JOHN YANG: From rising seas to more intense storms and droughts, climate change has brought about sweeping changes.

Now add education to that list.

Studies show that in more places in the country, there are more days in the school year hotter than 80 degrees than there were in 1970 and schools that can afford air conditioning are left to struggle with overheated classrooms, which researchers say pose both academic and health risks.

Anna Phillips was one of the reporters who looked into this for The Washington Post, where she covers climate change.

Anna just to be clear, we're not just talking about summer term.

Here are we?

ANNA PHILLIPS, The Washington Post: Oh no, definitely not.

We're talking about a problem that starts in the late spring when kids are taking state exams, for example, and becomes even more of a problem when they come back in the fall, when you start to see some really high temperatures setting in that would not typically have happened, but are now becoming very common.

You're getting heat waves in September and October in parts of the country that never experienced them before, or maybe very unusually for those parts of the country, and they have really no means of dealing with them, because their schools were built with that air conditioning.

JOHN YANG: In your story, you talk about the schools in the north in particular that didn't have to worry about this.

What are some of the examples of what you found?

ANNA PHILLIPS: Yeah, so you can pretty much draw a straight line across the country from New York and Philadelphia all the way out to the West Coast, and you're looking at a part of the country where most schools were built without air conditioning.

Many of these schools are very old.

Some of them are on the Historic Register.

They don't have the electrical capacity or the kind of infrastructure to put air conditioning in easily.

And so you're seeing places like Philadelphia, Baltimore, Detroit.

These are places that have had to close schools early and send kids home because the buildings have gotten so hot that it's not safe to keep kids in there and they're not learning.

What teachers are telling us is that it's just unbearable in some of these schools, that the temperatures are reaching into the high 80s, low 90s, that kids are throwing up, that their asthma attacks are being worsened by the heat, that they're spending all day in the nurse's station, and that it's an incredibly difficult environment.

JOHN YANG: What about in the south, where I would imagine that air conditioning was more usual, especially in the Deep South?

ANNA PHILLIPS: Yeah, so we don't typically think of the South as having this problem, because most schools do have air conditioning, but what's happening is a confluence of things where many of the air conditioners that are in place are very old.

You know, I talked to one superintendent in Arizona who's dealing with air conditioners that were put in in 1997 and the climate has become much more extreme.

You're seeing these longer lasting and more frequent heat waves, and the air conditioners they have just can't keep pace.

JOHN YANG: I mentioned when the introduction I'm talking about 80 degree days that's outside.

What about inside the classroom?

ANNA PHILLIPS: When it's 80 degrees outside, and you're an old brick school building, for instance, like you would see all over the northeast, what you're going to find that the temperature inside can reach into the low 90s or the mid-90s.

And we know that because in many instances, teachers actually have thermometers in their classrooms, and they have taken pictures, and they have posted them on Twitter, and they have, you know, alerted their unions to this, and parents, for sure, are paying attention and are very unhappy about this.

So we know that that these temperatures are not simply uncomfortable.

It's not like kids are a little bit sweaty.

These are not temperatures we would ever expect kids to learn it.

JOHN YANG: And is there evidence that any groups of students are being disproportionately affected by this?

ANNA PHILLIPS: Yes, the research shows that black and Latino students in particular suffer more learning loss when they experience hotter days in schools that are not air conditioned.

This is especially true in the US.

And the same researchers who have looked at this question have also found that there is something that makes this trend go away, and that is installing air conditioning.

JOHN YANG: And how easy is that for schools?

ANNA PHILLIPS: It's really not as simple as it sounds.

When you have these old school buildings, it's not like you can just put a window air conditioner in the classroom and walk away.

Many of these schools weren't built with enough electrical capacity to handle air conditioners.

If you install air conditioners throughout the building and try and operate them, they just won't function.

There's not enough power to serve them.

So that's one big problem.

The other problem is the money, which is incredibly hard to come by in many of these school districts.

We're talking about multimillion dollar, if not billion dollar, facilities campaigns.

There are plenty parts of the country where residents don't have much money and can't do that, or they're in a part of the country where the tax base maybe the city's population is declining, or it's getting older, and voters are not inclined to support paying more for that.

You also have kind of a perception problem, which is that people don't always recognize exactly how much hotter it's gotten.

And they often think of their own childhoods and they think, well, you know, I was in school.

It was a little uncomfortable during the spring and the fall, but we got by.

There's just not quite a recognition of how much worse it's gotten.

JOHN YANG: Anna Phillips of The Washington Post, thank you very much.

ANNA PHILLIPS: Thank you.