This is 99% invisible. I'm Roman Mars.

Last October, the mayor of LA, Eric Garcetti,

gave a speech about one of the biggest issues facing his city.

It's just way too hot.

And we know that climate change is not an abstract crisis. This is the fight of our lives.

Mayor Eric Garcetti in South Los Angeles today, rolling out key elements of his cool streets program.

This is the first of five neighborhoods across the city where we're rolling out new features

that will help us lower our temperatures.

The city is trying lots of things to cool down temperatures like painting sidewalks white

but the easiest way to solve this problem is shade. Just creating shade. Lots of neighborhoods

in LA don't have tree coverage or

high-rise buildings and because of city bylaws it's really difficult to build

features like shade sales or canopies. journalist Sam Block has spent a lot of time looking into Shade,

so I sat down to talk with him about why Shade is actually a matter of life or death

for people living in really sunny places.

So you used to live in Los Angeles,

and what did you notice about Los Angeles

when you started walking around the city?

What did I notice?

I noticed that there was no one around.

I noticed that the people who were around

would have to position themselves

...