A handful of super-strong tropical storms in the past decade and the possibility of more have led several experts to propose a new category of major hurricanes: Category 6.
Research shows that the strongest tropical storms are becoming more intense due to climate change. So the traditional five-category Saffir-Simpson scale, developed more than 50 years ago, may not indicate the true strength of the strongest storms, two climate scientists suggested in a study published Monday in the Proceedings of the National Academy of Sciences. They propose a sixth category for storms with winds exceeding 192 miles per hour (309 kilometers per hour).
Currently, storms with winds of 157 miles per hour (252 kilometers per hour) or higher are in Category 5. The study’s authors said the open-ended grouping did not adequately warn people of higher dangers from freak storms flirting with 200 mph (322 km) per hour. ) or higher.
Many experts who spoke to The Associated Press said they did not think another category was necessary. They said that while water is the deadliest killer in hurricanes, it could even give the wrong signal to the public because it is based on wind speed.
Since 2013, five storms, all in the Pacific, have experienced winds of 122 mph or higher, putting them in the new category; two of these hit the Philippines. As the world warms, conditions become more ripe for such large storms, including in the Gulf of Mexico, where many storms that hit the U.S. have become stronger, the study authors said.
“Climate change is making the worst storms worse,” said study lead author Michael Wehner, a climate scientist at Lawrence Berkley National Laboratory.
More storms are out of the question due to climate change. However, the strongest ones are more intense. University of Miami hurricane researcher Brian McNoldy, who was not part of the study, said the proportion of major hurricanes among all storms is increasing, and that’s because the oceans are warming.
At times, experts have suggested Category 6, especially since Typhoon Haiyan reached wind speeds of 195 mph (315 kilometers per hour) off the Pacific. However, the study stated that Haiyan “does not appear to be an isolated case.”
Storms with sufficient wind speed are called hurricanes if they form east of the international date line, and typhoons if they form west of the line. They are known as cyclones in the Indian Ocean and Australia.
The five storms with winds of 192 miles per hour or more are:
– Haiyan, which killed more than 6,300 people in the Philippines in 2013.
— In 2015, Hurricane Patricia, which reached speeds of 215 miles (346 km) per hour, weakened and hit Jalisco, Mexico.
— Typhoon Meranti in 2016 reached speeds of 300 kilometers per hour before passing over the Philippines and Taiwan and making landfall in China.
— Typhoon Goni, which reached 300 kilometers per hour in 2020, killed dozens of people in the Philippines as a weaker storm.
— Typhoon Surigae in 2021 reached speeds of 300 kilometers per hour before weakening and sweeping across parts of Asia and Russia.
If the world sticks to just five storm categories, “the potential risk will become increasingly underestimated as these storms get stronger,” said study co-author Jim Kossin, a former NOAA climate and hurricane researcher who now works at the First Street Foundation.
Pacific storms are stronger because there is less land to weaken them, unlike in the Gulf of Mexico and the Caribbean, and there is more room for storms to grow more intense, Kossin said.
Kossin and Wehner said that no Atlantic storm has ever reached the potential threshold of 300 kilometers per hour, but as the world warms, the environment for such a storm is becoming more favorable.
As temperatures rise, the number of days ripe for potential Category 6 storms in the Gulf of Mexico will increase, Wehner said. Now about 10 days a year would be a suitable environment for Category 6, but that period could extend to up to a month if the Earth warms 3 degrees Celsius (5.4 Fahrenheit) above pre-industrial levels. This would make an Atlantic Category 6 much more likely.
MIT hurricane expert Kerry Emanuel said Wehner and Kossin “make a strong case for turning the scale,” but that’s unlikely to happen because officials know most hurricane damage comes from storm surge and other flooding.
Jamie Rhome, deputy director of the National Hurricane Center, said that when warning people about storms, his office “tries to focus on individual hazards such as storm surge, wind, precipitation, tornadoes and rip currents rather than a specific category of storms.” The storm provides information about danger from wind alone. “Category 5 on the Saffir-Simpson scale already detects ‘catastrophic damage’ from wind, so it’s not clear that another category will be needed even if storms strengthen.”
McNoldy, former Federal Emergency Management Agency Director Craig Fugate, and University of Albany atmospheric sciences professor Kristen Corbosiero say they don’t see the need for a sixth, stronger storm category.
“Perhaps I will change my tune once the rapidly intensifying storm in the Gulf reaches Category 6,” Corbosiero said in an email.
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