July 2023 nailed an unfortunate world record: hottest month ever recorded

More than 6.5 billion people faced temperatures exacerbated by climate change

A photo of a busy street with people walking around and cars on the road. Heat haze can be seen on the road.

Phoenix sweltered under an unprecedented 31-day streak of daily temperatures reaching at least 43.3° Celsius (110° Fahrenheit), which only broke on the second to last day of July. Without climate change, the city's scorching July temperatures would have been 3.7 times less likely.

Mario Tama/Getty Images

Most humans felt the scorching touch of climate change in July.

July 2023 was the hottest month ever recorded, and climate change made the elevated temperatures across 51 percent of Earth’s land surface at least five times more likely, according to a study released August 2 by Climate Central.

Researchers had already spotlighted the fingerprint of climate change on recent heat waves in China, North America and Europe (SN: 7/19/23; SN: 7/25/23). But the new report shows that during July, climate change’s influence extended across much of the globe, especially “a tropical band around the planet that includes Africa, South and Central America, the Malay Archipelago and many of the small island nations in both hemispheres,” Andrew Pershing, a climate scientist with the Princeton, N.J., nonprofit, said at an August 1 news briefing.

While the World Meteorological Organization has yet to officially deem July as Earth’s hottest recorded month, it has confirmed the month’s first three weeks were the hottest three-week period on record. The highest global average temperature — 17.23° Celsius (63.01° Fahrenheit) — was recorded on July 6 (SN: 7/13/23). “It’s pretty clear that July is going to hit the record,” Pershing said.

He and his colleagues used computers to simulate the world with contemporary climate warming — 1.27 degrees C above preindustrial levels — and without it to isolate the influence of climate change on temperatures worldwide.

Last month more than 6.5 billion people, or 81 percent of the human population, experienced heat that was at least three times more likely in a world with climate change than without it, the researchers found.

The recent return of El Niño, a natural climate phenomenon that temporarily raises global average temperatures, is also “definitely having an effect,” said Pershing.

But humans are warming the climate so fast that this year’s elevated temperatures could soon return even without El Niño. “This is the hottest El Niño year we’ve ever had,” Pershing said, “and five years from now, this will be a normal year.”

Nikk Ogasa is a staff writer who focuses on the physical sciences for Science News. He has a master's degree in geology from McGill University, and a master's degree in science communication from the University of California, Santa Cruz.

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