If global temperatures continue to increase, causing storms more intenseSome researchers say the Saffir-Simpson scale, which measures a hurricane’s wind speeds, does not adequately address the dangers associated with extreme storms. In a new study, scientists examined a hypothetical expansion of the scale to include a category 6, and found that such a designation could help people focus on the worsening risks.
In a new study published Monday in Proceedings of the National Academy of Sciences, researchers found that the scale, which was created in the early 1970s and is still used to measure hurricane categorieshas a “weakness”: reaches the highest category in Category 5, even though “the destructive potential of the wind increases exponentially.”
Hurricane categories range from 1 to 5, with Category 5 hurricanes having winds of 155 mph or stronger — enough to cause “catastrophic” damage, which NOAA says could also result in “complete roof failure on many residential and industrial buildings.” as a long-term power outage.
Michael Wehner, lead author of the latest study, told CBS News that there have been several hurricanes in recent years with winds well above 155 miles per hour — and that this could warrant a full recovery. new category. He and co-researcher James Kossin looked at the potential impact of expanding the scale so that Category 5 would be capped at wind speeds of 300 km/h, and any hurricanes or cyclones above that would be classified as Category 6, to better serve people. inform about the consequences of the disaster. risks.
“We found that five storms had exceeded this hypothetical Category 6, and all of them were recent, since 2013,” Wehner told CBS News.
The most intense of those five storms was Hurricane Patricia, which peaked with winds of over 200 miles per hour before making landfall in Mexico as a Category 4 in October 2015. Patricia “intensified at a rate rarely seen in a tropical cyclone,” the National Hurricane Center said. NOAA reported that the storm hit maximum winds of 210 mph (345 km/h), nearly 60 mph (100 km/h) faster than the lower bar of the Category 5 designation.
The other storms with hypothetical Category 6 strength occurred in the western Pacific Ocean, the study said. Typhoon HaiyanThe storm, which hit the Philippines in 2013, was “the costliest storm to hit the Philippines and the deadliest since the 19th century, long before any significant warning systems were in place,” the study said.
The researchers also looked at a “state of the art” climate measurement system that analyzes potential intensity — “essentially a speed limit on how fast the highest winds can be in a perfect storm,” Wehner said.
“Our motivation here was to make the connection between the two climate change — that warming of the atmosphere, of the Earth, from the burning of fossil fuels — to hurricanes and tropical cyclones,” Wehner said, adding that he and Kossin consider themselves “relatively conservative climate scientists.”
“Because climate change increases temperatures and moisture — the sources of the energy for a hurricane or a tropical cyclone — you would expect this speed limit to increase,” he said. “And that is indeed true.”
Wehner and Kossin found a “significant” observed increase in wind speeds since 1982, and said in their study that it is likely that wind speed records will “continue to be broken as the planet continues to warm.”
They also ran simulations based on different global warming scenarios, and found that the risk of seeing so-called Category 6 storms “has increased dramatically and will continue to increase due to climate change.”
This study isn’t the first to look at a hypothetical study extension of the Saffir-Simpson scale. In 2019, former NOAA hurricane hunter and meteorologist Jeff Masters wrote that current hurricane categorizations are “inadequate.” He proposed expanding the scale to include a Category 6, starting with winds of 200 to 300 mph, and a Category 7, which would be used for storms with winds of at least 210 mph.
“Any move to expand the Saffir-Simpson scale, however, would have to come from the National Hurricane Center (NHC), and there is little support for such a move from the experts there,” he wrote in a blog post for Scientific American. “From a public safety/warning perspective, NHC experts I have heard from believe that including a Category 6 would do little good, as a Category 5 hurricane is already considered catastrophic.”
Wehner acknowledged it Saffir-Simpson scale has been heavily criticized because it is the only determination of the category of a hurricane. The scale is based only on wind speed, and while that is a crucial measure for determining the risk of a storm, it does not take into account the potential destruction caused by the size of the storm or the storm surge and flooding it can entail. Wehner’s research does not address these other hurricane factors.
Those hurricane risks should be more fully considered when explaining the risk of a storm, Wehner said.
“A single number is actually not very descriptive of the full risk of an approaching hurricane when you’re on the road,” he told CBS News. “You really need to know what types of hazards you’re being exposed to.”
The researchers said in their paper that they are not specifically proposing changes to the scale, but that they want to “raise awareness that the risk of wind hazards from storms currently classified as Category 5 has increased and will continue to increase.” Adding a sixth category to the scale could help raise awareness about expected changes in storm wind strength in coming years, and how that, among other hazards, could affect communities, they said.
“The stronger the wind, the stronger the storm surge. And there will be a lot more rain anyway,” Wehner said. “…From the context of global warming, in an attempt to put a single figure on what the increased risk of global warming is, which is a longer-term hazard, we think this scale is just fine is.”
Another criticism that Wehner says has become more widespread is the question, “If we add a Cat 6, does a Cat 3 storm not matter anymore?”
“And the answer is, ‘Of course it is,’” he said. “…Just because the worst storms are worse doesn’t mean severe storms aren’t bad.”
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