Experts Propose a Stronger ‘Category 6’ for Hurricane

There have been a few very powerful ocean storms in the last 10 years. The expectation of more to come has some experts proposing a new category of large hurricanes: Category 6.

Studies have shown that the strongest tropical storms are getting more powerful because of climate change. The traditional five-category Saffir-Simpson scale was created more than 50 years ago.

But two scientists suggested in a new study that the scale may not show the true power of the strongest storms. They propose a sixth category for storms with winds faster than 309 kilometers per hour.

The study recently appeared in the Proceedings of the National Academy of Sciences.

Currently, storms with winds of 252 kilometers per hour or higher are Category 5. The study's writers said that this grouping does not do enough to warn people about the greater dangers from storms with even stronger winds.

Still, several experts told The Associated Press that they do not think another category is needed. They said it could even send the wrong message to the public because the new proposed category is based on wind speed. Water is by far the deadliest part of hurricanes.

Since 2013, five storms had winds that would have put them in the new category, with two hitting the Philippines. All five happened in the Pacific Ocean.

As the world warms, such large storms become more likely.

"Climate change is making the worst storms worse," said Michael Wehner, the study's lead writer. Wehner is a climate scientist at the Lawrence Berkley National Lab in California.

There are not more storms because of climate change, but climate change makes the strongest more intense. The proportion of major hurricanes among all storms is increasing. That is because the oceans are getting warmer, said Brian McNoldy. He is a hurricane researcher at Florida's University of Miami. He was not part of the research.

Experts have proposed a Category 6 several times over the years, especially since 2013's Typhoon Haiyan reached 315 kilometers per hour over the Pacific. The study said that Haiyan "does not appear to be an isolated case."

Storms with high enough wind speed are called hurricanes if they form east of the international dateline. They are called typhoons if they form to the west of the line. They are known as cyclones in the Indian Ocean and Australia. There have been five storms that had 309 kilometer per hour winds since 2013.

Jim Kossin is a climate and hurricane researcher who was an author of the study. He said if the world keeps to five storm categories, people will misjudge the risks as storms get larger and more powerful.

Pacific storms are stronger because there is less land to weaken them and more room for storms to grow more intense. That is not the same situation in the Gulf of Mexico and in the Caribbean, Kossin noted.

Jamie Rhome is deputy director of the National Hurricane Center in Florida. He said that, when warning people about the storms, his office warns people about individual dangers. These dangers include "storm surge, wind, rainfall, tornadoes and rip currents, instead of the particular category of the storm." The categories, he added, only provide information about the dangers from wind.

I'm Dan Novak.

Dan Novak adapted this story for VOA Learning English based on reporting by The Associated Press.

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hurricane — n. an extremely large, powerful, and destructive storm with very strong winds that occurs especially in the western part of the Atlantic Ocean

scale — n. a device that is used for weighing people or things

proportion — n. an amount that is a part of a whole

isolated — adj. happening just once

author — n. a person who has written something

surge — v. to suddenly increase to an unusually high level