GEOFF BENNETT: We saw the flooding in New England at the start of tonight's program.

Tens of millions of people living in the Southwest, of course, are dealing with extreme weather of a different kind.

That part of the country is coping with day after day of triple-digit heat.

And the National Weather Service says it's one of the longest heat waves in modern history.

That heat is even more dangerous than you might realize.

We're going to focus on that with climate journalist and author Jeff Goodell, who's out with a new book on this very subject called "The Heat Will Kill You First: Life and Death on a Scorched Planet."

Thank you for being with us.

JEFF GOODELL, Author, "The Heat Will Kill You First: Life and Death on a Scorched Planet": Happy to be here.

GEOFF BENNETT: Some 54 million Americans are expected to see triple-digit heat this week.

And in your book, you liken extreme heat to having the barrel of a gun pointed at you.

Explain that.

JEFF GOODELL: You know, we talk a lot about heat, about global warming in our world now.

And there's this idea that heat is just as sort of gentle thing that we have to dress differently for or turn the air conditioning on a little bit.

I think what we're seeing now is the -- that heat is a very dangerous force, that heat is something that can kill you very quickly.

I mean, this book, for me, came out of that kind of experience when I was walking down the street in Phoenix, and it was a 115-degree day, and I was not sure I was going to make it to my destination.

And heat is a -- heat is a lethal force.

GEOFF BENNETT: You write about the tragic death in 2021 of a young California family on a hiking trail, two healthy parents, their baby, a dog found on a trail minutes from their home.

Tell us about that story and what takeaways there are from that.

JEFF GOODELL: That was an incredibly tragic story.

A family moved from Silicon Valley into the foothills of the Sierras to get away from the hustle-bustle, live more in the woods.

They hiked a lot.

They went out for a hike early one morning.

They had been warned that it was going to be a hot day.

They hiked down to a river canyon, and then around noon started hiking back up and had to hike up this two-mile switchback, where it was really very sunny and there was no shade because of wildfires the year before.

And the next day, they were found.

The entire family and found dead on the trail.

And what's tragic and sad about this is that it really underscores, even for people who are in good shape, even people who are outdoorsy, people who think that they understand heat don't understand how dangerous it is and how quickly you can get in trouble.

GEOFF BENNETT: How do we solve for the fact that three of the country's most populous states, California, Texas, and Florida, are right now experiencing a punishing heat wave, lots of people in places that are really hot?

And then, beyond that, you have got some 15 million people who spend part of their job outside, the so-called sweat economy.

JEFF GOODELL: These states have seen a big population growth in recent decades.

People like -- first of all, people like warmer weather in general.

They would rather live in a warmer place than a cooler place.

There's the myth of air conditioning, that it'll all be OK because we can just turn the air conditioning on and everything will be fine.

And I moved from the sort of relatively cool of the Northeast to Austin, and I moved there because I fell in love with a woman who lived there.

And so people move for different kinds of reasons, right?

But I think that, as climate change accelerates, as these heat waves become more and more brutal, it's going to change that equation.

And because there are -- it's fine if you are living in your air conditioned bubble, but millions of people do not live in the air conditioning bubble.

And our -- we can't air condition the wheat fields and the cornfields and all the other living creatures that are not going to be able to be sort of nestled into some cool spaces.

It becomes this sort of weird life in a bubble feeling when you're in a place like Texas.

GEOFF BENNETT: Well, based on your research, how hot can it get?

What should we expect in the years to come?

JEFF GOODELL: That is a really good and important and difficult-to-answer question.

We know we can talk about general warming of the planet averages.

But what we are seeing now and what we saw, for example, in the Pacific Northwest in 2021, when there was that extreme heat wave that killed 1,000 people, it got to be 121 degrees in British Columbia.

I mean, no climate models predicted that.

It was like snow in the Sahara or something like that.

So what we're seeing is, as we mess with the atmospheric dynamics of the planet with -- by putting -- by burning fossil fuels, putting more CO2 into the atmosphere, we're changing the dynamics in ways that we have not -- we can't really say what the next heat wave is going to hit, how brutal it will be, how long it will last.

And it's a little bit frightening.

In fact, it's more than a little bit frightening.

It's very frightening, because could it get to 125 degrees in Texas?

No one knows.

GEOFF BENNETT: Your book is in many ways an urgent warning.

What do people fail to grasp about the threats posed by excessive heat?

And what do solutions look like?

JEFF GOODELL: I think two things people don't grasp about it, one is that it can kill you, and it will kill you.

And it's predatory.

It goes after -- heat will kill first people who are vulnerable, who have any kind of heart conditions.

Heat puts a lot of strain on your heart.

So, if you have hyperthermia, or any kind of heart problems, taking certain kinds of medication that affect your circulation, you're increasingly vulnerable to heat.

And the other thing that people don't get about heat is that it is the primary driver of all these changes that we're seeing on our planet.

The wildfires, sea level rise, drought, all that stuff is happening because it's getting hotter and hotter.

And so heat is this sort of fundamental force that is shaping our world in ways that we don't really understand.

And what we can do about it, very first thing we need to do is cut fossil fuel emissions quickly, because our planet is warming up because we're putting more fossil fuel into the atmosphere.

Second, we need to get smart about the risks of heat.

We have to -- whether it's by reading my book, Googling, reading somebody else's book, whatever your method is, understanding the risks of heat.

And, third, we need to change how we build cities and where we -- and how we live in cities, because cities are much hotter than the rural areas around them.

So, everything from opening cooling centers, to planting more street trees, to thinking differently about how buildings are built, so they're not so dependent upon air conditioning, we really have to rethink how we live.

GEOFF BENNETT: Jeff Goodell.

The book is "The Heat Will Kill You First: Life and Death on a Scorched Planet."

Thank you for being with us.

JEFF GOODELL: Thank you.