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Forecast fears

Steve Patterson

Jacksonville Florida Times-Union USA TODAY NETWORK

From Jacksonville to Naples, the hottest, steamiest days of summer will multiply through the next 30 years as climate change makes Florida and much of the country swelter, a big-data forecasting group is warning.

The state’s west coast faces the most punishment from the shift expected to produce summertime heat index readings topping 125 degrees in more than a dozen Florida counties by 2053, says a peer-reviewed computer model from the nonprofit First Street Foundation.

Patches of Georgia spread from Charlton and Brantley counties in that state’s southeast to the Flint River and the Savannah and Hinesville areas are also projected to roast under changes the foundation says will bring an “extreme heat belt” to areas from Louisiana to Wisconsin and eastern areas from the Carolinas to Pennsylvania.

“We need to be prepared for the inevitable, that a quarter of the country will soon fall inside the Extreme Heat Belt with temperatures exceeding 125 … and the results will be dire,” First Street CEO Matthew Eby said in a written announcement of the foundation’s release this week of a home-by-home database reflecting heat risks across the country.

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The nonprofit, which already tracked statistical risks from flooding and wildfires, folded heat risks into the free website RiskFactor.com, which envisions heat levels that are rare now becoming almost summertime routines.

In Collier County, where heat index readings above 108.6 degrees now happen about seven times a year, First Street’s projections see that heat being exceeded 29 days a year by 2053.

First Street used each community’s top 2% of heat index readings – the “feels like” temperatures affected by humidity – to set a standard it called a “local hot day.” Then the nonprofit’s peer-reviewed model projected changes for the next 30 years and forecast how many days a week’s worth of today’s heat will fill by 2053. Lee, Manatee, Miami-Dade and Monroe counties were all forecast like Collier to top those top heat index readings (they varied from 104.9 degrees to 109.1, depending on county) for 29 days a year.

Charlotte and Sarasota counties were projected to exceed today’s “local hot day” temperatures for 28 days per year – four times the total now – followed by Pinellas and Broward counties with 27 days and 26 days in Hillsborough County. Communities that don’t top the heat list still face real challenges.

Jacksonville’s hot-day standard of 106.7 degrees is only projected to be exceeded 20 days a year by 2053.

But heat index readings above 100 are projected to rise from 41 days per year now to 86, a 65% hike that carries real risks for people whose jobs require working outdoors and people who are vulnerable to heat stress and don’t have easy access to air conditioning.

“This is a particularly dangerous issue because extreme heat kills more people per year than any other weather event,” said Adam Rosenblatt, a University of North Florida professor who spent part of the summer researching heat islands in Jacksonville in a study partly funded by the National Oceanic and Atmospheric Administration.

A 2020 report from the Environmental Defense Fund projected Florida experiencing an additional nine deaths for every 100,000 people because of rising temperatures. The level, the report said, was comparable to the number of Floridians dying from kidney disease and higher than the number whose deaths were attributed to high cholesterol.

Being hotter costs more, too, said Dawn Shirreffs, the defense fund’s Florida director.

She noted the 2020 research projected a $122 yearly increase in a typical Floridian’s home electric bills to handle additional cooling needed by 2040.

But Shirreffs said the real costs could be worse because the state’s utilities are heavily dependent on natural gas supplies whose prices can be volatile and subject to sudden market shocks. “There’s going to be a lot more risk and cost associated,” Shirreffs said, noting that some of that cost will fall on people already struggling to pay basic expenses. Energy bills often consume 8-10% of low-income households’ money, she said, adding the costs her organization projected would make that burden bigger.

In Duval County, First Street’s modeling projected that some amount of air conditioning would be needed 298 days out of each year by 2053, an addition of seven days from current levels.

How communities handle the additional challenges heat poses varies from town to town.

In Miami, the city’s resilience officer left her job and last year became Miami- Dade County’s chief heat officer, the first job of its type at that time.

“My administration is doing everything possible to mitigate the threats of extreme heat –– including for our public transit riders,” Miami-Dade Mayor Daniella Levine Cava tweeted this week, pointing to examples like planting trees and creating shade to cool bus stops and transit riders.

Jacksonville Chief Resilience Officer Anne Coglianese has mentioned heat as a subject she wants to include within the city’s resilience strategy, which is still being developed. A city spokeswoman said Tuesday that the strategy will be informed by a heat study developed from data collected in June by volunteers monitoring temperature and humidity data along 30 routes driven on the same day.

Rosenblatt said by email that “the most important thing is to decrease the city’s emissions of greenhouse gases” by transitioning away from fossil fuels and prioritizing public transit, but that other steps are also available.

Among those: including planting more trees with wide canopies, like oaks; incorporating more tree cover into commercial and industrial zoning requirements; repainting roadways and rooftops lighter colors to reflect sunlight; reducing requirements for parking lots, using that land instead for tree cover; and making “community cooling centers,” such as libraries and playgrounds with splash pads widely available.

“This is a particularly dangerous issue because extreme heat kills more people per year than any other weather event.” Adam Rosenblatt

University of North Florida professor

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