As if hurricanes needed any more kick.

Human-caused climate change is boosting the intensity of Atlantic hurricanes by a whole category on the Saffir-Simpson Hurricane Wind Scale, which rates hurricanes based on their peak sustained wind speed, researchers report November 20 in two new studies.

From 2019 to 2023, climate change enhanced the maximum wind speeds of hurricanes by an average of about 29 kilometers per hour (18 miles per hour), or roughly the breadth of a Saffir-Simpson category, researchers report in Environmental Research: Climate. Climate change similarly increased the intensities of all hurricanes in 2024 by an average of about 29 kph, escalating the risk of wind damage, a companion analysis from Climate Central shows.

As climate change heats up the equator, nature seeks to redistribute that heat to other parts of the world, says Climate Central’s Daniel Gilford, a climate scientist based in the Orlando, Fla., area. “The way that our atmosphere does it is with hurricanes.”

Gilford and colleagues developed a new attribution framework to rapidly measure climate change’s influence on a recent storm’s wind speeds. Drawing from historical sea surface temperature records that stretch back over a century and computer simulations of Earth’s climate, the researchers generated simulations of the modern North Atlantic Ocean in a world without climate change. They then calculated what the wind speeds of recent hurricanes would have been over these cooler Atlantic Oceans, and finally compared the hypothetical speeds to observed hurricane wind speeds.

Of 38 hurricanes that occurred from 2019 to 2023, 30 reached intensities roughly one category higher because of climate change. Three — Lorenzo in 2019, Ian in 2022 and Lee in 2023 — grew into Category 5 hurricanes.

Similarly in 2024, climate change increased the maximum intensities of every hurricane by 14 to 43 kph (9 to 28 mph). The top wind speeds of hurricanes Helene and Milton were respectively enhanced by roughly 25 kph (16 mph) and 40 kph (23 mph), pushing them from Category 4 to Category 5 (SN: 10/1/24; SN: 10/9/24).

Hurricane Rafael was enhanced by a whopping 45 kph (28 mph), going from Category 1 to Category 3 as it bore down on Cuba in November. “Climate change is now allowing very intense storms to persist later into the season,” Gilford says.