A powerful El Niño combined with global warming to drive record breaking extreme rainfall in 2024 with a new study warning that similar conditions could lead to another record in 2027.
Researchers from the University of California, Los Angeles (UCLA), found that the frequency of global precipitation extremes in 2024 was 20% higher than the baseline surpassing levels recorded during strong El Niño events in 1983, 1998 and 2016. The study was published on October 9 in the journal Science Advances.
According to the researchers, around 40% of the increase in extreme rainfall was linked to global warming, while El Niño accounted for approximately 20%. Other factors including unusually warm conditions across the tropical Atlantic and Indian oceans alongside warming in the Pacific also contributed to the record.
“Between El Niño and climate change, 2024 set a global record for the number of days with heavy precipitation,” said lead author Chad Thackeray, a climate scientist at UCLA.
The study found that extreme rainfall continued even after El Niño’s influence began to weaken. In previous strong El Niño years, heavy precipitation generally peaked during the first half of the year before declining as the tropical Pacific cooled during summer. In 2024 however, rainfall surged again, with extreme downpours peaking in August.
Researchers attributed this unusual pattern largely to climate change. A warmer atmosphere can hold more moisture increasing the potential for intense rainfall and severe storms.
“Compared to El Niños of the ’80s and ’90s, we now have baked in decades more of warming,” Thackeray said. He added that, by the middle of the century extreme rainfall events comparable to those experienced in 2024 could occur almost every other year.
The research also highlighted the role of simultaneous warming across three major ocean regions. During 2024, the tropical Pacific, Atlantic and Indian oceans experienced unusually warm conditions. The researchers said the last time a similar combination occurred was in 1998 which held the record for extreme rainfall until 2024.
Although the 2016 El Niño was stronger than the 2024 event, it produced less extreme rainfall suggesting that the strength of El Niño alone does not determine global precipitation patterns.
Senior author Alex Hall, director of UCLA’s Center for Climate Science and the Institute of the Environment and Sustainability, said climate change had transformed the background conditions in which El Niño developed. This helped make rainfall more widespread and persistent than in previous major El Niño years.
The researchers said the developing El Niño could peak during the winter and potentially become one of the strongest on record. They also noted that warming in the Pacific appears to be concentrated in the eastern Pacific, a pattern associated with wetter seasons than El Niño events centred in the central Pacific.
These factors could increase the likelihood of another year of exceptional global rainfall in 2027. Early scientific estimates also suggest that 2027 could surpass 2024 as the hottest year on record although such projections remain uncertain.
Hall cautioned that scientists cannot yet say whether 2027 will break the 2024 rainfall record. However the combination of a potentially strong El Niño and continuing global warming could create conditions favourable for extreme precipitation.
The study titled “Record setting heavy precipitation occurrence in 2024,” underscores how climate change can intensify the effects of natural climate patterns. Researchers said the findings highlight the importance of understanding how rising global temperatures may influence the frequency and severity of extreme rainfall in the coming years.