I’m looking at a map of surface temperatures in the Phoenix metro area.
So this is in Arizona, in the southwest US and it shows how hot the ground is in June.
And this is a map of child poverty rates.
Darker blue means more poverty.
So this is heat.
And this is poverty.
Heat.
Poverty.
Heat, Poverty.
The correlation is pretty obvious.
This is where it becomes clear that climate change and wealth inequality are not really
separate issues.
And you can probably find examples of that wherever you go in the world, but for this
story, I went... there.
"An excessive heat warning is in effect."
"Warmer is the new normal in Phoenix."
"The city's grappling with an increase in heat related deaths."
"Phoenix, last year, hitting 100 degrees or higher for more than 144 days."
"Climate change is one factor causing rising temperature.
"Urban development is the other."
The forecasted high that day was 112 degrees Fahrenheit.
That's 44 degrees Celsius.
But in reality, some areas can feel warmer or cooler than that.
So here I am in a neighborhood with some of the hottest surface temperatures, but when
I drove 8 miles north of there, I was in one of the coolest parts of Phoenix.
And it was in the hot neighborhood where I met up with Eva Olivas.
She's a local community advocate and Phoenix native.
It's nice to meet you.
OLIVAS: It's nice to meet you.
Can you tell me a little bit about this neighborhood and who lives here?
OLIVAS: So the community of Central City South is located just south of the downtown business district.
OLIVAS: The average income level for a family of four is about $19,000.
OLIVAS: The vehicle ownership rate is between 23-28% of the population.
Oh wow.
OLIVAS: Yes, very low.
So they’re very dependent on public transportation.
This zip code has the highest rate of heat-related illnesses in the city, what makes
people here vulnerable to extreme heat?
Well, I think it’s a combination of things.
We have the freeway.
OLIVAS: We have the railroad tracks on the north.
OLIVAS: We have the airport on the east.
OLIVAS: So we're like a little pocket.
That's a lot of pavement.
OLIVAS: A lot of concrete, a lot of industry here.
A lot of our streets, as you can see, don't have sidewalks.
You're having to walk in the street, like we are.
And there's not a lot of shade.
If you can look around, you don't see a lot of trees.
This is the Sonoran Desert, so of course the summers are hot.
But it also seems like this entire city was almost designed to capture heat.
The streets are so wide.
This isn’t a highway, this is just the Phoenix grid.
And the buildings are so flat and set back from the sidewalk, so they don’t create
much shade at all.
And then there’s the parking lots.
I read one estimate that there are more than 4 parking spots for every car in Phoenix.
The sun just beams into all that pavement.
And it doesn't just roast anyone who happens to walk across it, it’s also transferring
heat to the air, day and night.
Wow I really … did that poorly.
Also, I promise this is not a Chevy ad, I just borrowed my dad's car.
So what do you do to try to mitigate heat in a city like this?
Well, reflective roofs can help a bit.
The thermal image shows the surface temperature of the dark roof is hotter than the white ones.
And the city has also tried painting some roads with a more reflective coating.
But if you compare the hottest and coolest neighborhoods, it’s pretty clear that the
big difference between them isn’t the black or white surfaces.
It’s the green ones.
Plants are the variable that connects this map of heat to this map of poverty.
And studies have confirmed that the cooling effect of cool roofs and cool pavements is
smaller than the cooling effect of trees.
"One of the best ways to beat the urban heat."
"The more trees you plant, the more benefits."
"It's cleansing for the air."
"Reduce carbon footprint."
"Lower levels of stress."
"Decrease energy costs."
"Storm water management."
"It's a very important engine of cooling."
If you take an area that’s just parking lots and buildings, and cover at least a quarter
of the space with trees, you can lower air temperatures there by around 8 degrees Fahrenheit
or 4.4 degrees Celsius.
That’s according to a study from Arizona State University.
For those who are used to humid summers, it can be hard to understand just how much relief
shade provides in a dry heat.
You can easily see the temperature difference on my arms and on the concrete there.
So the city of Phoenix has committed funds to planting more trees.
They want all neighborhoods to reach a minimal level of canopy cover by 2030.
And I love the idea of recruiting an army of trees to protect the vulnerable from extreme heat.
But there’s a problem.
Outside of parks and along major streets, the urban forest currently depends not on
public resources, but on private ones.
What would it take for a street like this one to become one of those shady tree-lined
streets that they have uptown.
OLIVAS: Well, any tree that’s planted in this neighborhood in front of someone’s home,
they would have to maintain.
OLIVAS: The city does not maintain them in these residential areas.
I see, okay.
So there are some utility companies here that will give you a couple of free trees if you
agree to plant them on the west side or south side of your home, because eventually that
can end up saving something like 30% on your air conditioning bill.
But it sounds like that doesn’t really solve the maintenance issue.
OLIVAS: Correct.
OLIVAS: Because there’s that tradeoff between shade or increased water bill.
But it’s the cost of maintaining the trees that is challenging, obviously in a very low
income neighborhood like ours.
And it’s not a priority for them in their family, in their home.
Are there no programs here that are actually going to take on the watering cost?
OLIVAS: Zero.
That is the responsibility of the homeowner and you have to remember, what did I say?
These are mostly renters.
I walked with Eva along Buckeye Road where there’s a big triangular lot, it’s owned
by the city, and has been left unplanted.
She said that would probably change with the city’s new tree equity plans.
But she also hoped for some more basic things: like sidewalks, and shade shelters for all
the bus stops.
It was a reminder that wealth already affects access to infrastructure, even infrastructure
that doesn’t have to be watered and pruned.
And that's what will have to change if cities like Phoenix want to make sure that the heaviest
burdens of climate warming don’t fall on those who are least prepared to withstand them.