Climate Change: Slightly Stronger But Fewer Hurricanes, Expert Says

April 23-- Apr. 23--A warming Earth may add slightly more muscle to heat-hungry hurricanes, but also slash the number that form by 25 percent by the end of the century as drier air dominates the middle levels of the atmosphere.

According to a presentation given this week at the National Hurricane Conference in New Orleans, climate change is expected to intensify storms by about 3 percent, or a few miles per hour, by the year 2100.

Global warming likely added 1 percent to Hurricane Michael's Cat 5 power, or 1 to 2 mph, said Chris Landsea, tropical analysis forecast branch chief at the National Hurricane Center.

"That is a fairly small increase and most of the computer guidance by global warming models say maybe we could see 3 percent stronger by the end of the century," said Landsea, who spoke during a session on hurricane history. "That's really not very much."

Landsea, who has worked to correct historical hurricane tracks and intensities, based his presentation on work done by the National Oceanic and Atmospheric Administration's Geophysical Fluid Dynamics Lab at Princeton University, but said it's reflective of most climate models.

He spoke to a standing-room only crowd of more than 100 at the National Hurricane Conference, which drew 1,500 emergency managers, first responders, meteorologists, insurance experts and government officials from throughout the Gulf Coast, Florida, East coast and Caribbean. The conference follows two brutal storm years that saw three Category 4 cyclones hit the U.S. in 2017 and newly-upgraded Category 5 Michael in 2018.

While Hurricane Florence was a Category 1 storm when it hit North Carolina on Sept. 14, it drove storm surge a mile inland and dumped more than 30 inches of rain in some areas. Twenty-three people died, including 17 from freshwater flooding.

"As a meteorologist there is an emotional toll when it's your community, but at the hurricane center, any landfall feels like your community because you are doing everything you can to get the forecast as accurate as you can for everyone," said National Hurricane Center Director Ken Graham, who took over the position just before the 2018 season began. "Here we are at another season and it's back to preparedness and being able to take care of yourself after a storm."

This week's conference runs through Thursday with the general session Wednesday focusing on how to lessen the impacts of rain and flooding during hurricanes and how climate change is affecting seasonal forecasting and storms.

Landsea said there is an expectation that rainfall from hurricanes may increase 10 percent by 2100 because warmer air can hold more water.

But a warming planet may also mean fewer storms because of more wind shear and drier air in layers of the sky where thunderstorms need warm moist air to intensify.

While it seems as though the number of hurricanes has increased with the Earth's temperature since records began in 1851, the data is flawed by a lack of early observations when there no satellites or planes and fewer ships to make observations at sea. In a reconstruction of storms, Landsea said it's estimated the number has changed little, or even decreased.

"It's a bit surprising when we look at the meteorology behind it," he said. "Global warming provides an expectation for slightly stronger hurricanes, but substantially fewer of them."

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