Hurricane Helene and Hurricane Milton - which devastated parts of the southeastern United States - kicked off a particularly busy tropical storm season.
The Atlantic hurricane season is off to an ominous start. On July 2, Hurricane Beryl became the earliest Category 5 hurricane to form in the Atlantic since records began in 1920.
Unusually warm Atlantic temperatures — combined with changes in regional weather patterns — are thought to create favorable conditions for hurricane formation.
Across the main hurricane development zone – an area stretching from the west coast of Africa to the Caribbean – sea surface temperatures were around 1C above the 1991-2020 average, according to BBC analysis of data from the European Meteorological Agency.
Atlantic Ocean temperatures have been higher over the past decade, largely due to climate change and a natural weather pattern known as the Atlantic Multidecadal Oscillation.
Starting with Hurricane Helene, six Atlantic tropical storms have formed in succession.
Fueled by very warm waters — and now more favorable atmospheric conditions — these storms intensified, with five becoming hurricanes.
Four of these five storms underwent so-called “rapid intensification,” in which maximum winds increased by at least 56 km/h in 24 hours.
Historical data shows that on average only about 1 in 4 hurricanes rapidly intensify.
Rapid intensification can be especially dangerous, as this rapid increase in wind speed can give communities less time to prepare.
Hurricane Milton strengthened by more than 90mph in 24 hours and is one of the fastest-intensifying storms ever recorded, according to BBC analysis of data from the US National Hurricane Center (NHC).
Scientists at World Weather Attribution found that winds and rain from both Hurricane Helene and Hurricane Milton were made worse by climate change.
“One thing this hurricane season clearly illustrates is that the impacts of climate change are here now,” explains Andra Garner from Rowan University in the US.
For the remainder of the 2024 Atlantic hurricane season (June 1–November 30), high sea surface temperatures remain favorable for subsequent storms to strengthen into hurricanes.
There is also the possibility of La Nina appearing in the Pacific Ocean - a weather pattern that often promotes Atlantic hurricane formation because it affects wind patterns.
But subsequent storms will also depend on other atmospheric conditions, which are not easy to predict.
Regardless, this year's Atlantic hurricane season has highlighted how warming ocean waters due to climate change are increasing the likelihood of the most powerful hurricanes, and that is expected to continue as the world warms further, according to Kevin Trenberth, a scholar at the US National Center for Atmospheric Research.
