WILLIAM BRANGHAM: In coming days, more than 100 million people in the U.S. will be living under a heat advisory, as a brutal heat wave moves into the Midwest and Northeast.

A new analysis finds the heat that's been baking the U.S., Mexico, and Europe over the past month would be -- quote -- "virtually impossible" without human-caused climate change.

It comes from an international group of researchers known as the World Weather Attribution.

To help us understand more about this real-time assessment, we're joined by Bernadette Woods Placky.

She's the chief meteorologist and director at Climate Central, an independent group of scientists and communicators.

Bernadette Woods Placky, so good to have you on the "NewsHour."

This new report is part of a field of what is known as attribution science.

Can you tell us a little bit about what this study showed about the connection between climate change and these heat events?

BERNADETTE WOODS PLACKY, Climate Central: So, attribution science is when we can go into individual weather events and tease out the role of climate change.

We do that through three ways, one, our knowledge of a specific weather event.

And heat is one where we know a lot.

Two, historic temperature records.

We can go back in time to see what's happened before.

And, three, model data.

We can look and we can model different scenarios in our Earth's environment.

And when we bring down our levels of carbon dioxide or bring those up, we see changes in that.

When we put all of that together, we have what's called attribution science, and we get our confidence in whether we could recreate this event or not.

WILLIAM BRANGHAM: And that's what this report seemed to indicate, that it was impossible for these heat waves to be as long and as severe, absent climate change.

BERNADETTE WOODS PLACKY: Correct.

And, sadly, that's not surprising.

We know when we add more heat to our atmosphere through the burning of fossil fuels, that that translates into bigger, stronger heat events, which is the foundation for all of the climate changes that we see.

WILLIAM BRANGHAM: And is it simply a factor of the fact that this is a warmer atmosphere and we see warmer events?

Is that -- is that how the mechanism works or is it more complicated than that?

BERNADETTE WOODS PLACKY: So it doesn't mean every single place is getting the extreme heat all the time.

We're still going to have whether.

But when we really raise that platform to a different level, where we start with our heat, and you add additional heat into the whole Earth system, it's going to play out more intensely and more frequently with these big heat events.

WILLIAM BRANGHAM: The reason I ask this is that, every time we do a story like this, the critics always say, well, oh, it's hot in summertime?

How surprising.

So how can we really tease out the distinctions between summer weather and climate change?

BERNADETTE WOODS PLACKY: It is always hotter in the summer than it is in the winter, correct.

But certain summers are hotter than others.

And what we're talking about right now is record after record after record after record.

So you have to look at the pattern.

It's not just one individual event in one season.

We are looking at southern parts of Europe, a lot of North America and Mexico, China all at the same times, right?

So that's a lot of the globe spiking records like we have never experienced before.

And this continues to happen.

WILLIAM BRANGHAM: We're also entering the period of El Nino, which can warm the oceans and change the weather.

Remind us what El Nino is all about and how that might be playing into this.

BERNADETTE WOODS PLACKY: So, El Nino is a natural phenomena that happens in the Pacific, where we warm our -- well, the waters are warmed naturally.

And that changes some of our weather patterns around the globe.

It also adds additional heat to the atmosphere.

So when we get El Nino years, there's that boost in our global temperatures.

The thing is, when you want to look at the big picture, once again, our El Nino years of current years are breaking records.

And they're well above our El Nino years of the past.

WILLIAM BRANGHAM: I want to ask you about some of the solutions here.

I mean, we know that we have to drastically reduce our emissions to stop this human contribution to climate change.

But as your organization well knows, and as you strive to try to overcome, getting this change implemented is very, very difficult.

Do you believe that this current series of records falling globally, as you described, is going to be able to move the needle in any meaningful way?

BERNADETTE WOODS PLACKY: People are understanding more and more that connection between what we're experiencing and climate change.

The thing is, the warming is just happening faster than our responses.

So two things are happening at once.

There are some amazing solutions happening and being implemented around our country and around the globe.

But we have waited a long time to implement those solutions.

So our warming curve is faster.

What we need to do is bend that warming curve.

And that's where it gets really interesting.

Yes, we baked in a certain amount of warming already.

However, this isn't, per se, the new normal.

This is a changing normal.

We're still on a path to even hotter, unless we make those changes.

So it is upon us to make those changes so we can limit that future warming.

WILLIAM BRANGHAM: And how confident are you that we're going to do that?

I mean, the reason I ask is that we have had 30 years of international negotiations to address this, and very little to show for that.

Emissions keep going up.

Temperatures keep going up.

BERNADETTE WOODS PLACKY: They do.

It is frustrating, and especially when you follow this daily, and this is your world.

That is frustrating.

However, we do know a couple of things that do help people stay focused on a future of this.

One, if you take us back pre the Paris agreement, we were on a path to, say, five, six degrees Celsius of warming, right?

What we're experiencing right now, just for perspective, is 1.2 degrees Celsius of warming.

With the implementations and the changes we have made in the world, that five or six degrees of warming has come down.

It really has.

It's come down closer to like a three.

If you squeeze out all of the commitments, it could be a two.

There's a range in there.

It's not exactly precise.

However, it really depends on human behavior.

And as we all come together, we have already bent that curve.

We just need to accelerate and supersize our actions and bend it even faster.

WILLIAM BRANGHAM: Bernadette Woods Placky of Climate Central, thank you so much for being here.

BERNADETTE WOODS PLACKY: Thanks for having me.