This summer's record-breaking heat has extended to September. A new report from the National Oceanic and Atmospheric Administration, or NOAA, found that September 2023 was the hottest in its 174 years of climate records.

The striking thing was just how abnormally hot September was, says Ellen Bartow-Gillies, a NOAA climatologist and the lead author of the report.

"This was the warmest September on record, but it also beat out the previous record September, which was in 2020, by 0.46 degrees Celsius, or 0.83 degrees Fahrenheit," Bartow-Gillies says. "A pretty significant jump."

She said another way to think about it is that compared to the average July from 2001-2010, "September 2023 was actually warmer than that."

Two things are primarily driving this. The first is climate change, which is mostly caused by humans burning fossil fuels. And Bartow-Gillies says this heat is also driven by El Niño, a natural, cyclical climate pattern which drives up global temperatures.

The September heat affected people all over the world– even in the Southern hemisphere which is coming out of winter, not summer. The NOAA report found North America, South America, Europe, and Africa had their warmest Septembers on record.

A recent report from the World Weather Attribution Group, a research organization that partners with Imperial College, London and the Royal Netherlands Meteorological Institute, among others, found a link between the recent heat in South America and human-caused climate change. "Across the world, we're seeing this trend of heat staying around longer than climatologically it should," Bartow-Gillies says.

The NOAA report also found that Antarctica endured its warmest September to date, contributing to record low sea ice. And the report found that ocean surface temperatures were unusually high. The warmer oceans helped fuel more intense storms from New York City to Libya, where dam failures caused thousands of deaths.

Ultimately, these numbers have proved shocking to many, even climate scientists like Bernadette Woods Placky, chief meteorologist at Climate Central, who wasn't involved in the research. "Geez, these numbers. Whew," she said as she looked at the report.

"A report like this really screams the urgency for advancing our climate actions," Woods Placky says, noting that some key ways to reduce emissions include shifting from fossil fuels to renewable energy and changing how communities manage land.

"We've got some amazing climate solutions that already exist and some great people working on this around the globe," she says, "But we just need to do it faster, and we need to do it bigger."

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