The system currently used to classify hurricane severity may no longer be sufficient as tropical storms intensify.
Scientists are making the case that the Saffir-Simpson scale should be expanded to include a new Category 6 classification, Knewz.com has learned.
In a study titled "The growing inadequacy of an open-ended Saffir–Simpson hurricane wind scale in a warming world," published in the journal Proceedings of the National Academy of Sciences last month, climate scientists noted that rising ocean temperatures are leading to stronger and more destructive hurricanes. Therefore, the open-ended Category 5 classification may no longer adequately communicate the threat level posed by the most intense tropical storms.
“Our motivation is to reconsider how the open-endedness of the Saffir-Simpson Scale can lead to underestimation of risk, and, in particular, how this underestimation becomes increasingly problematic in a warming world,” Michael Wehner, the study's lead author from the Lawrence Berkeley National Laboratory in California, said in a statement.
A hurricane is considered a Category 5 if its wind speeds reach or exceed 157 miles per hour, according to the National Hurricane Center of the United States.
Global warming driven by human activity, according to Wehner, has significantly increased the temperature of the ocean surface and surrounding air in regions where hurricanes, tropical cyclones and typhoons form, further fueling their growth.
A Category 6 designation, as proposed by the study's authors, would apply to storms with wind speeds above 192 miles per hour.
"[That speed] is probably faster than most Ferraris; it's hard to even imagine," Wehner told The Guardian.
This number was determined by looking at the wind speed ranges covered by the lower categories.
"We find that a number of recent storms have already achieved this hypothetical category 6 intensity and based on multiple independent lines of evidence examining the highest simulated and potential peak wind speeds, more such storms are projected as the climate continues to warm," the researchers wrote in the study.
https://www.nhc.noaa.gov/video/SSHWS_animaton.mp4
Wehner's team found five storms between 1980 and 2021 that would have qualified for a Category 6 classification. The researchers also analyzed simulations to predict how climate change may continue to impact hurricane intensity.
They found that in a warming world, intense tropical storms will likely become less frequent, but more extreme when they do occur.
Their models showed that the areas most at risk of experiencing a Category 6 storm were the Gulf of Mexico and Southeast Asia. An increase of 2 degrees Celsius from pre-industrial temperatures showed a 200% greater chance of this hurricane intensity in the Gulf of Mexico, and a 50% greater chance in the Philippines.
“Even under the relatively low global warming targets of the Paris Agreement, which seeks to limit global warming to just 1.5°C above preindustrial temperatures by the end of this century, the increased chances of Category 6 storms are substantial in these simulations,” Wehner said. “Tropical cyclone risk messaging is a very active topic, and changes in messaging are necessary to better inform the public about inland flooding and storm surge, phenomena that a wind-based scale is only tangentially relevant to."
The study also found that the Northern Indian Ocean and the seas north of Australia were at a lower risk of Category 6 hurricanes, because intense tropical storms are "not nearly as commonly observed in these regions as conditions other than warm seas are not favorable for rapid intensification."
