As hurricanes strengthen, scientists consider adding Category 6

If global temperatures rise 2 degrees Celsius, the risk of Category 6 storms would double in the Gulf of Mexico, a recent study found.

Five storms in recent years have far surpassed the Category 5 threshold, which has some researchers considering adding a Category 6 to the hurricane scale.

Originally developed in the 1970s, the Saffir-Simpson scale tops out at Category 5 for storms with 156 mph winds even though “the destructive potential of the wind increases exponentially” as it surpasses that category marker, according to a new study, published in Proceedings of the National Academy of Sciences, which found “weaknesses” in the current scale.

Since 2013, five storms have far surpassed those speeds: Typhoon Haiyan (2013), Hurricane Patricia (2015), Typhoon Meranti (2016), Typhoon Goni (2020), Typhoon Surigae (2021).

The strongest of those storms was Hurricane Patricia, with wind speeds well over 200 mph before making landfall in Mexico as a Category 4.

The study’s lead author Michael Wehner, a senior scientist studying extreme weather events at Lawrence Berkeley National Laboratory, and co-researcher James Kossin, a distinguished science adviser at the climate nonprofit First Street Foundation, looked at expanding the scale so that Category 5 would be capped at wind speeds of 192 mph, and any hurricanes or cyclones above that be designated Category 6, to better help inform people of the risks. Category 6 would be for storms with wind speeds above 192 mph.

“Because climate change increases temperature and moisture — which are the sources of the energy for a hurricane or a tropical cyclone — one would expect this speed limit to increase,” Wehner told CBS News. “And indeed it does.” 

The study ran climate models into the future and found that if global temperatures rise 2 degrees Celsius, the risk of Category 6 storms would double in the Gulf of Mexico and increase by 50% near the Philippines. 

But not everyone is a fan of adding a Category 6. “Category 5 on the Saffir-Simpson scale already captures ‘catastrophic damage’ from wind, so it’s not clear there would be a need for another category even if storms were to get stronger,” Jamie Rhome, the deputy director of the National Hurricane Center told The Atlantic.

Plus, a sixth category wouldn’t necessarily change FEMA’s preparations before a storm makes landfall, either, because the agency anticipates that any Category 4 or 5 storms will have significant impacts, The Atlantic reported.

However, adding a Category 6 could increase awareness of the consequences of climate change. “If you want to send a message, as a scientific community, because we keep getting these really intense hurricanes – and they’re getting stronger and reaching that top end [of] 5 — if you want to send a message about climate change, the best way to do it is to add another category,” CBS News climate and weather contributor Jeff Berardelli said. 

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