We’ve already entered an El Niño phase, defined by the National Oceanic and Atmospheric Administration as a period when we see the temperature in a specific part of the Pacific Ocean get 0.5 °C hotter than usual, plus associated changes in the atmosphere.

And this could be a big deal for global temperatures. El Niño doesn’t actually add energy into the climate system or warm up the entire globe on a long-term scale. It’s essentially just taking heat that’s been stored in the oceans and releasing it into the atmosphere.  

But climate change has pushed a lot of heat into storage in the atmosphere and oceans—so combining the effects of this year-to-year variation with that long-term trend could have brutal results.

This El Niño is expected to be an especially notable one. Some forecasts predict that the event could peak at over 3.5 °C above the average, potentially making it the strongest on record. It also came on quite quickly, representing “one of the fastest onsets in the observational record,” writes climate scientist Zeke Hausfather in an analysis for Carbon Brief.

And while this El Niño is already starting to have an effect on temperatures, it’s still ramping up. El Niño’s effect on global temperatures tends to lag development of the ocean pattern by several months, and the effects will likely be more significant next year. 

In some recent El Niño periods, record-breaking temperatures came during the second calendar year of the event, Hausfather points out in his analysis. The most recent El Niño developed in 2023 and ran into 2024, and 2024 is the reigning hottest year on record. There’s some uncertainty in trying to predict how the rest of this El Niño will play out, but so far, it is set to be a doozy.

Given how brutal these summer heat waves have been, there’s a pretty high likelihood that much of the world could see even higher temperatures next year. “El Niño conditions will pour fuel on the fire of a warming world,” United Nations Secretary-General António Guterres said in a video statement in June.

It’s time to start preparing for it, and individuals can take some actions in the near term: If you’ve been putting it off, I’d buy that air conditioner, install solar and a backup battery, or upgrade the insulation in your home. 

In the longer term, though, temperatures will keep climbing because we’re still burning fossil fuels and driving climate change. As Guterres said in his statement, “The only effective response is climate action equal to the crisis: ending the addiction to fossil fuels, accelerating the shift to renewables, protecting the most vulnerable, and delivering early warning systems for all.”

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