In 2024, cyclones like Hélène, Chido, and Milton have highlighted a concerning trend of increasingly powerful storms. While the total number of tropical cyclones remains stable, the intensity and frequency of the most destructive ones have surged, with maximum wind speeds rising significantly. Climate change, driven by rising ocean temperatures, plays a crucial role in this intensification. As of mid-December, 42 cyclones were recorded globally, with Chido exemplifying the enhanced devastation linked to climate change.
Impact of Cyclones in 2024
Names like Hélène, Chido, and Milton have left a significant imprint in 2024, marking the year as one filled with devastating cyclones that are becoming increasingly frequent. According to a comprehensive international database analyzed by AFP, while the overall annual count of tropical cyclones has remained relatively stable in recent years, there has been a noticeable uptick in the occurrence of the most powerful and destructive cyclones over the last forty years. This trend aligns with the predictions made by climatologists.
Increasing Wind Intensity
Data reveals that since 1980, an average of 47 tropical cyclones—known as hurricanes in the Americas and typhoons in Southeast Asia—has been recorded annually, signifying a steady figure. However, when comparing the period from 1981-2010 to the last decade, there has been a 5% increase in the average maximum wind speed of these storms, rising from 182 km/h to 192 km/h. Notably, the frequency of hurricanes with wind speeds surpassing 250 km/h—classified as category 5 on the Saffir-Simpson scale—has risen from 1 in 10 to 1.4 in 10.
A study published last November by Climate Central revealed that the maximum wind speed of hurricanes in the Atlantic has increased by an average of 28.9 km/h between 2019 and 2023. Additionally, the World Weather Attribution (WWA) reports that violent hurricanes are now 2.5 times more likely to occur in the Atlantic, reinforcing the findings of the UN’s IPCC, which indicates that the rise in the number of severe cyclones (categories 4 and 5) is a predictable consequence of climate change.
The Role of Ocean Temperatures
In November, climatologist Daniel Gilford from Climate Central remarked that “all the cyclones of 2024 have been more powerful than they would have been 100 years ago,” attributing this to the “record warming of the oceans.” The elevation of global ocean temperatures serves as an ideal energy source for these formidable storms, similar to the rising temperatures in the atmosphere.
Météo-France emphasizes that for a cyclone to form, one crucial condition must be met: “The ocean temperature must be high in the first 60 meters to enable intense evaporation, facilitating the transfer of moisture from the ocean to the atmosphere.” With human-induced climate change, average ocean surface temperatures are on the rise. The warmer the ocean, the more moisture is available in the atmosphere.
While warmer ocean conditions do not guarantee cyclone formation, they can provide additional energy for already-developed storms, enabling them to strengthen in the humid atmosphere above heated oceans. As Météo-France highlights, “This additional humidity will lead to an intensification of cyclone rains, which in turn amplifies the system.”
As of December 15, 2024, there have been 42 recorded tropical cyclones globally, with 19 making landfall. Cyclone Chido, which wreaked havoc in Mayotte in December, was found to be more potent due to climate change, with a preliminary British study suggesting that global warming has increased wind speeds by approximately 5%, elevating it from category 3 to category 4.