AMNA NAWAZ: A heat wave is baking much of the country right now, leading to record highs and triple-digit temperatures in the Midwest and the South.

It is the latest in a series of extreme weather events that have led to damage, destruction and death this summer.

That includes the wildfires in Maui, a month of broiling temperatures in parts of the Southwest, and flooding in Vermont and Upstate New York.

Michael Mann is a presidential distinguished professor and director of the Penn Center for Science, Sustainability and the Media at the University of Pennsylvania and author of forthcoming book "Our Fragile Moment."

Michael Mann, welcome back.

And thanks for joining us.

These seem like very different events, storms and fires.

But what's the connection between all of these we need to understand behind why they're so extreme and what's fueling them?

DR. MICHAEL MANN, University of Pennsylvania: Yes, thanks.

It's great to be with you.

At some level, this is pretty basic.

You make the planet hotter, you're going to have more frequent intense, heat waves.

And, of course, we're seeing that.

You warm up the ground in the summer.

You drought the soils.

You're going to get worse drought.

You put the heat and drought together, you get worse wildfires.

But the atmosphere is warmer.

So, when you get a storm, there's going to be more rainfall.

It can produce more precipitation, more rainfall.

And so we see greater extremes at both ends of the scale.

But there's also something else that's going on, which is a little bit more subtle.

And it's actually an effect that isn't perfectly captured in the models that we use to sort of predict future climate change and to attribute events to climate change.

So that's an important caveat.

There's something that the models aren't doing very well, which is capturing the way that the pattern of warming - - it's warming more up in the Arctic than it is down here.

And that changes the difference in temperature as a function of the latitude.

Well, it turns out, that's what drives the jet stream.

So you slow down the jet stream and, under certain conditions, you get this very slow, wavy jet stream where the high- and low-pressure centers stay fixed in place for days after day.

That's when you get those heat domes, like that record heat dome we're seeing right now in the Central U.S. That's when you get that excessive flooding like we're seeing up in New England, like we saw in association with that hurricane, that tropical storm that made its way into California.

And so what that means is that, yes, there are some uncertainties in the science.

There are some surprises, but they're not pleasant surprises.

In many respects, we're seeing that the impacts are even worse than we predicted.

AMNA NAWAZ: And if I could just be clear about this, because you did mention climate change, is it fair to say climate change is fueling more extreme storms and with greater frequency?

DR. MICHAEL MANN: Climate change is now showing us all of its weapons.

These last couple of weeks, it's showing us everything it's got to offer, its full arsenal.

And that's what we're seeing.

So climate change is no longer some subtle, far-off, possible thing.

It's here and now.

It's impacting us here and now.

And the dangerous impacts are occurring now.

It's a question at this point of how bad we're willing to let it get.

AMNA NAWAZ: We have spoken a lot about events here in the U.S, of course, but this is all over the world.

We saw those deadly landslides in India after torrential rains, new heat records in Morocco and Japan, another heat wave in Europe.

And I just read recently one estimate put the deaths from last year's heat wave in Europe at over 60,000 people.

I mean, we talk about damage and destruction, but what about the death component of this?

Are these events something we shouldn't look at is something to be endured, but something we will struggle to survive?

DR. MICHAEL MANN: Let's make no mistake about this.

Climate change is deadly.

We are already seeing human deaths that can be attributed to climate change, that are caused by events that wouldn't have been as intense, that wouldn't have been as catastrophic as they were if not for the warming of the planet.

I fear that we're probably going to see a total of as many as 1,000 people from those wildfires in Maui when all is said and done.

And there were various attributes of that event.

And we can get into the complexities.

But, basically, climate change contributed to that event in various ways.

And so, as deadly as the pandemic was, as many lives that were lost due to the pandemic, far more lives will be lost due to climate change, if we fail to act while we still can.

AMNA NAWAZ: So, the last nine years have been the hottest nine years ever recorded on planet Earth.

The science has shown us, to change that trend, we need to dramatically reduce greenhouse gas emissions.

Globally, how would you say we're doing on that front?

DR. MICHAEL MANN: Yes, well, we're not doing well enough, we're making some progress.

So it's important to recognize that.

Carbon emissions seem to have plateaued.

They're no longer sort of following that ever-upward trajectory that they were on just a decade ago.

That's the good news.

The bad news is, they have got to come down dramatically.

It's not enough to just be at the summit of that carbon mountain.

We have got to come down it, and we have got to come down it quickly, 50 percent within the next 10 years, and all the way to zero within a couple of decades.

We're not doing that yet.

And what we need to see later this year, when we get COP 28, the next round of international climate negotiations, we do need to see the countries of the world commit to a substantial move away from fossil fuels, ending new fossil fuel infrastructure, putting in place policies that will dramatically move us away from fossil fuels towards renewable energy.

We need to do it now.

It can't be five or 10 years from now.

It has to happen now.

AMNA NAWAZ: In the 30 seconds or so I have left, I have to ask you, because folks will ask.

You look at the summer.

Temperatures are usually hotter.

Is there any chance these events we're seeing are just an outlier?

DR. MICHAEL MANN: No.

Unfortunately, they're even worse than a new normal.

A new normal just means, oh, well, we just got to cope with what we have now.

It will get worse if we continue to warm the planet.

That's the bad news.

The good news is, the science tells us that it will stop getting warmer if we stop polluting.

So, there is an immediate and direct impact of our efforts to decarbonize our world.

That's what we have got to do.

And we have got to do it quickly.

AMNA NAWAZ: Michael Mann, thank you so much for joining us tonight.

Always good to have you.

DR. MICHAEL MANN: Thank you.