ROB SCHMITZ, HOST:
Heat records have been set around the world this week. Global average temperatures soared, making July 4 the hottest day on record. How do we know that? Rebecca Hersher from NPR's Climate Desk explains.
REBECCA HERSHER, BYLINE: Scientists - they track day-by-day data about the air temperature on Earth. They plug in millions of measurements from things on the ground or from satellites into a computer model. And that preliminary data shows that the average temperature on July 4 on planet Earth was the hottest on record. And it beat out the previous record, which was from August 2016 by about half a degree.
MICHEL MARTIN, HOST:
One day, half a degree - that might not sound like a big deal, but Hersher says it really is.
HERSHER: This one really hot day - it's not that important all on its own, but it matters because it's part of a larger trend of record-breaking heat. The month of June this year was likely the hottest June ever recorded, and that's according to early data from the federal government.
SCHMITZ: And it isn't just the U.S. dealing with dangerous temperatures.
HERSHER: 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.
MARTIN: Hersher points out the rising temperatures are part of a pattern that began well before this summer.
HERSHER: If we zoom out even more, we can see that the last eight years - they are the hottest eight years on record, going back all the way to the 1800s. So the Earth is getting steadily hotter, and that is because humans are changing the climate.
SCHMITZ: But climate change is just part of the equation when it comes to this latest wave of sweltering heat.
HERSHER: 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 natural cyclic climate pattern that's happening right now called El Niño. El Niño 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.
SCHMITZ: And all that means this year could be the hottest on record. Transcript provided by NPR, Copyright NPR.
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