There is about a month and a half left in the 2023 Atlantic Hurricane season, and it’s a season that has seen some rapidly intensifying storms. In less than 24 hours, Hurricane Idalia went from a Category 1 hurricane to a Category 4 with winds near 130 MPH. The storm made landfall on Florida’s Gulf Coast as a high Category 3. Weeks later, Hurricane Lee grew from a Category 1 storm to a Category 5 in only 24 hours.

[Related: The future of hurricanes is full of floods—a lot of them.]

According to a study published October 19 in the journal Scientific Reports, Atlantic hurricanes may be more than twice as likely to strengthen from a Category 1 storm to a major Category 3 hurricane or higher in a 24-hour period than they were between 1970 and 1990. They also are more likely to strengthen more rapidly along the east coast of the United States.

As ocean temperatures continue to reach record highs due to human-caused climate change, the trend is worrying. Tropical weather systems like hurricanes and tropical storms gain strength over unusually warm sea surface temperatures. Warm ocean water is like carbohydrates for hurricanes and gives the storms more energy. Faster storm intensification has already been linked to climate change, but the changes in the intensification rates of storms across the 41 million square mile wide Atlantic Ocean Basin have been less clear. 

“Our oceans have absorbed about 90 percent of the excess warming that has occurred in recent decades due to human-caused climate change,” study co-author and Rowan University climate scientist Andra Garner tells PopSci. “I wanted to see what kinds of changes might already have occurred to the overall rates at which Atlantic hurricanes have been strengthening.”

In the study, Garner looked at every Atlantic hurricane between 1970 and 2020 and analyzed how the wind speed changed over each hurricanes’ lifespan. The storms were split into three time periods–a historical era (1970 to 1990), an intermediate era (1986 to 2005), and a modern era (2001 to 2020). To establish the maximum intensification rate, Garner calculated the greatest increase in wind speed over any 24-hour period within the hurricane’s lifespan. 

She found that the chance of a hurricane’s maximum intensification rate being 23 miles per hour or more had increased from 42.3 percent in the historical era to 56.7 percent today. The probability of a weak hurricane strengthening to become a major hurricane in 24 hours also increased from 3.23 percent to 8.12 percent. 

“The storms we’ve seen this year, like Hurricane Idalia and Hurricane Lee, align with what my research findings would tell us to expect,” Garner says. “Hurricane Idalia and Hurricane Lee both occurred over exceptionally warm ocean waters, and strengthened quickly as a result of those warm ocean waters (and other favorable conditions). I think that this lines up very well with a trend that my research indicates that we could expect to continue if ocean waters continue to warm.”

[Related: Florida’s aquatic animals prepare early for storms like Hurricane Idalia.]

The locations within the Atlantic Basin where hurricanes were most likely to see their maximum intensification rate has also changed between these eras. Hurricanes were more likely to strengthen most quickly off the Atlantic coast of the US and in the Caribbean Sea, and less likely to strengthen most quickly in the Gulf of Mexico. 

Better understanding these locations and intensification rates could help create better action plans for communities at risk. Three of the five of the most economically damaging Atlantic hurricanes have all occurred since 2017 and these storms all had rapid growth. According to Garner, this is an “urgent warning for humanity,” and it should continue without major changes to our behavior and quickly transitioning away from fossil fuels. However, there is still time to act. 

“It’s really important to remember that there is absolutely still hope. We know that we are the cause of this problem, which means we can also be the solution—and we already have the tools at our disposal (green energy, etc.) to actually be the solution,” says Garner. “So there’s hope that we could secure a more sustainable future.”