Hurricanes and global warming: separating fact from fiction

The Ocean Heat Content (OHC) is a quantity that describes the thermal energy stored in a volume of the ocean. The data presented here utilize the methology developed in the Upper Ocean Dynamics Laboratory at the University of Miami's Rosenstiel School in the late-1990s (e.g. Shay et al. (2000)) which is based on concepts developed in the early 1970s (e.g. Leipper and Volgenau (1972)).

With the Florida peninsula being struck consecutively by Hurricane Milton and Hurricane Helene, residents are questioning whether human-driven factors play a role in these types of events.

However, the main issue is not the frequency of these events but rather the way both swiftly escalated in intensity. Both systems underwent rapid intensification (RI) in the Gulf of Mexico, a process that allows hurricanes to strengthen significantly over a short period. 

Michael Fischer, an assistant professor at the Rosenstiel School of Marine, Atmospheric and Earth Science, points out that warming ocean temperatures are crucial to understanding just how powerful hurricanes can get.

 “That’s kind of their main energy source, drawing heat from the ocean,” Fischer said.  

Higher water temperatures increase evaporation rates, which provides storms with additional moisture to their intensification. 

“We’re lengthening the window over which we can potentially see tropical cyclones,” Fischer said. “As well as raising the ceiling for how strong these storms can get.” 

Sophia Galindo, a senior majoring in ecosystem science, explained that these changes are reflective of a worsening climate. 

“The water isn’t just getting warmer to make beach days more enjoyable — it’s the biggest warning sign that things are going south,” Galindo said.

Global warming is occurring, but it’s unclear whether it directly accounts for this spike.

In early 2023, the Atlantic Ocean began experiencing a rise in water temperatures, with no definitive explanation yet. While many have been quick to question if this is linked to climate change, there is not enough research to confirm that claim as a fact.

“There’s a very slowly growing change due to global warming, but this is just a big jump up,” said David Nolan, an atmospheric science professor at the Rosenstiel School. “Nobody has a documented published reason for that at this time.” 

“Very very fast intensifications have happened before,” Nolan said. “I don’t like it when you look at Hurricane Milton and say ‘Wow, that intensified. . . .  because of global warming.’ That could’ve happened 50 years ago.”

Rainfall patterns and storm surges are directly influenced by global warming

When systems accelerate, they tend to produce more extreme conditions. Specifically, storms that rapidly intensify are more likely to experience elevated rainfall, storm surge and wind speed, creating a range of safety hazards.

“It is well established that a warmer atmosphere is capable of holding more water vapor that could lead to heavier rainfalls,” said Micahel Fischer. “And so it makes sense that as the atmosphere warms, you potentially see more storms like Helene that produce devastating events.” 

In addition to heavy rainfall, rising sea levels due to global warming heighten storm surge risks, leading to more severe flooding and coastal damage. In recent years, sea levels have risen between six inches and a foot — an increase that may seem small but can be crucial. 

 “If it’s the difference between whether ocean water comes into your house or not, you know that’s a big difference,” said Nolan. 

Looking ahead, hurricane intensification is expected to rise due to global warming.

“Knowing how climate change is going to affect us certainly gives me some anxiety,” says junior ecosystem science major Alexa Smith. “As students at the University of Miami, many of us are fortunate enough to have resources to remove ourselves from these unsafe situations; many people in Florida don’t. I know that students will joke to make light of situations like these, but we also need to remember to have empathy at this time.” 

“Based on climate models, there is a general consensus that with climate change, we may experience fewer storms overall, but they may be more intense in the future,” said Samantha Nebylitsa, a Ph.D. student at the Rosenstiel School whose research focuses on RI. 

With Hurricane Milton demonstrating a record-breaking drop in pressure before landfall, it’s possible that warming waters may contribute to how future systems evolve.

 “If we’re raising the theoretical ceiling for how strong storms can get, we could maybe see more storms like Milton that are like the top five lowest pressures that we’ve ever measured,” Fischer said.