With El Niño and climate change, this week saw some of the hottest recorded weather

SCOTT DETROW, HOST:

Some of the hottest global weather ever recorded is happening this week. The average temperature worldwide yesterday, July 4, was the hottest on record. Rebecca Hersher from NPR's Climate Desk is here to talk more about it. Hey, Rebecca.

REBECCA HERSHER, BYLINE: Hello.

DETROW: So let's start with a basic question that a lot of people are asking around the world - how hot is it?

HERSHER: It is really hot, and that won't be surprising to a lot of people listening.

DETROW: Yeah.

HERSHER: If you live basically anywhere in the southern U.S., for example, you're dealing with really, really hot weather right now, you know? Heat indexes have been well over 100 degrees from Texas all the way to Florida. It's really, really dangerous. And it's also very hot in a lot of other parts of the world right now - so China, North Africa, the Middle East. Millions of people are experiencing life-threatening heat. And scientists - they track day-by-day data about the air temperature on Earth. They - basically, they plug in millions of measurements from, like, things on the ground or from satellites into a computer model. And that preliminary data shows that the average temperature yesterday on July 4 on planet Earth was the hottest on record. That's going back to 1979. And it beat out the previous record, which was from August 2016, by about half a degree.

DETROW: I mean, half a degree doesn't sound like that much. Why is this record important?

HERSHER: Honestly, this one record - this one really hot day - it's not that important on its own. But it matters because it's part of a larger trend of record-breaking heat. So here are some other records that kind of give a sense of that trend. The month of June this year was likely the hottest June ever recorded, and that's going all the way back to the late 1800s. And that's according to early data from the federal government. If we zoom out even more, we can see that the last eight years - they are the hottest eight years on record, again going back all the way to the 1800s. So the Earth is getting steadily hotter, and that is because humans are changing the climate.

DETROW: Yeah, so is climate change to blame for the particular record-breaking heat this week?

HERSHER: Yes. Climate change is a huge factor whenever we're talking about hot weather. And, of course, climate change is caused by humans burning fossil fuels and releasing greenhouse gases. Now, on top of human-caused climate change, there's also a natural cyclic climate pattern that's happening right now called El Nino. El Nino just started in June. It will ramp up all year. It means extra hot water in the Pacific, which drives hotter worldwide average temperatures, so it's not surprising that we're seeing record-breaking heat right now. And scientists expect that this year as a whole - it's likely to be one of the hottest years ever recorded. And that's because of that combination of El Nino plus climate change.

DETROW: Mmm hmm. That's Rebecca Hersher from NPR's Climate Desk. Thanks so much.

HERSHER: Thanks.

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