Early Monday, Hurricane Ian was a tropical storm with heavy rain and winds of at least 73 miles per hour. But experts say the storm is gaining strength rapidly, and if recent history is any guide, it could dangerously strengthen as it approaches Cuba as soon as Monday night.
As the Earth’s climate warms, many storms are experiencing this type of rapid intensity, evolving rapidly from relatively weak tropical cyclones into Category 3 or higher hurricanes in less than 24 hours, sometimes stunned forecasters and left residents with little time to prepare.
Here are important facts about how climate change could accelerate tropical cyclones.
Warming oceans fuel higher winds
More than 90 percent Excess heat from human-caused global warming over the past 50 years has been absorbed by the oceans. Since 1901, sea surface temperatures have increased by an average of 0.14 degrees Fahrenheit per decade, according to data from the National Oceanic and Atmospheric Administration.
That’s important, because storms gather strength over the ocean. And, the warmer the water, the more electricity they collect. Higher surface temperatures allow hurricanes to achieve higher maximum sustained winds, a common metric used to describe the intensity of a hurricane.
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Suzana J. Camargo, a hurricane expert and professor at Columbia University’s Lamont-Doherty Earth Observatory, said: “The emergence of more intense storms is something that we strongly believe in.
One year 2020 satellite image analysis shows that the likelihood of a hurricane strengthening to a Category 3 or higher, with sustained winds above 110 mph, has increased by about 8% in a decade since 1979.
Those winds get stronger faster
Not only does warmer oceans make hurricanes stronger, but it also speeds up their intensification, says Kerry A. Emanuel, meteorologist and hurricane expert at the Massachusetts Institute of Technology.
Rapid intensity technically refers to an increase of at least 30 knots, or 35 mph, in maximum sustained winds over a 24-hour period, according to the National Hurricane Center. Researchers have found that the likelihood of a hurricane strengthening rapidly has increased to 5% from 1% since the 1980s.
Some of the most intense Atlantic hurricanes of the past decade have rapidly intensified. Harvey 2017 was a Category 1 storm on the evening of August 24; the next day, when the storm reached Texas, it was a Category 4 hurricane with winds of 130 mph. And after that hurricane season, Maria strengthened from a Category 1 to a Category 5 hurricane in just 15 hours.
In 2021, Hurricane Ida has strengthened from Category 1 with 85 mph winds to storm near level 5 with 150 mph winds less than 24 hours later.
Dr Emanuel said on Monday morning that current conditions are “ideal” for Ian to follow a similar development path.
It’s not just the ocean that’s warmer
Several factors other than ocean temperature affect hurricanes, and scientists are less certain about other climate effects.
One of those factors is the longitudinal wind shear force, or a measure of how the wind changes in speed or direction at increasing altitudes in the atmosphere. Strong vertical wind shear can inhibit storm growth by tilting the storm’s structure and by pushing cool, dry air into its core. Dr Emanuel said: “It’s like pouring a bucket of cold water on a fire.
In a 2019 study Published in the journal Nature Scientific Reports, the researchers found that warming temperatures could lead to weakening vertical wind shear, allowing storms approaching the US East Coast to strengthen more rapidly. .
However, the study’s findings were localized; Dr Camargo, one of the study’s authors, said the different effects of warming on wind shear could be observed globally.
Short notice increase bet
The rapid and unpredictable increase in the number of powerful storms presents a difficult problem for forecasters, whose assessments can affect public preparedness. .
Dr Emanuel said: “The time frame for making a decision is getting smaller and smaller. For example, if officials, working with forecasters, issue evacuation orders too soon, they risk sending hundreds of thousands of people unnecessarily, and sometimes millions, highways are messy, jammed and the transit system roars. In some cases, that can be more dangerous, disruptive, and costly than staying in place.
“Then you cried the wolf,” Dr. Emanuel said. Next time an evacuation warning is issued, people may not listen.
However, make the call too late and everyone has no time to escape the impact of a dangerously strong storm.
“It’s forecasters’ worst nightmares, as a relatively weak storm can develop into a Category 4 or a Category 5 hurricane overnight,” Dr Emanuel said.