Are Category 5 hurricanes such as Dorian the ‘new normal’?

Category 5 Hurricane Dorian tore through the Bahamas like a buzz saw last week, killing dozens of people and leaving a ruined, broken landscape.

It was the fifth Category 5 hurricane in the past four Atlantic hurricane seasons, joining other monsters such as Matthew, Irma, Maria andMichael, each of which left its own trail of death and destruction.

Is this part of a new trend? Could this be the “new normal”?

“I fear it’s worse than that,” Penn State University meteorologist Michael Mann said. “As we continue to warm the planet, hurricane intensities will increase further. There’s no new normal. It’s an ever-shifting baseline toward more destructive storms as long as we continue to burn fossil fuels and load the atmosphere with carbon pollution.”

A Category 5 hurricane is the most destructive hurricane on the Saffir-Simpson wind scale, blowing winds of 157 mph or higher.

Category 5 winds can cause “catastrophic” destruction, the National Hurricane Center said: “A high percentage of homes will be destroyed, with total roof failure and wall collapse.” Power outages can last for weeks to months, and most of the affected area could be uninhabitable, the center said.

This isn’t the first onslaught of Category 5s: The early to mid-2000s had more than their share of these violent storms. “In 2005 alone, we had four Category 5 hurricanes (Emily, Katrina, Rita and Wilma),” Colorado State University meteorologist Phil Klotzbach said. “And we had seven Category 5 hurricanes from 2003-2005 – including Isabel in 2003 and Ivan in 2004.”

The reason for more Category 5s is clear, Mann said: “The basic physics is indisputable. Warmer oceans lead to hurricanes with greater potential intensities.”

Globally, oceans have warmed up about a degree Celsius (1.8 degrees Fahrenheit), he said, and they’ve warmed up a bit more in the tropical North Atlantic Ocean, which is where hurricanes that affect the USA come from.

Weather Underground meteorologist Robert Henson said, “There has been ample work for more than a decade showing that hurricane frequency hasn’t changed much globally, but the fraction of hurricanes reaching top levels (for example Category 4-5) has increased.

“This trend (fewer hurricanes but a larger share of them hitting the highest intensities) is consistent with what you would expect as sea-surface temperatures warm around the globe,” Henson said.

Other research indicates that as the climate warms, some hurricanes slow down (the way Harvey, Florence and Dorian did); some intensify rapidly (such as Michael); and others occur earlier in the hurricane season, according to University of Georgia meteorologist Marshall Shepherd.

The National Oceanic and Atmospheric Administration’s Geophysical Fluids Dynamics Laboratory said, “Although we cannot say at present whether more or fewer hurricanes will occur in the future with global warming, the hurricanes that do occur near the end of the 21st century are expected to be stronger and have significantly more intense rainfall than under present-day climate conditions.”

As the climate warms, storms like Hurricane Harvey, which swamped the Houston area under record-breaking rainfall in 2017, could become more common.

Original story from usatoday