Because of climate change: hurricanes are gaining strength faster and faster

Research shows that tropical cyclones in the Atlantic Ocean and the Caribbean Sea are becoming increasingly stronger. As ocean surface temperatures rise due to climate change, hurricanes can not only absorb more water vapor, but also do so faster, explains Andra Garner of Rowan University in Glassboro (New Jersey, USA) in the journal ‘Scientific Reports’ . . Tropical cyclones derive their energy mainly from the heat of vaporization of the water vapor they absorb above an ocean.

The development is worrying, especially because hurricanes are difficult to predict in their early stages and can potentially cause major damage, Garner said. Hurricanes Sandy (2012), Harvey (2017), Irma (2017), Ida (2021) and Ian (2022) caused the most damage between 2012 and 2022. In less than three days, the storm developed from a tropical storm to a Category 3 hurricane or higher on the Saffir-Simpson Hurricane Wind Scale, with winds of at least 110 miles per hour.

Garner had evaluated information from the hurricane database ‘Hurdat2’, which contains numerous values ​​for all hurricanes. She divided the hurricane data into three time periods: 1971 to 1990, 1986 to 2005, and 2001 to 2020. The middle period overlaps with the other two. The researcher then determined the 12-hour, 24-hour and 36-hour intervals during which the hurricane increased in strength the most.

This allowed her to compare the intensification rate, that is, the increase in wind speed, in the different time periods. While the average maximum intensification speed within 24 hours in the first period was 32.8 kilometers per hour, from 2001 to 2020 it was already 41.7 kilometers per hour. The highest intensification rate within 12 hours averaged 29.1 kilometers per hour, 28.7 percent higher than in the period 1971 to 1990 (22.6 kilometers per hour).

According to the analysis, hurricanes today are more than twice as likely to develop from a weak (category 1) to a strong hurricane (category 3 or more) within 24 hours: for the years 1971 to 1990 this was 3.23 per cent; the period 2001 to 2020 at 8.12 percent.

“Peak intensity speeds of 50 knots or more also become more likely over time,” Garner wrote. 50 knots corresponds to 92.6 kilometers per hour. From 1971 to 1990, the chance that a hurricane would reach this strength within 24 hours was 2.6 percent. In the most recent period this happened with a probability of 7.4 percent.

During the study period, the regions in which tropical cyclones occur in the Atlantic Ocean and the Caribbean have also changed. The likelihood of a Gulf of Mexico hurricane strengthening so quickly has decreased in all intervals examined (12, 24, 36 hours) from 1971 to 2020. However, this probability increased along the US Atlantic coast and in the southern Caribbean Sea.

“Tropical cyclones, which intensify particularly rapidly in the southwestern Caribbean, could have devastating effects in many relatively resource-poor countries in Central America,” Garner points out. Their research results underscore the need to curb global warming to limit an even faster increase in the strength of hurricanes, the study author writes. It calls for coastal planning and communications measures that enable vulnerable communities to adapt to the evolving threats of tropical cyclones. (rbu/sda/dpa)