GA scientists on the impacts of climate change

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Climate change is impacting communities both large and small throughout the year, from prolonged heat in the summer to wildfires in the West. As hurricane season peaks and Hurricane Ian hits Florida, climatologists are digging into what they know and looking to uncover how a warming climate will exacerbate future hurricanes and tropical storms.

Many ingredients are needed to prepare the ideal conditions for a hurricane: warm waters, low pressure, humid air. But analyzing the role climate change plays in this stew is a complicated task, one that climatologist Tom Knutson tackles at the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory.

Knutson works forward and backward. It examines past hurricanes to see changes over time, then uses models to simulate how hurricanes behave in a warmer world.

“It’s a complicated subject, especially for the Atlantic region,” Knutson said. For starters, Knutson said it’s important to note that the tropical Atlantic is warming, so not only are average global air temperatures increasing, but also, in this area, surface water is warming. In addition, rising sea levels make it easier for hurricanes to inundate coastal regions.

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More major storms, rapid intensification

These are the simple things scientists can identify, but when looking at the evidence of how the storms themselves have changed, the waters turn murky.

There has been no change in the number of hurricanes in recent years, according to Knutson. But since 1980, the intensity of storms has increased. More storms were major hurricanes (Category 3 or higher), and there was an increase in the proportion of storms experiencing rapid intensification.

Even with that evidence, Knutson said it’s hard for scientists to pinpoint where those changes came from, and that’s where his work is taking place.

“There were a few decades where things were active, then quiet for a few decades, then got active again,” Knutson said. “It is difficult to identify long-term trends as these large fluctuations occur between (multi-decade) time periods.”

Related:Savannah’s Storm History: Looking Back at a Century of (Mostly) Hurricane Near Misses

Knutson and his peers have a few theories: that the changes are due to natural variability, changes in ocean circulation, or that they could be related to aerosols, a form of air pollution, but none can yet be definitively identified as a cause.

Looking to the future, Knutson said he can use models to see how known changes in climate might impact hurricanes: for example, how a hurricane might form in a world 2 degrees warmer. Celsius. In this model scenario, Knutson said there is about a 7% increase in precipitation per degree of warming, as well as a 3% increase in maximum wind speed per two degrees of warming.

Pam Knox, agricultural climatologist and director of the UGA Weather Network

Longer hurricane seasons are possible

According to University of Georgia Weather Network Director Pam Knox, there are other impacts outside of these factors that hurricane watchers may see in the future. While warming may increase the intensity of hurricanes, she said it will also change the season as a whole. Knox said with hotter summers, hurricane season could start earlier and end later in a warmer climate, opening a bigger window of the year for more intense hurricanes.

“Not only do you have stronger winds blowing water onshore as the storm rolls in, but it also happens above rising sea level,” Knox said. “So it’s kind of a double whammy for the Georgian coast.”

People stop to take photos of the flooded cobblestones of River Street on Monday afternoon.  The Chatham Emergency Management Agency said that while Hurricane Irma brought less debris to Savannah than Hurricane Matthew, Irma's flooding was worse.

Beyond an expansion of the season, Knox said the geographic area in which hurricanes form could also grow as the climate warms, bringing hurricanes to cooler areas they didn’t have. tend to venture before.

“We’ve seen with Fiona this year that the water is pretty warm all the way to Nova Scotia, and that’s helping to keep the storm going longer,” Knox said.

Ultimately, Knox said there’s a lot scientists don’t yet know, from the impact of global warming on the jet stream to the impact of dust in the atmosphere that passes through the Atlantic from Africa, something she said scientists are just beginning to explore. But right now, Georgia is already feeling some of the pressure as Hurricane Ian crosses Florida and brings its rain and flooding to the Georgia coast.

Marisa Mecke is an environmental journalist. She can be reached at mmecke@gannett.com or by phone at (912) 328-4411.

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