How are hurricanes connected to climate change?

WLRN Public Media | By Amy Green,

James Bruggers

Published June 15, 2023 at 11:07 AM EDT

Hurricanes have become a symbol for climate change and a rallying call for action. Scientists still debate how climate affects hurricanes, but they know a lot more about the storms.

As NASA puts it, “Earth’s atmosphere and oceans have warmed significantly in recent decades. A warming ocean creates a perfect cauldron for brewing tempests” because “hurricanes are fueled by heat in the top layers of the ocean.”

Oceans warm earlier in the spring, allowing storms to form before the official season begins on June 1, as happened in 2020’s record setting hurricane season with Tropical Storms Arthur and Bertha in May.

Hurricanes are intensifying faster and dropping more rain. Because of global warming, their destructive power persists longer after reaching land, increasing risks to communities farther inland that may be unprepared for devastating winds and flooding, according to research published in 2020 in the the journal Nature.

In 2022, after flattening swaths of southwest Florida in September, Hurricane Ian left widespread flooding across the state’s interior, causing $113 billion in damage and 156 deaths. Ian ranks as the third-costliest hurricane in U.S. history after Katrina in 2005 and Harvey in 2017, according to NOAA. Ian was responsible for rainfall amounts not seen in Florida in hundreds of years if not longer, experts say.

With rising sea levels, cyclones also push tidal waters further inland, making storm surges more dangerous and deadly.

Why it Matters

There is a general realization that we are facing a more challenging reality,” Maarten van Aalst, director of the International Red Cross and Red Crescent Climate Centre, which connects climate science with emergency response, told Inside Climate News.

In the last quarter century, NASA has tracked the largest stretch of high energy hurricanes on record. “So while there aren’t necessarily more Atlantic hurricanes than before, those that form appear to be getting stronger, with more Category 4 and 5 events,” according to NASA.

By the Numbers

Hurricanes accounted for a record seven of 22 weather or climate disasters in 2020 that resulted in at least $1 billion in damages.
In 2020, researchers from the National Atmospheric and Oceanic Administration (NOAA) and the University of Wisconsin found an 8 percent per decade increase in the odds that any tropical cyclone globally could become a Category 3 or higher, or those with wind speeds of 111 miles per hour or more. The study encompassed 39 years of storms.
Climate change increased Hurricane Ian’s rainfall rates by more than 10 percent, according to one preliminary study by researchers at Stony Brook University and the Lawrence Berkeley National Laboratory.
Since 2017, at least 29 hurricanes have gone through a period of rapid intensification and eight of them, including Hurricane Michael in 2018, did so just before they made landfall in the United States, said John Cangialosi, a senior hurricane specialist at the National Oceanographic and Atmospheric Administration’s National Hurricane Center in Miami.
Michael was the first Category 5 hurricane to make landfall in the contiguous United States since Andrew in 1992.

What Else to Know

Hurricane experts have gotten very good at forecasting the path or track that hurricanes, also known as tropical cyclones, take as they spin across the ocean, making it easier for emergency managers and the public to make smart, life-or-death decisions on when to evacuate and where to go as a hurricane approaches.

At the same time, hurricane experts say forecasting storm intensity remains a big challenge. That’s especially true in an era of climate change that scientists say is likely producing more powerful and deadly storms.

A hurricane’s path is driven mostly by large-scale weather patterns—wind speeds and directions at different altitudes, for example—that occur on scales of hundreds to thousands of miles. These have become easier for hurricane foresters to see and interpret. That improvement has allowed NOAA to shrink the size of its forecast cones used on maps to illustrate the probable track of the center of a tropical storm or hurricane, reflecting the increasing accuracy.

The advances are largely due to new technology that has allowed improved data collection from satellites and from hurricane hunter aircraft, resulting in better observations of hurricanes, said John Nielsen-Gammon, the Texas state climatologist and a professor of atmospheric sciences at Texas A&M University.

Computer models can better assimilate all the data, he said, and “translate that into a full, accurate, three-dimensional representation of what’s going on in a storm right now,” he said.

But forecasting hurricane intensity remains a bigger challenge, even as NOAA has reduced its intensity forecast errors by 30 percent since 2010.

Intensity is determined by ocean heat as well as many smaller-scale ocean and atmospheric conditions found in the most hostile part of a hurricane— the ocean and atmospheric interface—where gathering much data is very difficult.

“We can tell when a particular environment is favorable for a storm to intensify, or when the wind shear, the winds at different levels of the atmosphere, are getting stronger, and might basically rip a storm apart, and make it weaker,” Nielsen-Gammon said.

“The challenge is in knowing how and when a particular storm will respond in a particular way to its environment, and some of that, as far as we know, is random,” he said. It’s like a thunderstorm or tornado forecast, he added, where many storms in similar environments behave in different ways.

This story was produced in partnership with the Florida Climate Reporting Network, a multi-newsroom initiative founded by the Miami Herald, the South Florida Sun Sentinel, The Palm Beach Post, the Orlando Sentinel, WLRN Public Media and the Tampa Bay Times