Hurricanes are a part of life for coastal communities, but what happens when the storms we thought we understood get a whole lot worse? Recently, a 2024 study in the Proceedings of the National Academy of Sciences proposed something that might seem shocking: a new Category 6 for the most intense tropical cyclones, with wind speeds starting at 193 mph.
At first glance, this might seem like a natural step in the face of increasingly severe weather driven by climate change. But a closer look reveals a deeper conversation with a surprising twist: some experts say a new category might not actually help.
Current Saffir-Simpson Hurricane Wind Scale
The case for Category 6
Researchers behind the 2024 study argue that the Saffir-Simpson Hurricane Wind Scale, which currently maxes out at Category 5 (for any storm with sustained winds of 157 mph or greater), is no longer sufficient. Their motivation is to more accurately communicate the extreme risks associated with today’s most powerful storms.
If a Category 6 were adopted, it would be reserved for the most extreme events. In fact, based on data from 1980 to 2021, the 2024 study identified five storms that would have met the criteria:
- Super Typhoon Haiyan (2013): Struck the Philippines with 196 mph winds.
- Hurricane Patricia (2015): Reached peak winds of 215 mph at sea in the Eastern Pacific.
- Super Typhoon Meranti (2016): Had winds of 196 mph between the Philippines and Taiwan.
- Super Typhoon Goni (2020): Made landfall in the Philippines with winds estimated at 196 mph.
- Super Typhoon Surigae (2021): Reached wind speeds of 196 mph over the ocean east of the Philippines.
The argument against a new category
Despite the scientific motivation, the National Hurricane Center has not adopted Category 6, citing concerns that it could complicate public messaging.
- Catastrophic is still catastrophic: One key argument is that the difference in damage between a high-end Category 5 and a high-end Category 6 is not meaningfully different in terms of public action. Both result in catastrophic destruction that requires immediate evacuation from vulnerable areas.
- Damage is already “total”: Robert Simpson, a co-creator of the scale, argued that Category 6 is unnecessary because Category 5 already represents “total destruction”. The scale was designed to measure potential damage, and that potential doesn’t escalate in a way that warrants a new category once winds surpass the Cat 5 threshold.
It’s also important to note that the Saffir-Simpson scale is currently only used for hurricanes in the Atlantic and Eastern Pacific and 4 of the 5 noted storms in the study occurred in the western North Pacific and only one occurred in the eastern Pacific. To date, there have been no storms in the Atlantic that would have reached this level.
Global activity vs. increasing intensity.
So, what about climate change’s role in all of this? While you might assume we are seeing an overall increase in hurricane frequency, the reality is more nuanced. Data from climate scientist Ryan Maue, featured on climatlas.com/tropical, reveals no significant global trend in the number of hurricanes or major hurricanes over the long term. In fact, Maue has highlighted periods of notably low global hurricane activity. A 2022 study also found a decreasing trend in global hurricane numbers from 1990 to 2021.
The real story isn’t about more storms, but stronger ones. Climate change could fuel future more destructive hurricanes with stronger winds, higher storm surges, and heavier rainfall. Warmer ocean temperatures provide more energy for storms. This supercharges the storms, leading to increased intensity. Time will tell.
What does this mean for us?
The debate over Category 6 highlights a critical challenge: how do we best communicate the evolving risks of climate change? While adding a new category might sound alarming, it could also provide a more accurate picture of the intensity of a small minority of intense storms. For the Atlantic and East Pacific basins where the Saffir-Simpson Hurricane Wind Scale is used, there has only been one storm that reached this category in the eastern Pacific, and none have yet reached this level in the Atlantic.
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