2100. If this should happen, sea levels may rise 2 to 3 feet, which will substantially increase storm surge created by hurricanes. Rainfall caused by hurricanes may increase by as much as 15 percent, which increases the risk of flash and severe flooding. The intensity of hurricanes, or wind speed, is expected to increase about 3 percent in the Atlantic Ocean region, while the number of Category 4 and 5 hurricanes is expected to increase by 10 percent in the same area.

Researchers also believed that sequential hurricanes would become more common in the future. This essentially means that once a hurricane strikes an area, another will follow. This occurred in 2024, with Hurricane Helene striking the United States on September 24 and Hurricane Milton reaching land on October 5.

According to the National Weather Service, an average of ten tropical storms per year develop over the Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. About six of these storms become hurricanes. About five hurricanes hit the United States coastline within three years. Of these, two are usually major hurricanes, Category 3, 4 or 5.

Increased development in coastal regions puts more people and property at risk. Nearly fifty million homes are within one-eighth of a mile of the coast. According to NOAA, populations along the US coastline and in countries in the Caribbean and Central America double every twenty to forty years.

Coastal communities need to take steps to bolster their resilience to powerful hurricanes. Measures should include preserving coastal wetlands, dunes, and reefs to better absorb storm surge. Buildings in vulnerable areas should be elevated to reduce the possibility and severity of flood damage. New building and development should not occur in flood-prone zones or in areas commonly affected by hurricanes. Building codes should require homes and buildings to be able to withstand high winds. All residents in high-risk hurricane areas should purchase flood insurance. Residents who are in low-risk hurricane areas should also purchase flood insurance as a precaution. Those living in an area where a hurricane is predicted should take precautions to protect property such as boarding windows and clearing property of potential flying debris. They should also develop an evacuation plan.

Bibliography

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