This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: Though strong El Niños have occurred only four times in as many decades, 2024's intense El Niño is already getting a sequel. New UCLA research shows that 2024 broke the record for extreme rainfall, with 40% of that increase tied to global warming—and conditions are ripe for a repeat.
"Between El Niño and climate change, 2024 set a global record for the number of days with heavy precipitation," said UCLA climate scientist and lead author Chad Thackeray. "We're getting into uncharted territory for how warm the coming El Niño is going to be, but the conditions are there for another record in 2027." In 2024, the occurrence of global precipitation extremes was 20% higher than the baseline, surpassing levels during the strong El Niños in 1983, 1998 and 2016, said Thackeray, a researcher in the UCLA Department of Atmospheric and Oceanic Sciences and UCLA's Center for Climate Science. In the new research, published Oct. 9 in Science Advances, UCLA scientists found that even as El Niño's influence waned in 2024, extreme rain continued globally due to climate change.
In previous strong El Niño years, the bulk of the heavy precipitation occurred in the first half of the year, before largely dissipating as the tropical Pacific cooled in summer. Even as the Pacific Ocean cooled in 2024, the rain surged again, with extreme deluges peaking in August, the study found. "That surge in 2024 is largely tied to climate change," Thackeray said.
"Compared to El Niños of the '80s and '90s, we now have baked in decades more of warming. A warmer atmosphere can hold more moisture, which can mean more severe rainstorms, and the chance of heavy rainfall is increasing over time. By midcentury, we would expect extreme rainfall like what we saw in 2024 almost every other year." Depending on how abnormally warm the tropical Pacific becomes, an El Niño is classified as mild, moderate or strong.
Since reliable satellite measurements began in 1979, scientists have data on only four strong examples of the weather phenomenon. Although the 2016 El Niño was stronger than the one in 2024, it produced less rain, the research noted. "In 2024, the year began during a strong El Niño, but unlike previous major El Niño years, the extreme rainfall was unusually widespread globally and persisted even after El Niño faded," said UCLA climate scientist and senior author Alex Hall, director of the Center for Climate Science and the Institute of the Environment and Sustainability.
"The record rainfall wasn't simply the result of El Niño. Climate change transformed the backdrop." The study found that in 2024, El Niño could explain only 20% of the record rainfall, while global warming was tied to 40%. A portion of the remainder was tied to a rare event: broad regions of the tropical Atlantic and Indian oceans were unusually warm at the same time that Pacific Ocean warming triggered El Niño.
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