Warming oceans have increased the severity of hurricanes: research

Rising sea temperatures led to significantly stronger hurricanes between 2019 and 2023 and pushed nearly a half-dozen storms to Category 5 status, including two this season, according to a newly released climate study.

Human-caused climate change has on average increased the peak speed of Atlantic hurricanes before landfall by 18 mph over the past six years, said Dr. Daniel Guilford, lead author of the study. study published in the journal Environmental Research: Climate.

“Every storm we studied in 2024 resulted in an increase in the intensity of warmer sea surface temperatures by about 9 to 28 mph,” Guilford said during a webinar Tuesday afternoon.

A total of 11 storms have struck over warming waters this Atlantic hurricane season, which ends Nov. 30.

Guilford, a climate scientist from Climate CentralThe nonpartisan, nonprofit independent group of scientists who research and report on the effects of climate change said that between 2019 and 2023 and during this hurricane season, storms over waters have become as much as 2.5 degrees warmer due to global warming.

The scientists found that faster rotation speeds for hurricanes correspond, on average, to about one category higher on the Saffir-Simpson hurricane wind scale. This scale does not take into account other potential destructive factors of hurricanes, including storm surge, which is also exacerbated by rising sea levels, and precipitation.

Companion study Also published Wednesday by Climate Central, it found that Hurricane Helen’s peak wind speeds are about 13 mph stronger due to climate change.

The difference is “a little smaller” than Guildford’s results, “but about the same,” said Dr Friederike “Fredi” Otto, senior lecturer in climate science at Imperial College London and director World weather attributiona group of researchers from several European institutions.

Otto said the accompanying study “really shows that these two very different lines of evidence are showing us the same thing.”

Guilford’s study tracked data from the International Best Track Archive for Climate Stewardship, or IBTrACS, which provides global information on cyclone tracks, as well as the National Hurricane Center’s GIS archive for hurricane analysis going back to 2019.

The researchers used observations and reanalysis from the National Oceanic and Atmospheric Administration. optimal interpolation sea surface temperatureor OISST, which is a long-term record of climate data and coupled climate models to see how sea surface temperatures are changing.

A companion study looked at stochastic models, which use mathematics that incorporates randomness and uncertainty to model hurricane behavior, including intensity, trajectory and landfall location.

From a scientific perspective, Otto said, changes caused by global warming show that a storm that would have been a Category 4 due to cooler sea surface temperatures is now reaching a Category 5, the highest of the Saffir-Simpson hurricane. Wind scale.

“It makes a huge difference and I think it could also make a huge difference in how we communicate about the impact of climate change because as we’ve seen there’s been quite a tragic loss of life this year and when extreme events happen there’s huge death toll. something people haven’t experienced before,” Otto said.

That was the case when Hurricane Helen tore through the Gulf Coast, making landfall Sept. 26 in the Big Bend region of Florida before speeding north through western North Carolina. The storm, which devastated mountain towns, destroyed roads and caused more than $50 billion in damage, killed more than 230 people in six states.

Although “there were really good warnings,” people in the Appalachian region had not experienced such an extreme event, so they didn’t know what to do with the warnings, Otto said.

“I think what we’re seeing now over and over again is that records are being broken, that wind speeds are higher than ever before, rainfall is higher than ever before. We really need to use this to make sure people don’t die,” she said.

Otto added that it might be time to discuss whether to add a sixth category to the Saffir-Simpson scale, “just so people know they’re going to be hit by something that’s different from anything else they’ve experienced before, and , therefore, more dangerous.”

Hurricanes Beryl and Milton were identified as the last of five hurricanes to become Category 5 hurricanes due to climate change, according to a study conducted by Guilford.

Earlier this year, NOAA predicted there was an 85% chance of an above-normal Atlantic hurricane season.

Hurricane Beryl first formed on June 28 and has broken a series of records this season.

It was the farthest eastward hurricane to form in June, the first Category 4 hurricane to form in June, and on July 2 it became the earliest Category 5 hurricane on record.

Just over three months after Beryl made landfall for the third and final time—the last in Matagorda County, Texas—monstrous Hurricane Milton appears to be sweeping the Gulf of Mexico as it heads toward the Florida Gulf Coast. The speed at which Milton grew brought longtime meteorologist and NBC 6 South Florida meteorologist John Morales to tears. whose live forecast went viral after he choked, reporting that the hurricane’s air pressure dropped by 50 millibars in 10 hours.

Morales, one of the speakers on Tuesday’s webinar, noted that in his 40-year career, he has seen more hurricanes go through cycles of extreme and rapid intensification in recent years compared to previous years.

“As far as I know, we can have four hurricanes a year, but if 50% of them become Category 3, 4 and 5, then we have a problem because most of them become very dangerous,” he said.