By Mark Woods
There were some mornings in May when I stepped outside, felt a surprisingly cool breeze, and thought two things. This is really nice and it can’t last.
It didn’t. Summer still is officially more than a month away, but the heat has arrived, along with its oppressive Florida sibling, humidity.
And not only are they going to be here for a while, the long-term forecast — not just days or weeks, but years and decades — should come with some new weather symbols. Maybe a sun with a red face. Or perhaps dead birds falling from the sky.
The latter is what happened during a recent heatwave in South Asia. As temperatures neared 120 degrees in India, an unusual number of birds suffered from heatstroke.
In today’s world, the canary in the coal mine isn’t necessarily underground.
Fortunately, the humidity was quite low. Because as the New York Times recently wrote, when it comes to human mortality, “according to the young science of ‘heat death,’ air moisture is as important as temperature.”
In our part of the world, we know quite well that air moisture is a part of summer, alongside thunderstorms and hurricane models.
And while we tend to boil our steamy records down to a single number — it reached this temperature on this date in Jacksonville — the reality is that it’s different temperatures all over town. And sometimes the difference between one spot and another can be fairly dramatic and, in some cases, even deadly.
That’s why I went for a walk the other morning with Dr. Adam Rosenblatt, a University of North Florida assistant professor of biology.
UNF is partnering with the City of Jacksonville — and with Duval County volunteers — to do an extensive heat-mapping study of one day in Jacksonville, with a target of some time during the second week of June.
Rosenblatt suggested we meet near Warren Schell Memorial Park, a few blocks south of UF Health Jacksonville.
We got lucky. It was one of those mornings that make me wish we could lock in at a certain temperature and stay there all year. But even if we seemed to have a lot of those this spring, Rosenblatt says we shouldn’t be lulled into thinking we don’t have a looming public health issue — one that will only get worse.
When it comes to climate change, I tend to quickly forget every statistic but always remember one bottom-line fact. We’re living on a planet that is warmer than the one our parents and grandparents lived on. The earth is warmer today than at any point in the history of human civilization. And it is getting warmer.
Rosenblatt, 38, has studied what this means for alligator behavior in the Everglades and insect and spider populations in Connecticut. So when he describes his latest project, he smiles and says: “This is my opportunity to apply my research skills to humans and maybe do something that is more directly beneficial.”
Before we started walking north on Boulevard Street, Rosenblatt pointed out the tree cover — or lack of it. That, he said, is why he suggested walking here. It’s an urban “heat island,” partly because it doesn’t have the tree cover of some other parts of town.
“There just aren’t a lot of big mature trees left,” he said. “I mean, you look around and there are these small magnolias. And there are palm trees, of course. Palm trees are horrible for shade.”
A nearby palm tree created a sliver of shade, maybe enough to shield one thin person from the sun. And, as Rosenblatt explained, it’s not just the lack of shade. It’s what happens where the sun beats down on the ground, literally heating up an area.
The difference between a heat island and a nearby neighborhood can be up to 20 degrees. And when the heat island is in a neighborhood where a higher percentage of residents don’t own cars — where they get around by foot and public transportation — it only adds to the public health issue.
“Heat kills more people every year than any other weather-related disaster,” he said. “Most people think of hurricanes or flooding or tornadoes. Heat is No. 1. It doesn’t get the attention because it’s a silent killer.”
It’s hardly news that Florida gets really hot. So there’s a tendency to shrug and say: “What can we do about it?”
As we stood in the sun at the intersection of Boulevard and 8th streets and waited for the light to change, Rosenblatt said there is quite a bit we can do about it. And it’s not just a matter of preserving or planting trees.
“The less sexy thing — and there’s always a less sexy thing — is building codes,” he said. “That’s where I feel like the real meat of it is.”
He said that if you looked at a Google Earth image of the area we were walking, you’d not only see how there was an abundance of concrete and parking lots and buildings, you could zoom in and see the tops of buildings — and, in a lot of cases, tar surfaces that absorb heat.
He said you can make rooftops reflect heat instead of absorbing it. You can build in ways that make an area cooler. But it isn’t something a city does overnight. (And I’ll add that it shouldn’t just involve spending hundreds of millions to create shade at the football stadium.)
“It’s a decades-long process, which is why we think we need to get started on this yesterday,” Rosenblatt said.
But the first step involves finding the hot spots. Which leads us to the heat-mapping project.
More to city’s resiliency than flooding
Rosenblatt explained that there are satellite images of Jacksonville that give a broad sense of temperature differences in the city. But this project, funded in part by the National Oceanic and Atmospheric Administration, will produce hyperlocal, block-by-block data.
He is working with Anne Coglianese, the city’s Chief Resilience Officer, and recruiting volunteers to be “citizen scientists.” (The Community Foundation of Northeast Florida has provided funding to pay the volunteers up to $75.)
The volunteers will mount temperature sensors on their vehicles and during three one-hour periods drive specific routes, collecting heat and humidity data. There will be 32 routes, each covering about 10 square miles. So it isn’t the entirety of a city with more than 800 square miles. It’s basically everywhere inside I-295, plus east toward the beaches and west toward Clay County. But that’s still a big undertaking.
Similar studies already have been done in dozens of other cities. And 14 other U.S. cities, from Las Vegas to Philadelphia, will participate in this year’s campaign. But Rosenblatt says none has covered 320 square miles.
“The largest one before this was in Houston,” Rosenblatt said. “I think they covered 310 square miles. We’re gonna beat them by just a little bit if we can pull it off.”
They haven’t picked the exact date yet. They’re working with the National Weather Service, hoping to select a June day with the best odds of no rain — just sunshine, heat, and humidity.
Meanwhile, I’m hoping for another day with a cool morning. I think it’s called “October.”
Mark Woods is a columnist with the Florida Times-Union in Jacksonville, which is part of the Invading Sea collaborative of Florida editorial boards focused on the threats posed by the warming climate.