AMNA NAWAZ: Welcome to the "News Hour."

Americans across the East Coast are preparing for one of the hottest Independence Days in recorded history.

A brutal heat wave is bringing dangerous temperatures to some 160 million from Mississippi to Maine.

Record-breaking triple-digit temperatures have disrupted travel, strained the energy grid, and forced some communities to change or cancel planned celebrations.

Yesterday, more than 100 people in Pennsylvania were treated for heat-related illnesses at an event tied to the 250th anniversary celebration.

In the capital, today's events on the National Mall were postponed for hours because of the extreme heat.

And, in New York City, where the heat index was expected to reach 110 degrees today, Mayor Zohran Mamdani urged residents to take precautions.

ZOHRAN MAMDANI (D), Mayor of New York City: What we ask New Yorkers to do is to be mindful of the danger that accompanies those temperatures.

That means make sure that you stay hydrated, make sure that you're putting on sunscreen, make sure that you're taking as many breaks as possible from being outside.

And, if you can, to stay indoors and to stay in air conditioning.

AMNA NAWAZ: Meanwhile, health authorities in Europe have now linked thousands of excess deaths to record heat.

To unpack it all, we're joined now by Jeff Goodell.

He's a contributing writer at "Rolling Stone" and the author of "The Heat Will Kill You First: Life and Death on a Scorched Planet."

Jeff, welcome back to the "News Hour."

Thanks for joining us.

JEFF GOODELL: Thank you for having me.

AMNA NAWAZ: So there's heat advisories in effect in almost 30 states.

The National Weather Service said today's temperatures are extremely dangerous.

What are the risks here and who's most vulnerable?

JEFF GOODELL: Well, the risks are tremendous.

I mean, anyone who goes to the doctor knows the first thing they do is check your body temperature to see when things go wrong.

Our bodies are very sensitive to changes in heat, and it makes these kinds of outdoor events on weekends like this all the more dangerous.

I mean, these extreme -- being out in extreme heat puts a lot of strain on your heart.

So anyone with any kind of heart conditions, often, that means elderly people are most at risk.

Young children, especially before the age of 2 or so, have not fully developed an ability to sweat, so they're very vulnerable.

People who are on certain kinds of pharmaceutical drugs like antidepressants get in -- they mess with our body's ability to regulate temperature.

They're at risk.

And, finally, I really urge caution to any women who are pregnant or think they might be pregnant, because a lot of recent research has shown that the risk of miscarriage during extreme heat is much higher.

AMNA NAWAZ: So, Jeff, we're heading into this 250th anniversary weekend.

There's a lot of outside events planned, people getting together for barbecues and parades and so on.

We know there's a World Cup match scheduled to be outside in Philadelphia, which is seeing some record high temperatures too.

What do officials need to be thinking about leading into these events and what should individual people be doing to prepare?

JEFF GOODELL: Well, officials need to be covering the basics, which is access to water, access to shade, access to cooling centers, even better than shade, places, tents that are air conditioned, places where people can get out of the heat, and also, importantly, having medical personnel around who understand the risks of heat, because that is -- you would be surprised at how many of them really don't.

So that's really important.

And, personally, what's important is drinking water.

And I want to clarify the drinking water is important, not because the act of drinking water cools you off, but because if you're dehydrated, you can't sweat, and sweating is how our body cools you off.

So what's important is to keep hydrated, so that you can continue to sweat.

Wearing light-color clothing is really important, and making sure that you know that you have access to somewhere cool that you can get to, whether it's a building that's air conditioned or a cooling center or something, because heat builds up in your body, and it kind of becomes a runaway train.

And what you don't want to do is get too far down the tracks on that runaway train before you start cooling off.

And last thing I want to say, and if I can correct Mayor Mamdani in your intro, sunscreen is important to wear outdoors.

It protects us from U.V.

rays, but it doesn't do anything to protect you from heat.

AMNA NAWAZ: I want to ask a big picture question here, which is, we know what the data shows us about climate change and the increasing threats and the warming of the planet and them leading to more frequent, more intense heat waves.

But let's be specific about that so people really understand.

What is driving that warming?

What is driving that climate change?

What should we understand?

JEFF GOODELL: Well, it's very clear.

Science have -- has understood what's driving this warming for a half-a-century, and that is increasing levels of CO2 in the atmosphere, primarily from the burning of fossil fuels.

There was a study that came out yesterday from a very highly respected scientific group in the U.K.

that basically said that these kinds of extreme temperatures that we're seeing right now would be virtually impossible without the higher levels of CO2 in the atmosphere.

So what we're seeing is a manifestation of climate change.

What we're doing is living in the future that climate scientists have been warning us warning us about for 50 years.

AMNA NAWAZ: Jeff Goodell, contributing writer for "Rolling Stone," joining us tonight.

Jeff, thank you so much.

Good to speak with you.

JEFF GOODELL: Thank you for having me.