Most powerful hurricanes on the rise

Global warming could lead to fewer but more-intense storms.

Quirin Schiermeier

The number of major Atlantic hurricanes per year may almost double by the end of the century in response to global warming, according to a new study. A team of hurricane researchers suggests that damage from a larger number of very strong — Category 4 and 5 — hurricanes is likely to outweigh a projected decline in less-intense storms¹.

In 2008, a group led by Thomas Knutson of the National Oceanic and Atmospheric Administration (NOAA) Geophysical Fluid Dynamics Laboratory (GFDL) in Princeton, New Jersey, projected a marked reduction in the overall number of tropical storms and hurricanes in the western North Atlantic Ocean².

That result, based on a simulation of Atlantic hurricane activity in a warming world, came as a surprise. Seeking an explanation, the team hypothesized that the western Atlantic Ocean might become less favourable for storms if rising sea surface temperatures further south attract storms from the Gulf of Mexico and adjacent regions.

However, at a resolution of about 18 kilometres, the models that the team used for their initial simulation were too coarse to resolve individual storm systems.
 

When they repeated their efforts with a model with much higher resolution, the scientists found a shift in the distribution of storms. The finer-grained simulation confirmed the decline in the overall number of storms, but it also showed an 80% increase in the frequency of the most intense storms — Category 4 (210–249 kilometres per hour) and Category 5 (faster than 250 kilometres per hour).