Climate & Hurricanes: Future Storms in the Carolinas, Part One

The following is the first of two guest blogs by Jay Barnes, author of Fifteen Hurricanes That Changed the Carolinas: Powerful Storms, Climate Change, and What We Do Next.

No matter where you get your news, it’s likely you’ve seen a recent uptick in the number of stories about climate. In 2021, historic wildfires, killer heat domes, widespread tornado outbreaks, and deadly urban flooding disasters made headlines, and 2022 is turning out to be no different. Earth’s seven hottest years have all occurred since 2014, and the connection between that heat and our worst weather disasters seems obvious. Scientists around the globe are on the case, offering new research in ever-more startling detail about the consequences of a warming planet and what to expect in the years to come.

The threat of more devastating hurricanes is often presented as one of the most serious climate-related perils we face. After his Oscar-winning documentary An Inconvenient Truth was released in 2006, Vice President Al Gore famously said, “What changed in the United States with Hurricane Katrina was a feeling that we have entered a period of consequences.” Since that time, climate change and its influence on tropical cyclones have remained in the news. More recently, some pundits and advocates for climate action have put forward the idea that epic hurricane disasters such as Sandy, Harvey, and Florence were the result of global warming.

From a historian’s perspective, that thinking seems flawed. Big, powerful, and destructive hurricanes are nothing new. The Carolinas have always been a hotspot, with Hazel, Hugo, Fran, Floyd, Matthew and Florence just some of the familiar names. Dozens of other big storms have battered the Carolinas for centuries, most unnamed and relatively unknown. North Carolina ranks fourth in the U.S. for hurricane landfalls since 1851; South Carolina ranks fifth (Florida, unsurprisingly, is first).

A closer look at the science reveals some unexpected ideas about what future hurricanes might be like in the U.S. Researchers use an array of ever-more-sophisticated computer forecast models, run out over decades, which factor increasing amounts of carbon dioxide, methane, and other greenhouse gasses to simulate conditions for future hurricane development.

Chris Landsea, chief of the Tropical Analysis and Forecast Branch of the National Hurricane Center, confirms one finding that may come as a surprise: it’s unlikely warming oceans will generate more storms, as the number of tropical cyclones is expected to remain the same or even decrease due to increased dry air and wind shear in tropical regions. Landsea says the highest category storms, the cat 4 and cat 5 hurricanes that do the most damage, may increase in number. But even if the number of storms doesn’t increase, the status quo is nothing to celebrate—each Atlantic hurricane season could still average fourteen named storms and seven hurricanes for decades to come.

And future hurricanes will be stronger, but only moderately so: “We’re looking at 3 to 5 percent stronger [storms] by the end of this century,” says Landsea. “So as an example, a 100 mph hurricane [today] might be a 105 mph hurricane at the end of the century because of global warming.” That’s a fairly small increase in strength, offering slightly more destructive potential, especially for those hurricanes where wind and tide are the primary factors.

It’s mostly been hurricane rainfall, though, that has swamped the Carolinas in recent years and caused ruin for so many. Record floods in central South Carolina in 2015 were followed by more devastating floods in the Carolinas during Hurricane Matthew in 2016—only to be topped by those of Hurricane Florence in 2018. Florence was poised to strike near Wilmington as a category 4, but it weakened and slowed as it made landfall, dumping record rains across a broad area. After the storm, 59 deaths and more than $24 billion in losses were reported in the Carolinas—making Florence the costliest hurricane in the history of either state.

Future storms will bring more record-breaking floods. Researchers are focusing on how climatic changes might slow tropical cyclone movement and produce stronger blocking weather patterns, yielding more rain. In 2019, researchers at the University of North Carolina at Chapel Hill published a study of high-precipitation events in North Carolina since 1898. They found that six of the seven greatest totals occurred in the last twenty years. Three of those: Floyd, Matthew and Florence. The authors concluded that “…either North Carolina has been very unlucky, or the historical record used to define storm statistics is no longer representative of the present climate regime.”

So, we might expect future hurricane seasons to have roughly the same storm frequency, but those storms that do strike will pack slightly stronger winds and be even bigger rainmakers. Across the Carolinas, inland floods will again sink homes and businesses, and homeowners—especially those without flood insurance—will again suffer dearly.

At the coast, residents will wrestle with another unavoidable consequence—rising sea levels, which over time will enhance any arriving hurricane’s destructive potential. Global ocean levels have been rising about one inch per decade over the last century, but the rate of increase is accelerating—alarmingly so—with the fear that as more polar ice melts, ocean levels could rise two or three inches per decade. “It doesn’t sound like much, but in areas where the terrain is pretty low-lying, even a foot over several decades is a big deal,” says Steve Pfaff, warning coordination meteorologist for the National Weather Service in Wilmington. “Places that don’t have much elevation, that are less than a few feet above sea level, are the ones at risk for having more flooding, more often.”

Hurricanes of the future will challenge the Carolinas, claiming untold lives and property, just as they have for centuries. The fact that their winds and rains will be enhanced by climate change is a real concern, and coastal areas grappling with sea level rise will become increasingly vulnerable. But it’s helpful to keep these changes in perspective, as there are arguably other factors—unrelated to climate—that will have far greater influence on the impact of future hurricane disasters in the Carolinas.

The second post in this blog series will discuss these other factors and their impact.

Jay Barnes, president and CEO of the North Carolina Aquarium Society is author of several books on hurricanes and often appears on media outlets such as the Weather Channel, NBC Nightly News, and the Discovery Channel.