- The 2020s may go down in history
as the decade of heat waves.
And as we begin to realize just how dangerous heat is,
scientists around the globe
are racing to find harm reduction solutions.
In the US, a policy that caused nearly a century of problems
might actually help shed light
on how to cool the hottest neighborhoods.
This goes much deeper than air conditioning
because counting on it alone not only warms the climate
but also strains vulnerable electrical grids that power it.
In 2021, when the northwest US was hit
by its most extreme heat wave on record,
Vivek Shandas documented something very unexpected.
- So I looked at my phone,
saw 111 degrees, saw 115 degrees,
and immediately thought, "A lot of people are gonna die."
- And they did, more than 750 in the US and Canada.
- We saw these large temperature differences
across neighborhoods and even individual streets
next to each other.
That difference is life and death.
- But that large temperature difference
also presents a very clear path forward.
In order to survive coming heat waves,
we need to make the hottest neighborhoods
more like the coolest ones.
But why does that difference exist?
And how can we change hot neighborhoods to cool them down?
We'll find out and list the top five things
that actually cool neighborhoods when it matters most.
(gentle music)
As we've shown in a previous episode,
cities are warming much faster
than the undeveloped areas around them.
They're also growing quickly
while the underlying climate is warming.
- We've had a very stable weather system
for human habitation for about 10,000 to 11,000 years,
and suddenly we're seeing rapid transformation
of that climate system,
which translates to our daily weather.
You put that together with the fact
that we have more people living in cities
than ever before in human history,
and that's two trains heading right towards each other,
and we're trying to figure out,
how hard is the collision of those two trains?
- So to help answer this question,
Vivek and his team developed mobile thermometers
that could be attached to cars or bikes
and taken out into the city to collect data
and create detailed temperature maps.
- It's a really hot day and what I like to do
is come out, get these devices set up.
And so we take this, put it in the backside over here,
and then I'm gonna turn this guy around
so it collects the air going forward, roll the window up.
It's connected to the satellites overhead,
the GPS that's telling us exactly where we are,
and we're off and running
to collect temperatures for the day.
(mellow music)
Six feet above the ground, two meters above the ground,
we would think that air has had a good chance to mix
and that the hotter air would go towards the colder air,
the colder air would go towards the hotter air,
and we would get this kind of convective mixing,
which is really what kind of stabilizes the temperature.
- [Maiya] But when Vivek drove
to different Portland neighborhoods
to measure temperatures during the 2021 heat wave,
he found something totally different.
- Well, we found a temperature difference
of about 25 degrees,
which is the largest air temperature difference
I had ever recorded in this city.
And as we started going out
and systematically collecting data
in these different cities,
we started seeing very similar patterns.
And so then the question became,
what had to happen in these cities decades ago
in order for these patterns to emerge?
And one of the most significant things
that happened decades ago
was a federal policy called redlining.
- In the 1930s, the federal government began a program
to prevent large numbers of foreclosures
in the wake of the Great Depression.
Banks would create loans guaranteed by the US Government
using a series of maps to rank neighborhoods A through D.
D neighborhoods were determined to be the highest risk
and marked in red.
The primary criteria for risk were race and ethnicity.
Black and Latinx people were considered the riskiest,
but in places like Chicago,
Italians and Russian Jews were considered almost as risky.
Buying a home in a C or D area was difficult or impossible.
In the 1970s, these maps were publicly released
along with notes from the surveyors,
and if you have any hope of them not being terribly racist,
I'm sorry to do this,
but here's Cate Mingoya with a surveyor's note.
- It's from Richmond, Virginia,
it's for a neighborhood that was graded C,
and it says, "Respectable people
but homes are too near the negro area D2."
That means that the very proximity to blackness
was enough to steal an opportunity
for economic growth and prosperity
from an entire neighborhood of people in Richmond, Virginia.
- But what does that have to do with heat today?
- That means that you're kept
from the benefits of home ownership,
that means that you are not going to be able
to maintain your property
by doing things like improving drainage
and making changes like planting trees.
Additionally, people who were living
in redlined neighborhoods,
their property values were a lot lower,
which meant that the taxes for homes in that area
were also a lot lower,
so you see things like sewage infrastructure
not being updated, parks not being cited there,
trees not being planted in the public right of way,
so there's a really long process of disenfranchisement.
- And we're still feeling the impacts
of that nearly century-old policy.
- It turns out that the color scheme that was set up
helped to explain what was happening in terms of difference
between one neighborhood and another neighborhood.
We were able to find that,
in looking at 108 cities across the country,
95% of them, meaning the vast majority,
followed a very similar pattern
to where the D hazardous neighborhoods
were consistently hotter than their A, best neighborhoods.
(gentle music)
- Okay, so what's the difference
between these neighborhoods?
This is the intersection that recorded
that 124 degree temperature
that was the hottest temperature recorded
during last year's heat dome.
There aren't a lot of trees here
so there's not a lot of shade in this neighborhood,
and you got a lot of pavement.
Let's actually compare this neighborhood
to the coolest neighborhood.
Here it is, the coolest neighborhood,
with an air temperature of 99 degrees.
There's tons of trees in this neighborhood
and it's surrounded by forests,
so we got a lot of trees, a lot of shade.
25 degrees cooler, though, 25 degrees.
But I'm glad we're here,
I'm glad we're seeing this in person
'cause it just gives us a map of what we can do
in hotter neighborhoods to make them safer.
- Tree cover and shade saves people's lives.
It's just that simple,
whether it's a senior who doesn't have any air conditioning
or just as simple
as folks that are waiting for the bus right now.
If you see this bus stop,
they're lucky because there's a big, ol' tree there,
and guess where everybody's sitting?
Up under the tree.
If you look down this way, there are bus stops down here
and there are no trees, right?
And there are many, many, many bus stops in the city
that have no trees.
Where we are today is Jackson Ward,
which is a traditionally African American neighborhood.
It's hot in this part of the city
and there are not enough trees.
And with development, trees get taken down
and little ones get put up,
and so we're constantly in a battle
of trying to maintain the tree canopy.
So we've planted a few hundred trees.
We're watering, at this point, 400 trees this season.
- Trees are not the whole solution,
but according to everyone we talked to,
planting trees, protecting existing,
and maintaining your city's trees
is the best way to cool urban areas.
Next, decrease impervious surfaces
by removing any pavement that can be replaced
by something else or something more efficient.
Add shade structures to public places like transit stops.
That could be planting trees or building roofs.
Promote air convection and mixing
by encouraging a variety of building heights
in all neighborhoods, especially near water,
and work with prevailing wind directions
to be sure tall buildings aren't blocking airflow
from other neighborhoods.
And finally, add surfaces that cool the area,
like green roofs, green walls, white roofs,
and water features in public spaces.
After helping discover the extreme temperature differences
we've been talking about,
folks at the Science Museum of Virginia
went to work on transforming two acres of pavement
on their campus into green space.
- Right now we're standing on top
of a brand-new four-story parking deck
that consolidated the area that we needed
for our parking for our guests,
allowing us to do something extremely dramatic
to the former surface parking lot
that we would use for that same purpose,
namely de-paving it and turning it into a civic green space
for us, our guests,
and all of our neighbors here in Richmond.
What's really special about this, I think,
is that it represents, to our knowledge,
one of the largest de-paving projects in the city's history.
When we look at the different types of options that we have,
unfortunately, parking, green space,
housing, and businesses
have all been kind of put in opposition to one another,
when, actually, responsible land use
allows us to take advantage
of the very limited space that we do have
to maximize the benefit for our neighbors
and our visitors here at the science museum,
as well as around the city.
So when we think of it,
parking, housing, green space, and business development
do not need to be in opposition.
In fact, they should be all seamlessly integrated
to provide the best opportunity for climate resilience
for our neighborhoods that we can provide.
- Friends of Trees has been working on the issue
for quite a while,
and that shows just how long it'll take
to reverse a century of lack of investment.
What is Friends of Trees doing in neighborhoods like this
to keep them cooler?
- Our mission is basically to plant trees
alongside community members.
In our 33-year history,
we've planted over 900,000 trees and native shrubs.
Due to several factors like development and heat waves,
we're barely maintaining.
In fact, we're losing canopy
in a lot of these East Portland neighborhoods
where we need that canopy the most.
What we do try to plant is more drought-resistant trees
because as the heat waves are coming, what we're finding
is certain trees are struggling to survive.
This is a climate emergency.
We should be planting as many trees as possible
to help kind of restore some of the wrongs of the past
as a community.
- Do you live in an area affected by redlining?
What about our friends in Europe, Asia, and everywhere else
that set temperature records this summer?
What efforts are going on
to protect people from extreme heat in your areas?
Let us know in the comments below, and thanks for watching.
(upbeat music)