Sep 27, 2023 - Energy & Environment

Global climate vaults into even rarer territory, with more to come

Monthly global temperature anomalies
Data: The Climate Brink Via Zeke Hausfather; Chart: Tory Lysik/Axios Visuals

This summer featured the hottest days yet recorded worldwide. And we're already seeing some of the biggest temperature anomalies of any fall season.

Our thought bubble: There have been so many temperature records set this year that some of the words we use to describe them — "unprecedented," "record" and "unusual" — are losing their punch.

The big picture: As climate scientist Zeke Hausfather points out, the past few days in September have registered the largest temperature anomalies so far this year.

  • Yes, it's getting cooler as summer gives way to fall. But temperatures recently have still been much warmer than the historical average for the end of September.

Details: Data from the Japan Meteorological Agency shows temperature departures from average of greater than 1°C (1.8°F). This is 0.5°C (0.9°F) above the previous record anomaly for this time of year, which is an unusually large margin.

  • Another global data set, maintained by NOAA, shows that Sept. 22 had the largest temperature anomaly of any day this year. That's based on the average temperatures from 1979 to 2000.
  • When compared to preindustrial temperatures, the differences are even more stark, and September's monthly average temperature could wind up reaching or even eclipsing 1.5°C (2.7°F) above preindustrial levels.

What they're saying: "What makes September so unusual is just how anomalously warm it is relative to what's usual [at] this time of year compared to any prior September or any other month since records began," Hausfather told Axios in an email.

  • "While we need to wait for more studies to know for sure why things are quite as crazy unprecedented as they are today, there are some contributing factors beyond just El Niño on top of human-driven warming," he noted.

What's next: 2023 is on track to be the hottest year on record, aided by both human-caused global warming and an El Niño event in the tropical Pacific Ocean, which temporarily adds more heat to the climate.

The huge temperature anomalies are likely to be a feature of the next several months as El Niño intensifies.

  • Because El Niño's full effects tend to have a time delay, expect 2024 to be even warmer than this year.

In other words... Buckle up.

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