AILSA CHANG, HOST:
Last month was the hottest July recorded on Earth by a long shot. I was feeling it. I know you were, too. This is all according to official data released today by federal climate scientists. Rebecca Hersher from NPR's Climate Desk is here to make sense of yet another broken temperature record. Hey, Rebecca.
REBECCA HERSHER, BYLINE: Hey.
CHANG: OK. So what exactly do these latest numbers show?
HERSHER: So they show that July was extremely warm here on Earth. And here are the actual numbers. This July was almost half a degree Fahrenheit hotter than any previous July, going back to 1850.
CHANG: Wow.
HERSHER: This is how the chief scientist at NOAA, Sarah Kapnick, explained it.
SARAH KAPNICK: That may not sound like a lot, but the margin for most global records is on the order of 100th of a degree or two. So last month was way, way warmer than anything we've ever seen.
HERSHER: And, in fact, it's so much warmer that it actually surprised scientists, which really doesn't happen that often. Russell Vose is one of those scientists at NOAA.
RUSSELL VOSE: I am rarely surprised. That's what my friends tell me.
CHANG: OK.
HERSHER: He has kind of a flat affect.
CHANG: (Laughter).
HERSHER: Vose has spent decades keeping track as temperatures just march higher and higher. That is his job. He says his motto is keep calm, carry on.
VOSE: Because our job is to keep score. But sometimes you get a little surprised with the score. And I was not expecting July to be this much of a record-setter.
HERSHER: You can kind of hear it, right? He's worried.
CHANG: Yeah.
HERSHER: And he's also worried about the long-term trend. You know, the last nine years are the hottest nine years ever recorded.
CHANG: OK. I get all these records are getting broken. But why was this July so much hotter?
HERSHER: So there are a few reasons. The really big one is human-caused climate change, which is making the whole earth heat up really quickly. There was record-breaking heat, these heat waves in July around the world, so across South America and Africa, in Asia and Europe, even in Antarctica. So the whole world was really hot. Here in the U.S., four states had their hottest July on record. But then there's also the oceans. We have to remember that there's a lot of the Earth where humans don't live. About 40% of the world's oceans are experiencing marine heat waves right now. And one reason for that is El Nino, which is this cyclic climate pattern that means warmer ocean water in the Pacific.
CHANG: OK. Well, then what about August? Like, what should we expect this month and for the rest of the year?
HERSHER: So that's where the news gets actually even more sobering, if that's possible. El Nino is getting stronger, and it will almost certainly continue well into next year. So that means even more heat in the oceans, which drives up temperatures everywhere. It's very possible that 2023 could end up being the hottest year on record - we learned that today from this latest data - and that 2024 could be even hotter than that, actually. And all that extra heat is really dangerous. You know, we're living with it right now. It makes droughts worse. It raises wildfire risk. It makes big, powerful hurricanes more likely to form. It kills marine animals, sometimes irreversibly. Of course, the solution is to reduce greenhouse gas emissions right now by a lot.
CHANG: Yeah.
HERSHER: That would slow down the warming. Otherwise, this year will actually be comparatively cool by the middle of the century.
CHANG: Imagine that. That is NPR's Rebecca Hersher. Thank you so much, Rebecca.
HERSHER: Thanks. Transcript provided by NPR, Copyright NPR.
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