Wonky Thoughts: Climate Change and Atlantic Hurricanes

Friday, November 21, 2025

Climate Change and Atlantic Hurricanes

Hurricane Melissa struck western Jamaica on October 28th, 2025 with maximum sustained winds of 185 mph. Melissa tied for the third strongest Atlantic hurricane on record, and tied for the strongest Atlantic hurricane at landfall. Melissa was also the third category 5 hurricane of the 2025 season, out of five hurricanes and thirteen named tropical storms. At least 96 deaths were attributed to Melissa, with an additional 29 people missing. The storm caused an estimated ten billion US dollars of damage on Jamaica, with additional major damage to Cuba, Haiti and the Dominican Republic.

Warm water fuels tropical storms and hurricanes by providing energy for convection and humidity for massive rainfall. Statistical studies show that warmer water is associated with more storms and stronger storms. A sea-surface temperature of 27 degrees seems to be an approximate threshold for storm development, and more than 80% of tropical cyclones develop above that threshold. In September of 2025, the waters of the Caribbean were 28.8 degrees C. about 1.5 degrees C warmer than the historical norm (1951 – 1980 average).

Globally, sea-surface temperatures have risen 1.0 degrees C in the past century. (Some sources indicate warming as high as 1.4 degrees C.) Most of that increase has occurred in the past 30 years, and is well-documented by monitoring buoys and satellite measurements. The sea surface in the Northern Hemisphere has warmed about 1.2 degrees C.

The annual number of tropical storms, hurricanes, major hurricanes and category 5 hurricanes have all increased over the past century. Warmer water is causing more rapid intensification of storms, and a higher percentage of storms are reaching the highest level of intensity. In the century from 1916 to 2015, 6% of tropical storms became category 5 hurricanes. In the past decade, that percentage rose to 16%, and in the past four years, 23% of tropical storms became category 5 hurricanes.

Similarly, the number of tropical storms strengthening to category 5 hurricanes has increased dramatically. In the century from 1916 to 2015, 3% of tropical storms strengthened to category 5. In the past decade, 7% of tropical storms became category 5 hurricanes, and in the past four years, 11% of tropical storms became category 5 hurricanes.

In the 1990s and 2000s, modeling results were unclear whether global warming would produce more or stronger hurricanes. With the experience of the past quarter-century, and the understanding that warmer water produces both more storms and stronger storms, it seems likely that future warming will produce more frequent and powerful hurricanes.

The situation today is not the endpoint of climate change. Global sea surface temperatures are now 1.0 degrees above historical averages, but by 2100, sea surface temperatures will probably have risen by an additional 2.7 degrees. The expected range of future temperature rise is between about 1 degree C and 4.5 degrees C. The 1 degree C scenario would require almost immediate cessation of fossil fuel use, which is an unlikely scenario.

References:
First National Climate Assessment, 2001:
“While it is not yet clear how the numbers and tracks of hurricanes will change, projections are that peak windspeed and rainfall intensity are likely to rise significantly.”
“Studies suggest that the rate of precipitation during tropical storms could increase due to the warmer conditions and the increased amount of water vapor in the atmosphere. Other studies confirm these results.”
“Potential changes in the intensity and frequency of hurricanes are a major concern.”