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

As we wrote this script, wildfires were ripping through Northern California,

burning millions of acres and filling our beautiful city with smoke.

At the same time, across the country, a massive tropical storm bore down on the Gulf Coast,

and Phoenix, Arizona, recorded its 50th day of the year above 110 degrees.

We know that these stories are connected to a bigger story, and honestly, trying to keep on top

of all the bad climate news can be unbearably depressing. They're the kind of headlines that make you want to just not click.

And so when it seems like there's a piece of genuinely good environmental news,

I always smash that link. Best producer Emmett Fitzgerald. Solar power prices at an all-time low.

Endangered tigers, making a comeback.

Exxon mobile, doing so poorly gets taken off the Dow Jones.

And one morning, in the summer of 2019, right after the warmest June and the history of June,

I got a surprise dopamine hit when I saw this headline.

Tree planting has mind-blowing potential to tackle climate crisis.

Now, to be perfectly clear, the most mind-blowing thing we could do to tackle the climate crisis

is to stop burning fossil fuels. But there are also ways that we can soak up some of the CO2

that we've already put into the atmosphere. We're developing machines to do this,

but trees and other plants actually do it naturally. They take in carbon from the atmosphere

and store it in their leaves and branches and trunks.

And so some scientists in Switzerland tried to calculate how much carbon could be removed

if we planted as many trees as possible all around the world.

They published a paper in the journal Nature, arguing that if humans planted a trillion trees,

...