The Future of Storms?

Early on the morning of August 27, as Hurricane Harvey pummeled Texas, floodwaters began lapping at the Nguyen family’s tree-lined front yard in Houston. Within hours, water rushed into their two-story brick house. The dad, Viet, plunged through the currents to grab life jackets and a raft from the garage. 

“Are we going to die?” asked Brayden, 9.

The Nguyens survived, but Harvey destroyed most of their belongings and did major damage to their home. It was one of the worst natural disasters in U.S. history. As the hurricane turned city streets into raging rivers, tens of thousands of people had to flee their homes. Thousands of others were left stranded, some waiting desperately on rooftops for rescue by boat or helicopter. At least 70 people died.

Early on the morning of August 27, Hurricane Harvey was pounding Texas. In Houston, floodwaters were starting to lap at the tree-lined front yard of the Nguyen family. Within hours, water rushed into their two-story brick house. The dad, Viet, plunged through the currents to grab life jackets and a raft from the garage.

“Are we going to die?” asked Brayden, 9.

The family survived. But Hurricane Harvey destroyed most of their belongings and did major damage to their home. It was one of the worst natural disasters in U.S. history. The hurricane turned city streets into raging rivers. Tens of thousands of people had to flee their homes. Thousands of others were left stranded. Some waited desperately on rooftops for rescue by boat or helicopter. At least 70 people died.

Hurricanes are some of the most destructive storms on Earth. Their strong winds and heavy rainfall often tear apart buildings, roads, and other structures in their path. Hurricanes can also push rising seawater inland, flooding entire neighborhoods.

The storms form over warm ocean waters, drawing their power from hot, moist air evaporating upward. Over the past century, Earth and its oceans have gotten warmer, creating more opportunities for tropical storms and hurricanes like Harvey and Irma.

Hurricanes are some of the most destructive storms on Earth. Their strong winds and heavy rainfall can easily tear apart buildings, roads, and other structures. Hurricanes can also push rising seawater inland, flooding entire neighborhoods.

The storms form over warm ocean waters. They draw their power from the hot, moist air evaporating upward. Over the past century, Earth and its oceans have gotten warmer. This creates more opportunities for tropical storms and hurricanes like Harvey and Irma to form.

Why is the planet getting warmer? Most scientists say that it’s because of a rise in greenhouse gases. Some of those gases occur naturally; others are produced by human actions. For example, the burning of fossil fuels like oil and coal—mostly from cars and power plants—creates carbon dioxide, the main greenhouse gas.

Greenhouse gases let sunlight through but also act like a greenhouse, trapping heat in the atmosphere. The higher the concentration of greenhouse gases, the warmer the planet gets. In the past century alone, Earth’s average annual temperature has risen about 1.5 degrees Fahrenheit (see graph, below). And for three years straight, the planet has broken records for highest global average surface temperature, according to NASA.

Why is the planet getting warmer? Most scientists say that it is because of a rise in greenhouse gases. Some of those gases occur naturally. Others are produced by human actions. For example, fossil fuels like oil and coal are burned, mostly by cars and power plants. This creates carbon dioxide, the main greenhouse gas.

Greenhouse gases let sunlight through. But they also act like a greenhouse, trapping heat in the atmosphere. The higher the concentration of greenhouse gases, the warmer the planet gets. In the past century alone, Earth’s average annual temperature has risen about 1.5 degrees Fahrenheit (see graph, below). For three years straight, the planet has broken its record for highest global average surface temperature, according to NASA.

Harvey didn’t behave like hurricanes usually do, experts say, because it continued to gain momentum even as it neared shore. Harvey also stayed intact for several days on land, and its punishing 115-mile-per-hour winds and rain were concentrated in the same area.  Storms usually move steadily inland or back out to sea, so their damage is spread out. 

Some scientists say Harvey’s last-minute power surge and its onshore duration can be tied to water temperature. The Gulf of Mexico, where Harvey formed, was already warmer than usual due, in part, to searing summer air temperatures. That heat transformed Harvey from a thunderstorm with strong winds into a major hurricane in roughly 48 hours, a day or two faster than is typical.

Harvey did not behave like hurricanes usually do, experts say. That is because it kept gaining speed and strength even as it neared shore. Harvey also stayed intact for several days on land. Its punishing 115 mile-per-hour winds and rain were concentrated in the same area. Storms usually move steadily inland or back out to sea, so the damage they cause is spread out.

Some scientists say Harvey’s last-minute power surge and the length of time it lasted onshore can be tied to water temperature. Harvey formed in the Gulf of Mexico, which was already warmer than usual. Extremely hot summer air temperatures were part of the reason the waters were so warm. That heat changed Harvey from a thunderstorm with strong winds into a major hurricane. This happened in roughly 48 hours, a day or two faster than is typical.

Not all scientists are ready to point the finger at climate change, though. Some say both Harvey’s and Irma’s devastation, coming during the peak of hurricane season, would have happened regardless. 

Miami, Florida, for example, is low-lying and one of the country’s most vulnerable spots for hurricanes. In addition, South Florida’s infrastructure isn’t fully equipped to deal with recent construction and population growth. More than 6 million people have moved to the state since 1990. 

“There is a constant battle between our ability to prepare for hurricanes and the pressure for urban expansion,” says Jean-Pierre Bardet, an engineering professor at the University of Miami.

Houston, too, is at high risk for hurricanes, scientists say. The low-lying coastal city is on the Gulf of Mexico, one of the most common spots for hurricanes to form. The city has struggled with flooding on and off for more than a century. 

As Houston grew rapidly over the past two decades, flooding only got worse. Some developers built entire neighborhoods next to or even inside floodplains—the areas most likely to end up underwater.

As the city expanded, it also added about 25 percent more pavement, cutting back on prairies and wetlands around the city. Unlike soil, roads and parking lots do not absorb water, making the effects of excess rainfall even worse.

Those conditions made an event like Harvey almost inevitable, say Suzana Camargo and Adam Sobel, science professors at Columbia University.

“Given a metro area of 6.5 million people that basically sits in a paved floodplain, crossed by bayous, creeks, and rivers, and the same [weather] situation, we would be seeing a very major disaster even without any human influence on climate,” the professors wrote in Fortune magazine.

Not all scientists are ready to point the finger at climate change, though. Some say both Harvey’s and Irma’s destruction would have happened anyway. Both storms came at the peak of hurricane season.

Miami, Florida, for example, is a low-lying area, and one of the likeliest places in the country to be harmed by hurricanes. In addition, South Florida’s infrastructure has not kept up with recent construction and population growth. More than 6 million people have moved to the state since 1990.

“There is a constant battle between our ability to prepare for hurricanes and the pressure for urban expansion,” says Jean-Pierre Bardet. He is an engineering professor at the University of Miami.

Houston, too, is at high risk for hurricanes, scientists say. The low-lying coastal city is near the Gulf of Mexico. That is one of the most common spots for hurricanes to form. The city has struggled with flooding on and off for more than a century.

Houston grew rapidly over the last two decades. During that time, flooding only got worse. Some developers built entire neighborhoods next to or even inside floodplains. Those are areas most likely to end up underwater.

As the city expanded, it also added about 25 percent more pavement, cutting back on prairies and wetlands around the city. Unlike soil, roads and parking lots do not absorb water. That makes the effects of excess rainfall even worse.

Those conditions made an event like Harvey almost impossible to avoid, say Suzana Camargo and Adam Sobel. They are science professors at Columbia University.

“Given a metro area of 6.5 million people that basically sits in a paved floodplain, crossed by bayous, creeks, and rivers, and the same [weather] situation, we would be seeing a very major disaster even without any human influence on climate,” they wrote in Fortune magazine.

At the same time that Harvey and Irma were wreaking havoc in the United States, extreme weather was ravaging South Asia. Flooding killed more than 1,000 people and displaced millions in India, Nepal, and Bangladesh this past summer. Mumbai, India, got as much rain in 12 hours on one August day as it usually gets over 11 days in a typical monsoon. Britain, Ireland, and parts of Africa also suffered from heavy floods.

Scientists worry that such extreme storms are a warning sign of what’s to come. Data shows that rising air and water temperatures could make powerful storms like Harvey and Irma more frequent. That idea scares people who live in hurricane-prone regions.

At the same time that Harvey and Irma were causing destruction in the United States, extreme weather was ravaging South Asia. Flooding killed more than 1,000 people and displaced millions in India, Nepal, and Bangladesh this past summer. Mumbai, India, got as much rain in 12 hours on one August day as it usually gets over 11 days in a typical monsoon. Britain, Ireland, and parts of Africa also suffered from heavy floods.

Scientists worry that such extreme storms are a warning sign of what is to come. Data shows that rising air and water temperatures could make powerful storms like Harvey and Irma happen more often. That idea scares people who live in hurricane-prone regions.