BAKU, Azerbaijan (AP) 鈥� Human-caused made Atlantic hurricanes about 18 miles per hour (29 kilometers per hour) stronger in the last six years, a new scientific study found Wednesday.
For most of the storms 鈥� 40 of them 鈥� the extra oomph from warmer oceans made the storms jump an entire hurricane category, according to the study published in the journal, Environmental Research: Climate. A Category 5 storm than 400 times the damage of a minimal Category 1 hurricane, more than 140 times the damage of a minimal Category 3 hurricane and more than five times the damage of a minimal Category 4 storm, according to the National Oceanic and Atmospheric Administration
For three storms, , the climate change factor goosed wind speed so much that the winds increased by two storm categories.
This isn't about more storms, but increasing power from the worst ones, authors said.
鈥淲e know that the intensity of these storms is causing a lot more catastrophic damage in general,鈥� lead study author Daniel Gilford, a climate scientist at Climate Central, which does research on global warming. 鈥淒amages do scale (up) with the intensity.鈥�
The effect was especially noticeable in stronger storms, including those that made it to the top of the Saffir-Simpson scale of storm intensity: Category Five, study authors said. The study looked at 2019 to 2023, but the authors then did a quick addition for the named storms this year, all of which had a bump up due to climate change.
鈥淲e had two Category Five storms here in 2024,鈥� Gilford said. 鈥淥ur analysis shows that we would have had zero Category Five storms without human-caused climate change.鈥�
This year鈥檚 three most devastating storms 鈥� , and 鈥� increased by 18 mph (29 kph), 16 mph (26 kph) and 24 mph (39 mph) respectively because of climate change, the authors said. A different study by World Weather Attribution had , which is close, said Imperial College London climate scientist Friederike Otto, who coordinates the WWA team and praised the Climate Central work.
鈥淚t absolutely makes sense from a fundamental standpoint that what鈥檚 going on is we鈥檝e added more energy to the system,鈥� National Oceanic and Atmospheric Administration chief Rick Spinrad said at United Nations climate talks in Baku, Azerbaijan. 鈥淭he change is going to manifest in terms of what we鈥檙e already seeing. You look at , 500 miles across. We鈥檙e going to see changes in terms of the velocity of these storms. We're going to see changes in terms of Hurricane Milton .鈥�
Since 2019, eight storms 鈥� 2019鈥檚 Humberto, 2020鈥檚 Zeta, 2021鈥檚 Sam and Larry, 2022鈥檚 Earl, 2023鈥檚 Franklin and 2024鈥檚 Isaac and Rafael 鈥� increased by at least 25 mph (40 kph) in wind speed. Humberto and Zeta gained the most: 31 miles per hour (50 kph).
In 85% of the storms studied in the last six years, the authors saw a fingerprint of climate change in storm strength, Gilford said.
Warm water is the main fuel of hurricanes. The warmer the Atlantic, Caribbean and Gulf of Mexico get, the more potential energy goes into storms. Other factors 鈥� such as high level crosswinds and dry air 鈥� can act to weaken hurricanes.
The waters in the hurricane area have increased by 2 to 3 degrees Fahrenheit (1.1 to 1.6 Celsius) in general and as much as 4 degrees (2.2 C) due to climate change, Gilford said. They know this because Climate Central has used scientifically accepted techniques to regularly track how much warmer oceans are because of the burning of coal, oil and natural gas.
That technique basically uses computer simulations to create a fictional world with no human-caused warming and then compares it to current reality, with the difference being caused by greenhouse gases. They account for other factors, such as the lessening amount of sulfate pollution from marine shipping which had been counteracting a bit of the warming before the skies cleared up more.
To go from warmer waters to stronger storms, the authors looked at a calculation called potential intensity, which is essentially the speed limit for any given storm based on the environmental conditions around it, Gilford said.
MIT hurricane expert and meteorology professor Kerry Emanuel, who pioneered potential intensity measurements, wasn't part of the study but said it makes sense. It shows the increase in storm strength that he predicted would happen 37 years ago, he said.
Past studies have shown that climate change has made hurricanes , and , which causes to be dumped.
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This story has corrected the spelling of Daniel Gilford's last name throughout.
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Seth Borenstein, The Associated Press
