(intense music) - [Maiya] 2020 was hot.

In fact, it was the hottest year since record keeping began over a century ago, and climate models point towards more warming and more records.

That might seem nice if you live in a cold place, but heat-related deaths across the US are on the rise.

We traveled to Phoenix, the hottest city in America, to take a closer look at this problem.

2020 was also, by far, their hottest year with 53 days that reached at least 110 degrees.

And while Phoenix highlights the grim reality of a warming world, it also exemplifies the hopeful potential of a community with no choice but to create new solutions.

(upbeat music) Phoenix has seen in an alarming uptick in heat related illness and death over the last five years.

Stacy Champion has worked with local government, aid organizations, and houses people to change that.

- At the beginning of April, the County decided to open up these two overflow parking lots and push the majority of the people in the tents into these lots and people have died.

We're gonna take Marty.

We're gonna go measure the temperature of these lots.

- [Ariane] Marty is a garden cart that measures mean radiant temperature.

And mean radiant temperature is essentially all the radiation that hits your body from all sides and it's the heat load that your body experiences.

It is very much different from what you get from a thermometer which would tell you the air temperature, because it incorporates the short wave radiation which is the, essentially the direct sunlight that hits your body when you're not in the shade and that adds a lot to your heat load when you're outdoors.

Mean radiant temperature is important for us here in Phoenix because it's the main stressor when you're outdoors in the heat.

(upbeat music) - I can't hold it.

(people chatting) It's like putting your hand on the stove.

(tools clicking) - [Ariane] I can look that up.

Mean radiant temperature is 56.

- [Camera person] How does that strike you knowing that we are right next to where some people sleep?

- So I'm very much concerned about people who have to live here because they don't have a home.

- Over the last year, Robert Ladoux lost his housing and has been forced to do just that.

- No doubt about it.

It could kill you.

Heat kills.

Nothing we can do it except get out of it, drink water, drink a lot of water.

(feet crunching) So here's my tent over here.

It's kind of out in the middle.

There is no shade out here.

- [Stacy] So one of the misconceptions about heat illness and death is that this is only an unsheltered or homeless person problem.

Heat can impact so many different people.

There was a woman named Stephanie Pullman.

She was in her 70's.

She owed $51 on her bill.

The cutoff for their disconnect at the time was $50.

So in essence, she owed $1 too much, was turned off on a day that was 107 degrees and died.

- During prolonged heat exposure, the human body can become dehydrated and lose its ability to sweat, which is how it cools itself.

As our body temperature rises, proteins and membranes around cells, especially in the brain, begin to fail.

Organs malfunction and heart muscles begin to break down, and that can stress our body until it causes one or more organs to fail, leading to illness or even death.

Heat doesn't affect all of us the same.

Age, overall health and even location are all factors that can play a big role.

And remember, the definition of high temperatures depends on where you live since our bodies adapt to the climate we live in.

While global warming is the underlying driver behind why places like Phoenix continue to get hotter, something called the Urban Heat Island Effect is warming cities at a much faster rate than the global average or even the natural areas around them.

- It's absolutely critical for Phoenix and other cities to be participating in the conversation around global scale climate change, but also really important to be thinking about local climate change.

Urban driven warming has been more than double the effect of global scale warming here on Phoenix thus far.

There are three key ingredients for the Urban Heat Island.

One, people have machines that emit heat into the environment.

Two, people use different materials than the natural landscape like pavement, asphalt, cement and so on.

And those materials absorb and release heat in a different way than natural materials.

And three, especially in cities, the geometry of the buildings does a really good job of trapping heat and then slowly re emitting it into the environment.

- And we see this effect most obviously with temperatures overnight.

It's when materials of the city slowly release the heat they absorbed during daytime, back out into the environment, and the effect can be dramatic.

(intense music) - [David] We're talking about something like seven, eight, nine 10 degrees Fahrenheit of higher nighttime temperatures.

When we look at our daytime temperatures, which are a mixture of this urban effect and the global effect, we only see an increase of a few degrees Fahrenheit.

So urbanization has been the dominant driver of climate change here in Phoenix and in many other cities.

- In August of 2003, the largest blackout in North American history left 50 million people in the Northeast without power for days.

With Phoenix's record-breaking 53 days over 110 degrees this summer, it's not hard to imagine a blackout that can become truly catastrophic, and Arizona State Professor Mike Chester worries that a larger, more deadly Katrina- like event is looming on the horizon if cities across the country like Phoenix don't address their infrastructure vulnerabilities quickly.

- When temperatures go up, people crank their AC down, colder, which puts more strain on the grid.

And when the temperature is hotter, hardware breaks more frequently.

So aspects of all infrastructure fail more frequently.

It's not for me a question of if it'll happen.

It's a question of when the next large-scale outage will happen.

If you have a large scale blackout, we're going to see excess mortality.

It's probably going to be somewhere on the order of hundreds or thousands of additional deaths.

- But there's a lot we can do to prevent heat related tragedies, and some of it is pretty simple, like increasing shade and decreasing heat absorbing materials' exposure to the sun.

(intense music) - We have a church here and, that has a huge parking lot and currently there's not even a single car standing here.

We have a mean radiant temperature of 150.

And that's a common issue in cities that they have a lot of impervious surfaces, impervious means they're not penetrable by water.

And they heat up a lot in the day and they give the heat back overnight.

And it makes a huge difference whether you have a parking lot or whether you actually place lawns, native nature, that cool the area.

- And it's not just lawns.

Well maintained public parks and green spaces help cool the areas around them, but access to these spaces is not equally distributed.

Across the country, lack of investment in low-income neighborhoods has left them hotter than their wealthier counterparts.

With fewer shaded public parts, getting out of the heat in a blackout is even more difficult.

- There are a lot of studies that show that wealthier neighborhoods are usually cooler than foreign neighborhoods, just because they have more vegetation, more lawns that are irrigated.

And that just makes it cooler in this environment.

So here we have an air temperature of 40 degrees Celsius which is about 104 degrees Fahrenheit.

So it's much cooler here in the shade with all the vegetation in the surrounding.

There's this push to plant more trees and provide more shade to help people in poorer neighborhoods.

(intense music) - So we're here in a residential neighborhood near downtown Phoenix where some of this cool pavement has just been applied.

The sun's been up for only three hours, now.

Let's see how different the temperature is of the surface between traditional pavement here and this cooler pavement.

So on the traditional pavement, we're looking at 125, 126 Fahrenheit.

We'll come over to this cool seal pavement, and it is 121.

So the sun's been up for just three hours and already we're seeing a four degree Fahrenheit difference in temperature between these two surfaces.

That's gonna grow over the day to be upwards of 15 degrees Fahrenheit by the time we get to sunset.

- Black objects absorb all colors turning the light waves into heat while white objects reflect them, keeping them much cooler.

- If we were to take an airplane and fly over Phoenix right now, we'd see many roofs that are already painted white.

Some folks in the private sector have figured out that the math works.

If you make your building cooler, you're gonna spend less money on electricity.

Let's get that, you know, let's make that initial investment.

- [Maiya] There are thousands of miles of roads in Phoenix and other cities that could be treated with cool pavement surfacing, as well as countless roofs that could be painted white.

- So we're at Justice Center, and it's one of the better places to get out of the heat.

And they have huge, huge fans.

Really thankful for places like this, because if it wasn't for them, we'd be out here sweltering in the heat.

- It's 34.5 degrees Celsius, which is just over 90, and it's 105 out there, so it's much cooler in here.

- This is literally a lifesaver.

(intense music) - Nothing like water.

- There's not been enough that has been done proactively.

I believe that the majority of heat deaths are preventable deaths.

- We're trying to think of Phoenix as an innovation laboratory.

The ideas for coping with extreme heat may very well come from here out of necessity.

We need to find the solutions before other cities, as we head into a warmer future.

- While scientists, activists and officials strive to find solutions to living on an ever warming planet, remember to do what you can to stay safe during hot weather.

First, stay hydrated and get out of the sun whenever possible.

But if you do have to be out in the heat for whatever reason, make sure to pay close attention to signs of heat exhaustion, and heat stroke such as dizziness, confusion, cramping, and fatigue.

Heat related illness can become very serious very quickly and may need medical attention.

So don't be afraid to ask for help and to help others.

People who are isolated are far more likely to be at risk.

So when it's hot, check on the more vulnerable people in your community.

The world is getting warmer and we need to look out for each other.

Thank you so much for watching.

If you haven't yet, check out our previous nine episodes for more info on natural disasters, how they're changing and how you can prepare.

Thanks again for watching, see you guys next time.

(intense music)